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GPS Newsletters 2001..

1. CONT ix In SKI Pro you can do the same on the Classical 3D Pa rameters page from the Da tum amp Map Configuration The Advantage The Classical 3D transforma tion does not distort your GPS measurements and fully maintains your GPS accuracy Therefore this type of trans formation can be used over virtually any area as long as the local co ordinates are ac curate Remember e The Ellipsoid and the Pro jection have to be known to calculate a Classical 3D trans formation from local grid co ordinates e Common points have to be known tn position and height e You can use this type of transformation over large areas amp etca Geosystems The Onestep Transformation Last week s newsletter ex plained the basics of the Clas sical 3D Transformation This week we continue with an al ternative approach which can be more useful in some situa tions The Onestep Transfor mation When to use it Imagine a site where the co ordinates of the control points are based on a purely local grid The co ordinate values within this grid are totally ar bitrary and are in no way connected with any ellipsoid Or map projection Obviously the Classical 3D approach cannot be used here as Car tesian co ordinates cannot be calculated from such a grid Or imagine some of the con trol points which you wish to use have only position co ordinates or the height co ordinate is unreliable In such a
2. 5 1 Start ArcPad by se lecting on Start gt Programs gt ArcPad 5 0 1 5 2 From the Tools Op tions menu item set ArcPad s GPS port settings as follows GPS GPS Pot ia Garia Pain Ge Lt Pot I ores ed Baad 0 E Paip H Da i Sigla B Leica Geosystems GPS Newsletter GS5 GS5 and ArcPad 5 3 Select Add Layer to open the file selection window and open the worldmap jpg file 5 4 From the GPS menu select GPS Active A yellow cross hair with a red circle around it should appear 5 5 Turn the GS5 GS5 system on The system will begin outputting data How come my GPS Active choice is greyed out The GPS tools or buttons are only enabled when a layer with an associated projection or prj file is added The layers need to be in a projection supported by Arc Pad and should have the projection defined in prj files If your layers are in a Supported projection then you can create projection files by the following method 1 Open the Layers window and then click on the Define Projection button on the top right of the Layers window 2 In the File Browser navi gate to the Coordinate Sys tems folder located under the ArcPad 5 01 installation folder by default C ESRI ArcPad 5 01 CoordinateS ystems 3 Select a projection file from one of the common pro jection prj files included with ArcPad The selected prj file will be copied to the layers in your ArcPa
3. When you are ready to start surveying or staking out with the rover you press SHIFT F4 CONEC in the MAIN the SURVEY or the STAKE OUT panel The rover then dials the reference station the connec tion is established and RIK data is passed from the refer ence to the rover The GSM icon appears and the RIK lightning bolt icon flashes When you wish to discon nect press SHIFT F4 DISCO and the GSM link is ended Combining Radios and GSM Of course the ideal situation is to combine radio and GSM to get the best of both worlds Use radio for 90 of the sur vey where you can receive the radio signals and the data transmission is free When ever you go out of radio range or behind a hill or building and lose radio link simply switch to GSM to complete the survey This allows maxi mum productivity and mini mal problems with RTK GPS Of course this means that you need both a radio and System 500 GSM device attached to the rover sensor Not a problem attach the radio to one port normally port 1 and the GSM to another port nor mally port 3 the System 500 backpack is made large enough to take both On the reference again at tach the radio to one port and the GSM to another with both GSM and radio attached simple to set i up and use and no cables GSM i py T E But now you may be think ing that a System 500 refer ence can only output RTK on one port at on
4. ID can be chosen to be Used or not within the averaged point In some countries points have to be observed at least twice and independently The use of two or more reference stations fulfils this require ment Covering Wider Areas Using more than one refer ence also allows a much greater area to be surveyed without having to return to keep moving the same refer ence station Imagine you need to survey a large open cast mine or along a 30km stretch of road With only one reference sta werner daxinger leica geosystems com 3008 if ONT PO USE TMF O A rie z pi e a ge a T a na aa rera E I i Ke Me iia ie tion and standard radio modems it may be necessary to move the reference several times to cover the whole area needed to be surveyed You may of course be able to use GSM and then this problem would not occur However using two or more references which are opti mally positioned allows the whole survey area to be cov ered without moving ence stations refer Obviously it is necessary to allow a small overlap of the coverage from each reference station The cost of purchasing the second reference station will quickly be compensated by the time saved in having to keep moving just one refer ence station Remember e Separate solutions ob tained from different refer ence stations provides independent solutions for quality control e The creation of a
5. first point of the grid is se Station Beg in this case 20m to the right of the first row You have a choice you can return to the start of the line again to stake out this row of grid points but this would mean you would waste time walking back to the start For this job it is more efficient to stake out the grid points in the second row in the reverse or der to the first In the line definition panel press F5 PARAM again Set the Horz Offset to 20m and set the Station Inc to be 20m which means these points will be staked out in the reverse direction A DAA mM Horz Of Ff Sets 20 000 f tine Wert Offset f l lected to be staked out The Station Inc Z0 00A f However with System 500 it position of this point on the aaan aiia is possible to stake out a grid grid is shown at the top of the CONT ee CURT J such as this knowing the co ordinates of only 2 points The Grid Stake Out Routine Choose the Stake Out type Grid in the STAKE OUT Begin panel and the job in which the points are stored After entering the STAKE OUT Grid panel a line needs to be defined from 2 points These 2 points are the points from which the grid of points will be constructed STAKE OUT Grid Station Begs A BAA M Horz ffzet A BAA M Wert OF FSetbe A BAA M 28 888 fi Station Ine Scale CONT REFLHICURST After defining the line the parameters of the grid can be defined The Station Beg
6. is less used but is more flexi ble and perhaps more power ful The differences are described below Thematical Coding Thematical coding should be considered as point related coding Basically each surveyed point can be stored into the database with a code assigned to it this code is physically at tached to the point Only one code can be assigned to one point Free coding Consider free coding as time related coding Surveyed points are not as signed codes in the same way as thematical coding the code Is not physically attached to the point A code only relates to a point due to the chronological order in when a point was sur veyed and stored and when a free code was chosen and stored When this data is exported and it must be sorted by time in order to retain the chronological sequence of points and free codes and then imported into a CAD package the CAD package will assign the codes to points simply due to the fact that a code is chronologically immedi ately before or after a point Codelist Features Most System 500 surveyors create their codelists in SKI Pro and then use these codelists on the sensor in the field Codelists can be as simple or as powerful as the user requires However there are some nice features which can be built into the codelist which as will be de scribed can really help the sur veyor in the field Note the features described below within the
7. ordinates to the Penpad computer using NMEA messages These NMEA messages are then used by the Prism software to give the necessary co ordinates to the locations of features on the map The penpad computer is mounted on the pole and the surveyor uses a pen to operate the OS software and update the map The TR500 Teminal is not used by the surveyor instead the penpad computer runs a Terminal Emulator software also specifically developed for OS The sensor charlotte heinz leica geosystems com Operates in Remote Mode and if required the surveyor can steer the sensor as if the TR500 was attached to the sensor using the emulator software Productivity Increase with System 500 An 8 month pilot project to investigate the use of System 500 for data collection was initiated by OS starting in No vember 2000 Four field of fices throughout Great Britain were selected to carry out this pilot project One of the aims of this pilot project was to investigate the different ways to collect data using System 500 such as in conjunction with a DISTO This was actually so success ful all OS surveyors using System 500 are now equipped with DISTO Another aim of the pilot project was to find out if the quantity of data collected using System 500 has increased over the more traditional methods of col lecting data Traditional methods include taping and total stations for example The ultimate
8. Also included is thematically coded data and free coded data to be used in exer cises in the manual Getting Started with Format Manager e Sensor Language Files this includes various language files for the sensor firmware and lan guage files for the various appli cation programs e Control Station this is soft ware allowing the remote opera tion of certain functions of the sensor This is dongle protected software requiring a control sta tion dongle for full functionality but certain operations are possi ble without a dongle e Acrobat Reader Acrobat Reader v4 can be installed from the CD e Manuals Manuals in various languages are included Note these manuals can be automati cally copied to the PC during the CD start up Manuals It is worth explaining in detail what manuals are included on the CD e GPS Equipment User Manual contains information on how to use System 500 in a safe manner e General Guide to Static and Rapid Static extremely useful information on collecting data for post processing and also alastair green leica geosystems com A one page weekly newsletter on System 500 GPS 01 22 June 05 2001 guidelines on actually proc essing data within SKI Pro e Getting Started with Static and Kinematic Surveys gen eral guidelines as to how to conduct static and kinematic surveys with System 500 e Getting Started with Real Time Surveys general guide
9. ME 201 O Condition oe O Species m Height Attribute Condition fixed text attribute default value Living Athibute Default Hame Condition Fired Values Value 7 Text Hone 7 o Living attached to codes can be of type fixed mandatory or nor O Species Mandatory 7 Text d Choice List 7 Fine mal mo Height Mandatory ka Real Range None A fixed attribute means that oO 7 7 this attribute will always take Seica Geosystems alastair green leica geosystems com Codima Tyee Ciel ist GPS Newsletter General e Attribute Species manda tory text attribute using a choice list Default value is Pine e Attribute Height manda tory real attribute with a range limit between O and 2 No de fault value Using Codes in the Field Once the codelist is trans ferred to the sensor and se lected to be used in the configuration set points can be surveyed with codes Remember it is in the same panel where the codelist is se lected to be used that it is cho sen if thematical or free coding is to be used Also in this panel F3 CODES allows the codes to be viewed and F5 LAYER allows the indi vidual layers to be turned on or off This may help a surveyor if the full codelist contains hun dreds of codes and he wishes to only use codes in specific layers for a particular survey LIF GURE log Temat ical Using a codelist in the field is a straightfo
10. Pro CD This describes the use of the Format Manager and contains 3 simple exercises to create different format files It is very simple to make a format file with many users creating many different for mat files have been created including GSI8 and GSI16 Geodimeter Zeiss and Sokkia formats However there are also some features of the Format Manager and Format Files that are not so well known alastair green leica geosystems com Defining the Format of Indi vidual Export Variables Double click on an export variable to access the Format ting Options for Export Vari able dialog Here the alignment signing length precision and the fill character for that export vari able can be defined This allows different export formats to be defined for indi vidual export variables For example a user could require that co ordinates are output to 3 decimal places and are left aligned whereas the CQ should be output to 2 decimal places and right aligned Setting Default Values for Variables It could be that not every export variable is always out put For example a user may usually assign a code to most surveyed points but he may choose not to code some points or may have forgotten to code them A format file can be written to output this collected data However the user wishes that if a point was not coded in the field then the words No Code should be output for that point This is possibl
11. aim of the pilot project is to define the work ing procedures that must be followed by all OS surveyors using GPS and to gauge effi ciency gains Initial feedback shows that productivity has increased And remember this increase in productivity has been achieved by field surveyors who had previously no expe rience in using GPS this shows how simple System 500 can be to use Remember e It is planned that the use of GPS within OS will greatly increase in the future A great success story for the partner ship between Leica Geosys tems and Ordnance Survey Seica Geosystems GPS Newsletter General A one page weekly newsletter on System 500 GPS 01 17 April 30 2001 Static and Rapid Static GPS The next few newsletters dis cuss the traditional way of computing baselines with GPS Static Surveying This news letter looks into the back ground of Static and Rapid Static GPS surveys and dis cusses how much data should be collected for such survey Future newsletters will de scribe the post processing of data within SKI Pro and dis cuss the effects of the iono Sphere on surveying with GPS A Little History In the early days of GPS all baselines were measured us ing Static GPS Data was typi cally collected at greater intervals Say 30sec over a pe riod of more than 3 hours with baselines of all lengths being measured In 1992 Leica introduced Rapid Static GPS which al lowed base
12. and from National Grid Other projects focus on the development of a definitive National Grid transformation a National Geoid model and on an active RTK network e For more information look to the excellent OS web site this also includes some very useful general information on the use of GPS http www ordsvy gov uk http www gps gov uk Seica Geosystems a GPS Newsletter General A one page weekly newsletter on System 500 GPS 01 16 April 23 2001 Last week Last week s newsletter men tioned that Great Britain s Na tional Mapping Agency Ordnance Survey OS is us ing System 500 to keep Brit ain s maps up to date OS could end up using sev eral hundred receivers a total value of several million pounds this is the biggest order for GPS ever received by Leica The National Topographic Database All of Great Britain s maps are stored in digital format in an accurate electronic mas ter map of Britain called the National Topographic Database NTD This is a MASSIVE database and in cludes over 200 million differ ent features of the British landscape from the shape of individual buildings to the ex act location of public tele phone boxes It has already been men tioned that one of the main objectives of OS is to continu ally update the existing maps of Great Britain this effec tively means to update the NTD As with any country the in frastructure
13. antennas then this newsletter explains what you need to know when mixing different antenna types Phase Centre Variations A PCV is primarily a result of a non spherical phase re sponse pattern of the GPS antenna The measured phase of the incoming signal de pends on the direction of the angle of incidence The aim of using PCV calibration files is to minimise this effect GPS Newsletter General A one paqe weekly newsletter on System 500 GPS 01 12 March 26 2001 f 0 001 f 0 000 f 0 001 0 002 f 0 003 200 40 Azimut 300 The figure above shows how the PCV varies with azimuth 20 Elevation 0 and elevation on the L1 sig nal The influence of PCV to the final result is often underes timated it could be that the incorrect treatment of the PCV is the reason for unsolved ambiguities Relative Calibrations The most commonly used PCV correction models are estimated in relative field calibrations Using this rather uncomplli cated approach the PCV are always calibrated relative to a given reference antenna The IGS International GPS Serv ice standard reference an tenna is JPL s Dorne Margolin Choke Ring antenna Model T The PCV of the reference antenna are set to zero and their offsets are set to a cer tain value The antenna phase centre correction models de livered with System 500 in cluding the _ re calibrated System 300 antennas are all relative m
14. best overall fit to our pear shaped earth the WGS84 ellipsoid So now the position of our point can be described as 48 N 10 E and ellipsoidal height of 500m And now we have it our point has a WGS84 ellipsoidal height of 500m This means our point is 500m above the surface of the WGS84 ellipsoid WGS84 ellipsoid height True shape of earth Local Ellipsoidal Heights But of course most coun tries do not use the WGS84 ellipsoid as the local ellipsoid for that country Switzerland uses the Bessel ellipsoid and UK uses the Airy ellipsoid This is because these ellip soids fit better to the true shape of the earth in these parts of the world So now converting our point to local geodetic co ordinates including any transformation that may be required results in co ordinates of 48 00 ellipsoid 0 82316 N 9 59 49 66165 E and a local ellipsoidal height of 1468 783m This means our point is 1468 783m above the surface of the local ellipsoid In the diagram below the local ellipsoid is shown to fit the true shape of the earth better for where our point is located But even the local ellipsoidal height is still not so useful to surveyors Surveyors usually need to know the height of surveyed points above the true shape of the earth or thometric heights not the heights of points above a convenient mathematical shape As already mentioned the true shape of the earth is pear sha
15. codelists apply to both free and _ thematical codelists It is only the use of free and thematical codelists in the field and the exporting of free and thematically coded data which is different Layers A layer could also be called a code group and as described below can have more than one use Typical layers could be alastair green leica geosystems com Vegetation for features such as trees bushes etc Roads for features such as centre lines kerbs verges etc Most CAD packages handle layers in a similar manner al lowing different layers to be assigned different line styles or colours or layers can be turned on or off allowing layers to be viewed or hidden Even if a CAD package does not use layers or a user does not want to use layers within the CAD package assigning groups of codes to different layers can still help the sur veyor in the field As described later this may help a surveyor in the field Note when creating a codelist within SKI Pro even if a user does not wish to use layers one layer must be created be fore codes can be created Codes The codes themselves are of course the flag that indicates to the CAD package that a sur veyed point is a tree or a road centre line etc The CAD pack age then assigns the appropri ate symbol or line style to this point Obviously the codes that are used within a codelist depend on the codes that are being used in the CAD package
