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InstantTrack 1.50 user manual (PDF format, 72 pages)

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1. Orbital Period This is the duration of one orbit measured from perigee to perigee Computed from mean motion and decay Perigee Height Apogee Height These are the distance from the Earth s surface to the satellite i e height when the satellite is closest e at perigee and farthest e at apogee 24 InstantT rack Latitude of Apogee Satellites in highly elliptical orbits are usually used when they are near apogee It is therefore useful to picture what part of the Earth will be below the satellite at apogee Latitude of apogee is computed from argument of perigee and R A A N Because both of these quantities change with time latitude of apogee also changes with time Both the present value and rate of change are shown Argument of Perigee R A A N These values change with time The values contained in the orbital elements are the values as they were at E poch Both the present value and rate of change are shown on the right hand side of the screen Longitude Increment It is sometimes useful to think about just how much a satellite s footprint moves in the longitude direction from one orbit to the next Especially for high inclination satellites each orbit of a satellite provides coverage of a different portion of the Earth Mostly this happens because the Earth rotates a certain amount during each orbit of the satellite but the satellite s orbit is also slowly changing with time and this too provides a small contri
2. Understanding Derived Values They will disappear temporarily to make room for parameter entry if you type the key to enter a parameter 6 1 3 Satellite Elements Maintenance Functions The Update Satellite Elements Menu allows you to do some additional things besides the basic functions described above Specifically 4 OLD Delete satellites with old orbital elements 5 CRASH Delete satellites that have crashed 6 DELETE Delete a satellite manually 7 SQUISH Compact the satellite elements database Because I nstantT rack can handle such a large number of satellites you may never need to delete anything from the database My philosophy is that if you dont need to delete objects then you should probably leave them in the database and urge you to adopt this philosophy However if you often load elements for short lived objects or missions discarded boosters shuttle missions etc the database may become cluttered with entries which are no longer valid or the database may simply fill up Selections 4 5 6 allow you to get rid of unwanted objects Option 4 OLD deletes all satellites with an epoch older than some number of days You can specify the age cutoff It defaults to 100 days Elements older than 100 days can still be useful especially for high orbiting satellites This threshold assumes that a satellite that hasn t been updated in 100 days is no longer of interest Optio
3. groups string in the satellite element editor A groups string is just all of the group names that apply to the satellite with no intervening spaces Example The satellite RS10 shows Groups rla In my convention this means it is Russian and Low Earth Orbiting and an Amateur Radio Satellite 6 4 Understanding Derived Values The D command causes several derived values to be displayed on the right hand side of the satellite elements edit screen These numbers are derived from the orbital elements of each satellite but are not easily computed in your head They are intended to provide a more convenient description of the orbit than the original elements Epoch Age This is simply the time since the epoch This tells you how old the orbital element set has become Satellite Age This is a quick and dirty estimate of how long ago the satellite was launched It is computed from Epoch Rev and Mean Motion Of course mean motion changes during a satellite s life and the elements don t give us any historical information so we just assume for this calculation that mean motion has been constant For most satellites the error in the computed age seems to be less than 1 For low E arth orbiting satellites near end of life the error will be larger because mean motion has been changing For OSCAR 10 the computed age may be completely wrong depending on the source of your elements because NASA publishes an incorrect epoch rev
4. move the mouse on the map screen Answer Some versions of the Logitech mouse driver can cause this If you have a Logitech mouse contact Logitech for an upgrade to the latest version of their mouse driver Question What do doif get the message Overlay Not Found Answer The most common cause of this message is an infection by the erusalem B virus Geta virus checker program and test all your disks for a possible virus infection Question How accurate are the Moon predictions Answer The maximum error is approximately 0 05 degrees more than good enough for moonbounce InstantT rack 53 15 Copyright Notice and Distribution Policy This program is Copyright 1989 2000 Franklin Antonio and Paul Williamson All Rights Reserved Copies of InstantTrack are distributed in the United States from AMSAT NA a non profit organization which constructs and launches amateur radio satellites When you obtain a copy of InstantTrack from AMSAT NA the entire donation goes toward the amateur radio space program InstantT rack is distributed in the United Kingdom by AMSAT UK and in Australia by AMSAT Australia and in Germany by AMSAT DL Address information for the AMSAT organizations can be found in the bibliography Any distribution of InstantTrack requires a license 16 No Warranty No warranty is expressed or implied This software has been written as an amateur hobby effort and will only support it at that level
5. Answer nstantTrack will run under DESQView The secret is to set up the DESQView parameters for InstantT rack so that DESQView gives InstantT rack enough memory and knows that InstantT rack will write to the screen directly Pull up the change a program screen in DV and set the following parameters Memory size in K 450 Writes directly to screen Y Displays graphics Information Y Then hit the F 1 key to go to the Change a program Advanced Options screen and set the following parameters 52 InstantT rack Starting Height 25 Starting row 00 Starting Width 80 Starting column 00 Uses its own colors Y Uses math coprocessor Y Question What do doif I nstantT rack seems to freeze sometimes when use my mouse Answer Unfortunately some versions of the Microsoft mouse driver contain bugs that may cause this Specifically several users have observed these symptoms while using version 7 00 7 01 7 02 or 7 03 of MOUSE COM Earlier versions seem to work flawlessly and version 7 04 seems to work for most people Call Microsoft customer service if you need to obtain a copy of the 7 04 version of the mouse driver In the meantime here s a workaround When the program appears to freeze it s actually only the screen that s frozen You can still type commands Usually typing the U command twice gets things working again Question What do do if little mouse droppings are left behind when
6. This is the display which InstantTrack was originally designed for Everything works Maps are displayed using the 350x640 16 color graphics mode This mode may cause compatibility problems on newer computers since support for EGA modes is not high on the priority list for hardware designers anymore There is a setting in the IT INI configuration file that will solve some of these problems by forcing InstantT rack to use the BIOS for 60 InstantT rack character output If you have trouble with text on the map displays see the ITINI DOC TXT file for information on the force_bios_chargen_g setting in IT INI VGA Video Graphics Array The VGA can do everything the EGA can do and a little more InstantTrack will display maps using the 480x640 16 color graphics mode However you have the option of switching to a lower resolution map mode if you want You can optionally change graphics resolution by modifying a parameter in the IT INI file The parameter is named vga_resolution Set it to 1 for 350x640 and to 2 for 480x640 This parameter has no effect if you do not havea VGA See the file TINIDOC TXT for more on the IT INI configuration file In addition you can force the VGA to display everything in shades of gray and you can control exactly which shades of gray are used This can be useful for a monochrome display such as an older laptop LCD See the file TINIDOC TXT for information on changing this parameter in the T INI config
7. the degrees symbol on the R A Declination version of the display is not a standard ASCII character and may not look right on your printer No attempt is made to do anything fancy with the printer so it should be compatible with any printer that can print plain text files If you havea PostScript printer printing directly from nstantTrack may or may not work depending on the printer and its settings If you havea printer that only works under Windows but you re not running Windows right now then it probably will not work In that case capture to a file and use your usual procedures for printing to print the file InstantT rack 41 10 The Satellite Schedule Display This display provides you with a quick indication of when satellite operations may be possible The schedule shows you when a satellite will be above the horizon as viewed from your station If you have entered a satellite schedule for this satellite in the satellite database then the satellite operating mode will also be shown whenever the satellite is up There are three different forms of the schedule display You can display a single satellite for 20 days or 20 satellites on a single day or a single satellite for a single day from the viewpoint of several observers You will be prompted for the starting date and time As with all time prompts in InstantTrack you may enter date or time or both date and time You may also type neither in which case starting time wi
