SEAHATS LAND TRIALS - University of New Brunswick
Contents
1. is 72 Each record sent from the PS 01 to the Apple is displayed on the Apple monitor For complete information on the PS 01 see Nickerson 1983 Note that the Mini Ranger III Manual in Appendix F of this PS 01 manual refers to an older type of Mini Ranger than the one we used which is described in Motorola 1983 For important user details see the User s Guide Appendix A to this report 2 3 The Mini Ranger III Positioning System The Mini Ranger III provides accurate determination of the position of any mobile unit such as a hydrographic vessel like the Mary 0 dredge aircraft or land vehicle as used in these tests It is a range range system operating on the principle of pulse radar The Mini Ranger III measures the range or distance from a receiver transmitter R T station located on the mobile unit to a minimum of two fixed reference stations remote stations transponders located on points with known coordinates We use two reference stations The elapsed time between the interrogation transmitted by the master receiver transmitter R T station and the reply received from each reference station is the basis for determining the ranges which are displayed on the range console The range console is used on board the vessel and is connected with the R T station The ranges are displayed in metres The range information together with the known coordinates of each reference station can be trilaterated to obtain the position of2. 67 291622 291621 14 291068 83 290808 75 COORDINATES OF OFFSETS FROM CONTROL POINTS Number of Fix Point 656 In forward direction TABLE 4 4 DISCREPANCIES BETWEEN AVERAGED SEAHATS POSITIONS Northing W NOVO PF Easting MN O N AND OFFSETS CONTROL POINT POSITIONS 4168 10 1 10 4167 4 17 20 4369 4 28 31 4142 6 37 42 4145 6 51 56 In reverse direction 4145 7 58 64 4142 6 75 80 4369 4 87 90 TABLE 4 3 Point 4168 4167 4369 4142 4145 Point In forward direction 4168 4167 4369 4142 4145 In reverse direction 4145 4142 4369 23 very important The problem of detecting and throwing out unacceptable ranges is handled by program NAV by establishing a window based on sample interval and maximum velocity around the previous range The next range must fall within that window or it will be rejected Otherwise when a bad reading occurs say due to reflections the resulting coordinates which will be used as initial coordinates in the next fix calculation will be wrong and the next fix may be far off the real position The window used now is quite small a sample interval of 4 seconds with a maximum speed of the vessel of 20 km h gives a window of 22 m This window could be made even smaller see Section 2 1 In Figure 2 1 c is always smaller than a b so c can be a certain percentage of a b Two kinds of calculations could be used to reject more ranges One is
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4. as possible Hopefully the delay could be reduced to 2 seconds by changing the screen update method to modifying only the characters being updated in the screen memory map rather than writing out a whole new screen each time There are no problems in using the 25 01 interface 31 REFERENCES anon 1982 Operator s manual for the HYNAV NAVBOX INDAS system 33 pages McCarthy T J 1983 Software development for hydrographic surveying Project report for computer science 4993 University of New Brunswick Fredericton 73 pages Motorola 1980 User s manual operation and installation instructions Mini Ranger III positioning system Document 68 P03802R 76 pages Nickerson H J 1983 Operation and technical manual for the 25 1 Radio Positioning Echosounder Computer Interface Final report for CADMI project 8302 Fredericton 210 pages 32 APPENDIX A USER S GUIDE A l Connections The system consists of an Apple computer the 25 01 interface and a Mini Ranger III positioning instrument The Apple computer is connected to two disk drives which get their power from the computer and are used to read and write to the diskette containing the program and the diskette containing the output f les The Apple is also connected to a monitor which needs 120 VaC power The Apple is connected to the PS 01 via a cable a so called RS 232 C 25 pin D connector The Apple and PS 01 need both 120 Volts AC and the
5. be stopped as closely as possible to the offset reference points Even more precision could be achieved by removing the R T unit from the van at each point and mounting it over the LRIS monument itself CHAPTER 5 SEA TEST DESIGN A test of the SEAHATS equipment was done aboard the Mary O in St Andrews New Brunswick on 4 February 1984 The goal of this test was not to evaluate the accuracy as for the land tests but to judge the general operation of SEAHATS on a moving vessel Convenient LRIS control points were not available so the remote stations were put on points the coordinates of which were scaled from a hydrographic chart The R T station was mounted on the mast of the Mary 0 and the rest of the SEAHATS equipment was mounted inside on a shelf We succeeded in making it work The power supply of the boat 120V was good We ran along a survey line but the disk output was lost This is probably because we used the wrong commands at the end of the line not CTRL Q and Q uit due to inexperience see Appendix A Except during the period November to May when the St John River is frozen SEAHATS can be tested on the Mary O in the same test area as this land test east of the Princess Margaret Bridge The same reference points can be used namely BRIDGE and 318NEW The test area could likely extend 1500 metres downriver east of the Princess Margaret Bridge In case of visibility problems with point BRIDGE point 2