16. form It will cover a topic which you have certainly come across when working with SKI Pro Point Classes and Co ordinate Trip lets They build one of the fun damental concepts of SKI Pro In the SKI Pro database there may exist more than one co ordinate triplet for any point They are called co ordinate triplet simply because the co ordinates typically comprise of three values X Y Z or Lati tude Longitude Height or Easting Northing Height The hierarchical order of these co ordinate triplets is represented by the so called Point Class Imagine you import GPS raw data for post processing then just the navigated co ordinates for a point will be stored After processing a baseline addi tionally the processed co ordinates are stored using the Point Class Measured If more than one baseline is stored the averaged co ordinates are staved in addition to all the measured ones If later the point is used in an adjustment the adjusted co ordinates are also added The following list gives an overview of all existing Point Classes in a hierarchical order highest one on top e Control e Adjusted e Reference e Averaged e Measured e Single Point Solution e Navigated e Estimated The Point Class Measured is the only one which can hold more than one co ordinate triplet All other Point Classes are unique They only have one triplet Adding new triplets classes It is not possible to create som
17. general test which tests the overall model A failed F test indicates there is a problem but it is not spe cific the problem could be due to such things as an ob servation blunder or over optimistic variance covariance information However before attempting any scaling of the variance covariance matrices you should eliminate any blunders The W and T tests can provide assistance with this process The W test is based on the principle of testing each ob servation element in a network for a blunder against a computed critical value The critical value is computed based upon the chosen level of significance which is typi cally set to 95 100 alpha and the power of the test which is typically set to 80 1 Beta Because of the 1 etca Geosystems dimensional nature of this test it works particularly well for TPS observations direc tions vertical angles and distances For GPS observa tions each element DX DY and DZ are tested separately against the computed critical value The T test is a multi dimensional test and there fore is ideally suited for testing GPS baseline observa tions with the 3 elements together The test is also use ful for testing the coordinates of the known Control points where data entry typing er rors may occur The W tests and T tests are both key indicators in the data snooping process There is one additional test in SKI Pro this is the An
18. is a 2D transformation exactly as with the Onestep transforma tion 84 at 2 GD E Pre Transformtion aa a gt 1 oy E System B Projection Preliminary Grid Co ordinates 2D transformation and height shift at ae L De Compared to the Onestep transformation the first step avoids any distortions due to the fact that the preliminary grid co ordinates are built on a different ellipsoid than the local points And even more importantly the second step makes sure that the influence of the scale factor of the map projection is equally taken into account before the final 2D transformation is done For these reasons the trans formation will fit much better over larger areas than a One step transformation The height part is independent of the position transformation and is identical to the ap proach taken for the Onestep W hich Pre Transformation to use Any Classical 3D transforma tion can be used as the Pre Transformation of the first step This will typically be a gerhard walter leica geosystems com rough transformation valid for your country If no such pre transformation is available you can enter and then select a zero transformation zero shifts and rotations and still make use of the benefits from the second step The Operation Twostep transformations can be calculated in SKI Pro and on the Sensor In Da tum amp Map the type and the Pre Transformation can be selected on the Config
19. it CONT HEM EDIT DEFLT Additionally the Siemens 25 S35I the Sagem MC850 the Bosch 908 909 and the Sprint PCS Motorola Time port P8167 are also sup ported These are normal handys and would not be used in a radio housing DOP Limits It is now possible to set a DOP limit HDOP VDOP PDOP or GDOP such that if this limit is exceeded it is no longer possible to collect points Limit DOP J es a a es eee This may be useful for sur veys where the client de mands that data is only collected with a DOP under a specified limit MaxTrak MaxTrak was introduced with v2 firmware and was then only available on the GS50 and SR510 After many requests from customers It is now also pos sible to use MaxTrak on the SR520 and SR530 MaxTrak basically lowers the threshold at which satel lites are no longer tracked by the sensor The advantage of this is that it is possible to track satellites and obtain a position measurement even under more severe condi tions Of course because noisier data is being used to compute the position co ordinates the accuracy of the computed po sition will be reduced This may be acceptable for certain applications where a lower accuracy is acceptable Note that only code position solutions are possible when MaxTrak is activated Also only code data will be im ported into SKI Pro when raw data is collected with Max Trak Keyboard Locking Afte
20. leica geosystems com prietary ClearTrak technol ogy Although a TR500 terminal can still be attached it is only used for some basic sensor configurations i e remote port definition or to monitor some sensor specific status information Typically all sensor operations are per formed using a PC based application like a Reference Station software Thus nor mally the operator will not need a TR500 at all The MC500 GPS sensor has also proven useful for some projects which required a ruggedized sealed casing Leica Reference Station Antennae Reference stations are ex pected to provide high accu racy and reliable data There fore locations with optimal conditions are used where ideally a clear sky view down to low elevations are avail able In order to minimise any possible multipath degrada tion of the satellite signals typically high precision choke ring antennae are used and recommended These type of antennae do also provide the best possible phase centre stability Leica offers two types of high precision choke ring antennae both equally suited to meet reference station requirements e AT503 Dual Frequency Choke Ring Antenna Recommended for most reference station applica tions at excellent price quality ratio eca Geosystems GPS Newsletter Reference Stations e AT504 JPL Design Dual Frequency choke ring antenna Fully complies with Interna tional GPS Service IG
21. mapping da tum in some cases removing the need to com pute transformations CSCS models for UK France Denmark and Holland are already currently sup ported and it is simple to add the co ordinate shifts for addi tional countries Contact your local Selling Unit or Dealer for more information Many Other Features Many other features are in cluded within the new v3 firmware You should shortly receive the v3 Release Notes from your Selling Unit or dealer which detail all new features Take your time to read these release notes and learn how you can become even more productive with System 500 Upgrade now Remember e V3 firmware contains many new features which will im prove your productivity with System 500 e Read the Release Notes as soon as possible eca Geosystems Use Device Port End of Meg Annot 1 Annot 2 Annot 3 Annot He CONT J ANNOT DEUCE GPS Newsletter Sensor A one paqe weekly newsletter on System 500 GPS 01 14 April 9 2001 V3 Firmware continued Last weeks newsletter de scribed some of the major new features and improve ments that have been intro duced with the System 500 v3 firmware There are of course more than just major new fea tures in the new firmware there are many other smaller but important improvements This newsletter describes some of the other new func tionality with v3 firmware ASCII Input This functionality allows yo
22. on the new antenna to access the antenna properties On the General page change the Vertical offset to 0 0505 Name far 502 Height Meter Horizontal offset ao m Serial number Vertical offset ffo 0505 m Picture 4 Antenna Properties in SKI Pro Copy the antenna onto a PC card then insert the PC card into the sensor and choose 04 Antenna Info from the TRANSFER Menu panel This will transfer the antenna from the PC card to the sensor system RAM All on the pole Accessories Kit GHT37 Picture 5 Balanced All on the Pole solution The original All on the Pole solution has been improved by a more balanced operation of the pole where the sensor position is parallel to the pole The All on the Pole Accesso ries Kit GHT37 includes an antenna and a terminal cable with optimised length to op erate the set up as RIK rover The kit is to be used in com bination with the GHT26 to fix sensor and terminal to pole as for the backpack set up The new All on the Pole Ac cessories Kit again highlights the extreme flexibility in mor phology of Leica s GPS System 500 Repeater Box GHT38 Overcome restrictions of ra dio range by applying a repeater A repeater is a spe cially configured radio modem Usually it is set up somewhere in the middle between reference and rover on a tripod with radio antenna and battery It receives the RIK data from the reference and broadcasts the data fur ther to
23. quite rightly you do not care about ambiguity search routines and statistical analysis You need the system to give you co ordinates as quickly as possi ble but these co ordinates must be correct System 500 is not only one of the quickest RIK systems available it is also certainly the most reli able We sometimes hear com plaints that I had to wait 30 seconds with Leica RTK to get cm accurate solutions that Is not good enough the com petitor could do it in 27 sec onds But always remember which RTK system would you prefer A system which in 30 gs 2 2 he 2 2 seconds has resolved ambi guities twice and then is con tinuing to check the reliability of this solution by re computing ambiguities or a system which has only re solved once and has there fore possibly a wrong solution in 27 seconds and then conducts no further am biguity searches Really there is only one answer If System 500 does not give cm accurate positions as quickly as you would like re member there is a reason for this it simply does not want to give you the wrong an swer The Future So what is possible in the fu ture Ultimately surveyors want cm accurate positions immediately after starting to receive satellite data This single epoch RIK is much talked about and is possible today But the reliability of such solutions should be seri ously considered So is it possible to reduce
24. the RIK solution of any GPS RIK sys tem available today With v2 0x firmware a cm solution could be available in under 25 seconds Now with v3 firmware the cm solution can be available in under 10 seconds And remember the ambi guities are resolved twice in this time AND the ambiguity check still continues to be re peated once ambiguities are fixed Reliability is just as good as with v2 firmware greater than 99 99 This performance and reli ability has to be seen and tried to be believed RTK Output on 2 Ports Newsletter 01 10 explained how the optimal way to work with RTK is to combine GSM and radio Use radio for 90 of the survey and when the radio link is lost simply switch to GSM to complete alastair green leica geosystems com the survey without having to return to the reference station Improved Auto Logging As explained in Newsletter 01 11 the collection of points with auto logging has been greatly improved Auto logged points can now be coded viewed in Point Manager and exported with format files from the sensor Additionally the control of stopping and starting the col lection of auto logged points is also improved Staking Out Staking out with System 500 has always been simple and efficient with 10Hz position update rate and very low la tency It was also possible to orientate using one of several options the sun and north orientation being the most popular We hav
25. to ensure that the cor rect antenna record is used when processing data within SKI Pro There is some information con tained in the RINEX data im ported from the reference station but only the antenna number and type ANT and TYPE and the antenna offsets DELTA H E H What is not stored in the RINEX file is the antenna PCVs This means that it is Important to already have the full antenna record information including PCVs stored within SKI Pro During import of the RINEX data if an antenna of the same name is available within SKI Pro as the antenna type ANT TYPE recorded in the RINEX file then the imported data will be as signed this antenna If an antenna of the same name does not exist within SKI Pro as recorded in the RINEX file then a new antenna will be cre ated within SKI Pro with the name as seen in the RINEX data and the imported data will be assigned this new antenna Of course though this new antenna does not contain the necessary PCV information it only con tains the offset values alastair green leica geosystems com G RIHES VERSION 7 TYPE 26 11 1 16 64 PGH Z RUN BY Z DATE OBSERVER AGENCY MARKER MAKE HARKER NUMBER REC 7 TYPE Z UERS AHI F APPROX POSITION XYZ AHTEHHA DELTA HZEZH 00729 00307 00333 In this case it is then neces sary to assign the correct an tenna to the imported data once the data has been im ported This is a two stage pro cess assumi
26. was revolu tionised So How Does It Work The RTK rover and reference both simultaneously observe the same satellites The satel lite observation data from the Possible solutions key to this is to search for the correct ambiguities using the most efficient RTK algorithms possible Unfortunately this newslet ter does not have the space to discuss the ambiguity search in detail or even explain what an ambiguity is However it can be considered in the fol lowing way The RTK algorithms are try ing to determine the number of full wavelengths between each satellite and the rover antenna Once this number of full wavelengths is known for each satellite then it is possi ble to compute the rover co ordinates to cm accuracy Unfortunately there are many possible number of whole wavelengths that could be between the satellites and the rover Because of this there are always many possi ble sets of ambiguity solu tions The diagram below tries to show this it is very much simplified for only two satel lites in reality this could be an 8 or 9 dimensional inter section problem Thus a search routine is needed to determine which of ambiguities and hence the correct co ordinates of the rover as quickly as possible Leica uses a search routine that as you know is fast but even more importantly is reli able If the sensor were to use one correct set of ambiguities then this wo
27. we will now send out a 2 or 3 page newsletter at the end of each month If there are any aspects of System 500 or any topics re lated to GPS in particular that you would like to read about then please contact your local selling unit or dealer They can then pass your wishes to Heerbrugg and we can con sider them for future newslet ters Also you may or may not be aware that there is a News letter Book available This is a compilation of all newsletters in pdf format If you would like to receive this then please contact your Selling Unit who will forward it to you The SKI Pro CD Did you know that there is more on the SKI Pro CD than just SKI Pro Depending on which SKI Pro version CD you have the con tents may be slightly different the contents are always being updated However this is what the v3 Firmware v2 1 SKI Pro CD contains e Firmware and SKI Pro ob viously the v3 firmware and v2 1 SKI Pro is included on the CD e Geoids several country specific including American and Canadian geoid models and the EGM96 global geoid model e Omni Drive drivers for most operating systems in cluding Windows 95 98 and NT e Papers technical papers on ClearTrak System 500 RTK and a General Paper on the flexibility of System 500 e Sample Data real time and post processing data to be used in the exercises in the manual User Manual Getting Started with SKI Pro
28. EO This method is based on GPS field observations in several thousand different antenna Orientations rotations tilts Absolute antenna models are only available for a few an tennas at the moment and mainly used in Germany Absolute and relative correc tion models must not be mixed Remember e When mixing antenna types you should always take care to use the correct PCVs e Never mix correction mod els which refer to different reference antennas e Neglecting to use the cor rect antenna models may dramatically reduce the sys tem performance eca Geosystems GPS Newsletter Sensor A one paqe weekly newsletter on System 500 GPS 01 13 April 2 2001 Introduction This week we are very pleased to announce the re lease of v3 firmware for Sys tem 500 Again this latest firmware contains both new functional ity and improvements to ex isting features A couple of previous news letters have hinted at some of the new features within v3 firmware this newsletter ex plains why you should invest in this new firmware for all your System 500 sensors SR5x0 GS50 RS500 and MC500 as soon as possible Improved RTK Newsletter 01 06 and 01 07 explained how RTK works within System 500 Briefly ambiguities are resolved twice before a phase cm ac curate position solution is available and then this solu tion is continually checked This technique results tn the highest reliability of
29. For example in the standard code tables in LISCAD a tree could be coded as tr or even as the number 201 It does not matter what code is actually assigned to a feature but it is important that the CAD package correctly interprets this code When codes are created in SKI Pro it is then possible to Specify the code type for each code The code will be of type point for thematical coding or of type free for free coding Leica Geosystems GPS Newsletter General Within System 500 it is also possible to assign a Code De scription to codes This could be very useful when using a codelist with a large number of codes or when numbers are used to represent codes or if a new surveyor joins a company and is not familiar with the codelist Simply give each code a meaningful code description this description can then be viewed in the field along with the code when surveying points in the field Attributes Attributes belong to individ ual codes Assigning attributes to codes allows additional in formation to be recorded about the point to be surveyed Note some people use the words info blocks instead of attributes particularly in rela tion to free codes An info block can be considered to be identical to an attribute For example a point could simply be coded as a tree but using attributes would allow the condition the species and the height of the tree to addi tionally be recorded Attribut
30. RINEX data using the standard CORS IGS data file naming convention and data structures e RINEX file compression e Configuration of RTK DGPS output in all sen sor supported formats Leica CMR RTCM Latitude N47 24 00 000000 GPS Time 18 13 30 0 Longitude E009 33 00 000000 LocalTime 20 13 30 0 JobName My Site Logging Ext Int R B OFF OFF OFF Height 480 00m Sensor Mode Ref Station 7 Operations Status I ype SR530 Protocol ype ID 326 Sensor Sensor Voltage Satellites Tracked 7 Satellites used 0507 09 14 26 30 Clock Offset Satellites Visible 05 07 09 14 18 21 24 26 Elevation Anale PDOP HDOP GDOP YDOP Display Graphics Logging Comm Error Log Sensor hica fia Xx G Receiver e Channels PC Logging By Transmission C Sensor Info gt Site Configuration S Internal Data CH SY AZ ELY o1 4 095 012 02 5 263 O66 03 a O47 024 04 9 111 OF 05 14 314 024 D6 18 241 003 Oo 21 278 009 08 24 125 002 09 26 171 012 10 29 326 oo 11 30 253 029 aS es Ses ees frank pache leica geosystems com e Monitoring conditions and using of alarms for logging communication and sensor operation For all details please refer to the commercial literature The softwa