8. ACTS telephone time service Send any questions or comments about that service to them These folks used to be known as the National Bureau of Standards KCT gt L L Grace Communications Products P O Box 1345 Voorhees NJ 08043 609 751 1018 This company manufactures the Kansas City Tracker have no affiliation with L L Grace Send any questions regarding the KCT to them Authors gt Franklin Antonio N6NKF 2765 Cordoba Cove Del Mar CA 92014 n6nkf amsat org Paul Williamson KB5MU 5331 Channing Street San Diego CA 92117 3206 kb5mu amsat org InstantTrack was originally written by Franklin Antonio and this update was prepared by Paul Williamson Both authors welcome your constructive comments about this software Make sure you ve read this manual before you write If you write to us please use email if at all possible If you can t do that please write a paper letter If you would like a response please enclose a self addressed stamped envelope We get lots of letters amp phone calls from users of InstantTrack would much rather receive a letter from you than a phone call and am much more likely to reply to a letter if you ve enclosed a SASE But email is best of all 64 finis InstantT rack A Altitude 10 AMSAT 54 63 AMSAT format 11 57 AMSAT Australia 63 AMSAT UK 63 antenna rotor 38 Argument of Perigee 16 24 attitude 21 Azimuth 27 B Bahn
9. Earth including approximate boundaries between countries Some recent geopolitical changes are not shown accurately No political statement is intended Displayed on the map are 1 The observer you A yellow x marks the location of the observer An additional yellow x marks the location of the visiting observer if one has been set The x is red instead of yellow if it appears against a yellow country 2 The Sun A purple dot appears at the sub sun point on the Earth If you stood at this point on the Earth the Sun would be straight up 3 The grayline Sometimes called the terminator This shows what parts of the Earth are in sunlight The grayline is drawn in two shades of purple The lighter purple is the sunlit side of the grayline 4 The satellite A white dot appears at the sub satellite point on the Earth 5 The satellite s geometric footprint This shows what parts of the Earth arein view of the chosen satellite call it the geometric footprint because it is determined by geometry alone with no consideration of which direction the satellite s antenna may be pointing Other programs call this simply the footprint The geometric footprint is drawn in white On the Orthographic map you might wonder why the geometric footprint is smaller than the whole globe That s because you are looking at the Earth from a higher vantage point than the satellite much higher in the case of a LEO s
10. In this case InstantTrack will not know the spacecraft attitude and therefore will not calculate offpointing squint angles or the good squint angle regions on the map This will not affect operation of the more basic calculations Azimuth Elevation Doppler etc Attitude is optional You may also enter the value None Set or just N to indicate that you don t know the spacecraft attitude 22 InstantT rack You enter the value Local Vertical or just L to indicate that a spacecraft is designed to point toward the center of the Earth Note that local vertical satellites typically have antennas that are not designed to have the most gain aiming straight down Instead they are designed to have gain at some angle to the vertical in order to compensate for the greater distance to ground stations not directly below the satellite This means you ll need to learn by experience how what offpointing angles are the best for each satellite For spin stabilized satellites attitude is described by two angles often called Bahn Latitude and Bahn Longitude or ALAT and ALON These are published from time to time for the elliptical orbit amateur radio satellites in various amateur satellite publications When the satellite is under active attitude control the attitude may change only a few times per year When the satellite s attitude is uncontrolled as in OSCAR 10 since its on board computer failed the attitude drifts slowly ove
11. MacMillan Available from Sky Publishing Co the people who publish Sky amp Telescope magazine This 200 page book tells you all about visually observing satellites Somewhat dated but the basic ideas are still correct Artificial Satellite Observing by Howard Miles 1974 American Elsevier Contains information similar to that in King H ele s book Your Window for Visually Observing Satellites by Vern Riportella WA2L QQ in QEX magazine 77 uly 1988 published by American Radio Relay League 225 Main St Newington CT 06111 Nice introductory article on criteria for visual observability of satellites 62 InstantT rack Artificial Space Debris by Nicholas L J ohnson amp Darren S McKnight 1987 Orbit Book Co Inc Krieger Publishing Co Melbourne FL 111 pages ISBN 0 89464 012 7 34 50 Only 5 of the 7 000 trackable objects in orbit are functioning satellites Nifty book on the debris pollution of near E arth space A Non Cosmetic mprovement to the W3I WI Tracking Algorithm by Bob McGwier N4HY in AMSAT NA Technical J ournal V1 1 Summer 1987 Available from AMSAT NA Describes a computational technique for quickly finding a satellite s rise time Strong mathematical content AMSAT NA gt The Radio Amateur Satellite Corporation AMSAT 850 Sligo Avenue Suite 600 Silver Spring MD 20910 4703 Phone 1 301 589 6062 This is a North American non profit group that builds and launches amateur sa
12. OSCAR 13 near perigee for example then the antenna pattern cone misses the Earth entirely then there is no intersection hence no antenna footprint and the antenna pattern is bad everywhere It is quite common for only a single arc of the antenna footprint to be visible This occurs when the offpointing angle is moderate and the cone just barely intersects the Earth Because the antenna pattern footprint may be a new concept for you it may bea little confusing Don t let this bother you If you can t visualize what the antenna footprint means on the cylindrical map switch to the Orthographic map where things seem to be much more obvious 34 InstantT rack 7 Groundtrack This shows the track on the Earth that the sub satellite point will follow during the next full orbit or the next 24 hours for the Sun and Moon Only visible if it s been enabled via the G command It can also display more than one orbit if the G command is preceded by a digit In fact it can display up to 60 orbits if the G command is preceded by two digits A map display with many orbits displayed can be quite educational try 60G on different kinds of satellites and see for yourself It is possible to run out of free memory when requesting multiple orbit groundtracks If this happens try a smaller number The sun satellite groundtrack and various footprints are redrawn from time to time as the satellite Earth and sun move 7 8
13. You are encouraged to report bugs however 17 Acknowledgments ve borrowed most of the good ideas from other tracking programs I ve used Namely the WOSL tracking program written by Roy Welch WOSL which is a derivative of the W3I WI Orbit program by Tom Clark W3I WI and of course QuikTrak tm by Bob McGwier N4HY The idea for the com pact schedule display came from J ohn Mezak K2RDX All the code in InstantTrack however is my own Paul Williamson KB5MU provided extensive assistance testing version 1 00 of this program Paul also wrote the TSR part of OrbitDRV and all of TRACK and DUMMYKCT Other beta testers of version 1 00 included Mike Brock WB6HHV Dave Guimont WB6LLO Steve Wilmet WB6BDY Harry Bluestein N6TE Ross Forbes WB6GF J ohn Fail KL7GRF Glenn Moody N40UL Vern Hajek K6UGS Chuck Dowling KI 6TG Graham Ratcliff VK 54GR Steve Roberts N4RVE Courtney Duncan N5BF Ron Broadbent G3AAJ Tom Lafleur KA6I QA Steve wrote a review of InstantTrack in the November 89 issue of 73 magazine Paul Williamson KB5MU is now the primary maintainer of InstantTrack and has created this new release version The voice I in this document is usually Franklin but sometimes Paul 54 InstantT rack Appendix 1 Example Satellite Element File Formats NASA Format This is the format used by NASA to distribute satellite elements in their NASA Prediction Bulletin The origin of the
14. angles so to be specific we say that argument of perigee is the angle measured at the center of the Earth from the ascending node to perigee Example When ARGP O the perigee occurs at the same place as the ascending node That means that the satellite would be closest to Earth just as it rises up over the equator When ARGP 180 degrees apogee would occur at the same place as the ascending node That means that the satellite would be farthest from Earth just as it rises up over the equator By convention ARGP is an angle between 0 and 360 degrees Eccentricity aka ecce or Eq or e This one is simple In the Keplerian orbit model the satellite orbit is an ellipse Eccentricity tells us the shape of the ellipse When e 0 the ellipse is a cirde When eis very near 1 the ellipse is very long and skinny To be precise the Keplerian orbit is a conic section which can be either an ellipse which includes circles a parabola a hyperbola or a straight line But here we are only interested in elliptical orbits The other kinds of orbits are not used for satellites at least not on purpose and I nstantTrack isn t programmed to handle them For our purposes eccentricity must bein the range 0 lt e lt 1 Mean Motion aka N related to orbit period and semimajor axis So far we ve nailed down the orientation of the orbital plane the orientation of the orbit ellipse in the orbital plan