6. collection and transmission of data Ultimately the data is stored on floppy diskette on the Apple computer The communication protocol has been designed to be unspecific for the Apple it can work well with almost any computer with an RS 232 interface Also the microcomputer can be replaced by a CRT or ASCII terminal for a printout With a few slight changes the 25 01 can be connected with other radio positioning instruments for example LORAN C In the future the PS 01 will be interfaced to a Skipper 802 echo sounder which provides depth data as well as to other positioning systems The front panel contains only a power indicator lamp the rear panel a power switch fuse holder AC power cord two RS 232 connectors and three cables to connect to the Mini Ranger III Data records are transmitted from the local buffer in the PS 01 to the computer in the following format nn yy mm dd hh mm ss A xx AS xx AR xxxxxx B xx BS xx BR xxxxxx DP xxxxx CR LF where nn is the number of data records left in the buffer yy mm dd is the date the sample is taken hh mm ss is the time the sample 15 taken A B are the transducer channel codes 01 04 AS BS are the signal strengths from channels A and B the Mini Ranger III used for this test had no signal strength option installed AR BR are the observed ranges in metres DP is tbe depth value from the echo sounder presently set to zero The record length without CR carriage return and LF line feed
7. e 38 li ACKNOWLEDGEMENTS I would like to thank Dr David Wells for giving me the opportunity to come to Canada to work on the SEAHATS project And I would like to thank Tim McCarthy Harvey Nickerson Hal Janes and Pantelis Hourdakis for their pleasant cooperation This work was supported in part by a Strategic Grant entitled Marine Geodesy and a Strategic Equipment Grant entitled Integrated Navigation Microprocessor Equipment both awarded to Dr Wells by the Natural Sciences and Engineering Research Council of Canada The possibility of working in Canada on this project was arranged through the International Association for the Exchange of Students for Technical Experience IAESTE van was borrowed for these tests from the UNB Department of Civil Engineering A Mini Ranger III system was borrowed from the Bedford Institute of Oceanography The assistance of Jack Davidson is appreciated This project forms tbe practical work required for the Engineering degree from the Technical University of Delft iii CHAPTER 1 OBJECTIVES The SEAHATS system being developed at the University of New Brunswick UNB is the Surveying Engineering Apple based Hydrographic data Acquisition and Track control System My work was to put the parts of the SEAHATS system together test the system and look for possible improvements The SEAHATS system is an alternative to the present HYNAV Navigator Anon 1982 by Marinav T
8. on one diskette which has to be inserted in drive 14 The output diskette for the logged data must be inserted in drive 5 During the input the program reads ranges twice so the vessel must be at a spot where the Mini Ranger III is able to measure 36 ranges The first range is read after the input of the shore station s coordinates the second time after the input of the approximate coordinates Menus are used during manual data input The sample interval should be chosen to be no less than 4 or 5 seconds since this is the time needed for the program to read the record do the calculations and update the display After the input of the sample interval SI the VIDEO RCVD indicator on the Mini Ranger III will light every time a sample is taken In the data options menu the program now also asks for the maximum speed of the vessel If only one survey line is used 0 can be entered for the SET LINE SPACING When you enable disk output answer 1 for ENABLE DISABLE DISK OUTPUT the program asks for the file name Input 5 FILENAME FILENAME can be any name but different names have to be used for different files The lamp on disk drive 5 will now come on Every 20 records the accumulated data is logged from memory to diskette The remaining records at the end of a line are logged when CTRL Q 15 pressed Each time data are logged the disk lamp comes on If you want an output of all calculated positions answer O for INTERSTA LOGGING DIST
9. on the 55 232 interface card in the right way remove the cover of the Apple power OFF On the interface card you will see two rows of switches The switches have to be set as follows O corresponds to off and 1 to on Baud Switches Apple Row 1 1 0 2 1 3 1 baud rate 1200 4 1 5 1 6 1 7 1 Row 2 1 1 one stop bit 2 0 seven data bits 3 0 even parity 4 0 even parity 5 0 do not generate line feeds 6 1 do forward interrupt 7 0 off for communications mode 35 Note that McCarthy 1983 states that SWITCH ROW 2 NR 6 is OFF Actually it must be ON 1 Whenever there are doubts about the communication between the PS 01 and the Apple check it in the following way Type twice CTRL RESET appears on the screen Type IN 2 Hold down the CTRL key and press the A key at the same time Then APPLE SSC appears Type T T Give any of the following commands TM CM ST SD SI SA SB BY EX RQ ZR ID IN If there is a response like OO NO ERROR or similar the 25 1 has received commands given by the computer and the communication is alright If there is no response something is wrong Check for example that the baud rate switch settings in both the PS 01 and the Apple are right A 3 Software For the input of the program see McCarthy 1983 Chapter 3 page 16 Here are some remarks For the PSOLINIT program the code filename is PSOLINIT for the NAV program the filename is MINI They are both