31. S standards Recommended where these standards have to be met For both types of choke ring antennae protection covers radomes are available and highly recommended to pre vent long term antenna dam age Single Site software solution The ControlStation software is especially developed for sin gle site reference station opera tion It fully supports all func tions provided with a System 500 sensor ControlStation is suitable for a wide range of applications and many different users ControlStation is a fully Win dows based product which features an interactive and easy to use graphical user interface GUI See screen snapshot Once set up and in operation it runs fully autonomously and without any further user inter action required Intuitive icons provide quick access to the essential operations to set up Operations Units View Window Help l ala lS Sl 2 ed A 2 and activate raw data logging and real time data transmis sion Various continuously updated status displays pro vide the user with the full overview on all significant operation information ControlStation features the following operations e Site configuration amp management e Sensor internal data logging e Direct PC data logging e Sensor internal ring buffer data logging e Automatic and manual download of sensor in ternally logged data e Automatic and manual conversion to standard RINEX format e Archival of raw and
32. and later walk through a predefined set of steps particular to a collection The Next Step feature en ables the user to progress to the next step step back or continue with manual func tions This provides ease and flexibility and makes for streamlined use for both ex perienced and first time users Greg pendleton leica geosystems com Image Referencing One of the best kept secrets of GIS Da taPRO is image referencing Using a bmp or tif file and the known co ordinates for two or more objects are all you need to georeference your own photos Best of all is the creation of a correspond ing world file which allows subsequent import to your GIS or CAD software of choice Simple Smarter Selection with SQL The search by SOL function allows you to query by code attribute value accuracy and time Selected data can then be exported to ASCII Post Processing Muscle DataPRO incorporates the SKI Pro engine if you should ever need to post process e Smart Internet Download allows the download of data from the nearest stations with 1 click Add and edit you own custom sites to the DataPRO library and with one click up date the current site list e Interpolation to 1 second to smooth data logged at greater intervals e Import Reference data from any Leica or RINEX for mat Import and Export In addition to ESRI format DataPRO can import and ex port to your CAD and GIS AutoCad dwg and dx
33. anisations start to in vest in is the installation of permanently operating GPS reference stations Thus re moving the need for field crews to spend any time on the daily set up of a field reference sta tion In addition they provide a stable and fixed link to the ex isting geodetic survey network Other applications can also take advantage of permanently operated GPS stations To list just a few applications there are Surveying Land GIS Mapping Con struction Stakeout Mining Machine Guidance and Con trol Civil Engineering Ma rine amp Hydrography frank pache leica geosystems com Motion Earthquake Volcano Landslide Engineering Dam Bridge Large Build ing Monitoring Deforma tion Studies Research Atmospheric Studies Orbit Determination Plate Mo tion Why is a permanent Refer ence Station different to a conventional field refer ence station As a permanent reference station is continuously oper ating it requires an advanced reliable and robust infrastruc ture Typically a PC is con nected to the GPS receiver Application software running on this PC is used to configure and control the GPS opera tions and has to perform some or all of the following tasks e Manage site parameters e Sensor configuration e Sensor operation control e Monitor amp display GPS sensor operation status e Enable provide RTK RTCM data transmission e Raw data logging and archivi
34. ates On the sensor the projection and ellipsoid are selected in the COORDSYS Type Selec tion screen Selecttidoh coord SyS My Tranfo TR anes or M Muy Trarnfo Trans Type Classical Ellipsoid Bessel Projection UTM 32F Geoid Model In SKI Pro Datum amp Map you do not have to select an ellipsoid and a projection the co ordinate system attached to the project of the local co ordinates contains this infor mation So now knowing the WGS84 Cartesian co ordinates and the local Cartesian co ordinates for at least 3 com mon points it is now possible to compute the 7 unknown parameters of the Classical 3D transformation Less than 7 parameters If there is only one common point it is still possible to calculate a Classical transfor mation if you fix the rotations and the scale parameters Such a transformation will fit perfectly in the vicinity of the common point but will get worse with the distance from that point because neither the orientation of the local refer ence frame nor any scale fac tor within the local datum can be taken Into account To fix parameters when de termining a transformation on the sensor press SHIFT F5 PARAM in the COORDSYS Determine Clas sical panel where you match the common points In the next panel scroll to the pa rameters and press F4 FIX Hame z My Tranfo Trans models Bursa HolfF Rotation x A B00AA Rotation Y A HADAA Rotation z
35. ation even though the Original military title remains Today the OS is a free standing UK Government De partment an Executive Agency and on 1 April 1999 became a Trading Fund Workforce and What They Do In total 1880 professional staff are involved in many fields including geographical information systems GIS capacity building and data base development and sur veying and mapping The majority are based at the Southampton headquar ters where surveying data is converted products for cus tomers are developed mar keted and support services are provided for the agency s work One quarter of the staff looks after 71 local field of fices across Britain It is here where most of the surveying and data collection is done The OS is a 100 million a year business generating a Small profit to sustain the trading fund The OS sells products maps education material services and licenses They also supply information to customers which they use to convert Ordnance Survey National Grid coordinates to WGS84 co ordinates Internationally the OS is known as the master agency for surveying and cartography It is the only governmental organization which was awarded the Citizens Charter Mark three times certifying its extraordinary services to the public and its innovation in creating new customer orientated products But that s not all The OS ts also the first organisation worldwide with on
36. avail ability Black is active Blue is available but not used and Red is low signal strength The GPS Mode shows the type of mode in which you are re ceiving data 2D 3D or DGPS The cursor on the map should be changed to a crosshair cen tred within a red circle and dis plays your current position on the map To collect GPS data you must be getting at least a 2D positional fix If GS5 is used because it includes a two channel beacon receiver for real time differential correc tion you will get 1 2 meter ac curacy in DGPS mode Also displayed on the window Speed Over Ground SOG and Course Over Ground COG Data Collection In ArcPad all editing and drawing takes place after a data layer is set as editable in Lay ers The target layer needs to be set as editable in the Layers dialog box Once a layer is set as editable the Edit Drawing toolbar IS automatically opened Geosystems GPS Newsletter GS5 GS5 and ArcPad Ge el t o 4 LR check and change the read only the black compass arrow and ila 50 85 3 flag for SHP SHX and DBF direction to the destination in ah aK files that you are trying to edit red i Capiure Line Can I UNDO my edits in Arc More Information at Captures Fgigon Pad For more information on Arc Pad check ESRI on the Web at No ArcPad edits the original www esri com Shapefile It does not operate on When collecting data using a copy of the file and ther
37. be or thometric heights and geoid models WGS84 Ellipsoidal Heights An ellipsoidal height is the height of a point above the ellipsoid In other words it Is the perpendicular distance from the surface of the ellip soid to the point But why do we need to have an ellipsoid at all The earth is not shaped like an ellipsoid in reality the earth is actually shaped like a pear Why does GPS use the WGS84 ellipsoid to approximate the true shape of the earth Remember that the funda mental co ordinates of points derived using GPS are Carte sian co ordinates based on the World Geodetic System 84 WGS84 The origin of this co ordinate system is approxi mately at the centre of the earth As explained in newsletter 00 20 a point could be meas ured with GPS and be found to have Cartesian co ordinates 4211089 525m 742528 701m 4717247 902m in WGS84 But these co ordinates are virtu ally useless to a Surveyor Is this point on the physical sur face of the earth in the air or where alastair green leica geosystems com WGS84 ellipsoid In order to make these Car tesian co ordinates more use ful and understandable they can easily be converted to Geodetic co ordinates lati tude longitude and ellipsoidal height And remember it is an ellipsoid that is required to convert between Cartesian and Geodetic co ordinates Because WGS84 is a global co ordinate system an ellip soid is chosen which is the
38. by the amount of the mis take Remember e Corrections are automati cally applied to System 200 300 antenna height read ings after import into SKI Pro to relate System 200 300 an tennas to the System 500 definitions e Wrong antenna height readings can be corrected during or after import etca Geosystems 1 GPS Newsletter SKI Pro A one paqe weekly newsletter on System 500 GPS 01 03 January 22 2001 Flexible Data Output We quite often receive ques tions in Survey GPS Support asking if it possible to output data from the Sensor or SKI Pro in a particular format This particular format may be needed to import point data into a CAD package or to import baseline data into a 3 party adjustment package or a user may require a simple re port style output containing point Ids co ordinates code information CO and DOP val ues etc These output formats are all possible by using a Format File Format Files and the Format Manager Format Files are created within the Format Manager Format Manager is installed automatically with SKI Pro A format file is basically a template or an output mask When surveyed data is exported from the Sensor or SKI Pro the data is then output in the format as de fined by the format file A format file needs only to be created once and then is simply used as required The Getting Started with the Format Manager manual is included on the SKI
39. case you would like to sepa rate the position transforma tion from the height transformation The Onestep transformation can be used for both these situations How does it work It is Important to remember that the position and height components of this transfor mation are treated separately For the position transfor mation the WGS84 geodetic co ordinates of the points to be used in the transformation computation are projected onto a grid using a temporary Transverse Mercator projec tion The central meridian of this projection passes through the centre of gravity of the common points This results in preliminary grid co ordinates for the WGS84 points Then these preliminary grid co ordinates are matched with the local grid control points in order to compute the easting and _ northing shifts the rotation and the scale factor between these two sets of points This is known as a Classical 2D trans formation ot ae LO E TM projection WGS Co ordinates projected to TM grid 2D transformation and height shift at OR If only one height control point is used the WGS84 heights are simply shifted to fit to that one local height control point If two height control points are used an av erage plane is computed if three or more height control points are used a best fitting tilted plane is computed to approximate the local heights Any disadvantage The only real disadvantage of the Onestep a
40. d be clear that in order to perform a meaningful ad justment with its associated statistical tests redundant observations are required otherwise there is nothing to adjust However you should also not include any of the so called trivial GPS baselines in the adjustment in order to artificially raise the number of observations and redundancy Free and Constrained Ad justment The recommended proce dure is to first perform free network adjustments before the constrained adjustment The objective in the free network adjustment is to check for observational errors matthew amor leica geosystems com GPS Newsletter SKI Pro A monthly newsletter on System 500 GPS 01 27 October 31 2001 and this is best done without imposing additional con straints from fixed points Once you are satisfied that outliers have been eliminated fixed Control co ordinates can then be added to perform a constrained adjustment In the constrained adjustment the emphasis is on analysing the fixed coordinates and on computation of the final co or dinates Statistical Testing The main aim of the statisti cal testing is to identify outliers It is also used as a general check on the correct ness of the mathematical and stochastic models The tests are all based on the analysis of the least squares residuals There are three main tests implemented in SKI Pro the F test W test and T test The F test is a
41. d project How do I know if am receiv ing data from the GS5 GS5 ArcPad has a GPS Debug screen which will allow you to view incoming NMEA data To view incoming NMEA mes Sages select GPS Debug from the GPS Position dropdown list NMEA messages will ap jian zhou Leica GPS com pear in the GPS debug window yeent j ae GFS Active k GFS Tracklog By GPS Debug What if my GPS debug screen is blank If you are not receiving NMEA data from the GS5 GS5 check the following 1 Is the GS5 GS5 system turned on A green light should appear on the power switch 2 IS everything connected properly Make sure that the se rial connection between the GS5 GS5 and the IPAQ Is OK 3 Are the batteries charged Sometimes the green light on the power switch is on even though the batteries are running low 4 Check the GPS Port settings in ArcPad If you checked all the above and still don t see any data on the debug screen you may have hardware problems In this case contact Leica service What if I get an Error opening port message on my iPAQ You need to do a normal reset by pressing the reset button on the bottom with the stylus pen GPS Position Window Select the GPS Position to open the GPS Position window Geodetic DMS 33 48 S1 230 N 118 1 00 600 The Skyplot Satellite Status Shows the positions of satel lites SV in the sky The colour of the SV indicates its
42. d semi permanently e g using land line modem con nection to the GPS sensors This set up provides central reference station manage ment and data archive The set up is still reasonably sim ple and very efficient for managing a number of sta tions Networked System permanent connection Again at the reference sta tion sites only GPS and communication hardware is installed The central station is per manently connected to the GPS sensor receiving con tinuous GPS raw data stream All sensor control and GPS RTK Data V Picture 2 Multi Site Central System etca Geosystems GPS Newsletter Reference Stations data archiving is performed at the central location Also RTK DGPS data is now man aged centrally and can be dis tributed via the network to the end user This is certainly the most complex and demanding ap proach suitable for large scale networks and service provid ers who require a fully cen tralised system The different configurations obviously require a different scale of engineering effort and communication infrastructure Therefore also different amounts of installation and maintenance efforts and cost are to be expected Any poten tial reference station operator has to define his requirements and adjust these to costs and efforts involved Leica GPS for permanent Ref erence Stations Today Leica has realised many projects for permanently Operated GPS refer
43. dios operating in TrimTalk mode by using Pa cific Crest RFM96W or PDL radios System 500 can receive RTCM corrections and Trim ble CMR RTK data formats GPS Newsletter General RINEX files do not contain the full antenna records with PCV information En sure to assign the correct antenna to data imported into SKI Pro It is best to de fine the appropriate anten nas before importing the data Ideas for Future Newsletters If you have any ideas or wishes for topics that you would like to be discussed in a future newsletter please contact your local selling unit or representative These ideas can then be passed to Heerbrugg Thank you Seica Geosystems alastair green leica geosystems com T GPS Newsletter General A monthly newsletter on System 500 GPS 01 29 December 20 2001 Accessories Sensor firmware and office software upgrades are cer tainly the big noticeable improvements News about these upgrades are usually widespread But there is more than this Accessory im provements make your System500 more effective and your life a lot easier A couple of accessories have been added to the GPS prod uct basket lately In this newsletter we would like to introduce them to you Instrument Height Meter GHM007 How do you measure the an tenna height on a tripod set up The majority of GPS users probably work with the height hook It is inserted into the antenna carrier and the
44. e alastair green leica geosystems com Also F5 POS takes you di rectly to the CONFIGURE Po sition Logging panel V3 Even More Control With v2 firmware if you chose to collect auto log points the logging of auto points began as soon as the SURVEY panel was entered You can now choose be tween the options Controlled or Immediate If Controlled is chosen then auto logging Remember e The logging of auto points in v3 is greatly improved more control coding view in Point Manager and export e The use of auto logged points allows a lot of points to be collected very quickly e The most efficient way to survey can be to collect both normal points and auto logged points Seica Geosystems L1 PCV m Introduction We often receive questions in support about the treat ment of Phase Centre Varia tions PCV This newsletter explains what PCVs are and briefly de scribes the methods of how a PCV calibration is performed It is necessary to understand the principles of how an an tenna calibration is actually done it will then be clear when it is necessary to take PCV into consideration or not Ultimately this should help to almost eliminate this error source If only Leica antennas are used then the correct PCV corrections are already stored and automatically applied when using these antennas This applies to both the field system and SKI Pro However if you wish to use 3 party
45. e F3 LAST displays a list of the 5 last used codes If a code Is then chosen from this list of last used codes the attribute values for the attributes of this code are also recalled e F4 ATRIB allows attributes to be entered for this code de scribed below e F5 INFO toggles between displaying the layer to which the code belongs and the code de scription Note also the asterisk in the code list panel on the right hand alastair green leica geosystems com side indicates if that code has attributes belonging to that code Using Attributes in the Field FA ATRIB in the code list panel accesses the MANAGE Attnbutes panel This panel allows the entry of attribute values for the attributes at tached to this code However there are some rules as to the attribute values that are displayed in this panel 1 The selected code was not used for the previously sur veyed point In this case any displayed attribute values are the default attribute values for this code 2 The selected code was used for the previous point and at tribute values were changed for that point In this case the changed attribute values are displayed for this point now being surveyed 3 The code was selected using F3 LAST In this case the at tribute values displayed are those that were used when the code was last used This is par ticularly useful when string ing points allowing the last used string values to be re ca