15. can be used here InstantT rack will jump to the next time the current satellites rises above the horizon at that location or sets at that location Some examples may help aos kb5mu rise san diego los DM12 set 32N 117W aos s then pick from the menu aos c then pick from themenu InstantT rack 31 Or you can enter the word phase or phs followed by a number from 0 to 255 and the time will jump forward to the next point in time when the current satellite s phase is equal to that number Or you can enter the word mode followed by a mode letter and the time will jump forward to the next point in time when the satellite switches into that mode If the satellite is already in that mode time will jump forward to the beginning of the next session of that mode 7 5 Controlling the Observer List The realtime text screen will display station related parameters azimuth elevation squint path loss etc for a list of up to four stations When you first fire up the screen only one station is shown This is always the first station station 1 from the station database This section describes how you can add stations to or delete stations from the station list using the O command After you type O you will be prompted to specify the station you want to add to the list Observer name city gridsquare lat lon s c or d What this prompt tells you is that you can type almost anythin
16. file named T ORB is automatically updated 6 1 2 Manual Satellite Element Entry To examine orbital elements of satellites in the I nstantTrack database or manually enter or edit them specify option 8 View Edit satellite elements by hand on the Update Satellite Elements screen InstantTrack will then present you with a satellite selection menu so that you can specify which satellite elements you want to view or edit Enter the number or the name of the satellite you want After you pick a satellite the Manual Edit Satellite Elements screen will appear showing the present elements for the satellite you picked For example Satellite ao 13 Object Number 19216 NASA Designation 1988 51b Element Set 123 Epoch Time TO 88 361 0000000 12 26 1988 00 00 0 00 Epoch Rev KO 377 Mean Anomaly MO 126 35640 Mean Motion NO 2 096985043 Inclination 10 57 40580 Eccentricity EO 0 66206910 Arg Perigee W0 195 23090 R A A N O0 228 38820 Beacon Frq F1 145 8120 Decay N1 7 00000e 008 Attitude 2 212 Diameter 3 0 Groups a Schedule 003B100J 150B240 The meaning of each of these values is explained in the following section labeled Understanding Satellite Elements At this point the following commands can be used E move cursor to previous element Tanes move cursor to next element es move to previous satellite in database aan move to next satellite in database Sees edit this element DD tee Sess
17. horizon On modern computers this happens so fast you may never see a white satellite Initially the selection menu displays all satellites in the database There is also a group command which restricts the selection menu to display only a certain group of satellites The group concept is explained in the section on satellite parameters The group command is the character G followed by a one letter group name You can type G with no following letter or G to go back to the full list Select your satellite by typing its number on the menu or its exact name as it appears on the menu unless it starts with a G sigh After you type Enter the realtime tracking screen appears You do not need to wait for the names to change color before typing your choice 7 2 Understanding The Realtime Text Display This screen contains almost everything you would ever want to know about the present location of one satellite and the view of that satellite from one or several observers on Earth The display normally operates in real time which means that it displays information about the satellite which is valid right now It is also possible to enter a specific time other than right now using the T command or run the display in fast forward mode using the F command The numbers on the screen are displayed to lots of decimal places This doesn t mean that the numbers are really accurate to that many places though some o
18. manual InstantT rack 5 4 Time and Timezones InstantTrack must know time correctly before it can locate satellites correctly The program reads your computer s DOS clock which it assumes is set to your local time zone Local time is then converted to UTC Coordinated Universal Time also known as Greenwich Mean Time which is used in the orbit calculations So there are two requirements First you must set your computer s DOS clock with reasonable accuracy Second you must tell nstantTrack what time zone it is in 4 1 How Accurate How accurately must you set your computer s DOS clock The answer depends on orbital mechanics and geometry Assuming the goal is to point an antenna at a satellite we can determine how much time error will produce a certain amount of antenna pointing error There are several sources of antenna pointing error of course Time error is just one contribution Low Earth Orbiting LEO satellites move the fastest and therefore require the most accurate time Consider a satellite orbiting at 250 km altitude This is about as low as useful satellites go The angles change fastest when the satellite is directly overhead so we ll compute that case Pointing error for 250km satellite directly overhead Time Error Pointing Error 1 second 1 8 degrees 10 seconds 17 degrees 1 minute 61 degrees This is a worst case In most situations time accurate to 30 seconds is probably fine There are se
19. most humans don t think in terms of latitude and longitude These are not user friendly coordinates Nearest City This is the user friendly way to describe a location on the Earth It displays the distance and direction to the nearest city The nearest city is chosen from nstantTrack s database of 1794 cities worldwide For example the subsatellite point 40 0N 110 0W would be displayed as 142 7 km East of Provo UT If this display bothers you you can turn it off by typing C for City Gridsquare Radio Amateur operators sometimes use a gridsquare coordinate system to identify places on the Earth InstantTrack also displays the subsatellite point as a gridsquare Our example 40 0N 110 0W is in gridsquare DM59ax An article listed in the bibliography describes the gridsquare system Altitude This is the altitude of the satellite above the Earth s surface Rev This is a number that indicates how many times the satellite has orbited since launch Rev increments each time the satellite passes through perigee This value depends on the accuracy of the Epoch Rev from the satellite elements which may or may not be reliable 28 InstantT rack Phase This is a number that increments from 0 through 255 during each orbit of the satellite See the discussion of mean anomaly in the Understanding Satellite Elements section Mode This is the operating mode of the satellite as determined by the satellite schedule S
20. node 306 2255 deg Eccentricity 0 6029797 Arg of perigee 333 9978 deg ean anomaly 5 4273 deg ean motion 2 05877131 rev day Decay rate 4 4e 07 rev day sq Epoch rev 3933 InstantT rack 57 Both of these formats and many other similar ones will be read correctly Since the AMSAT format is not precisely defined however cannot guarantee that everything anyone might call AMSAT format in the future will work 58 InstantT rack Appendix 2 Bugs Problems and Futures AT amp T 6300 Computers Users of AT amp T DOS 3 2 have noticed that when they use nstantTrack to set DOS time from NIST time may be incorrect by up to one minute This is due to a bug in AT amp T DOS The DOS function which sets DOS time ignores the seconds field and always sets seconds to 00 STB VGA Cards Some users of STB VGA cards have had a problem where the map screens appear to overwrite the menu screens They ve reported that the problem can be solved by obtaining an upgraded version of the VGA BIOS EPROM chip from STB Microsoft Mouse Driver version 7 See discussion in the Questions and Answers chapter Logitech Mouse Drivers See discussion in the Questions and Answers chapter Mouse vs DESQView Some users have had trouble running I nstantTrack under certain versions of DESQView wherein multiple applications fight over the mouse If you do have this problem you tell InstantTrack to ignore the mouse by starting IT up with the M sw
21. not struggle with this feature of InstantTrack for very long Instead download one of the many easy to use programs available for this purpose and use that instead In addition to Windows programs that use NIST ACTS and other similar services there are programs that use your Internet connection to set your computer s clock InstantT rack 47 13 Non numerical Geography Maps Cities and Gridsquares Traditionally satellite tracking programs have indicated the position of a satellite by displaying two numbers latitude and longitude don t know about you but don t immediately recognize a location or its distance from me or other known locations when presented with latitude longitude coor dinates nstantTrack uses three more human friendly methods Maps Of course pointing at a map is the most user friendly way to specify a location I nstantTrack contains a map of the world and a map of the sky both of which are described above under the heading Understanding the Realtime Map Display Cities InstantTrack contains a database of the names and locations of 1794 cities worldwide About half of these cities are in the United States and the other half scattered around the rest of the world Data for U S cities were obtained from magnetic tapes available from the U S Geological Survey The selection criteria for U S cities was population West of 99W longitude all cities gt 20 000 pop are included East of 99W long