10. the mobile unit There must be line of sight between the R T and the reference Stations because the system operates at microwave frequencies around 5500 MHz The minimum measuring range is 100 m the maximum range is 37 km using standard equipment and up to 185 km with optional high powered equipment The measuring accuracy is 2 metres This is the standard deviation of a set of observations A single observation can be 3 sigma 6 metres in error To minimize the position error the sites for the reference stations should be selected so that the angle of intersection between the lines from the R T to the two reference stations is between 30 and 150 90 gives 10 the best accuracy because then the position error is the smallest The antenna of the R T and reference stations must be kept 60 cm from and above large metal surfaces or masts larger than 15 cm in diameter The range console does not operate below 0 C The minimum temperature for the reference stations and the receiver transmitter is 50 c During the test using the van the R T station was mounted on top of the van and on the Mary O it was mounted above the mast The reference stations were mounted on tripods Each has a certain code unique delay between two returned pulses These are denoted 1 2 3 or 4 The REF STATION SELECT switches on the range console must agree with the codes of the reference stations being used The position error of the Mini Ranger III de
11. 1018 0943 0904 0834 0813 0811 0807 0807 0810 0802 0748 0710 0672 0595 0558 0487 290453 Northing 736393 6405 6446 6464 6500 6511 6518 6516 6516 6517 6519 6546 6567 6589 6648 6679 6741 736753 Time 13 08 23 27 35 39 47 51 55 09 03 07 11 15 23 27 31 39 43 51 13 09 59 Control Fix Point 4369 4369 4369 4369 81 82 83 21 ranges and positions for each of these stops are shown in Table 4 2 The measuring accuracy of the Mini Ranger III is 2 m but a single observation can be 6 m in error Therefore the difference between the highest and lowest four second observation could be as much as 12 m The difference between the highest and lowest range reading in each set was not that high for this test but the test involved limited numbers of observations The NAV program is written in the Apple PASCAL language which is capable only of single precision 6 to 7 decimal digit arithmetic Whether this results in a significant error was tested in the following Way Ranges to the transponders were calculated using the average coordinates at each stop These calculated ranges were compared with each of the averaged ranges The maximum difference between the calculated and averaged observed ranges is 0 6 m Simulations to evaluate the error resulting from the least squares calculation of the coordinates in the program resulted in errors of as much as 1 m but most times it was lower th
12. 2 13 03 51 736376 291073 1726 1339 42 4142 55 6376 1070 1725 1342 43 59 6375 1076 1728 1336 44 04 07 6348 1131 1771 1283 45 11 6321 1171 1810 1244 46 15 6299 1217 1847 1200 47 23 6246 1324 1938 1100 48 27 6228 1379 1977 1049 49 35 6219 1492 2036 940 50 39 6227 1549 2057 882 51 4145 47 6220 1621 2099 814 52 4145 51 6219 1622 2100 813 53 4145 59 6221 1623 2099 812 54 4145 05 03 6219 1621 2100 814 55 4145 07 6220 1623 2100 812 56 4145 11 6219 1622 2100 813 57 15 6221 1636 2106 799 58 4145 06 23 6226 1622 2095 811 59 4145 27 6224 1620 2095 814 60 4145 31 6224 1620 2095 814 61 4145 35 6224 1621 2095 813 62 4145 39 6227 1623 2094 810 63 4145 43 6228 1622 2093 811 64 4145 51 6225 1620 2094 814 65 55 6226 1604 2085 829 66 59 6227 1582 2073 850 67 07 03 6226 1542 2054 889 68 11 6222 1461 2019 970 69 15 6216 1408 2000 1023 70 19 6233 1358 1964 1069 71 27 6276 1263 1886 1157 72 31 6301 1213 1844 1204 73 39 6352 1123 1765 1290 74 43 6373 1084 1732 1329 75 4142 51 6382 1065 1718 1347 76 4142 55 6380 1068 1720 1344 77 4142 59 6382 1073 1720 1339 78 4142 08 07 6381 1070 1720 1342 79 4142 15 6382 1072 1720 1340 80 4142 13 08 19 736379 291065 1720 1347 Range to 318NEW 1364 1394 1469 1509 1580 1602 1605 1608 1608 1606 1614 1669 1709 1749 1832 1873 1953 1989 Range to BRIDGE 1702 1681 1622 1595 1545 1530 1522 1524 1524 1523 1520 1485 1459 1433 1368 1336 1275 1265 20 Easting 291048
13. 42 could be used This point is high on the bridge so it can be seen from far off It may be better to survey a point on the east side of the bridge 242 is on the west side The Mini Ranger III transponder would have to be installed higher than the 90 cm high steel fence on the bridge There will be a large slant range error near the bridge so program NAV should be 25 26 modified first to correct for this The Mini Ranger III manual Motorola 1980 gives the rule for the selection of the shore sites in order to obtain a satisfactory position error namely a maximum position standard deviation of 7 7 m According to this rule the intersection angle between the two ranges should be between 30 and 150 See Figure 5 1 Only a very small part in the test area does not satisfy this rule In the middle of the river the intersection angle is around 125 over the whole length The best geometry is along the southern shore of the river A one waypoint test has to be done This is difficult to do on land On a boat it is a problem to know precisely the coordinates of the centre point of the circle There are no control points in the water As the centre point perhaps point 4369 could be used Only a part of a circle could be run Perhaps a tracking EDM instrument could be mounted over the centre point 4369 to provide reference ranges to the boat If this is not possible control positions for the boat would have to be determined from theod