46. e by accessing the Settings dialog box click the settings icon and define the String default value to No Code by default this value Is Scales Units Default values Values Floating Point default value 1 00 Integer default value no String default value N Code Using a Format File within SKI Pro It is straightforward and most people know how to use Settings a format file within SKI Pro Simply choose to export a Project or Co ordinate Set as Custom ASCII cst Save as type Custom ASCII file cst The sorting co ordinate classes and other parame ters of the data and the selec tion of format file to be used during export can be selected by clicking the Settings but ton However if a user tends to use more than one format file and or uses different settings depending on the data to be exported then it may become tiring to keep constantly clicking the Settings button and defining these settings For this reason it is possible to define Export Templates Right click in the Settings drop down menu and choose New from the drop down box that appears Now enter a name for this export template such as GSI16 Then click the Settings button and define the export settings including the format file and then click OK This has defined the pa rameters for that export tem plate You may now define additional templates such as Sokkia SDR33 if required Now wheneve
47. e complete National Topography Database NTD for all large scale maps This electronic endless map consists of over 200 million objects of the British landscape e g telephone boxes private garages 800 000 street names and half a million kilometers of streets From the NTD basic information is derived for water quality overview counting of population building plans underground pipelines etc GPS at OS The OS sustains an Active GPS network over the whole UK see picture The 31 per manent GPS stations have ISDN links to a server where the data are stored online for 30 days with full public access via website Surveyors may download RINEX data in order to tie their GPS work into the OS network charlotte heinz leica geosystems com A one page weekly newsletter on System 500 GPS 01 15 April 16 2001 But onLewe Thirsa l5 Glasgow Edinburgh isle of thant Flam borough Leeds Point Lynas Daresbury Nottingham King s Lynn Droitwich Nor fiampton Camarthen pow s icto andon Nash Point Bristol North Foreland Southam phori St Catherine s Point Phniouth Lizard Additionally a passive net work of 1000 accurately co ordinated points exists The points are monitored every 5 years The public can fully ac cess the searchable database for the 1000 passive GPS sta tions via Internet including their full station description A further service allows WGS84 co ordinates to be converted online to
48. e factor can be calculated 3 Always check the residu als after computing a trans formation On the sensor the residuals are shown in the COORDSYS Residuals panel and in SKI Pro Datum amp Map in the Results view The point with the biggest residual is not necessarily an outlier but you may try to improve the transformation by excluding this point Note that the re maining control points should still be evenly distributed Remember e Neither the Ellipsoid nor the Projection have to be known to calculate a Onestep transformation e Common points can be given in position and height In position only or even in height only e Applying Onestep trans formations is limited to smaller areas than Classical 3D transformations etca Geosystems T GPS Newsletter Sensor A one page weekly newsletter on System 500 GPS 01 10 March 7 2001 GSM The use of GSM with RTK GPS is becoming ever more popular and as you will read for very good reasons This newsletter explains the use of GSM with System 500 and if you do not already use GSM why you should seri ously consider using it Why Use GSM The most common method to send RIK data from the reference station data to the rover is to use a radio modem data link Satelline Pacific Crest etc For most users and situations this is fine but there can be limits and some times problems with using radio modems radio range and jamming being the ma
49. e geoid models tend to be more accurate than a Global Geoid Model but can only be used over a limited area Of course there are an infi nite number of equi potential surfaces As already stated the surface that is normally chosen for a global geoid model is the one that coin cides best with the global ocean surface However the surface that may be chosen for a local geoid model is the surface that is the best fit to that country s levelling datum Orthometric Heights and GPS As described last week points measured with GPS directly result in ellipsoidal Physical surface Geoid model GPS Newsletter General A one page weekly newsletter on System 500 GPS 01 20 May 21 2001 heights So how can GPS be used to measure orthometric heights The answer is that it is only possible indirectly by using a geoid model All geoid models describe the distances between the geoid and a reference datum the Geoid Ellipsoid Separa tion normally called N The reference datum is normally an ellipsoid but as we will see next week it could also be a plane surface and is the da tum to which the geoid ellip soid separations should be applied For example when creating a new geoid model in SKI Pro the WGS84 ellipsoid should be selected to be used with EGM96 So measuring a point with GPS provides the ellipsoidal height of that point and knowing the geoid ellipsoid separation at that point ta
50. e is no GS5 GS5 use the collect by UNDO functionality Remember GPS Tool pull down For ex e The GS5 provides 3 4 m ample select Capture Point a Navigation autonomous accuracy the one epoch location will be In ArcPad tades GS5 1 2 m accuracy in DGPS taken followed by an attribu oe ey ee mode tination point using the Informa tion form ArcPad supports l l PP tion or Find tool e Both system are used in customised forms created by ae ArcView 3 2 to provide a combination with ArcPad from ESRI running on a on Com method for adding meaningful paq s Windows CE device captions to field names and a tr 2 user friendly interface to the Faid Fac o e Information on satellites and database In this example for ma T the data receiving mode can be point collection install date found in the GPS Position win field is customised so that user dow and GPS Mode may select a data from a cal o l e For editing and drawing a endar Also a combo box con trol is used on the form for the data layer has to be set as edit able in ArcPad condition field to provide a choice list ic Di 33 498 S1 278 N can not get the i 1 18 21 01 002 W Edit Drawing toolbar to come up on my Arc Pad When I try DPZ eae and tick the edit box a mes ee ones Sage comes up saying Error NST 468m enabling write mode on layer ERG Too shp What s happening HFE NJA It could be that the shape files are read
51. e next point Remember e The quickest and most effi cient way to stake out a lot of points on a regular grid is to use Grid stake out e To construct the grid only 2 points are needed e t is possible to stake out subsequent rows of points in Opposite directions Seica Geosystems KY ie Lab Mien Man Looks wiens Le 4t Uatt amp Ja f GPS Newsletter GIS DataPRO A one paqe weekly newsletter on System 500 GPS 01 05 February 05 2001 GIS DataPRO GIS DataPRO is Leica s software liaison between your GIS in the office and your GS50 in the field This news letter gives an overview of the software Built on ESRI s MapObjects engine DataPRO works in a native shapefile format No more imports or export to ArcView Arclnfo or any Arc product In fact GIS data flow be comes so seamless that shapefiles can even be shared between programs Try that with the competition Views DataPRO is a graphical mapping program designed to be intuitive to both experi enced and novice GIS users The main display is separated into three informative views Map GPS Summary and Tabbed Map View An interactive graphical map allowing selec tion edits deletion and query Summary View A graphical timeline showing a distribu tion of located objects vs DOP Accuracy GPS objects are interactively related to the map view Tabbed View Consists of the following views e Project View Dis
52. e no reflecting surfaces nearby that could cause multi path and also no powerful transmitters TV radio etc close by In particular for Rapid Static Surveys it is important that the survey should be performed when the GDOP is less than 8 ideally less than 5 Remember to use the Satellite Availability software to compute GDOPs at the locations to be surveyed Remember e Mainly for historical reason the terms Rapid Static and Static are still used although there is no clearly definable dif ference between the two e Read the manual General Oh Ain cate i Baseline Anprosinate observation Metho c GDOP z 8 Guide to Static and Rapid Static for useful tips and Length time fF He fi AE an guidelines on collecting data api or mare Up to 5 km 5 io 10 mane Mires 7 State A ar ree 5 fio 10 km 10 o 20 ming Bio 10 ming for static or rapid static sur Sor rere 10 fo 15 kimi Cheer 20 mina o io 20 mire veys Static 40rmare 15 to 20 bm 1 ts hours 1 hor aor rear Over 30 km 2 to 3 hours 2 hur Seica alastair green leica geosystems com Geosystems GPS Newsletter General A one page weekly newsletter on System 500 GPS 01 18 May 07 2001 The Twostep Transformation Please refer back to Newslet ters 01 09 and 01 10 which explained the Classical 3D and the Onestep Transformations With the new v3 0 Sensor Firmware and v2 1 SKI Pro there is now another trans formation type avai
53. e now also added an arrow as an orientation option simply push the pole away from you and the arrow im mediately points to the direc tion in which to walk We have also now added a co ordinate check when you measure the point you have just staked out If the meas ured co ordinates of the staked point are greater than the defined limit then a warning message is dis played Even more quality control CSCS Models V3 firmware now supports Country Specific Co ordinate Systems CSCS a feature unique to System 500 The original mapping da tums of most countries was established over many many years using a variety of tradi tional survey equipment from chains to total stations The result of this is that most mapping datums are distorted due to the limitations of the equipment and survey tech niques available at that time Most countries of course wish to retain the original dis torted mapping datums but also wish to be able to use GPS within these datums Be cause the GPS measurements are too accurate for these distorted datums co ordinate shifts are required to convert between the computed GPS co ordinates and the original distorted mapping datum More and more countries are now publishing look up tables which contain these co ordinate shifts Using CSCS models with v3 firmware it is now possible to survey with GPS and use these co ordinate shifts to di rectly tie into the
54. e of the point classes manu ally For example SKI Pro estab lishes the measured co ordinates builds the average or calculates the adjusted co ordinates The only Point Classes which you can add manually are the classes Control and Estimated You can do this in the Point Properties page Generel Siokasica ThernsicaData Portit Note that from only the screen shot above you cannot see which point classes actually al ready exist because Control and Estimated will always show up in the drop down box to allow adding new triplets of this type To find out which Point Classes are stored for that point double click in the Point Class column of the Points view J 112 The Current and the Main Class Always one of the existing point classes is currently active This ts the one which is dis played in the Points view in the Points Properties page and for which the corresponding symbol is Shown in the View Edit screen According to the hierarchy the Main Class is the highest class which exists for a point This class can be used in all kinds of ASCII exports where the point class to be exported can be selected gerhard walter leica geosystems com Coord Cigi Setting the class to Main will ensure you typically get the best co ordinates during ex port Current may be used if you wish to get different point classes for individual points Setting it to All will export all existing triplets fo
55. e time This would mean that you would have to return to the reference when you wish to switch from radio to GSM on the rover to reconfigure the sensor No longer true We will shortly release v3 firmware with a new feature that allows the reference to transmit RTK on 2 ports si multaneously using differ ent devices Switch between using GSM and radio on the rover with no need to return to the reference Remember e The use of GSM with System 500 is simple the user is in complete control and there are no cables Ask other manufacturers how they han dle the use of GSM e The morphology and de sign of Leica GPS System 500 allows complete and_ total flexibility with regards to data links Seica Geosystems T GPS Newsletter Sensor A one paqe weekly newsletter on System 500 GPS 01 11 March 19 2001 Auto Logged Points Have you ever used the functionality on System 500 to collect survey data using auto logged points This method of data collec tion is ideal for collecting a lot of points very quickly such as data for a DIM or for meas uring a quarry or stock pile This newsletter discusses what is possible with v2 firm ware and how collecting data with auto logged points has been improved with v3 firm ware Logging Options Auto logged points can be collected in one of 3 ways by time by distance or by height Normally by distance is the most useful option if you then stop m
56. ed the new class Refer ence Whenever another base line is to be processed and stored the vector will be added to the already existing reference triplet Reference triplets are automatically created by SKI Pro and not by the user either after importing RTK results into your project or when storing post processed results To keep the consistency of a complex network the reference triplet will always be passed to the processing kernel if it al ready exists This principle is kept even if you later add a Con trol triplet to your point This approach makes sure you do not use different reference co ordinates for the same point Note that reference triplets are always stored in the WGS84 co ordinate system This makes sure that the WGS84 reference co ordinates do not change be cause of a change in the at tached co ordinate system It is also important to know that Con gerhard walter leica geosystems com trol co ordinates given in Local Grid will therefore only be used to build the Reference triplet if the attached co ordinate sys tem allows the conversion to WGS84 Changing reference triplets An example You are com bining RTK and post processed work in the same project With RTK you were using a HERE position in the field because you wanted to find the best co ordinates for your reference station later as a result of your post processing You should first import the post processing data find y
57. educe cost and efforts to and man made struc maintain traditional pas tures sive networks News on the Leica website A weekly updated almanac and the Satellite Availability program can be downloaded from the Leica website http www leica geosystems com gps almanac htm English http www leica geosystems com gps almanac _de htm German http www leica geosystems com gps almanac_cn htm Chinese Ideas for Future Newsletters If you have any ideas or wishes for topics that you would like to be discussed in a future newsletter please contact your local selling unit or representative These ideas can then be passed to Heerbrugg Thank you etca frank pache leica geosystems com Geosystems Adjustment Why do we need Adjust ment Which model is used and why Which tests are applied and why These are some of the general questions which are ad dressed in this newsletter together with some practical tips for making the best use of the Adjustment component in SKI Pro in practice Why use Adjustment Adjustment serves as one of the principle quality control tools It enables the surveyor to assess whether the work which has been done actually meets the requirements in terms of precision accuracy and reliability It also provides analysing measures which assist the surveyor in identi fying errors when the requirements have not been reached In addition in Design mode the Adjus
58. ence sta tions and networks of reference stations All types of GPS sen sors have been used single and dual frequency as well as System 200 300 and 500 sen sors in various different con figurations To list just few of these proj V v RS500 RS500 GPS GPS oe Internet or Dedicated Network PC Central Station emna Server ects there are e Various State amp Gov ernmental networks in many different countries e Engineering Networks i e for resund Bridge project or Hong Kong Bridge e Volcano Monitoring in Japan e Dam Monitoring in Cali fornia Leica Reference Station Sen SOrs Basically all Leica GPS sen sors can be used for reference station applications However because typically dual frequency equipment is used and most of our sensors offer much more application func tionality than that required for a permanent reference sta tion Leica has developed the RS500 GPS sensor The RS500 sensor is specifi cally designed to be operated using PC based application software It can be controlled using the Leica proprietary Outside World Interface OWI command language The RS500 provides all functional ity required for precise high quality GPS data acquisition logging and RIK data trans mission Like all System 500 sensors it uses the Leica pro RTK Broadcast RS500 Y GPS Mobile Phone or ail FM Station Data distribution Picture 3 Networked System frank pache
59. es have names an attribute name is given to the attribute when the attribute Is created In the field during the Survey attributes are then given values attnbute values For example an attribute name could be Species and the at tribute value could be Pine When creating the attributes for codes within a codelist in SKI Pro try to use the many useful properties that attrib utes can have e Attribute types attributes the default value assigned to this attribute The user cannot edit this value in the field A mandatory attnbute means that when this code is used in the field the user must enter an attribute value before the point can be stored A normal attribute is simply not mandatory or fixed e Value types attributes at tached to codes can be of value type integer real or text The meaning of this is clear and can prevent simple mistakes being made in the field For ex ample if it is required to enter the width of a tree being sur veyed then the attribute Width could be assigned the value type real which ensure only a nu merical value can be entered for this attribute e Value region all attribute types integer real or text can if required be assigned a choice list of attribute value In the field the user can then select the attribute value from this choice list Alternatively attributes of type real and integer can be as signed a range of values Then in the field the user must e
60. f Mi crostation dgn and Maplnfo are all supported User defined ASCII export as well as RINEX are also avail able Remember e DataPRO is simple to learn to use but also extremely versatile and powerful Try it etca Geosystems 4 GPS Newsletter Sensor A one paqe weekly newsletter on System 500 GPS 01 06 February 12 2001 RTK Did You Know The RIK performance on System 500 is so good that most people use it without even considering what is go ing on behind the scenes This newsletter explains what is happening inside the sensor and why System 500 is simply the best GPS RTK sys tem available today But first a little history It All Began Until RTK became available GPS was mainly used to measure static baselines for networks or control purposes Kinematic GPS was also pos sible using techniques such as Stop and Go or Kinematic GPS and then the user would have to post process this data Obviously the main problem with post processing any sur vey is Have I collected enough good data to get the results need RTK first became available with System 300 which as today allows users to survey points and ensure that they have cm accurate positions Overnight surveying with GPS became much more pro ductive the number of points that could be collected in one day increased enormously Staking out with GPS also be came possible quite simply GPS surveying