22. prompt you may enter a date and time using any of the same formats described under Setting a Specific Time for the real time text screen above Plus if you have a mouse and a ground track or sky track is visible you can click on the track to jump forward to the moment when the satellite will pass through that place on the track Finally the F command puts the program in a simple fast forward mode This is useful when you want to see where a satellite is going in the next few minutes or hours Actually you probably want to see where its footprint Offpointing Angle Doppler etc are going When you type F this screen will start to move ahead in time steps which are approximately 1 100th of an orbital period for the chosen satellite Typing a second F will pop you back to realtime The speed of the fast forward can be controlled from the IT INI file see TINIDOC TXT for details At the risk of belaboring the explanation will point out that these commands can be used together You can useT tojump to next Tuesday then F to fast forward from there and then space to mo mentarily freeze the fast forward InstantT rack 37 8 Driving an Antenna Rotor and Radios InstantT rack will optionally drive an automatic antenna rotor controller to make your antennas track a satellite in real time InstantTrack is programmed to communicate with a TSR rotor driver program that follows the interface conventions defined for the Kans
23. rendition of the maps See appendix 3 for details 7 7 Maps of Earth The map of the world can be displayed in either a Cylindrical Equidistant or Orthographic projection Cylindrical Equidistant is a rectangular looking map projection It is similar to the Mercator projec tion which was probably what you first used as a child for your first introduction to geography This projection has the advantage that we can display it very quickly because it always looks the same The Orthographic projection is a perspective view of the Earth from a long distance away It resembles photographs of Earth taken from the moon or an Earth globe held at arm s length It has the advantage of a very realistic look and very low distortion except near the edges of the globe It has the disadvantage that it is much slower to draw because of the amount of math required to calculate screen coordinates This is the only operation in InstantTrack that s still somewhat slow on modern computers Cylindrical maps are roughly centered on 0 0 longitude unless you enable scroll mode by typing S after which cylindrical maps will be centered roughly on the satellite By putting the satellite near the center of the screen the scrolling mode minimizing the probability that the satellite footprint will wrap around the sides of the screen am personally more comfortable with the non scrolling mode Take your pick InstantT rack 33 These maps show the whole
24. satellite elements is easy Understanding them is a bit more difficult have tried to make the section titled Understanding Satellite Elements as easy to read as possible Luckily you don t need to understand the elements in order to load and use them In addition to the classical Orbital Elements I nstantTrack s satellite database contains several other pieces of information about each satellite schedule beacon frequency etc These are stored in the same database and edited the same way that the orbital elements are edited They re described in a separate section below titled Understanding Satellite Parameters 6 1 Entering Satellite Elements Satellite elements are widely distributed on the Internet and via Amateur Radio bulletin boards of both the telephone and the packet radio varieties Many amateurs involved in satellite operation have tuned in to one of these sources These sources have a tremendous advantage over printed sources such as AMSAT newsletters because the elements are available in computer readable form Here area few sources totry http www amsat org amsat keps http Awww celestrak com There are two common formats in which orbital elements are distributed These are called the NASA and AMSAT formats NASA format files are also called NORAD and 2 line format files Both are ASCII text files that can be read by both humans and computers although the NASA format is diff
25. tell I nstantT rack to use a different command Second InstantTrack drops the DTR signal Data Terminal Ready at the end of the phone call This should tell most modems to hang up Unfortunately lots of modems ignore the DTR signal unless you tell them otherwise On some modems you do this by moving a dip switch On most modern modems it s a software command Read the documentation that came with your modem Look for a discussion of the Data Terminal Ready signal If you figure out how to enable DTR on your modem but then the modem doesn t work at all check your modem to computer cable Make sure the cable actually has a wire to carry the DTR signal It s on pin 20 of a 25 pin RS 232 cable Question Why isn t the Earth round in the orthographic projection On my screen it looks like a watermelon Answer Most EGA VGA monitors are supposed to autosize when the EGA or VGA card switches modes Some dont doit right Some monitors have switches that control autosizing Sometimes these switches are on the back and sometimes they re on the front under a hidden panel My monitor has some switches on the back and some under a panel on the front You might just have one of these obscure switches in the wrong position On areal true blue IBM computer and on any EGA VGA setup where autosize works correctly the Earth should be round Question Can run InstantTrack under DESQView How dol set up DESQView to make this work
26. the Earth etc This display of course updates in real time so you can see crosslinks appear and disappear Satellite Offpointing sometimes called Squint Angle InstantTrack computes the angle by which the satellite s antennas are pointed away from you for two types of satellite stabilization system Helps you understand why the quality of communications varies InstantTrack s graphics show you where a satellite s antennas are pointing Maps display a contour line of squint angle Stations within this line have low squint and typically can establish the best links via such satellites Path Loss nstantT rack shows the path loss between your station and the satellite in real time Schedules nstantTrack can show you the next three week s schedule for a satellite or one day s schedule for 20 satellites or 4 observers on one easy to read screen Realtime Rotor Control nstantTrack supports realtime antenna rotor control via the Kansas City Tracker interface or any interface with a compatible driver Realtime Radio Control nstantTrack supports realtime transceiver control for Doppler compensation via a defined programming interface Background Mode A unique background mode allows you to track satellites point antennas and tune radios in real time while you run other programs Sun and Moon nstantTrack tracks the Sun and Moon as well as the satellites in its database Fast Rise Time Finder nsta
27. toggle between local UTC timezones a ee advance to next satellite ene go back to previous satellite Ctrl gt advance to next satellite in this group Ctrl lt go back to previous satellite in this group If you don t remember all these commands remember that you can type while the realtime text screen is running and this menu of possibilities will appear instantly on your screen To exit that help screen as usual type Q All these commands should operate in a fairly obvious fashion except for the O and T commands which are described in the following sections 7 4 Setting a Specific Time InstantT rack normally displays satellite positions in realtime In other words the calculations assume the position of the Earth and satellite right now If you want to see the calculations for some specific time type T You will then be prompted to enter a specific time Here and all other places that InstantTrack prompts for a time any of several formats will be accepted See the section How Timeis Displayed and Entered for more detail You can return to realtime calculations by typing T followed by Enter You may also respond by typing the words rise or set or aos or los which will cause time to be set to the next time the current satellite rises above the horizon or sets Any of these keywords can be followed by and a location Any of the observer location formats described in the next section
28. view hide derived values is quit editing go back to main menu 14 InstantT rack To change the value of an element move the cursor to the appropriate line type the key then type a new value for the element followed by the Enter key The program will not allow inappropriate values to be entered but you still need to be careful to enter the value correctly Note that Epoch Time is displayed on two lines The first line displays epoch as a year and day number The second line displays the same epoch in common units Epoch may manually entered on either of these two lines Enter on the first line if you are typing a time in the year and day number format don t forget to put a space between them and on the second line if you are using the more familiar m d y h m s form As you make changes to the elements these changes are recorded in the copy of the satellite elements database that I nstantTrack is holding in memory If you have changed any elements I nstantTrack will ask you whether the changes should be written to the satellite elements file on disk when you exit the Manual Edit Satellite Elements screen If you answer no the changes you have made will be temporary and will be lost when you exit InstantTrack You might want to do that in order to experiment with various element values The D command causes derived values to appear on the right hand side of the screen These values are explained below in the section labeled
29. will show a negative Drag At first this may seem absurd Drag due to friction with the Earth s atmosphere can only make a Satellite spiral downward never upward There are several potential reasons for negative drag First the measurement which produced the orbital elements may have been in error It is common to estimate orbital elements from a small number of observations made over a short period of time With such measurements it is extremely difficult to estimate Drag Very ordinary small errors in measurement can produce a small negative drag The second potential cause for a negative drag in published elements is a little more complex A satellite is subject to many forces besides the two we have discussed so far Earth s gravity and atmospheric drag Some of these forces for example gravity of the sun and moon may act together to cause a Satellite to be pulled upward by a very slight amount This can happen if the Sun and Moon are aligned with the satellite s orbit in a particular way If the orbit is measured when this is happening a small negative Drag term may actually provide the best possible fit to the actual satellite motion over a short period of time You typically want a set of orbital elements to estimate the position of a satellite reasonably well for as long as possible often several months Negative Drag never accurately reflects what s happening over a long period of time This program will accept negative valu