14. ANCE Immediately after the last question of the main menu is answered the Apple will take samples and the program starts running So if you have entered the coordinates etc but you want to wait before starting the survey just do not answer the last question In the two waypoint mode the last question is the waypoint number at the end of the line and in the one waypoint mode the centre point number of the circular path It is important when execution is stopped at the end of the line and you want to have disk output never type CTRL RESET you lose your disk 37 output and never remove the diskette no end of file is written so it is not possible to read to diskette later You must first type CTRL Q hold down the CTRL key and type Q At this point the buffer will be written to diskette Then type Q quit Also if you want to stop execution in the middle of a line type CTRL Q 38 APPENDIX B OBSERVATIONS AND CALCULATIONS IN SURVEYING POINTS BRIDGE AND 318NEW a Wild T2 theodolite was used For For the angle measurements distance measurements an AGA was used The measurements were made 5 November 1983 The new points were observed from points 4168 and 4142 B 1 Observed Distances 000 47 41 8 Mean for BRIDGE From To BRIDGE To 318NEW 4168 987 779 2200 893 2 896 779 890 Mean 987 780 2200 893 4142 1726 964 1343 471 964 472 965 472 Mean 1726 964 1343 472 B 2 Observed Ho
15. NIT initializes the PS 01 interface by setting the date time sample interval the time difference between two consecutive observations measured by the positioning instrument and channel identification numbers code numbers of the two reference stations of the Mini Ranger The second program NAV handles all data initialization handles navigation routines for one and two waypoint modes displays results and logs the data The present version of the NAV program used for this report has some differences from the version of the program documented in McCarthy 1983 The least squares adjustment was not changed The changes are described below One of the changes that had to be made was to add a rejection of wrong range observations due for example to reflections Once the NAV program has accepted a bad reading the calculated position is wrong Since the last position is used as initial coordinates for the calculation of the next position the rest of the calculated points will be far off the actual position The rejection is done as follows see Figure 2 1 The ship moves from 1 to 2 a is the measured range at position 1 b is the measured range at position 2 c is the distance between point 1 and REFERENCE STATION FIG 2 1 point 2 d is the distance calculated by multiplying the sample interval and the maximum speed of the vessel which are both manually input by the operator during program initialization Always d gt
16. SEAHATS LAND TRIALS WILLIE PETERS February 1984 TECHNICAL REPORT NO 105 PREFACE In order to make our extensive series of technical reports more readily available we have scanned the old master copies and produced electronic versions in Portable Document Format The quality of the images varies depending on the quality of the originals The images have not been converted to searchable text SEAHATS LAND TRIALS by Willie Peters Technical University of Delft The Netherlands Department of Surveying Engineering University of New Brunswick P O Box 4400 Fredericton N B Canada E3B 5A3 February 1984 Reprinted August 1986 TABLE OF CONTENTS Page Table of Contents d Acknowledgements e e I 1 iii l Objectives N 5 e e e 1 Za Equipment and Software i A 3 5 4 2 1 Software e s 5 5 5 1 5 5 4 2 2 The PS 01 Radio Positioning Echo Sounder Computer Interface 5 5 5 7 2 3 The Mini Ranger III Positioning System 3 9 3 Design of Static Land Test e 5 8 13 4 Results of Land Test 8 17 5 Sea Test Design e 3 e e 5 1 A 25 6 Conclusions 3 A 1 5 28 References e 5 5 3 s 5 31 Appendix A User s Guide 5 5 32 Appendix B Observations and calculations in surveying points BRIDGE and 318NEW
17. azimuth of the line you want to run bearing azimuth of the line you have actually run five asterisks which show your five previous positions an arrow which shows if the helmsman has to correct to the left or right The logged data on the disk consist of line number point number northing easting depth variance covariance matrix of the position raw data observations A disadvantage of the HYNAV system is that there is a one second lag between the position and depth samples The SEAHATS system will hopefully solve this problem An advantage of the SEAHATS system is that it is cheap the 25 01 and required Apple equipment costs around 5000 Can total It will be used for educational purposes aboard the UNB vessel the Mary 0 but it can also very well be used for bathymetric surveys near the coast After some problems we succeeded in making the system work and doing a land based test using a van Also we made the system work on the Mary O Further tests and further improvements in the software are planned CHAPTER 2 EQUIPMENT AND SOFTWARE 2 1 Software The software was written by Tim McCarthy The language is Pascal and it is written for an Apple computer The test was done with an Apple II computer For detailed information see McCarthy 1983 Small changes were made which I shall mention in this chapter and in Appendix A The software consists of two programs The first program PSOLI
18. c gt a b If a b gt d b is not accepted The program will give the message SPURIOUS RANGE READING REJECTED As a further improvement not yet implemented it would also be possible to calculate the ship s speed between 1 and 2 from the coordinates of 1 and 2 and use this to calculate the approximate coordinates of 3 The rejection criteria will be smaller and the approximate coordinates of 3 can be used in the calculation of the position of 3 instead of using the position of point 2 so fewer iterations would be needed for the fix This would not work when the ship is accelerating so e the distance between 2 and 3 is bigger than c However it would be a better method when the ship s speed is constant The PS 01 is connected with the Apple by a RS 232 Super Serial Card in the Apple In the 25 01 User s Guide Nickerson 1983 the switch settings of this card are given The 25 01 has a buffer which contains up to 20 records with the range information from the Mini Ranger Every time the Apple program requests a record the 25 01 sends one The coordinates of the vessel are calculated by a least squares adjustment McCarthy 1983 page 8 Since we use only two 6 stations the number of observations is always two so there is no redundancy The convergence criteria for the iteration is 0 5 metres The program needs normally two or three iterations to reach that The number of iterations is now fixed at three to save time During th