61. face At any position on this surface the gravitational force to the earth is the same as at any other position This surface may be represented by a mathematical model which is called a Geoid Model Try to think of the geoid as a levelling surface If you were to use a level instrument and level all the way around the world when you came back to your exact start point you would theoretically have a closing error of 0 In effect you would have measured heights relative to a geoid Whenever height differences are measured between two points with a levelling instru alastair green leica geosystems com ment orthometric height dif ferences are being measured Note the geoid does not necessarily follow the physi cal shape of the ground In mountainous regions the level of the geoid may differ significantly from ground level of earth N If a geoid model models the geoid over the whole of the earth then this ts called a Global Geoid Model EGM96 is a global geoid model and is supplied on all SKI Pro CDs The advantage of these geoid models is that they are freely available and cover the whole of the earth but may not be as accurate as required Many countries also provide geoid models valid only for that country or part of that country these are called Lo cal Geoid Models the Dan ish Dutch Swiss and some USA geoid models are sup plied on all SKI Pro CDs Thes
62. he CO drops to the cm level Typically to measure enough satellite observations solve the ambiguities twice perform the statistical analy sis and then compute the rover co ordinates takes well under 30 seconds And remember this is all done with signals transmitted from satellites 20000km above the earth In addition the rover could be used under trees where the signal is be Ing interrupted or near to buildings where signal disrup tion could be even greater Quite incredible alastair green leica geosystems com And Then Do It Again and Again and Again So now even though the system has fixed ambiguities twice and the system is measuring positions to cm accuracy this is not the end of the story In order to ensure the high est possible reliability of the computed positions the am biguity search routine is con tinually repeated in the background as you survey The ambiguities d f Code compute rom solution these repeated E Ambiguity search routines are ate compared with INE eerie current solution If they agree all is fine Ambiguity if they disagree the oe system beeps the Y solution type change Phase to a precision navi solution gation code solu eha tion and the whole ambiguities ambiguity search routine starts again Checking ambiguities from the beginning Speed versus Reliability If you are using System 500 in the field and simply want to complete your survey
63. height to the point on the ground is measured E c Whig a a a Ba Picture 1 Height Hook There might however be a customers using TPS and GPS instruments Until now no equivalent to the height hook existed for TPS However now with the Instrument Height Meter GHM007 plus Spacing Bracket GHM196 you can measure the metric TPS instrument height rapidly And in addition you can use the same tool to determine the height of a GPS antenna on a tripod Picture 2 Instrument Height Meter and Spacing Bracket After the instrument set up the spacing bracket is clicked onto the tribrach the tape measure is inserted and the measuring tongue is moved down to the point on the ground The perpendicular height of the instrument is read off directly Originally the GHM007 was designed for instruments with a tilting axis height of 196 mm All necessary conver sions are taken into account on the scale The second side can still be used as normal tape measure The side for height reading of the instru ment iS marked with additional triangles to avoid confusion Even though the GHM007 scale is designed for instru ments with a tilting axis height of 196 mm you want charlotte heinz leica geosystems com to be able to type in the height reading directly into the field Ant Height on the sensor when applying the Instrument Height Meter for GPS For GPS tripod set up the vertical height reading plus
64. ight click and Select All then copy everything into a text edi tor and then save this file as a text file In SKI Pro access the Antenna Management component and right click and choose Import Antenna File Browse to find the antenna text file we have just created which will then im port all the antennas listed in the text file This antenna file con tains many antennas we only need the TRM33429 00 GP the rest of the antennas can be de leted H E Antennas 3 5A299 399 Internal 47504 Tripod So now the correct antenna is stored in SKI Pro The next step is to transfer this antenna record to the System 500 sensor Access the Sensor Transfer component right click on the TRM33429 00 GP antenna and choose Send To If the sensor is connected to your PC then you can transfer the antenna directly to the Sen sor System if not then transfer alastair green leica geosystems com TRM33429 00 G2 GPS Newsletter General A monthly newsletter on System 500 GPS 01 28 November 30 2001 the antenna to the PC card For information the antenna is stored in a file called list ant which is stored in the GPS di rectory on the PC card Name Vertical offset Phase center offset verti amp ATS04 Tripod eigenen ae ATS Find Sehear Interial 9 AT503 Tripod Sensor PC Card 9 AT503 Properties Sensor System l Bh ATEN Trina n acon If the antenna is stored
65. in two A GSM modem is a device that can hook into the local mobile phone network the GSM network Thus instead of RTK data being transmitted over the direct radio link the data is transmitted over the GSM network Think of using GSM as if you are using your mobile phone to dial a friend on his mobile phone the only difference with GPS is that one sensor is phoning another sensor What Are The Advantages Clearly the two main prob lems of using radio modems are removed with GSM There is no limit to the range you can dial your friend even if he is in another country and jamming is not a problem no one else can in terrupt your phone call You will of course need to ensure that the areas tn which you will work are covered by GSM network As mobile phones become increasing popular the areas covered by GSM also grow There are of alastair green leica geosystems com course costs in using a GSM connection but these costs are minimal depending on the network provider and are be ing continually reduced Some calls can even be free at the weekend How Does it Work Using GSM is simple A GSM modem can fit into normal System 500 radio housing which is then at tached to the sensor in the normal way no extra cables The configuration set is then edited to select the cor rect GSM device and the tele phone number of the reference to which the rover should dial is entered on the rover
66. ion from the field and is typically accurate to a few me ters When a Single Point Solution iS processed and stored the point class SPP is added using the resulting co ordinates The point class Estimated is not needed for pure GPS proc essing networks It is only re quired to support the Adjustment component with initial provisional co ordinates when a point is only observed with terrestrial observations M easured and Averaged Measured co ordinate triplets are stored in the database ei ther after the import of real time measurements or when storing post processed results It is worthwhile knowing that RTK and post processed solu tions can be distinguished by the additional Point Subclass RTK results have subclass Phase whereas post processed results have subclass Phase Fixed Measured triplets can not be edited When more than one meas ured triplet exists for any point the Averaged triplet is automati cally created You can then ac cess the different solutions on the Mean tab of the Points Prop erties page This is also where you can include or exclude solu tions from the Mean a i Umma uima aeaa i ep g a a at F Prem Reference The Reference triplet is the guarantee that in SKI Pro always the same co ordinates are used to construct the baselines from Whenever a point becomes ref erence for the first time the co ordinates of the highest point class are copied and the point is award
67. ive data in the field on top of existing GIS data Installation Installing ArcPad is only a three step process 1 Install Microsoft Activ Sync 3 1 or higher on your desktop PC 2 Run setup exe to install ArcPad and selected compo nents on your desktop PC 3 Run the Windows CE in stall programs from your desk top PC to install ArcPad on your iPAQ The Windows CE install programes are accessed from your desktop PC by clicking on Start gt Programs gt ESRI gt ArcPad 5 01 jian zhou Leica GPS com How to connect desktop PC to IPAQ ArcPad Windows CE installation programs are created when Ar cPad is installed on the desktop PC The ArcPad Windows CE in stallation program uses a Micro soft ActiveSync connection to install the appropriate programs for your Windows CE computer If you are running Windows 98 Windows 95 or Windows 2000 you may connect your iPAQ to your PC via USB To do so fol low these steps on your desktop computer 1 Open ActiveSync 3 1 2 Under the File menu choose Connection Settings 3 Check the box Allow USB connection with this desktop computer 4 Click OK This activates the USB port for ActiveSync 3 1 You need to con figure your iPAQ to use USB as the default connection This is done by selecting Start Set tings Connections and PC Check Automatically synchro nise when serial cable is con nected using Select USB in the dropdown box Now y
68. ke to be discussed in a future newsletter please contact your local selling unit or representative These ideas can then be passed to Heerbrugg Thank you Seica gerhard walter leica geosystems com Geosystems GPS Newsletter General A monthly newsletter on System 500 GPS 01 24 J uly 30 2001 Coding and System 500 Many surveyors have differ ent opinions and ideas on the subject of coding what code list to use how to code fea tures in the field how to import the data into the CAD package However what is agreed by all surveyors is that the coding in the field must be as efficient as possible to not only mini mise survey time but also to minimise time spent in the of fice producing the final plot And of course the aim of any survey is to ultimately produce the final plot of the survey showing all features correctly and accurately repro duced It is for this reason that cod ing with System 500 is ex tremely flexible It allows surveyors to work how they wish to work in the field Additionally the flexibility of the output of data from SKI Pro or the sensor particularly with Format Files allows the coded survey data to be imported into most CAD packages Coding Types Two types of coding are sup ported by System 500 the matical coding and free coding Generally thematical coding IS more commonly used and perhaps initially easier to un derstand whereas free coding
69. ken from the geoid model it is then possible to compute the orthometric height of the point measured with GPS Thus Ell height Ortho height N Ellipsoidal Orthometric height height Geoid Ellipsoidal separation Ellipsoid Remember e An orthometric height is the distance of a point above the Geoid measured along the plumb line e The geoid is a gravitational equi potential surface e Knowing the ellipsoidal height and the geoid ellip soid separation allows the orthometric height to be computed Seica Geosystems A GPS Newsletter General Using Geoid Models The last 2 newsletters have defined ellipsoidal and or thometric heights and geoid models This weeks newsletter focuses on the use of geoid models and computing or thometric heights within SKI Pro Unfortunately this newsletter does not have the space to de scribe how to create a new geoid model and a co ordinate system containing a geoid model please refer to the SKI Pro On Line Help if necessary Computing Geoid Separations Once a co ordinate system is defined containing a geoid model and is attached to a project N values the geoid ellipsoid separations and or thometric heights can be com puted for the points in that project With the project open simply click on Tools and then Com pute Geoid Separations In the points tab view of the project it is then possible to see the N values and ortho
70. lable the Twostep transformation This Newsletter explains how it works and why we have introduced this W hy another transformation Remember that the Classical 3D transformation is the most rigorous transformation type It is a similarity transforma tion which keeps the full geometrical information Knowledge of the ellipsoid and the map projection is re quired and all common points have to be known in position and height The Onestep transformation does not need the knowledge of the map projection of the local points and also does not need position and height in formation for the common points as it treats position and height separately As for the position trans formation of a Onestep the WGS84 geodetic co ordinates are projected onto a prelimi nary grid using a temporary Transverse Mercator projec tion Onestep transformations are limited to areas of about 10km square The new Twostep transfor mation combines the advan tages of the two approaches It allows treating position and height separately but is not restricted to smaller areas How does it work In the first step the WGS84 co ordinates of the common points are shifted closely to the local datum using a given Classical 3D Pre Transformation In the second step the co ordinates are projected onto a preliminary grid but this time using the true map projection of the local points The final part of the positional transformation
71. lines as to how to conduct real time surveys with System 500 e User Manual Getting Started with SKI Pro excel lent manual to learn how to get started with SKI Pro Includes 3 Quick Tours very useful ex ercises to complete in SKI Pro using sample data on the CD e Getting Started with Format Manager useful manual to learn how to use the Format Manager Includes 3 exercises to create 3 different format file types a report style format and two GSI16 format files one for thematical coded data and one for free coded data e Technical Reference Manual If you have any question about the functionality of the sensor look in this manual first The answer is probably there e GPS Basics an excellent guide to the workings of GPS in general A very good way to increase your knowledge of what GPS is and how it works Well worth reading Remember e Explore the CD there is a lot of useful information in cluded on it e There is a lot to learn from reading all System 500 manu als especially when learning to use System 500 e Get into the habit of looking into the Technical Reference Manual to learn more about the use of System 500 Even expe rienced users can learn some thing from here Seica Geosystems GPS Newsletter SKI Pro A monthly newsletter on System 500 GPS 01 23 J une 29 2001 Point Classes and Triplets This is the first Newsletter in our new monthly
72. lines of up to around 20km to be measured with greatly reduced occupa tion times of around 15 min utes This was achievable using ambiguity resolution techniques and the FARA Fast Ambiguity Resolution Ap proach algorithms developed by Dr Erwin Frei of Leica Wild in those days This was a big breakthrough in GPS surveying at that time Mainly for historical reasons the terms Static and Rapid Static surveys are still used today However it is actually difficult to precisely define the difference between a Rapid Static survey and a Static sur vey or to say when a Rapid Static survey becomes a Static survey Maybe the best way to de scribe any difference between a Rapid Static and a Static sur vey is as follows If a baseline is being com puted using longer occupation times maybe gt l hour then this could be described as a Static survey If a baseline is being computed using shorter occupation times maybe lt hour then this could be de scribed as a Rapid Static sur vey Obviously because more data is then being collected during a Static survey than a Rapid Static survey the re sulting co ordinates from a Static survey will generally be more accurate than a Rapid Static survey this is discussed further in a future newsletter The Big Question The question asked by most newcomers to Static and Rapid Static GPS is For how long should collect data These newsletters still use the
73. lled Additionally F6 CLEAR clears all default values and F5 DEFLT recalls default at tribute values if the attributes were assigned default values F4 NEW A allows new or ad ditional attributes to be added to that code An attribute name entered on the left hand side of the panel can be entered and if required a default attrib ute value entered on the left hand side of the panel can be entered for that attribute Note all new attributes created this way are of type text and nor mal see above J eca Geosystems GPS Newsletter GS5 GS5 and ArcPad A monthly newsletter on System 500 GPS 01 25 August 31 2001 Introduction In this month s Newsletter we will cover the basics of us ing ArcPad on Compagq s Win dows CE device iPAQ with Leica s GS5 GS5 Some trou bleshooting tips are also in cluded The GS5 class of receiver is specifically designed as an all in one turnkey system It is ideal for users who need zero hassle highly accurate GPS input to field mapping pack ages such as ESRI s ArcPad There are two receiver types available the GS5 which pro vides 3 4 m autonomous accu racy and the GS5 which includes a two channel beacon receiver and offers 1 2 m ac curacy in DGPS mode The Arc Pad field mapping soft ware is a handheld mobile GIS application from ESRI the world leader in GIS Use GS5 GS5 together with Arc Pad you have the capability to view your l
74. metric heights for all points Useful to Know W Tools Data Processing Adjustment Export Wir Show Mrection e Distance Show loop Mieclosue j Eompute Swe Lombined Factor Compute Geoid Separations Based on the queries we re ceive in support about the use of geoid models the following notes may be of use in ex plaining the use and function ality of geoid models e Geoid separations are only ever computed on demand using Tools and then Com pute Geoid Separations as just described and during the ex port of points For example if additional data is imported into that project or the co ordinates of points are changed then the corre sponding geoid separations and heights are not automati cally re computed and up dated e f a new point is created within a project as a local point with orthometric heights and geoid separations are com puted then a local ellipsoidal height is computed for this point using the entered or thometric height and com puted N value e N values are individually computed for all co ordinate triplets of all points within a project e The N values and or thometric heights of points can only be viewed in the points tab view when points are being viewed as local co ordinates N values and orthometric heights of points can never be viewed when points are being viewed as WGS84 co ordinates Using WGS84 Geoid Models In particular the use of WGS84 geoid model
75. ng e Creation and archival of RINEX observation files e Support of other exter nal devices like Meteo or Tilt sensors e Perform all operations highly automated with out any user interaction required A monthly newsletter on System 500 GPS 01 26 September 28 2001 To provide a highly reliable permanent reference opera tion requires a more rigorous definition of the complete infrastructure as compared to a field reference Site monumentation must be precise stable and highly durable The site co ordinates are typically to be known pre cisely in local and global ref erence frames with known fixed transformation parame ters between the two The most popular global reference frame is the Inter national Terrestrial Reference Frame ITRF which has been defined in different years and epochs Power supply for all equip ment must be guaranteed and sufficiently protected against failures and outages Depending on the location further protection may be required against vandalism theft and electronic surge Access to data must also be available Depending on the users of the reference station data this may be simply by direct or remote access to the PC or may also be expanded to Internet or FTP data distri bution All this requires addi tional infrastructure on the reference station which an operator has to consider Networks of Reference Sta tions Organisations that are re sponsible fo