30. 0 has an unusual attitude 62 26 and is therefore a good example Select the map screen by typing 2 at the main menu then select OSCAR 10 from the satellite menu then switch to the orbit view by typing 3P A note for students of Celestial Mechanics In the center view the W vector points toward you out of the screen In the edge view on the left the P vector and in the edge view at the top the Q vector points out of the screen 7 9 The Sky View The sky view projection is a map of the sky from the perspective of an observer at your location looking toward the satellite The satellite is shown on this map along with the 920 brightest stars and possibly the Sun the Moon and the horizon if they happen to bein view The map is a Gnomic projection which is a fancy way of saying that it is a perspective projection of the celestial sohere from the viewpoint of a person at the center of the sphere with a field of view that extends 100 degrees horizontally and 60 degrees vertically The sky view is always roughly cen tered on the satellite InstantT rack 35 The satellite is drawn as a red dot Stars are small white dots of various sizes depending on the magnitude of the star The sun if present is shown as a big yellow dot The moon if present is shown as a gray dot The horizon if present is a horizontal brown line If you type G for groundtrack a light gray line a sky track will appear showing the path o
31. 150 239 modeB 240 255 Off The schedule string you would enter into InstantTrack in this case is O03B100 150B2400 Read this as At phase 003 change to mode B At phase 100 change to mode ec You are free to use whichever letter you find easy to remember for each mode Actually you can use most any character recommend you use a hyphen for the Off mode to improve readability of schedules In that case you might use 003B 100 150B240 for the schedule above Another trick is to use both upper and lower case For example Mode B may be represented by B when the gain antennas are in use and by b when the omnidirectional antennas are in use Attitude aka Bahn Coordinates or BLAT and BLON or ALAT and ALON J The spacecraft attitude is a measure of how the satellite is oriented in space Hopefully it is oriented so that its antennas point toward you There are several orientation schemes used in satellites This program assumes that the satellite is either spin stabilized or local vertical A spin stabilized satellite maintains a constant inertial orientation i e its antennas point a fixed direction in space examples OSCAR 10 OSCAR 13 Local Vertical satellites as you might expect always point toward Earth examples OSCAR 14 and most geostationary satellites If spacecraft attitude has not been set then it will display as None Set in the satellite element editor
32. 7 5 Controlling the ObeerverlIst 32 7 6 Understanding The Realtime Map Display 33 TAM ApS OF Cl NEE 33 CR Uer Or Bite Wie eege gedet ged SE ted eeadeaddiach di E E E E 35 KO Dn NN EE 35 7 10 Commands on the Map Gcreen nn nnnn nnna 36 8 Driving an Antenna Rotor and Radios ccccccsecceeeeseeeseeeeeeeeseeeeeeseeeeenenseeeeneeseeeeenenseeeenens 38 9 Satellite Position Table Ephemerris ccccsssceceseeeceeesneeceenseeeeenseeeeensneeeenseeneeenees 39 9 1 Entering Parameters cu eaa cient REESEN aaea EEN 39 9 2 Understanding The Dieplaw 39 DISC OMIA EE EE 39 9 4 Printing or Capturing toa File eee ceeeeeeeeeeeeeeeeeceaeeeeeseeeseeseeeeseeeseeeesaeetaaeeaaee 40 10 The Satellite Schedule Display cccssecceseeeeeseeeseeseseeeeneeeeeeeeeeseaesesneeeneeeeseeeseseaeenseeeeeees 42 10 1 Understanding The Display 42 LO 2 C OMUMANGS EE 43 11 The Satellite Covisibility Display ecccsseceseeeseeseseeeenseeeeeneeeseaeeesneeeneeeeseeeseneeeeneeeeeees 44 11 1 Understanding The Display 44 LL 2 C OMIMANGS EE 44 12 Setting Time Via NIST ccesccecesesceeeeeesceeeeeeeceeeesnseeeseseeeeeseeeeesesesceeseseeceeseseseenenseeeenes 45 12 What is CHEN WEE 45 T22 Procedure EE 45 123 What Can GO WIroOnd moenia ase Gaia e dain ath deed TEE as arn 46 12 4 Technical Notes on Dialing modems 0 ccc ee eeeeeeeeeeeeseeeeaeeeeeeeeteeteeeseeeseeeeeaeeeaaee 46 12 5 If 1t Doesn t
33. Coordinates 22 Beacon Frequency 21 C cities 48 Clark Tom 54 clock 6 coprocessor 3 Copyright 54 crosslink 44 Cylindrical Equidistant 33 D Davidoff Martin 62 Declination 29 delete 14 derived values 14 23 Diameter 22 dR dt 27 Drag 16 E Eccentricity 16 Eclipse 30 elements 11 Elevation 27 Epoch 16 Epoch Age 23 Epoch Rev 20 equatorial 16 Escobal Pedro 62 InstantT rack Index G Gnomic 35 green 4 26 gridsquare 28 32 48 Groups 22 I IJK coordinates 29 Inclination 16 IT 3 it cty 49 it exe 49 it hlb 49 it ini 46 it mp 49 it orb 13 49 it qth 10 49 it str 49 itinidoc txt 46 ITNCP 3 itncp exe 49 ITRACK DOC 38 K Karn 22 Karn Phil 62 Kelso 14 Kelso T S 55 Kepler Johann 16 King Hele D G 62 L latitude 10 28 Latitude of Apogee 24 longitude 10 28 Longitude Increment 24 M magnitude 30 map 33 McGwier Bob 54 63 Mean Anomaly 16 Mean Motion 16 Mezak John 54 Miles Howard 62 mode 29 modem 6 45 N NASA format 11 55 Nearest City 28 NIST ACTS 45 NIST ACTS 64 noise temperature 29 O Observer list 32 Offpointing Angle 27 OrbitDRV 38 ORBITDRV DOC 38 Orbit View 33 35 Orthographic 33 OSCAR Satellite Report 63 P Path Loss 27 Period 23 perturbations 16 Phase 29 polar 16 Proj
34. InstantTrack Version 1 50 Satellite Tracking software for the IBM PC and compatibles Copyright 1989 2000 Franklin Antonio and Paul Williamson Table of Contents Ts troduction eaaa aaa a a a aea apa eaaa aaa aa ai aada aaiae 1 1 1 Required Be ge ON E EE ag Lt ET EE E 2 The Main Menu Screen eme ENEE EENS A 3 Online H lp SO O NS 2 Seebegtegee deeg Siebegegg deeg aeon raaa daaa aaa EegeeegeggdE e Beeegg eegiegg e ees 5 4 TIME ANG NW TE 6 Ga Die Re een le 6 4 2 Setting Y our Time Zone ene aiai aaae eai Ae Aaa E EAA Aaaa EE Ee Aa aK EAEE aaia 7 4 3 How Time is Displayed and Enterel AAA 8 5 Station Elements Where Are YOU ccccssseceeesseeceenseeeseensaeeeenseaeeeenseaeeeenseaeeeenseeeenenees 10 6 Satellite Elements What Are The Orbits ccccsseeceseseeeeeeeseneeeeseeseeesneeeeenseaeseenenes 12 6 1 Entering Satellite Elements ue 12 6 2 Understanding Satellite Elements 17 6 3 Understanding Satellite Parameters cecceceessecseeceee cee ceeeeeeeeeeeteeeteeeseeeseaeeeaeeeaaee 21 6 4 Understanding Derived Values 2 cccecceeeceeeeeeeeeeeeeeeeeecaeeeaaeeaaeeaaeseaeseaeseaeseeeeseeeseeeeeaee 24 7 Tracking a Satellite in Real Tirme cccsccsseceeneeeeseeeseeeeesneeeneeeeseaeseseeesnseaeeseeeesnaesaseenenenees 26 JA Choosing a Satellites c 5 vias nachna Asin die ale ae ae 26 7 2 Understanding The Realtime Text Display 26 RES Ge oul ul CEET 31 7 4 Setting a Specific Kl 31
35. KKKKKKKKKKKKKKKKKKKKK KKK OsGar L OCOOBBBBBBJJJBBBBB 42 InstantT rack In the third form each observer is shown as a row on the display A portion of the display looks like this Day 01 21 90 Satellite Oscar 13 Hours UTC Os che e AR 6 E 292 EE KE LO DS AA e BS N6ONKF OBBBBBBJJJBB Sek N40UL OOOCOCOCOBBBB 9Q5EE BJJJBBBBBBBBBBB A green indicates that the satellite is below the horizon Any yellow character indicates that the satellite is above the horizon If you have entered a schedule for this satellite then these characters will correspond to the operating mode If you have not entered a schedule then is used to indicate above horizon Even though the display only has room for three columns per hour one point every 20 minutes this display will reliably indicate the presence of satellite passes as small as 1 minute As with other displays yellow and green are used to indicate above and below the horizon have carefully avoided use of special characters which might not appear properly on a printer After the schedule is complete use Shift PrtSc to capture a copy to your printer Totry something familiar display a schedule for the moon The idea for this display format came from a program written by J ohn Mezak K2RDX 10 2 Commands During the schedule display the following commands apply Se toggle between local UTC timezones Quasi quit the schedule g
36. S memory They swear by it Users of Headroom tell me it s a complex program so you really need to read the manual carefully 3 If you re running on a 386 based machine or higher there are utilities such as 386 M AX or QEMM 386 commercially available that can move all of your drivers and TSRs into extended or expanded memory Later versions of MS DOS included some of these capabilities built in Look up the LOADHIGH command in your DOS 5 0 or later manual Question The program bombed and printed out all this stuff on my screen What the heck is it Answer nstantTrack is written in a style where assumptions that the program makes about its internal data are tested at critical places even though logically these assumptions must be correct This is known as defensive programming This approach does not guarantee that the program will be bug free It does make problems easier to detect and it makes the task of finding the cause of a problem a bit easier once the problem is detected No doubt you have seen programs that malfunction in subtle ways producing incorrect output or crashing your computer when you stumble onto a bug The goal here was to never do that If something is wrong my hope is that it will be detected by one of the assertion tests that I ve written into the program So far about 99 9 of the time that s exactly what happens If you stumble on one of these then a stackdump will appear o