19. e convergence criteria is 0 5 m This is a much smaller effect than position errors resulting from Mini Ranger III ranging errors For example when the system is run dynamically only single observations are taken which may have errors of four to six metres Depending on the angle of intersection between the range lines this may result in position errors of six to nine metres The NAV program displays coordinates rounded off to integer values whole metres Position errors could be made smaller by retaining decimals in the coordinates However because the ranges are measured in whole metres the results would not be improved significantly So the uncertainty in the results is almost totally due to the Mini Ranger III observation errors A good calibration before operating is Highest Lowest Range NV OV BE B BH B B 22 TABLE 4 2 AVERAGED POSITIONS FROM SEAHATS DATA Average Ranges 318NEW 2197 8 1984 1607 5 1340 33 813 812 43 1343 17 1606 25 Average Ranges BRIDGE 987 5 1264 25 1527 75 1725 33 2099 67 2094 43 1719 67 1523 25 Northing 737056 727 736762 268 736520 628 736378 323 736223 004 Average Calculated Northing 737053 736753 736512 25 736376 17 736219 83 736225 43 736381 736516 75 Easting 290312 136 290464 621 290812 214 291071 351 291623 238 Average Calculated Numbers Easting 290309 9 290457 75 290807 5 291071
20. e test using the van the system calculated positions a little less often than every four seconds The reading of the record from the 25 01 takes a half second refreshing the screen display takes 1 5 to 2 seconds and the fix computation takes 1 5 to 2 seconds The 40 character monitor display mode is used instead of the 80 character mode optionally available because it is faster to refresh and most of the text can be seen on the 40 character screen To see the rest of the text the operator must hold down the CTRL key and press A To go back to the left half of the page press CTRL A again For suggested further improvements to the program see Chapter 6 For some remarks on using the program see the User s Guide Appendix A to this report 2 2 The PS 01 Radio Positioning Echo Sounder Computer Interface The PS 01 intelligent interface was designed and built by CADMI MICROELECTRONICS MICROELECTRONIQUE INC Nickerson 1983 For the present it acts as a data collection buffer between an Apple microcomputer and a Mini Ranger III positioning instrument The position data coming from the Mini Ranger is collected and temporarily stored in a local buffer of the 25 01 along with time and date information The position data come from two channels on the Mini Ranger III The data is then formatted and transmitted to the Apple microcomputer via an 255 232 interface card the Apple issues commands to the PS 01 on the RS 232 and can control the
21. es in program 7 The program should calculate the initial coordinates of the vessel from the ranges measured by the Mini Ranger III At present the user has to enter them manually This is difficult because at sea it is not always easy to know the present coordinates of the vessel particularly if the vessel is moving during or after the coordinates are entered At present the vessel must be stationary at known coordinates while the program is started and initial data are entered The program should calculate the coordinates automatically immediately before or after the start of the survey Note that at present when the vessel is far from the survey line or circular path more than 200 m the initial position has to 30 be entered as a waypoint and the two waypoint mode can be used navigate to waypoint 1 for this part disk output is not necessary 8 The program is not very forgiving when you input a number in the wrong way For example when you input 260939 2 instead of 260939 2 the program will give the message INPUT INVALID DIGIT and there will be an arrow gt at the beginning of the next line However there is no way of correcting it Whatever the next input is there will be another arrow at the beginning of the next line The only way out of this trap is to restart the input from the beginning 9 Now the fastest display update rate is around every four seconds It is desireable to have the display updated as fast
22. etween four and ten four second samples taken The average 17 18 TABLE 4 1 SEAHATS OBSERVATIONS AND RESULTS Control Range to Range to Fix point Time Northing Easting BRIDGE 318NEW 1 4168 13 00 19 737054 290309 987 2199 2 4168 23 7052 0308 989 2199 3 4168 27 7050 0310 990 2197 4 4168 31 7054 0310 986 2198 5 4168 35 7052 0313 988 2195 6 4168 39 7054 0310 986 2198 7 4168 43 7051 0308 990 2199 8 4168 47 7056 0310 985 2199 9 4168 51 7055 0309 986 2199 10 4168 59 7052 0312 988 2196 11 01 03 7035 0319 1003 2184 12 07 7012 0328 1024 2169 13 11 6982 0342 1050 2147 14 19 6907 0371 1120 2100 15 23 6865 0389 1159 2073 16 27 6826 0412 1195 2043 17 7 35 6753 0453 1265 1989 18 4167 39 6752 0459 1265 1983 19 4167 43 6757 0459 1260 1983 20 4167 51 6750 0460 1267 1981 21 59 6748 0467 1269 1974 22 02 03 6741 0483 1275 1957 23 07 6721 0505 1294 1932 24 15 6666 0576 1350 1854 25 19 6631 0613 1386 1812 26 27 6565 0700 1460 1719 27 31 6541 0747 1489 1670 28 4369 39 6514 0806 1526 1609 29 9 42 6513 0807 1527 1608 30 4369 51 6511 0806 1529 1609 31 4369 55 6511 0811 1529 1604 32 59 6503 0828 1540 1587 33 03 03 6485 0863 1565 1551 34 11 6447 0943 1621 1469 35 15 6423 0985 1655 1427 36 23 6385 1053 1711 1359 37 4142 27 6376 1068 1724 1344 38 4142 31 6377 1073 1725 1339 39 4142 39 6376 1073 1726 1339 40 4142 13 03 43 736376 291073 1726 1339 19 Control Range to Range to Fix Point Time Northing Easting BRIDGE 318NEW 41 414