76. ng you have already imported the antenna records from the NGS web site as described earlier Firstly copy the antenna you need from the Antenna Man agement component of SKI Pro into the Antenna tab view of the project where the RINEX data was imported This is easy to do by dragging and drop ping the antenna as shown in the screen shot below iE Project Sample PP Vertical offs FD Antennas TRAM33429 00 GF O 000 GALFGAL O 000 Go O 000 A AT502 Tripod 0 36 AT502 Pole 9 SA299 399 Internal GALFGAL Go Secondly within the Data Processing tab view of the project right click on the inter val on the point you wish to edit and choose Properties In the Interval Properties dialog box you can now select the correct antenna The data can now be proc essed with the correct antenna assigned to the appropriate measured data etca Geosystems Remember e It is possible to use 3 party receivers and anten nas with both real time in the field and during post processing with SKI Pro It is Important to ensure that the correct antenna re cords are being used both in the field and in SKI Pro If you are unsure why an tenna records are so impor tant then read Newsletter 01 12 again If the correct antenna rec ords are not used then it is possible that both the field system and SKI Pro may have problems resolving ambiguities It is possible to listen to Trimble ra
77. nter an attribute value within this range e Default value all attributes can be assigned a default value This means that when the at tribute is used the default value iS presented this can be useful if the user mostly enters the Same attribute value for a par ticular attribute Of course the default value can still be changed Attribute Attribute Type Value Type Value Region An Example We have been asked to sur vey a plantation area where many new trees have been planted The client has asked us to collect the following in formation about the trees e The Condition Either living or dead Since we have been asked to only surveying living trees this can be fixed to living Thus the attribute Condition is fixed to the value living e The Species The trees area mix of pine fir ash and some others but mostly pine Thus the attribute Species is a text choice list containing the choices pine fir ash and other but with the default being pine e The Height The client wants trees only between 0 5m and 2 0m tall to be surveyed Thus the attribute height is a range allowing real values to be en tered between 0 5 and 2 0 Our Codelist Our CAD package interprets a point coded with the code 201 to be a tree this code is as signed to the vegetation layer as shown here The attributes we assign to this code use the features just described and as shown below 4 Example ae Vegetation
78. o be reduced Adjustment is a qual ity control tool which helps to identify errors from ob served data It is also a quality as surance tool when used in design mode prior to col lecting data Various statistical tests are provided to assist the data snooping process but all test results must be con sidered together with user interpretation Build up large net works step by step con ducting free adjustments to help locate errors Export class Adjusted to ensure that the best co or dinates are exported etca Geosystems GPS Newsletter SKI Pro Ideas for Future Newsletters If you have any ideas or wishes for topics that you would like to be discussed in a future newsletter please contact your local selling unit or representative These ideas can then be passed to Heerbrugg Thank you Seica Geosystems matthew amor leica geosystems com Mixing Leica and 3 Party GPS Receivers It is becoming increasingly common for GPS users to use GPS systems manufactured by different GPS suppliers One reason for this is that a previous 3 party GPS user has now bought Leica System 500 and wishes to use the better system the Leica as the rover and his old GPS system as the reference Another reason is that many construction proj ects will use one or more ref erence station to cover the whole site which may or may not be Leica but the site sur veyors wish to
79. o have differ ent values Antenna Type SR299 399 Internal Horizontal Offset 0 0000 m Vertical Offset 0 0000 m Height Reading 1 4060 m Measurement Type Verica Total vertical Height 1 4060 m Why the difference The Use of Antenna within System 500 For all antennas within Sys tem 500 Leica introduced a new standard Antenna Me chanical Reference Point MRP which is always at the bottom of the antenna see chapter 2 11 1 of the Technical Reference Manual for further details All System 200 300 and 500 antennas were then calibrated against one reference antenna the Dorne Margolin Type T antenna which has become an industry standard Amongst others this has the advantage that antenna cali brations from different or ganisations often found on the Internet can also be used because they typically refer to this antenna The results of the calibra tions of these antennas are stored in the SKI Pro Antenna Management and on board the System 500 sensors Whenever data from a Leica antenna is imported the an tenna type is automatically recognised and the corre sponding elements for that antenna are automatically used for all processing tasks The Use of Antenna within System 200 300 The definition of the MRP is different compared to how System 200 300 and SKI 2 3 behaved Within System 200 300 the Internal SR299 SR399 antenna was used as the reference an tenna due to the fact tha
80. odels with respect to this standard antenna These correction models have been derived in collabo ration with the Astronomical Institute of Bern Additional antenna correction models of other manufacturers referring to the same reference antenna can be downloaded from the web page of the Bern Univer sity ftp ftp unibe ch aiub BSWUSER GE N and then directly imported into SKI Pro Other sources for antenna models are the NGS web site http www grdl noaa gov GRD Hem Import ii di file Modify Delete DEL Save Ag Print Ctrl P Find Properties bernhard richter leica geosystems com where also correction models for most common antennas are available and can also be imported into SKI Pro Both correction models use the Dorne Margolin T as ref erence therefore the models from the two sources can be mixed When mixing antennas it needs to be checked whether the same standard reference antenna is used or not Re member the best choice would be to use correction models of the same field cali bration never mix models which refer to different refer ence antennas Absolute Calibrations The second group of PCV calibrations are absolute which define the phase centre correction variations in an ab solute sense Usually abso lute calibrations make use of artificial signals in anechoic chambers A different method to derive absolute calibration models was developed by G
81. of a country is always changing new roads and houses are being built other buildings are demol ished even relatively small things such as the position of a post box being moved all these changes need to be sur veyed Clearly the NTD then needs to be updated with these newly surveyed fea tures Updating the NTD Obviously it is desirable that the NTD can be updated as soon as possible once the surveyor has completed his work in the field in this way the maps of Great Britain are as up to date as possible The most efficient way for OS surveyors to update the NTD is to actually update the NTD in the field This is of course impossible the whole NTD is too large however OS sur veyor can do the next best thing At the start of the day an OS surveyor knows in which area of the country he will work and will download the relevant part of the NTD in effect download a section of the map into his Penpad computer The Penpad runs a software called PRISM which was specifically developed for OS Basically this software allows the surveyor to view the map of the area in which he is working as he works He can then actually survey the new roads buildings and post boxes with System 500 updating and creating the new map as he works At the end of the day this updated map is uploaded back into the NTD and another part of the British maps has been updated The System 500 sensor sends the surveyed co
82. on the PC card then insert the PC card into the sensor and choose 04 Antenna Info from the TRANS FER Menu panel This will transfer the antenna from the PC card to the sensor system RAM Finally it is just needed to edit the configuration set Ac cess the CONFIGURE Real Time panel and choose the TRM33429 00 GP antenna as the Ref Antenna The Ref Sen sor should be set to Unknown RA Time Data Rover Data Formats CMR CMR Port 21 Pacific Cres Ref Sentor UAE Aowr Ref Antenna TRMS3429 88 6GPF Use Phase YES Radio Down Don t Log Obs r CONT L ECE The Leica rover is now able to apply the correct antenna PCV values to the RTK reference sta tion data RTK Messages The Leica SR530 can receive most of the common RTK mes sage data formats broadcast by most RTK reference stations including RICM messages 18 19 20 and 21 and the Trim ble CMR RTK message Choose the correct Data For mat in the CONFIGURE Real Time panel Note that with RICM mes sages it is also possible to choose the RTCM Version and the number of Bits Byte by choosing F6 RTCM in the Seica Geosystems CONFIGURE Real Time panel This may need to be config ured for some reference sta tions It is possibly interesting to know that the option to trans mit RTCM RTK messages on most Trimble receivers is an option which needs to be pur chased RTK Data Link The RTK data link used by the 3 par
83. only To check this Select GPS Position to open you need to have your mobile the GPS Position window Select device hooked up to your PC the Satellite Status twice to with a cable and ActiveSync show the Compass The Com Use the Windows explorer to pass shows the direction with Ideas for Future New sletters If you have any ideas or wishes for topics that you would like to be discussed in a future newsletter please contact your local selling unit or representative These ideas can then be passed to Heerbrugg Thank you Seica Geosystems jian zhou Leica GPS com GPS Newsletter Reference Stations Welcome to the application of GPS Reference Stations and Networks This is the first newsletter to discuss the GPS permanent Reference Station applications It should be useful for users who already operate a GPS Reference Station and those who have yet to discover the benefits Most GPS applications require a Reference Station When talking about GPS posi tioning with an accuracy of better than 5 m it is obvious that a reference station needs to be used The reference sta tion provides the user with the required data for differential processing of the rover data be it in real time or off line in order to achieve the desired accuracy Today most people working in survey or GIS data acquisi tion with GPS daily set up their own reference station in the field What more and more people and org
84. ou have to ensure that your device is found On your desktop PC open ActiveSync 3 1 and under the File menu choose Get Con nected and let the wizard run its course If all the cables are con nected securely and Windows has already identified the USB port on Pocket PC See your user manual for more details you re in business If you are running Windows NT which does not yet support USB you need to connect via a senal cable In the dropdown box for the PC connections on your IPAQ you will need to make a new connection Set the Baud Rate Select Advanced to be sure that connection preferences are the following Data bits 8 Parity None Stop Bits 1 Flow Control Hardware Test the connection from Ac tiveSync 3 1 If the connection fails make sure that the serial cable is securely connected to the desktop PC and review the configuration settings Some times you may also need to lower the baud rate i e from 57600 per second to 19200 bit or lower per second Getting Started with GS5 GS5 1 Connect the antenna ca ble to the antenna and battery holder 2 Insert two GEB 121 bat teries into the battery holder 3 Place the battery holder in the upper pocket portion of the backpack The antenna cable and the DB9 cable should come through the bottom portion of the pocket 4 Connect the DB9 cable to the iPAQ with iPAQ supplied cable 5 Set up the ArcPad to re ceive NMEA data from the GS5 GS5
85. our best co ordinates and store these results If now the point you used as a reference in your RTK job also was reference during your post processing then a reference triplet will al ready exist in your project This is likely to be different to the HERE position When you then import the RTK job SKI Pro will create a new point ID Refer ence 2 for that point as the reference triplet has to be unique However since version 2 0 you are able to change the reference triplet without delet ing the baselines SKI Pro will then apply the corresponding shift to all rover points which are connected to that reference Adjusted and Control After performing an adjust ment an additional triplet of class Adjusted is added to the database Note that only one adjusted co ordinate can exist which means that adjusted co ordinates will be overwritten by another adjustment run Control is the highest class and is used to hold points fixed in a constrained adjustment Points can be fixed in either position height or position and height Geosystems Note that also for points which have a Control triplet stored an Adjusted triplet is created after storing the ad justment results This is impor tant for example if you are holding points fixed in position only The Adjusted triplet will then inherit the fixed position but will have the adjusted height It is therefore recommended that after an adjustment in vol
86. oving a mass of points are not collected in the same location The quickest way to collect the points may be to attach the antenna to the roof of a car or other vehicle Remem ber then that you must meas ure the height of the antenna above the ground and enter this as the moving antenna height It is likely that you only wish e Better control over the starting and stopping of the logging of auto logged points e To code auto logged points e To see auto logged points in Point Management e To export auto logged points with a format file on the sensor Is this now possible with v3 firmware V3 Improved Control If you now choose to log auto positions then a new F3 AUTO button will be seen in the main SURVEY panel Pressing this button takes you to the AUTO POS panel Point Id Point Code f 00 2 2 2 2 2 2 Code Name Ant Height 2 888 M oD Quality A d mM In this panel you can use F6 STOP START to stop and start the collection of auto logged points change the moving antenna height and see the point ID of the auto logged points and the number of auto logged points that have been collected since pressing start does not start until you press Start as described above If Immediate is chosen then auto logging starts as with v2 firmware as soon as the SURVEY panel is entered V3 To DB Or Not To DB In the CONFIGURE Position Logging panel it is now also possible to choose
87. pa rameter allows the distance to the first grid point along the reference line to be defined The Horz and Vert Offset de fines the horizontal and verti cal offset from the reference alastair green leica geosystems com panel as XXXX XXX YVYVYVY YYY where X is the distance along the reference line and Y is the horizontal offset from the line This point can be staked out in the normal manner If this point is then occupied the suggested point ID for this point is as described above If you wish to use a different point Id for this point press SHIFT F3 PT ID to toggle be tween another point ID relat ing to the line or press SHIFT F3 PT ID again to use the cur rent point Id as defined in the point ID template After having staked a point you are then moved to the next point in the grid to be staked along the line Stake Out the Next Line When all grid points on that line have been staked out then it is needed to stake out the next row of grid points Now press F4 CURST which means that you will now stake out relative to the current sta tion the current station being the last grid point you have staked out Skipping Points It may be that it is not physi cally possible to stake out every grid point It is therefore possible to skip points if necessary In the line definition panel press SHIFT and then choose F3 STAT or F4 STAT to skip a point and move up or down to th
88. ped No ellipsoid could ever accurately repre sent the true shape of the earth Somehow we need to be able to convert between ellip soidal heights either local or WGS84 ellipsoidal heights and orthometric heights This can be achieved by using geoid models Orthometric heights and geoid models are described next week Remember e An ellipsoidal height gives the height of a point above the ellipsoid e t is possible to have both WGS84 ellipsoidal heights and local ellipsoidal heights Seica Geosystems Ellipsoidal and Orthometric Heights and Geoid Models This weeks newsletter con tinues on from last week and discusses orthometric heights and geoid models next week it will be shown how geoid models are used in SKI Pro The Geoid and Orthometric Heights Last week it was described that an ellipsoidal height is the height of a point above the WGS84 or local ellipsoid An orthometric height can be similarly described it is the distance of a point above the Geoid measured along the plumb line through the point This sounds straightforward but first we must define what exactly is the Geoid Is it the shape of the ground on which we physically walk Or is it some other surface And then a big question to answer how can we measure orthometric heights with GPS The Geoid In geodetic terms a geoid is a gravitational equi potential surface which roughly coin cides with the global ocean sur
89. perated permanently or on an as needed basis but with fixed installation De pending on the area this may also be two three or more in dividual stations But also local state and na tional organisations in many parts of the world are now be coming increasingly interested in setting up networks of GPS reference stations frank pache leica geosystems com Reference Station Schemes Single site system A single GPS sensor is set up with a PC at the GPS site location All data is stored and managed locally at the spe cific site A radio or GSM may be connected to provide RIK DGPS data Direct serial connection provides sensor to PC communication GPS Y Faa Serial Link PC ControlStation Picture 1 Single Site Several of such single sites may still be interconnected to one central location for e g remote control and data ac cess This may be by means of a computer wide area net work or using telephone mo dems to access each GPS sensor co located PC Central Station RTK Data Multi Site Central System semi permanent connection At the reference station sites only GPS hardware is installed and GPS raw data is logged inside the sensors internal memory A radio or GSM may be connected to provide RTK DGPS data PCs are not required at each site Receiver control and GPS raw data archiving is based at a central location The central station computer is con necte
90. plays a GIS theme layer data structure codes referenced shapefiles images and documents e Waypoint Manager Allows the creation of GIS waypoints via co ordinate input graphi cal selection and import of shapefiles Waypoint data includes attribution as well as position Very useful for in ventory inspection and moni toring of infrastructure assets e Feature Browser View and edit attribute information on selected objects Tools GIS DataPRO offers many tools familiar to SKI Pro users and tools unique to DataPRO Codelist Manager This allows the user to define point line and polygon feature codes as well as their attribution Fields can be defined by a range a picklist or manual entry Fields can also be specified as man datory to ensure you get all the information the first time Co ordinate System Manager Allows custom co ordinate systems datums transforma tions projections and geoid models to be defined These are used to convert GPS data stored in WGS84 co ordinates to more useful local grid co ordinates These systems can be used to transform the shapefile for ASCII and CAD export or simply for transfer to the sensor Sensor Transfer Allows co ordinate systems jobs code lists antennas and waypoint files to be up or downloaded to a PCMCIA card or to the GS50 Sensor via RS232 cable Workflow Manager Unlike a brute force batch file the Workflow Manager allows the user to set up