37. STAR drag term if GP4 general perturbation theory was used Otherwise radiation pressure coefficient 63 63 Ephemeris type 65 68 Element number 69 69 Check Sum Modulo 10 Letters blanks periods 0 minus sign 1 plus sign 2 Line3 Column Description 01 01 Line Number of Element Data 03 07 Satellite Number 09 16 Inclination Degrees 18 25 Right Ascension of the Ascending Node Degrees 27 33 Eccentricity decimal point assumed 35 42 Argument of Perigee Degrees 44 51 Mean Anomaly Degrees 53 63 Mean Motion Revs per day 64 68 Revolution number at epoch Revs 69 69 Check Sum Modulo 10 All other columns are blank or fixed Note that the International Designator fields are usually blank as issued in the NASA Prediction Bulletins 56 InstantT rack AMSAT Format There are several very similar formats generated by several different people that seem to be called AMSAT format have tried to make InstantT rack compatible with all of them This format is very user friendly and can be easily read and or edited by humans Spaces are not significant Each orbital element must appear on a separate line The order in which orbital elements appear is not significant except that each element set should begin with a line containing the word satellite This file format optionally contains a checksum as a separate line at the end of each element set InstantTrack searches each line of the file for several possible keyw
38. T TZ XST3 in the winter and when summer comes around manually change this to SET TZ XDT2 InstantT rack 7 If you leave your DOS clock set to UTC which doesn t have Daylight Saving Time then use SET TZ UTCO If you don t set TZ at all it defaults to PST8PDT Microsoft is located in the Pacific time zone You can use any three letter code you like for your timezone For example if you think of your local time as local time instead of Pacific Standard Time you can use SET TZ LOC8LOC if you find that easier to understand If you re running under Windows you might think that setting the Windows clock would take care of setting TZ automatically It really ought to since that s the standard DOS way to tell programs what timezone they re in Unfortunately Windows doesn t do that so you still have to make this setting manually 4 2 2 Setting Your Time Zone using IT INI You can also tell nstantT rack the name of the local time zone by setting a variable in the IT INI configuration file The setting in IT INI overrides the TZ environment variable You may want to use this method if 1 Some other program wants to use the TZ environment variable differently or 2 Your timezone is on a half hour or quarter hour offset from UTC or 3 You just don t like to mess with environment variables If any of these applies to you read the section in this document on the IT INI configuration file and the
39. The Orbit View The Orbit View projection is a simple line diagram showing the orbit ellipse and the Earth drawn to scale Similar diagrams can be found in any book on orbital mechanics The satellite is shown in its current position on the orbit ellipse but of course the satellite is drawn larger than scale This view is designed to help you visualize the relative geometry of the orbit and the satellite attitude The orbit ellipse is drawn as if it were in the same plane as your computer s display screen with perigee on the left and apogee on the right The orbit ellipse is white the Earth is a brown circle the main observer you is a green x and the satellite is shown as a red dot The satellite travels counterclockwise on this ellipse If you have set the satellite s attitude then the direction of the satellite s antennas is shown with a small light blue arrow Ideally this blue arrow would point directly at the green x your location Because this arrow may not lie in the orbital plane i e Bahn Latitude may not be 0 two additional views of the orbit appear These are edge views The one on the left of the screen is a view of the orbit from the direction of perigee In other words it is as if you bent your head around and looked at the orbit ellipse from the left side of your screen The view on top is similar as if you viewed the orbit ellipse from the top of your screen looking down At thetime am writing this OSCAR 1
40. Up and PgDn keys then pick a city by number Finally if you know the latitude and longitude of the station you want to add you can just type them in Type latitude first followed by a slash then longitude If he s at the north pole for example you would type 90N OW Remember to use the NSEW letters to specify the correct hemisphere The O command can also be used to delete a station from the observer list After the O type d followed by the position in the list of the station you want to delete You are not allowed to delete the first station on the list That s you The realtime screens show up to three visiting stations and these can be deleted D1 would delete the first visitor etc 7 6 Understanding The Realtime Map Display The Realtime Map Display is similar to the Realtime Text Display described above except that there is a map on the screen and less room for text Four different kinds of map can be displayed Two of these Cylindrical Equidistant and Orthographic are maps of Earth The third Orbit View is a geometric view of the orbit ellipse and Earth The fourth Sky View is a map of the sky as viewed from your location You may switch among these maps at any time using the P command The color map displays are only available if you have an EGA or VGA display The following descriptions apply to the color maps If you have a CGA or Hercules HGC graphics board you can get a monochrome
41. Work for YOU sirana iaee iraia iana iraani ces a aiaa ded apt a a ea ete 47 13 Non numerical Geography Maps Cities and GridSquares ccseceesesseeeeseeeeeees 48 14 Files used by INStantTrack ccccccceeeceeeeneeeeeeeneeeeeeeneeseeeeneeseeeeneeseeeeneeseeeeneeseeeseeseeesneeseeeeees 49 InstantT rack Common Questions ANd ANSWEYSS cccccssssesseceseeeceacsseeesesueeeeansaseseseeeseneuansasseeseeeseauanneeseesens 51 15 Copyright Notice and Distribution Policy c ccsccsseessseeeeseeeseeeseseeeeeeeeeeeseeeseeeseseenenseees 54 16 No Warranty E 54 17 Acknowledgments cccceeeeeceeeeeeeeeenseeeeeensneeeeensneeeeessneeseessneeseessneeseseaneesesssnesessaneeseessnaeeeae 54 Appendix 1 Example Satellite Element File Formats cssccsssessseeeeseeeeeseeseseeeenseeeeneas 55 NASA FOE FOE cidade tei ira ee Ala ileal ene tat 55 AMSAT Oe due 57 Appendix 2 Bugs Problems and FUtures ccsecccccsseeeeeeeeneeeeeeeeeeseeeseeeseeesneeseeeesneeseeeenenes 59 Appendix 3 Video Adapters MDA CGA HGC EGA VGA cccssecceceseeeeeeeseeneeeesneeeeeeeees 60 Bibliography EE 62 Je E 65 ii InstantT rack InstantT rack 1 Introduction InstantTrack was designed to assist amateur radio operators who need to track a large number of Earth orbiting satellites point antennas at them in real time estimate when communications links will be possible with operators in other parts of the world etc I
42. aii The only cost of using the service is the cost of a very quick long distance call More information is currently available at http Awww boulder nist gov timefreq service acts htm 12 2 Procedure Toset your computer s DOS clock via NIST ACTS select Housekeeping Functions at the main menu then Update Time NIST via modem at the Housekeeping Menu InstantT rack will tell your modem to dial and all characters exchanged between the modem and computer will be displayed on the screen NIST sends one timestamp every second As soon as InstantTrack has correctly received two time stamps in a row it will hang up the phone and tell you the results An example session follows At any time during the modem dialog you can type any key and the program will hang up the phone and exit immediately A sample session Modem dialog follows Type any key to abort HELP National Institute of Standards amp Technology Telephone Time Servic D LD MJD YR MO DA HMG ST S UT1 msADV OTM 47511 88 12 16 06 03 44 00 0 1 045 0 UTC NIST 47511 88 12 16 06 03 45 00 0 1 045 0 UTC NIST Setting DOS Date amp Time to local 12 15 1988 22 03 44 Your DOS time was ahead of NIST by 5 22 seconds Info only Your hardware real time clock reads 12 15 1988 22 04 44 Don Phone call duration was 20 4 seconds Note that your DOS clock is set to your local time zone controll
43. ally defining it If you can tolerate a minor digression l Il do that now Teachers have told children for years that the vernal equinox is the place in the sky where the sun rises on the first day of Spring This is a horrible definition Most teachers and students have no idea what the first day of spring is except a date on a calendar and no idea why the sun should be in the same place in the sky on that date every year You now have enough astronomy vocabulary to get a better definition Consider the orbit of the sun around the Earth know in school they told you the Earth orbits around the sun but the math is equally valid either way and it suits our needs at this instant to think of the sun orbiting the Earth The orbit of the sun has an inclination of about 23 5 degrees Astronomers dont usually call this 23 5 degree angle an inclination by the way They use an infinitely more obscure name The Obliquity of The Ecliptic The orbit of the sun is divided by humans into four equally sized portions called seasons The one called Spring begins when the sun pops up past the equator In other words the first day of Spring is the day that the sun crosses through the equatorial plane going from South to North We havea name for that It s the ascending node of the Sun s orbit So finally the vernal equinox is nothing more than the ascending node of the Sun s orbit The Sun s orbit has RAAN 0 simply because we ve defined the S