23. f the measuring accuracy is 3 metres all position errors are 3 2 times bigger The electrical power demand of the Mini Ranger III is as follows Range Console Reference and R T Station Voltage 24 Vdc 24 Vdc Current on standby no interrogation 2 5 A 0 5 A Current at maximum interrogation rate 3 0 A 1 0 A INTERSECTION ANGLE 160 180 100 120 140 80 60 20 po _ POSITION ERROR DUE TO GEOMETRE NT N o CO O N qum qum q POSITION ERROR M FIG 2 2 CHAPTER 3 DESIGN OF STATIC LAND TEST For the land test we used a van from the UNB Department of Civil Engineering The van is equipped with a power supply providing 120 volt power for the PS 01 Apple computer disks and monitor The receiver transmitter was mounted on an ski rack on top of the van The rest of the equipment was mounted on shelves in the van The test was done on Wednesday 31 January 1984 The test area is east of the Princess Margaret Bridge in Fredericton see Figure 3 1 The test area control points and geometry are described in this chapter Control points on the south side of the St John River were used to check the accuracy of the SEAHATS system Coordinates for the monuments were taken from microfiche of the Land Registration and Information Service LRIS in the Maritime Provinces of Canada These microfiche contain all the survey data about every control point in New Brunswick updated to January 1983 The Universal Transver
24. he system consists of a Mini Ranger 111 positioning system Motorola 1980 which we borrowed from the Bedford Institute of Oceanography BIO in Dartmouth N S an Apple II computer with software written by Tim McCarthy McCarthy 1983 and a PS 01 Radio Positioning Echosounder Computer Interface between these devices designed by Harvey Nickerson of the Centre for Advanced Microelectronics CADMI at UNB Nickerson 1983 The 25 01 is designed in such a way that it will be possible to use other positioning instruments and other computers The system performs horizontal positioning aboard a vessel and in the future depth determination will be possible by connecting a Skipper 802 echo sounder The SEAHATS system computes the position of a vessel gives corrections on a display to the helmsman of the vessel every few seconds so that he can navigate along a pre determined survey line and logs positional information on a diskette The survey line can be a straight line between two points two waypoint mode or a circular path a whole circle or a part around one point for example a shoal point in the water one waypoint mode The display consists of line number of the survey line line point number of the position of the vessel point f northing N of the vessel easting E of the vessel along track distance ATD across track distance XTD amount of correction distance to go DTG depth course
25. ir power cables have three wire plugs The PS 01 is connected with the Mini Ranger III via three cables so called Amphenol Military connectors which have to be inserted in the appropriate mating jacks on the rear of the Mini Ranger III Two cables are for channel A and B CHA CHB on the PS 01 CHANA BCD J5 and CHAN B BCD J4 on the Mini Ranger III However interchanging these cables gives no resulting errors in data collection The third cable is for external control EXT on the PS 01 EXT CONTROL J2 on the MR III The connection between the PS 01 and the Skipper 802 echo sounder Will be defined at a later date On the rear panel of the 25 01 are two RS 232 connectors A and B The system will only work when the RS 232 C cable is connected to connector B The Mini Ranger III consists of a range console an R T station and two reference stations The range console is connected with the R T via a cable which also supplies power to the R T The range console receives its 33 power from two 12 volt batteries Take the three prong plug of the power cable and put alligator clamps on the two smaller cables inside the thick cable The white cable is positive the black cable is negative Also each reference station gets its power from two 12 volt batteries There are four connecting cables The red cable is positive the black is negative and the two green cables are the jumpers between the batteries The Mini Ranger III needs 20 minutes warm up bef
26. ks or the arrow so the helmsman will see at a glance in what direction and how much he has to correct Now he has to look for the XTD value between all the other values This is especially important when there is a screen output every few seconds 3 When the van was run in reverse direction during the test in the two waypoint mode with the mobile unit at the end of line enter in the 28 29 program that you want to do the same line in reverse direction the OUT OF RANGE arrows were pointing in the wrong direction namely lt lt lt lt lt lt lt lt instead of gt gt gt gt gt gt gt gt This must be corrected 4 The input coordinates of the shore stations and all other input data should also be logged on the output diskette 5 The values entered for shore station coordinates waypoints and data options should be entered into a file so that they need not be re entered every time 6 There are some spelling mistakes in the program in procedure number 26 LINEWIDTH DISTANC DISTANCE appears on screen in procedure number 28 INITIALOLDRANGE VARIAABLE VARIABLE just comment in procedure number 29 APPROXCOORDS MAXIMIN MAXIMUM appears on screen in procedure number 33 INITDATA WAYPIONT WAYPOINT in procedure number 31 LISTDATAOPTIONS DISABELED DISABLED in procedure number 34 LISTOPTIONS WAYPIONT WAYPOINT in procedure number 35 CHECKRANG3 MAXIMIN MAXIMUM in procedure number 37 RECIEVE RECIEVE RECEIVE several plac