91. pproach is that it is limited to areas of about 10km square This is mainly because no projection scale factor is applied and to compute the preliminary WGS84 grid co ordinates a standard IM projection is used How big can the errors grow if the area is extended This is very hard to answer and mainly depends on how quickly the scale factor of the local points change within the area However the errors may sometimes quickly reach sev eral centimetres Heights may also no longer be accurately modelled with the plane approximation This problem can be resolved by using a local geoid model gerhard walter leica geosystems com GPS Newsletter General A one page weekly newsletter on System 500 GPS 01 09 March 05 2001 Use of geoid models is dis cussed in detail in a future newsletter Transformations in General Regardless of what trans formation type is used there are a few guidelines which should always be followed 1 Firstly and most impor tantly is the distribution of the common points Ideally the common points should sur round the area in which you want to apply the transforma tion Do not extrapolate trans formations too far outside the area covered by the common points 2 A Onestep transformation can be used with only one common point Note how ever that such a transforma tion cannot correct a local grid which is not rotated to the true Geodetic North and addi tionally no scal
92. r each point Using one of the other classes will enforce that only the se lected class is exported Deleting Triplets You can remove co ordinate triplets from the SKI Pro data base using the context menu in the View Edit screen Se eee etn Her aia an Delte do Fon i Inberal l R l iarca Edi riiva Note that deleting an aver aged co ordinate will also re move all measured co ordinates and the correspond ing baselines Deleting a point of the point class Reference will remove all baselines derived from that point as well This ensures that data integrity is maintained You can also remove triplets for more than one point at once To achieve that you have to select the points in the View Edit screen and then se lect Edit Delete Triplets from the main menu This can be useful if you want to re move for example all Control points or all adjusted solutions from your project Geosystems GPS Newsletter SKI Pro Ce ee Jei jang pee pe ee ja Le fos aj fie amp wd Note that the actual point is only removed from the data base when deleting the last existing triplet Only then the raw data for that point would be removed as well The next paragraphs explain the different point classes in more detail Navigated SPP and Estimated When GPS raw data is im ported the points will be as signed the point class Navigated This is the navi gated uncorrected code solu t
93. r several requests from customers it is now possible to lock the keyboard of the TR500 use ALT then L to lock and unlock But remember that it is even better to simply remove the TR500 from the sensor the sensor will continue to func tion as normal Remember e V3 firmware not only con tains big features such as the new RIK but many small features which will also im prove your use with System 500 e Many new features come from ideas from existing Sys tem 500 users e ALL new features are fully explained in the Release Notes eca Geosystems The Ordnance Survey Earlier this year the Ord nance Survey Great Britain s national mapping agency and Leica Geosystems signed a partnership agreement This contract involving Leica Sys tem 500 GPS is one of the most significant orders ever won by Leica Geosystems This newsletter outlines the history and describes some of the work of the Ordnance Survey OS and next weeks newsletter will focus on the use of System 500 GPS within the OS A Little History The history of the OS goes right back to the year 1791 a time when Britain feared in vasion from Europe after the French Revolution As in many other countries the foundation of mapping agen cies was linked with the mili tary need for good maps publication of first map by the Board of Ordnance was on 1 J anuary 1801 In 1983 Ordnance Survey became a wholly civilian or ganis
94. r surveying tasks over larger areas may want to install more than just one permanent station In these cases establishing a network of reference stations linked etca Geosystems GPS Newsletter Reference Stations together in just one central location may be favourable There are several steps to re alise this From very simple solutions up to complex real time networked systems In terms of traditional sur veying reference systems net works of GPS reference sta tions can be referred to as ac tive networks as opposed to traditional passive networks using e g triangulation meth ods to establish and maintain survey control Modern state of the art ac tive networks of GPS refer ence stations may ultimately replace at least reduce the need for the traditional survey marks and networks This will lower the efforts and cost in volved in the establishment densification and maintenance of the traditional survey net works Who would be interested in GPS Reference Station or Network operation As can be seen from the ap plications listed above many organisations may be inter ested in setting up permanent GPS reference stations or net works of reference stations Within the traditional Leica customer base there are first of all the surveying and engi neering offices which may want to install a permanent station for their own use These are typically individual stations o
95. r you need to export data in the GSI16 or Sokkia SDR33 format simply choose the appropriate export template All export settings for that template are then used Remember e Data can be output form the sensor or SKI Pro in most common data formats by us ing a format file e Use export templates for commonly used format files and export settings within SKI Pro feica Geosystems GPS Newsletter SKI Pro A one page weekly newsletter on System 500 GPS 01 04 January 29 2001 Staking Out Grids We once had a report of a System 500 customer who had won a contract to stake out the positions of hundreds of small bore holes over a proposed landfill site These bore hole positions were at regular 20m grid spacings over the site He was given the co ordinates of the cor ners of this grid and was told to work out the co ordinates for the rest of the points and then stake them out He computed the positions of all the bore holes and transferred all the points into a job on the sensor He then staked out all positions as in dividual points using the normal Point Stake Out rou line to the first grid point The Station Inc parameter allows the increment between grid points along the reference line to be defined in this case this is 20m SE Defined Reference Line D Distance to Station Begin H Horizontal Offset VY Vertical Offset l Increment Upon returning to the STAKE OUT Grid panel the
96. re includes a comprehensive online help to support advanced operations All types of data devices supported with System 500 can be used for real time data distribution This includes also the dual use of GSM and radios attached to the two available output ports In addition solutions for service providers that want to supply RTK via GSM only but require multiple users to receive the data are avail able For this kind of applica tion Data Broadcasting de vices can be used to connect n GSM modems to one GPS receiver s real time out put port ControlStation on every System 500 CD For all Leica System 500 us ers who wish to try the Con trolStation software it is in cluded on every System 500 SKI Pro CD ControlStation can be installed from this CD and can be run in demo mode if no activated security protection key is attached ControlStation demo mode allows the user to explore the site set up and sensor con figuration All status informa tion panels are available Only data logging and download operations are protected etca Geosystems Remember e Transmit data for RIK e Supports non survey GPS Reference Stations and and GIS rovers applications such as active Networks can be used weather forecasting i e Transmit DGPS for many O precise navigation appli e Provide local state or na cations tion wide geodetic con e Monitor movements of trol fault lines volcanoes e R
97. rns a value of 46 584m this is the difference between the geoid and the WGS 84 ellipsoid at this particular point This value of 46 584 is applied to the WGS84 ellipsoidal height which results in an orthometric height for this point of 391 083m The user now chooses to view the points as local co ordinates within the project The local ellipsoidal and orthometric heights are seen but the geoid separation is shown as 72 549 This is quite correct because as already stated the local N value is only ever shown and this is computed as the differ ence between the local ellip soidal and orthometric heights Thus 463 632 391 083 72 549 Remember e Geoid separations are only computed on demand or dur ing the export of points e Geoid separations are only shown when viewing local co ordinates in the points tab view e Geoid separations com puted from a WGS84 ellipsoi dal model are transformed and displayed as local geoid sepa rations Seica Geosystems A GPS Newsletter General The Newsletters It was just over a year ago that we produced the first GPS newsletter Over this time we have cov ered may aspects of System 500 and SKI Pro and also cov ered more general GPS related topics Hopefully you have enjoyed reading the newslet ters and just as importantly you have found them worth while to read We now plan to change the format of the newsletter Be ginning at the end of this month
98. rs 3 GPS Newsletters 2001 Index Index of Newsletters 2001 01 01 Sensor Using Two or More Reference Stations 01 02 SKI Pro Handling of System 200 300 Antenna 01 03 SKI Pro Flexible Data Output 01 04 Sensor Grid Stake Out 01 05 GIS GIS DataPRO 01 06 Sensor RTK 1 01 07 Sensor RTK 2 01 08 Transformations Classic 3D 01 09 Transformations Onestep 01 10 Sensor GSM 01 11 Sensor Auto Logged Points 01 12 General Antenna Phase Centre Variations 01 13 Sensor v3 Firmware 1 01 14 Sensor v3 Firmware 2 01 15 General Ordnance Survey 1 01 16 General Ordnance Survey 2 01 17 General Post Processing 1 01 18 General Transformations Twostep 01 19 General Heighting 1 01 20 General Heighting 2 01 21 General Heighting 3 01 22 General SKI Pro and Firmware CD 01 23 SKI Pro Point Classes and Triplets 01 24 General Coding 01 25 GIS GS5 GS5 and ArcPad 01 26 General Reference Stations 01 27 SKI Pro Adjustment 01 28 General Mixing 3rd Party GPS 01 29 General Sys500 Accessories etca Geosystems GPS Newsletter Sensor A one page weekly newsletter on System 500 GPS 01 01 January 08 2001 Using More Than One Refer ence Station In the last newsletter practi cal field procedures were de scribed on how to use more than reference station for an RTK survey This newsletter describes why a user may want to
99. rward procedure for both free coding and the matical coding Remember with free coding more than one code can be stored in be tween surveying points This then allows that operation codes for example in LISCAD to be used where multiple code entry is needed Thematical coding however means that only one code can be stored with one point which as described earlier is the whole philosophy of the matical coding When choosing the code free or thematical it is always pos BHA RE HEEF IDUL es Point Ig Point Code i Code Name Species Pet Sarit sible to see the code description this is why it is useful to use meaningful code descriptions fo PIE RIE HL Living trees Pine T E a BEA DEFLT COLEAF Also remember to always use the search facility when choosing a code this is par ticularly useful with large code lists Highlight the Code line or Free Code line if free coding and then press the first character of the code you wish to use This Fase Hater Ifcpect Cover Agad CL Pade of Bisck CONT HEH ee then opens the code list box panel revealing all codes and places the focus on the code that begins with this letter The cor rect code can then be selected with FI CONT It is worth describing other functionality and features in the code list box e F2 NEW allows new codes to be added to the code list in cluding attributes if needed
100. s The different stages of the conversion process are best summarised below using the buttons from the co ordinate toolbar in SKI Pro A Classical 3D transforma tion consists of up to 7 pa rameters 3 shifts dX dY dZ 3 rotations Rx Ry Rz and a Coordinate Format x uel OR Projection oordinate Format ua OE The route from WGS84 Geodetic co ordinates to Local Grid co ordinates and back coordinate Format Bae WGS84 i Local Ellipsoid T PE E Ellipsoid Coordinate Format x 84 eet 1 QE coordinate Format ual OR WGS84 Co Local Co ordinate ordinate Side Side gerhard walter leica geosystems com scale factor These parame ters describe the different origin and the different orien tation of the Local Reference Frame with respect to WGS84 To calculate all 7 parameters at least 3 common points have to be known in both WGS84 and local co ordinates and you must be able to com pute the WGS84 and local Cartesian co ordinates for these points Points surveyed in the field are stored on the Sensor as WGS84 Geodetic co ordinates and it is trivial to compute the WGS84 Cartesian cO ordinates Local co ordinates are typi cally entered as local grid and knowing the ellipsoid and the map projection on which the Local Grid is based the local Cartesian co ordinates can be computed Note that they must be known in position and height to be able to get to local Cartesian co ordin
101. s is some times not fully understood the following information may help e Even if a WGS84 geoid model is being used N values and orthometric heights of points can still only be viewed when points are being viewed as local co ordinates e When using a WGS84 geoid model the N value that is dis played is always the local N value that is the difference between the local ellipsoidal height and the orthometric height This value is unlikely to be the same as the computed N value from the WGS84 geoid model This is initially difficult to un derstand and is worth ex plaining further Imagine a co ordinate system containing a transformation the Bessel el lipsoid projection and a WGS84 geoid model which is alastair green leica geosystems com A one page weekly newsletter on System 500 GPS 01 21 May 28 2001 attached to a project Surveyed points are then imported into the project Immediately after import the WGS84 and local co ordinates including the WGS84 and local ellipsoidal heights of the points can be viewed in the points tab view of the project For example point 9001 has a WGS84 ellipsoidal height of 437 667 and a local ellipsoidal height of 463 632 remember these are the heights of the point above the surface of the corresponding ellipsoid The user then chooses to com pute the geoid separations using the WGS84 geoid model as defined in the co ordinate system The geoid model re tu
102. sed in a future newsletter please contact your local selling unit or representative These ideas can then be passed to Heerbrugg Thank you charlotte heinz leica geosystems com Geosystems
103. stair green leica geosystems com these possible solutions is correct this is known as an ambiguity search routine Many many papers have been written about ambiguity search routines all with the same goal to find the correct How can we be even more certain of having found the correct ambiguities To be Continued Next Week etca Geosystems GPS Newsletter Sensor A one paqe weekly newsletter on System 500 GPS 01 07 February 19 2001 RTK Did You Know This newsletter continues from last week with the ques tion How can we be even more certain of having found the correct ambiguities The answer is that System 500 performs the same ambi guity search routine a second time Immediately after having completed the ambiguity search routine and computed the most likely ambiguities with one set of GPS observa tions the rover then repeats the whole ambiguity search routine again using a different set of GPS observations This leads to a second set of ambi guities The ambiguities computed from this second search rou tine are then compared with the ambiguities computed from the first ambiguity search If the two sets of am biguities are identical then the ambiguities are consid ered to be correct and an RIK position to cm accuracy is computed on the rover It is at this stage the sensor beeps the icon changes to show it has a high precision navigation phase solution and t
104. t at that time no standard an tenna such as the Dorne Mar golin had established its place as an industry standard When measuring in the field with System 200 300 it is never known whether the data will be processed with SKI 2 3 or with SKI Pro or both When data collected with System 200 300 is imported into SKI Pro a correction has to be applied to account for the new Antenna Reference gerhard walter leica geosystems com Point This is done automati cally after assigning the data In the above example the following happens The antenna is recognized as the SR299 399 Internal The new Vertical Offset is 0 000 and the Height Reading has changed to 1 406m These changes are made due the difference in the antenna definition between System 200 300 and System 500 The value 1 406 is calculated from 1 056 0 441 0 091 1 406 where the mi nus 0 091 is the correction for this antenna to move the MRP defined within System 300 to where the MRP is defined with in System 500 This value is the difference from the old to the new refer ence point This correction together with the new definition of the SR299 399 Internal antenna stored in the SKI Pro Antenna Management leads to correct results Antenna height readings wrongly entered in the field can be directly corrected in the Assign dialog during im port If the data has already been imported then simply change the new height read ing
105. tenna Height test This test is always computed if GPS baselines are included in the network The test consists of separate W tests for the East North and Height residual components The antenna height is only rejected if the height component is rejected and the east and north com ponents are accepted Interpretation of the tests As already mentioned the data snooping investigations should mainly take place when performing free net work adjustments In addition especially where large net works are concerned it is good practice to build up the network gradually and ana lyse the network step by step rather than attempt to identify potential errors after all ob servations have been imported This is because the general testing concept is based upon the hypothesis of detecting a single error In a situation where many errors are present it is difficult to identify the specific errors because the errors tend to get spread by the least squares process In general with all testing results you must also keep in mind that all tests are based upon a certain degree of probability The tests only suggest where outliers may exist they do not categori cally state that an outlier does exist In the end it is the re sponsibility of the surveyor to combine the adjustment tools with other information drawn from experience common sense and other external in formation when deciding whether to reject observations from a ne
106. the rover Consequently the overall radio range increases Repeaters from Satelline fit into the Leica housing GFU5 Those from Pacific Crest fit into the GFU6 housing Picture 6 Repeater Box With the Repeater Box GHT38 the GFU5 and GFU6 charlotte heinz leica geosystems com housings can be attached to the tripod The power supply for the radio modem is en abled with an external battery and a cable connected to the repeater box Picture 7 Repeater set up with Repeater Box 3m antenna pole For difficult fieldwork condi tions many customers ask for a 3 m antenna pole You can not purchase one directly but be flexible and create your own 3 m Antenna pole Normally you will work with a 2 m antenna pole consisting of a bottom section and a top section For the aluminium pole this is the GLS17 plus GLS 18 For the carbon fibre pole it is the GLS20 plus GLS 21 Additionally if you prefer a top section pole with stub GLS19 or GLS22 you need the GAD31 screw to stub adapter to work with an antenna pole of exactly 2 000 m For a 3 m antenna pole you will just need an additional top section pole with 5 8 screw GLS18 or GLS20 Place that 1 m long extension element between your bottom Seica Geosystems a GPS Newsletter General E _GLS18 GLS21 i E GLS17 GLS20 Picture 8 3 m antenna pole Season Greetings and top section and you can continue