44. articular time In the Keplerian model satellites orbit in an ellipse of constant shape and orientation The real world is slightly more complex than the Keplerian model and I nstantT rack compensates for this by introducing minor corrections to the Keplerian model These corrections are known as perturbations The perturbations that I nstantT rack knows about are due to the lumpiness of the Earth s gravitational field which luckily you don t have to specify and the drag on the satellite due to atmosphere Drag becomes an optional eighth orbital element Orbital elements remain a mystery to most people This is due think first to the aversion many people including me have to thinking in three dimensions and second to the horrible names the ancient astronomers gave these seven simple numbers and a few related concepts To make matters worse sometimes several different names are used to specify the same number Vocabulary is the hardest part of celestial mechanics The basic orbital elements are 1 Epoch 2 Orbital Inclination 3 Right Ascension of Ascending Node 4 Argument of Perigee 5 Eccentricity 6 Mean Motion 7 Mean Anomaly And the optional 8 Drag The following definitions are intended to be easy to understand More rigorous definitions can be found in almost any book on the subject I ve used aka as an abbreviation for also known as in the following text E poch aka Epoch Time or Tel A se
45. as City Tracker KCT sold by L L Grace Communications Products see bibliography The KCT is a single board interface that plugs into an IBM PC style ISA slot However the software interface used by InstantTrack is generic and can be used to control nearly any kind of hardware Drivers for some popular hardware designs are available for download at http Avwww amsat org amsat ftpsoft html pc rot The driver must be loaded and run before InstantTrack is run When I nstantT rack is in one of its realtime screens the R command enables or disables realtime rotor control If InstantTrack cannot locate a valid rotor driver TSR it simply beeps to indicate the error If InstantTrack finds a rotor driver TSR the indication RotorDRV appears on the top text line of the screen to indicate that InstantTrack is directly communicating with the rotor driver InstantT rack can also work in concert with a TSR program called OrbitDRV which allows your computer to track satellites and control your antennas in the background while you use your computer for other things or visit other screens within InstantTrack OrbitDRV is described in detail in the file ORBITDRV TXT An alternate command interface for OrbitDRV is described in the file ITRACK TXT When I nstantT rack finds itself working through OrbitDRV the indicator OrbitDRV appears along with the name of the satellite being tracked in the background by OrbitDRV InstantTrack ca
46. atellite The white line marks the horizon seen by the satellite which depends on the satellite s altitude 6 The satellite s antenna footprint This shows what parts of the Earth arein the good part of the satellite s antenna pattern Specifically this is a line of constant offpointing angle equal to 20 degrees See discussion of offpointing angle in Understanding the Text Display above The antenna footprint is drawn in light blue There are several situations in which the antenna footprint is not drawn a No antenna footprint is drawn if the satellite s attitude has not been set Some satellites do not have directional antennas and others do not have published attitudes Yet others have attitudes that InstantTrack doesn t know how to calculate If InstantTrack doesn t have all the necessary information to compute the attitude it can t display the footprint b No antenna footprint is drawn in the case where the whole area within the geometric footprint has a good offpointing angle Think of the antenna pattern as a cone shining down from the satellite The antenna footprint is the intersection of this cone with the Earth If this cone encloses the entire Earth there is no intersection and the antenna pattern is good everywhere c No antenna footprint is drawn in the case where all area in the geometric footprint has a bad offpointing angle If the satellite s antenna points away from the Earth
47. aterial here Not suggested as a first text on the subject however Bahn Coordinates Guide Satellite Orbits by Phil Karn KA9Q AMSAT Satellite ournal J an Feb 1986 pp 8 11 Describes the coordinate system that AMSAT uses to describe satellite attitude Conversion Between Geodetic and Grid Locator Systems by Edmund T Tyson QST Magazine J anuary 1989 This article gives a clear explanation of the grid locator system The Satellite Sky published by Air amp Space Smithsonian Institution Washington DC 20560 ISSN 0886 2257 This is a 21 x 34 poster listing over 250 satellites and their name purpose owning nation launch site launch date altitude etc Communications Weather Photo Recon Electronic Surveillance Navigation Earth Sensor and Research satellites are listed Amateur radio satellites are not The RAE Table of Earth Satellites 1957 1986 compiled at The Royal Aircraft Establishment Farnborough Hants England by D G King Hele et al Published in the U S by Stockton Press New York ISBN 0 333 39275 2 I ve also seen it listed as ISBN 0 935859 05 5 This book lists 17000 objects from 2869 launches many of the objects are fragments with name designation launch date estimated lifetime mass shape dimensions and basic orbital parameters Expensive Probably can be found in the reference section of your local college li brary Observing Earth Satellites by Desmond King Hele 1966
48. bution For low E arth orbit satellites increment is often in the range of 20 to 30 degrees West per orbit For OSCAR 13 the increment was about 172 degrees per orbit almost half way around the Earth So after two orbits OSCAR 13 would move West by twice this amount 344 degrees which is just 16 degrees shy of 360 This means that every other apogee of OSCAR 13 occurred in almost the same place over the Earth moving by just 16 degrees East each time Sun to Spinplane Angle This angle is meaningful for spin stabilized satellites only If you have entered attitude coordinates InstantT rack assumes that the antenna axis and spin axis are the same then computes the angle between the sun and the planein which the satellite is spinning This may help you visualize how the sun illuminates solar panels on the spacecraft For example for OSCAR 10 and OSCAR 13 the power generated by the panels was roughly proportional to the cosine of this angle The sun to spinplane angle only appears if you have entered attitude coordinates for the current satellite Sun to Orbitplane Angle This is another angle which may help you visualize properties of an orbit There are many low orbiting satellites designed to take pictures of Earth Satellites designed for Weather Earth Resources Spying etc Of course the position of the sun matters to anyone taking pictures For a satellite aiming its camera straight down toward Earth this angle tells us t
49. ch Rev for OSCAR 10 and OSCAR 13 Unless you use the revolution number for your own bookkeeping purposes you needn t worry about the accuracy of Epoch Rev InstantT rack 21 Beacon Frequency You can specify a frequency of interest for each satellite This is typically the frequency of a beacon transmitter on the satellite This number is used in the calculation of Doppler path loss and Tsky Doppler path loss and Tsky are described in the section on realtime tracking You can edit this item even on the Sun and Moon in order to enable the Tsky calculation to work for EME Schedule Many satellites have several operating modes and switch from one mode to another at predefined places in their orbits I nstantTrack understands satellite schedules which are based on phase mean anomaly expressed in units of 256ths of a circle This is one common scheduling technique for amateur radio satellites If given a schedule InstantTrack will calculate and display the satellite mode The scheduleis a string of numbers and letters A three digit number specifies the phase at which a mode begins then a single letter specifies the mode This is repeated up to 12 times In other words a schedule may contain up to twelve mode changes but no more The numbers in the string must bein an ascending sequence No spaces are allowed For example at one time OSCAR 13 s schedule read Phase Mode 000 002 Off 003 099 modeB 100 149 mode L
50. d be at least 5 degrees below the horizon 4 The satellite should be bright enough to see The cutoff here depends heavily on your local situation city light pollution etc The code letters are H The satellite is below the Horizon E Thesatelliteis in Eclipse S The Sun is up V The satellite is Visible Brightness is presented in units of magnitude which is a scale created by astronomers to categorize the brightness of stars It is a logarithmic scale like decibels or wire gauge Every increase of one magnitude means 2 5119 times less light Bigger magnitude numbers correspond to dimmer objects The nice thing about these magnitude units is that star charts usually show the magnitude of each star so you can usually find some nearby reference points Here s a brief guide to interpretation of visual magnitudes 4 Wow 0 As bright as the brightest star in the sky 4 Barely visible to the naked eye on a clear night in the city 6 Barely visible to the naked eye on a clear night in the country where the sky is dark enough to see the Milky Way clearly 9 Barely visible with good binoculars in dark sky Because many factors affect the brightness of a satellite you should use the number IT calculates only as an estimate IT takes into consideration only the size range and sun angle of the satellite Other considerations affecting brightness are shape and reflectivity If you were building a spy satellite for exampl