27. ode 3 318 292410 111 736421 289 destroyed 242 290240 200 737907 134 high on bridge Before the test the Mini Ranger III range console was calibrated at point 4142 by adjusting the REF STATION CAL screws The calibration should be done in similar environment to that in which the instrument will be operating with the ranges approximately equal to the range of operation The van was driven along the Lincoln Road from point 4168 to 4145 and then in reverse direction The length one way is around 1650 metres Two other LRIS points would have provided longer survey lines But point 4185 was not found back in a field and point 4146 could not be used because the reference stations are not visible from this point 16 This test was a static test The van stopped at the control points to check the accuracy of the coordinates determined by the SEAHATS system against the known LRIS values The control points were marked by poles A dynamic test will hopefully be done later In this case the van would drive along the road without stopping and the time when it passes a monument is recorded for later comparison with the SEAHATS data at that instant requiring interpolation of the recorded SEAHATS data In order to check that the SEAHATS system can track rapidly changing Mini Ranger III ranges the speed of the van was around 50 km h This is much faster than the speed of the Mary 0 which is normally around 15 to 20 km h No problems were enco
28. olite intersections which will involve problems in synchronizing the timing of the observations FIG 5 1 TRAN 5 gt ABLE ARE 318 NEW G 129 dns es p 2 90 M ua ANY YAY NS u BRIDGE lt gt TEST AREA 27 SEATEST DESIGN CHAPTER 6 CONCLUSIONS After some problems the system was put to work and tested Hopefully these problems are solved now and will not occur in the future Some improvements in the software can be made The system needs more testing with the Mini Ranger III Software should be written for the Hewlett Packard computer of the Department of Surveying Engineering to simulate the Mini Ranger III and PS 01 in order to speed up software development and testing Improvements which should be made in the software 1 The display should not scroll Display of the records from the 6 01 and the spurious range readings should be omitted except for a debugging mode Only values of northing easting line running values and the arrows and asterisks should be displayed Changes to any of these whenever a record from the PS 01 is taken would be easily seen This display fits almost perfectly onto the 40 character screen The only thing that does not fit is the rightmost column This could easily be changed 2 It would be better if the XTD value across track distance amount of correction were shown near the newest asteris
29. ore calibrating and operating The PS 01 manual Nickerson 1983 Chapter 3 page 1 says that for the PS 01 to function properly the front panel DISPLAY RATE control of the Mini Ranger III must be fully counter clockwise in the EXTERNAL EXT position and that the channel code switches also must be in the EXTERNAL position to allow remote selection The PS 01 has been slightly changed so that the system will also work when the channel code switches are in the INTERNAL INT position However in this case the range measurements will not be synchronized in time with the time tag assigned to them by the PS Ol clock A 2 Switch Settings Before the 25 01 is connected to a power source the serial interface should be configured using the dip switches internal to the chassis To change the switch settings lift the top cover after removing the four retaining screws The switches are labelled 1 through 8 and must be set as follows 34 Baud Switches 25 1 1 OFF 2 OFF baud rate 1 2 k 3 OFF 4 ON 5 ON l stop bit 6 ON 7 data bits 7 OFF even parity 8 OFF enable parity The baud rate must be 1200 because the NAV program now uses an assembler routine which requires this For proper communication between the 25 1 and the Apple the baud rate on the interface card inside the Apple computer must also be 1200 When they are both for example 9600 the PSOLINIT file will work but not the MINI file In order to set the switches
30. pends on three factors 1 System errors caused by equipment tolerances jitter and weather These have been minimized by the design of the system 2 Slant range error the Mini Ranger III measures the slant range instead of the horizontal distance which is what we want to know An accepted practice is to work no closer than ten times the height difference of the two antennas of the R T and one reference station Under these conditions the resultant range error will be no greater than 0 5 percent longer than the actual range The height differences in the test area for the van and the Mary 0 are too small to bring this error into consideration However it would be possible to modify the NAV program to automatically correct for slant range requiring the operator to input heights of reference station and vessel antennas during initialization using 11 r 7 r 1 dh r 2 where r is the observed slant range dh is the height difference between reference station and vessel and ru is the corrected horizontal range 3 Geometry changes a measured range has a certain accuracy which affects the accuracy of the calculated position depending on the angle of intersection of the lines from the R T to each of the reference stations A certain intersection angle gives a certain position error see Figure 2 2 Intersections of 90 give the smallest error Figure 2 2 is based on a measuring accuracy of the Mini Ranger III of 2 metres I