107. the time taken still further to resolve ambiguities and ob tain cm positions but still re tain the high reliability of this solution We will soon be re leasing v3 00 firmware for System 500 try it and see Remember e System 500 RTK is the fastest and most reliable RTK available today e Before cm accurate posi tions are available ambigui ties are fixed twice to give the highest reliability e After fixing ambiguities the ambiguity search routine is continually repeated e Other RTK systems may occasionally solve ambigul ties quicker but are the re sults reliable etca Geosystems GPS Newsletter General GPS A one page weekly newsletter on System 500 GPS 01 08 February 26 2001 The Classical 3D Transformation Leica System 500 offers dif ferent kinds of transforma tions between measured WGS84 co ordinates and Lo cal Grid co ordinates This newsletter discusses the Clas sical 3D approach which can be used both in SKI Pro and on the Sensor Remember the facts Look back to the Newsletters 00 20 and 00 21 They ex plained the conversions be tween different co ordinate types e A map projection is needed to convert between Grid co ordinates and Geo detic co ordinates e An ellipsoid is needed to convert between Geodetic and Cartesian co ordinates e The Classical 3D transfor mation provides the link be tween the WGS84 Cartesian and the Local Cartesian co ordinate
108. the vertical offset of 0 3600 m bottom of height hook to base of thread of the carrier refer to the base of the thread of the Leica carriers The height of a carrier is 145 5 mm This means that the dif ference of 0 0505 m between the TPS tilting axis height and the carrier height must be taken into account The best remedial action is the defini tion of a new antenna type with a vertical offset of 0 0505 m Create the new antenna type in SKI Pro It is only here that the phase centre eccentricities are taken over when copying an antenna type definition Defining the antenna type on the sensor does not copy the eccentricity values and will therefore lead to wrong re sults Contents Name amp Antennas AT201 fa AT201 AT202 302 H E 47202 302 47202 302 GP H E A4T202 302 GP AT303 Q AT303 AT501 ATS01 AT501 Pole m AT501 Pole AT501 Tripod H E AT50 Tripod E AT502 AT502 4 AT502 Pole AT502 Pole H E AT502 Tripod AE Tripod 4 AT502 Height Meter AT502 Height Meter Picture 3 Antenna Management for creating a new antenna type in SKI Pro To create the new antenna in SKI Pro go to the Antenna Management In the Report View right window highlight the appropriate antenna e g AT502 Tripod Copy and paste then rename the an tenna with a meaningful Seica Geosystems T GPS Newsletter General name like AT502 Height Me 1 ter Right click
109. tment component can be used to design a net work and thereby give the surveyor an indication of the expected precision which can be achieved in advance As such Adjustment can also assist with Quality Assurance measures before a survey is done Adjustment is a tool which helps to prevent costs associ ated with poorly designed networks or undetected er rors In addition of course it pro vides the process through which you can determine the best coordinates from the data The Mathematical Model SKI Pro uses the powerful MOVE3 adjustment kernel This is a fully rigorous three dimensional model The model has the advantage that it is not necessary to reduce any of the observations be fore they can be used the observations which are ob served are those which are entered into the adjustment This ts particularly tmportant because it means it is also not necessary to convert the sto chastic information which accompanies the observa tions It should be noted that the stochastic model is equally important as the mathemati cal model The mathematical model describes the relation ship of the parameters co ordinates to the observa tions The stochastic model describes the relative weights or precisions of the observa tions A least squares adjustment is performed in which the observations are adjusted in order to minimise the sum of the squares of the weighted observation residuals It shoul
110. to store auto log points to the DB Da taBase If you choose YES then it is possible to code auto logged points to see the auto logged points in the Point Manager and to export auto logged points using a format file If a codelist is configured to be used then codes and up to 3 attributes can be attached to the auto logged points Ac cess the codelist and enter attribute values using exactly the same procedures as for normal occupied points AUTO POS RT Sample Auto Pt Ig Auto Pt Cog autogr r Code Mame Centre Line Mow Ant Hote 2 000 m ST Gualit y 0 29 m SUR JATRIE POS START So now for example it is possible to be coding the auto logged points as spot heights and collecting these points for AUTO POS AT ample Auto Pt Id to collect points of a certain accuracy for example only points of a phase cm accu the DIM model while collect ing and coding normal oc cupied points for all other aULOBLS Moy Ant Ate rate solution This is possible Positd 7 A i by st Monitor CO to YES sD Guality 2 55 m eyo a ills aris Pe Sun POS STOR a and entering an appropriate value It is also possible to set a beep for when each auto logged point ts collected But as useful as collecting auto logged points with v2 ox firmware was many custom ers still had additional wishes for when using auto logged points The most common wishes wer
111. twork One should also keep in mind that it is not the goal to get all tests accepted but to detect errors and correct or eliminate them where possi ble An observation or co ordinate should never be ed ited in order to make it fit better with the other data in the network unless there is clear evidence of the source of the error eg typing error It is also sometimes quite acceptable to retain observa tions which are marked as suspect especially if they only just exceed the critical value for the test Finally we have to keep in mind that depending on the level of significance there is always a chance of rejecting a valid observation Final results Once you are happy with your adjusted coordinates the next step is often to export them If the network contains control coordinates which are fixed in just position or height matthew amor leica geosystems com GPS Newsletter SKI Pro then it is recommended that you export the Adjusted class rather than the Main coordinates This is because the main co ordinates will choose the Control in prefer ence to the Adjusted co ordinates and the Control co ordinates may contain only approximate co ordinates for the parts that are not fixed Remember Adjustment assists in determining the best co ordinates from your data A fully rigorous three dimensional model is used which does not require the observations or stochastic information t
112. ty reference station will in most cases be a radio mo dem If the radio being used by the 3 party reference is a radio already supported by System 500 such as a Satelline or Pa cific Crest then simply choose this as the real time device Most Trimble reference sta tion set ups use a radio mo dem that operate in TrimTalk mode The Pacific Crest RFM96W needs firmware 5 06 and the Pacific Crest PDL radio modems can be configured to Operate in the TrimTalk mode This can be done by using the configuration software avail able from Pacific Crest You must also ensure that the Trimble reference radio and the rover radio are operating on the same frequency This can be achieved by changing the channel on the Pacific Crest RFM96W in the normal way with a System 500 sensor If the channel you require is not yet programmed into the RFM96W then you should con tact your local selling unit or dealer They will have software from Pacific Crest which allows the frequencies which are pro grammed into the radio mo dem to be configured OBSERVATION DATA SHABSS 1 TRH33429 88 6P Post Processing Raw observations collected by the 3 party reference station can be imported into SKI Pro in RINEX format It is necessary to first convert the data collected on the 3 party receiver using the 3 party s data converter As when using RTK with 3 party receivers and antennas at the reference station it is also important
113. u to connect virtually any device to the System 500 sensor and record the ASCII data being sent from the device as an annotation of a stored point Imagine you wish to com plete a survey of a small lake measuring the depth of the lake The depth sounding de vice is constantly measuring the depth and outputting this information as an ASCII string With v3 firmware it is pos sible to connect the depth sounder to the sensor and whenever a point is measured and stored the last received depth measurement is stored with that point as an Annota tion CONFIGURE ASCII InNet CRAY Depth Sounder This data can then be im ported into SKI Pro and the position and depth of all points measured over the lake and the depth of these points can then be exported But of course you can con nect other devices barome ters Geiger counters cable detectors bar code readers alastair green leica geosystems com Additional Laser Devices Supported System 500 now supports the Leica Vector binoculars and the replacement of the Vector the Laser Locator You can literally be a one man walking total station using these devices Additional GSM Devices Supported The Wavecom WMOD2 GSM device is now supported and fits into a normal radio housing As described in newsletter 01 10 it is simple to use GSM with System 500 and Ports Laser Locator LaserAce 3AA tLaser Atlanta tegt aor
114. uld give one set of co ordinates If it were to use the next correct set of ambiguities this would give another and different set of co ordinates If the system chose the wrong set of ambi guities then this would be clearly unacceptable for the surveyor basically you would be measuring points with the wrong co ordinates So how does the rover know which correct solution to use Rigorous statistical techniques are used to de termine the most probably correct solution and the second most probably cor rect solution These two most probable solutions are then compared and if the probability that the first solu tion is much more likely to be correct than the second solu tion then the first solution is taken as the correct answer And Then Do It Again So now we found ambigui ties that are considered to be most likely correct But we have already said that if we did have the wrong ambigui ties even after applying the statistical analysis to deter mine the most likely correct solution we would get the wrong co ordinates for the N reference is then sent to the Full wavelengths e rover rover over the data link from satellite 2 Full wavelengths from satellite 1 Using both the reference and rover observations and knowing the co ordinates of the reference the rover must now find the correct solution that is Compute the correct co ordinates of the rover The ala
115. uration page accessible in the Match tabbed view On the Sensor the Pre Transformation is selected in the COORDSYS Type Selec tion screen together with the ellipsoid and projection of the local points Any disadvantage The map projection has to be known otherwise the dis tortions of the projection could not be modelled This would of course restrict the area over which the transfor mation can be applied Also the same restriction for heights applies as for the Onestep Geoid models can of course be used with the Twostep transformation Remember e Applying Two ostep trans formations is not limited to smaller areas e Common points can be given in position and height in position only or even in height only e As with Classical 3D trans formations the Ellipsoid and the Projection have to be known to calculate a Twostep transformation A Pre transformation also has to be Geosystems A GPS Newsletter General A one page weekly newsletter on System 500 GPS 01 19 May 14 2001 Eflipsoidal and Orthometric Heights and Geoid Models One of the less well under stood topics of surveying with GPS or other survey instru ments is heighting and dif ferent height types What is the difference be tween an ellipsoidal height and an orthometric height What is a geoid model how is it used and what does it do This newsletters explains el lipsoidal heights next weeks newsletter will descri
116. use more than one reference sta tion and what would be the advantages Quality Control of Measure ments Using more than one refer ence station provides a very useful way to estimate and control the quality the points measured by the RIK rover The reference stations need to be set up such that the same area within which you need to work is covered by both reference stations As described last week the radio channels of each of the refer ences must be different By switching radio channels on the rover it is then possible to obtain independent solu tions from each of the refer ence stations This is then a thorough check of the quality and reliability of the RTK solu tion It may be that not all points within a survey need to be measured more than once from each of the reference stations but only specific control points within the survey This technique was used for the RT Sample data which is included on all SKI Pro CDs These control points should be measured with a solution obtained from each of the ref erence stations 3003 3044 If the point is given the same Point ID when measured from each reference station then an average co ordinate is cre ated for this point It is then possible to see in the field the co ordinate differences from each reference station and assess the quality of the dif ferent solutions for this point All individual measurements of points using the same point
117. use Leica Sys tem 500 as rover units Whatever the reason for mixing different GPS manufac turers equipment there are some guidelines which should be followed This newsletter describes some of the things that should be considered when using a 3 party GPS re ceiver and Leica GPS equip ment Antenna Newsletter 01 12 explained why it is important to ensure that the correct antenna mod els are used when using GPS This is necessary to ensure that the correct antenna char acteristics are used and in par ticular that the correct antenna phase centre variations PCVs are applied As described in that newslet ter neglecting to use the cor rect antenna models may reduce the systems perform ance possibly increasing the time taken to fix ambiguities or in some cases preventing am biguities to be fixed at all Imagine a user is using a Trimble 4700 as the reference with a Trimble Micro Centred antenna with Ground Plane s n 33429 00 As described in the 01 12 newsletter the correct antenna calibration file for this antenna can be downloaded from this NGS web site Note this web address has changed since Newsletter 01 12 http www ngs noaa gov ANT CAL Within this web site access the Complete Relative Antenna Calibration File This text file contains many calibrated anten nas Including the TRM33429 20 GP which is the antenna we need The easiest way to download this file is to r
118. veraged points allows co ordinate dif ferences to be viewed and as sessed e Using more than one ref erence station on a large proj ect can save a lot of time compared to moving a single reference station etca Geosystems 1 GPS Newsletter SKI Pro A one paqe weekly newsletter on System 500 GPS 01 02 January 15 2001 Handling of System 200 300 data with SKI Pro Antennas SKI Pro was designed to im port System 200 300 500 and RINEX data This newsletter explains how height readings and antenna offsets of System 200 and System 300 data are handled in SKI Pro An Example Imagine you were measur ing with a SR399 Internal an tenna using a tripod setup In the field you would have entered a height reading and an antenna offset into the System 300 Controller The height reading would have been the tape reading from the height hook say 1 056m and the antenna offset would have been a constant value 0 441m for this antenna and setup During Raw Data Import you can check these values in the GPS300 raw data properties dialog accessible from the An tenna tab of the Assign View Data dialog Gps300 raw data properties General Antenna Thematical Data Dictionar Height reading fi 056 m Antenna vertical offset 0 441 m After assigning the data to the SKI Pro project in the In terval Properties for that in terval you will see that the height reading and antenna offsets appear t
119. ving points fixed in posi tion only or height only the Adjusted class is chosen when exporting to obtain the best M ore information To read more about Point classes subclasses or co ordinate triplets you may check the Online Help J ust type Point Classes in the Index Also note that you can switch on the legend in the View Edit screen which gives a short ex planation what the symbols mean iiei ee Oe E Come 2D Ere comedies Peed ni poo ad et E Cyd 2 Breer okt fed ini pow E Com reer ccc Ped fini heh ce ipa i ee e a a EE nh ira Prince Vag ere Feal Fiai Bee nae oe ee GPS Newsletter SKI Pro Remember Any point in SKI Pro can have more than one co ordinate triplet Co ordinate triplets are organised in the hierarchy of Point Classes Only the point class Meas ured can comprise of more than one co ordinate triplet All other point classes are unique If a co ordinate triplet of the point class Reference al ready exists for a point it will be used again for sub sequent baselines to be processed or stored If not co ordinates ee yet existing the highest a Corea chert r Sarge Poi Perin oe J Krie Comite deed cong he ued oe Bama eget icin eh eb class is used to create a new reference triplet Control triplets are used to hold points fixed in an Ad justment Ideas for Future Newsletters If you have any ideas or wishes for topics that you would li
120. words Static and Rapid Static even though we have just said there is no definable difference This question is impossible to answer because it depends on the conditions under which the data is collected the length of the baseline being measured the number of satellites being observed the DOP of the sat ellites the rate at which the data is being collected the io nospheric activity etc However we do provide guidelines to address this question The table below is taken from the General Guide to Static and Rapid Static manual Some users rely on the Stop and Go indicator built into the System 500 sensor for Rapid Static surveys This is a set of algorithms which estimates for how long data should be col lected The algorithms take into account the rate at which the data is being collected the number of satellites being ob served and the DOP values with the user only having to enter the length of the baseline being measured As data is being collected the system will indicate how much data needs to be collected However you decide how much data to collect remem ber it is always better to col lect too much data than too little Get Into Good Habits The GPS data being collected Should always be as clean as possible This means always try to choose the best possible locations to site the GPS an tenna A suitable site should have no obstructions above 15 degrees there should b
121. your field work with a 3 m antenna pole Of course you will need an additional extension for the antenna cable to connect the sensor with the antenna During the survey please remember that the antenna height is not longer 2 000 m but 3 000 m Remember Contact your nearest Leica selling unit or dealer for more information and orders It is possible to use the TPS Instrument Height Me ter GHMO007 plus Spacing Bracket GHM196 also for GPS In this case create a new antenna type in SKI Pro using a vertical offset of 0 0505 m The new Accessories Kit GHT37 guarantees a sta ble all on the pole solution The repeater box is designed to attach a Satel line or Pacific Crest radio in the Leica housings to the tripod e A 3 m antenna pole can easily be created simply add a 1 m extension pole GLS18 or GLS21 between the bottom and top sections pole and use It together with an extension for the antenna cable All the best for the holidays and a Happy New Year with success in both your working and your private lives But above all we wish you a year in peace and health We hope the newsletter accompanied you with some useful information through the year 2001 We are looking forward to working further with you again in 2002 and we will be back in January with the next edition of the GPS Newsletter Ideas for Future Newsletters If you have any ideas or wishes for topics that you would like to be discus

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