31. rizontal Angles From I II Average I II Reduced angles 4168 BRIDGE 354 11 6 174 12 12 2 354 12 03 9 000 00 00 0 318NEW 87 59 20 1 267 59 35 3 87 59 27 7 93 47 23 6 4167 133 27 58 2 313 28 11 7 133 28 05 0 139 16 00 9 BRIDGE 354 11 53 3 174 12 15 2 354 12 04 3 Mean for BRIDGE 354 12 04 1 4142 BRIDGE 000 47 47 180 47 37 000 47 42 000 00 00 0 318NEW 107 19 03 287 18 45 107 18 54 106 31 12 2 4145 125 06 30 5 305 06 18 5 125 06 24 5 124 18 42 7 BRIDGE 000 47 46 180 47 37 000 47 41 5 Horizontal Distance 987 753 2200 893 1726 958 1343 471 39 B 3 Observed Vertical Angles B 6 From To I II Average I II 4168 BRIDGE 90 23 50 269 35 17 90 24 16 5 318NEW 90 01 13 269 58 15 90 01 29 4142 BRIDGE 90 09 47 269 49 43 90 10 02 318NEW 89 56 25 270 02 58 89 56 43 5 B 4 Reduction of Distances EDM Target Zenith From To Measured Height Height angle dh 4168 BRIDGE 987 780 1 415 1 185 90 24 16 5 7 31 318NEW 2200 893 1 415 1 185 90 01 29 1 2 4142 BRIDGE 1726 964 1 360 1 185 90 10 02 4 66 Known Coordinates Point Easting Northing 4168 290307 050 737053 563 4167 290460 921 736758 568 4142 291069 007 736373 952 4145 291622 501 736212 933 Calculated Coordinates BRIDGE 290532 551 738015 403 318NEW 292412 007 736410 876 40 BRIDGE Z SupPoRT 165 CM 88 5 CM 5 E Z S SLoT IN SS CONCRETE p pie SKETCH oF STATION BRIDGE ST TOHN RIVER 318
32. se Mercator UTM coordinates referred to the ATS77 adjustment performed by LRIS of the control used for this test are shown in Table 3 1 in metres Two new stations were established on the north side of the St John River for the Mini Ranger III reference stations These stations were called BRIDGE and 318NEW see Figure 3 1 and the surveys and computations used to establish their coordinates are contained in Appendix B of this report Point 242 on the Princess Margaret Bridge would also be a good reference station point because it is high above the river But it is 13 4369 Gz105 eec Hh GEOMETRIE 94 4167 G 6 14 Point 318 was a well situated point We established the new point 318NEW Point 319 between the bridge and 318 cannot Point number Easting Northing 4168 290307 050 737053 563 4167 290460 921 736758 568 4369 290814 231 736524 942 4142 291069 007 736373 952 4145 291622 501 736212 933 so instead we established the new point under the Princess Margaret Bridge but the monument had been destroyed CONTROL STATION COORDINATES SOUTH BANK between a lot of steel in the neighbourhood of 318 be seen from the other side of the river TABLE 3 1 TABLE 3 2 REFERENCE STATION COORDINATES NORTH BANK Point number Easting Northing BRIDGE 290532 551 738015 403 Mini ranger III code 2 318NEW 292412 007 736410 876 Mini ranger III c
33. the method described in Section 2 1 Another way that could be used when the ship s speed is almost constant as on a survey line is the following the program calculates the vessel s speed from the two previous positions From this it calculates the window which will be smaller Also the initial coordinates of the next point could be predicted instead of using the coordinates of the previous point The resulting position fix may converge in fewer maybe even one iterations More tests have to be done From this single test without even a complete disk output it is difficult to draw conclusions Dynamic testing is especially important Another problem is to know more precisely the coordinates of the reference points offset on the road from the LRIS control points monuments and just where the van will be stopping for static tests or where it will be during dynamic testing Even more challenging is to know precisely 24 reference positions for dynamic testing aboard the Mary O For this test offset points from each LRIS monument were measured to the edge of the road perpendicular to the road The coordinates of these points are in Table 4 3 These offset points are on the side of the road on which the van stopped during the forward run except for point 4369 Table 4 4 compares the reference coordinates in Table 4 3 with the average SEAHATS coordinates in Table 4 2 The differences are only a few metres In future tests the van should
34. untered CHAPTER 4 LAND TEST RESULTS The two way test run in the van took about ten minutes to complete The SEAHATS sampling interval was set at four seconds the assumed time required for the NAV program to complete the processing of one set of observations The data recorded by SEAHATS on the Apple disc is shown in Table 4 1 The forward run contained the first 57 fixes in Table 4 1 The NAV program detected the end of the first line at fix 57 and stopped computing fixes as it is designed to do The van was turned around and the second reverse line began at fix 58 about 70 seconds later Where there is a sign beside the time in Table 4 1 SEAHATS did not record a position fix but according to the sample interval of 4 seconds there should have been one This happened 32 times Possible reasons for this are there was an obstruction between the van and a reference station there was a spurious range reading the program skipped one record since reading calculating and displaying one record may take more than four seconds The recording of data onto the Apple disk stopped at fix 98 The reason is not clear The realtime monitor display continued to the end of the reverse line At that point control point 4168 the Distance to go value shown on the screen was 2 metres which indicates that the position fixing continued without problems In this single static test the van was stopped near each control point and b
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