51. e There are some interesting cases where you may wish to update only the elements for one particular satellite option 2 For example shortly after OSCAR 13 was launched an incorrect NASA element set was widely distributed If you load new elements then find that the orbit for one satellite is fouled up you can use this feature to recover an older set of elements for that satellite assuming you have kept the element files around You will be asked the name of the file you want to read The file can bein NASA 2 line format or in AMSAT verbose format or any combination of the two Type in the name of the file you downloaded If the file is on a different drive or in a different directory than the one you ran I nstantTrack from you ll need to specify the complete path If you re running under OS 2 or Windows remember that InstantTrack is a DOS program and can only understand filenames and path names that are up to eight characters plus optionally a dot and up to three more characters Spaces are not allowed in DOS filenames If you specify a filename on a floppy disk like A PLAN OUT and you get one of those annoying Abort Retry Fail errors you can choose any of the three reponses If you choose Abort by typing AT InstantT rack will immediately exit If that s not what you want you should probably choose Fail instead by typing F In that case nstantTrack will tell you it failed but you knew that already and ask f
52. e and the shape of the orbit ellipse Now we need to know the size of the orbit ellipse In other words how far away is the satellite Kepler s third law of orbital motion gives us a precise relationship between the speed of the satellite and its distance from the Earth Satellites that are close to the Earth orbit very quickly Satellites far away orbit slowly This means that we could accomplish the same thing by specifying either the speed at which the satellite is moving or its distance from the Earth Satellites in circular orbits travel at a constant speed Simple We just specify that speed and were done Satellites in non circular i e eccentricity gt 0 orbits move faster when they are closer to the Earth and slower when they are farther away The common practice is to average the speed Y ou could call this number average speed but astronomers call it the Mean Motion Mean Motion is usually given in units of revolutions per day In this context a revolution or period is defined as the time from one perigee to the next InstantT rack 19 Sometimes orbit period is specified as an orbital element instead of Mean Motion Period is simply the reciprocal of Mean Motion A satellite with a Mean Motion of 2 revs per day for example has a period of 12 hours Sometimes semi major axis SMA is specified instead of Mean Motion SMA is one half the length measured the long way of the orbit ellipse and is direct
53. e you might consider painting it black so it would be difficult to see On the other hand if you were building a satellite specifically to be observed you might cover it with mirrors Ajisai also called EGP is a 2 meter diameter mirrorball built by the J apanese for just this purpose The difference in brightness between these two cases could be substantial The model in IT has been calibrated against two experienced observers and their observations differ as much as or 1 5 magnitudes from Te estimates for commonly observed objects such as Mir and Salyut 7 IT will not attempt to calculate brightness of an object unless the Diameter parameter has been entered in the satellite database 30 InstantT rack Two items listed in the bibliography give more information on observing satellites 7 3 Commands While in the realtime tracking text screen the following one character commands apply Space freeze unfreeze the display Bieser enable disable the bottom row display Guinean enable disable nearest city display EE look at orbital elements for this satellite K enable disable F ast F orward East enable disable display of XYZ coordinates RE add delete a station observer Basen enable disable antenna rotor and radio control iesse enable disable RA Dec T sky M agn display RRE set a specific time or return to realtime Wasser enable disable display of next rise set time BE zen quit tracking go back to main menu EE
54. e exact character strings that should be sent to your modem to dial and hang up The Hayes type commands that ve included by default will probably work with most modems but if you require something different you can just change it The program also raises DTR and RTS before dialing and drops them after dialing Some modems hang up the phone in response to a falling DTR instead of a command Finally while most commercial programs attempt to interact with the call progress indications i e detection of dial tone busy signal etc provided by most modern modems have ignored them completely simply dial then wait for characters from the modem that look like the NIST format This has the disadvantage that if anything goes wrong during the call say for example a busy signal this program will simply wait until its timeout occurs A program that listens for the call progress info from a modem would know what had happened immediately and tell you This simple minded approach has the advantage that it is compatible with a wide variety of modems and it has not yet been an inconvenience have yet to get a busy signal from NIST You can of course immediately abort a call at any time manually by typing any key on the keyboard 46 InstantT rack 12 5 If It Doesn t Work for You Nevertheless experience shows that you may have trouble getting the Update Time feature to work If you are running under Windows you probably should
55. e menu of 1794 cities shows you which cities are visible from the selected satellite even before you choose a city Graphics nstantTrack displays color high resolution EGA VGA maps of the Earth showing satellite and observers position two kinds of satellite footprint grayline etc Two map projections are selectable You can also select either a diagram of the satellite s orbit showing the orientation of the satellite or a map of the sky showing the satellite s position against the field of stars You can move from map to map or satellite to satellite with a single keystroke instantly Large Number of Satellites amp Stations nstantTrack maintains a database of 200 satellites and 50 observer locations A unique grouping feature allows you to categorize satellites and perform most operations on either a selected group or the entire database InstantT rack 1 City Database nstantTrack includes a database of 1794 cities worldwide Locations of the satellite sub satellite points and observers are displayed relative to the nearest city Observing stations can be specified by entering as little as their city name Grid Squares nstantTrack understands the gridsquare system Observing stations can be specified by typing only their gridsquare Satellite Covisibility nstantTrack shows you when satellites can see other satellites i e when crosslinks are possible when satellites arein eclipse in the shadow of
56. e of a time zone followed by number indicating the number of hours difference between UTC and your time zone followed by an optional three letter name of a daylight saving time timezone There must not be any spaces in this command except the one between SET and Tz For Eastern Standard Time with Daylight Saving Time SET TZ EST5EDT For Mountain Standard Time with Daylight Saving Time SET TZ MST7MDT If you live in an area where daylight saving time is not used or where the rules are different from those in the U S you should leave off the last three letters For example if you livein Arizona where they don t have Daylight Saving Time you should use SET TZ MST7 Or if you live in Western Australia where they dont have Daylight Saving Time you should use SET TZ HST 8 Notice in the example above that the number can be negative Use negative numbers if your timezone is ahead of UTC Use regular positive numbers if your timezone is behind UTC The number has to be a whole number though so if your timezone is a half hour or quarter hour off from UTC see the next section In the U S Daylight Saving Time starts at 2 AM on the first Sunday of April and ends at 2 AM on the last Sunday of October If you live someplace where Daylight Saving Time is used but it starts and ends on different dates you must change your timezone setting each spring and fall For example you might use SE
57. e the coordinates shown on star charts Tsky This is the sky noise temperature in the direction of the satellite i e the direction in which your antennas are pointed The stars generate radio noise That s what Radio Astronomy is about This noise is largest when your antennas are pointed toward the plane of the galaxy also known as the Milky Way and very large when pointed toward the center of the galaxy Tsky also depends on frequency Tsky is larger at lower frequencies If you have entered a frequency in the satellite database for a particular satellite then InstantTrack will compute and display the expected sky tem perature Noise temperatures can be added directly You can therefore add Tsky to the temperatures of other noise sources in your receiving system preamp cable attenuation sidelobes when calculating receiving system performance See the ARRL Handbook InstantT rack 29 Visibility Magnitude InstantT rack attempts to provide you with an estimate of whether a satellite might be visible to the eye We estimate the brightness of reflected sunlight from the satellite and a one letter code which indicates whether all the conditions for visibility are met Here are the conditions normally required for satellite visibility 1 The satellite should be above the horizon 2 The satellite should bein sunlight e not eclipsed 3 The sun should be down so the observer is in darkness We use the rule that the sun shoul
58. eave extra blank space at the bottom of each page You can use either F or P for capturing toa file You can also use either F or P for capturing directly to a printer Use whichever you prefer If you don t want a file but instead want to print the table directly to the default printer enter PRN for the file name You can also enter the special DOS name for the port your printer is connected to such as LPT1 or LPT2 If your printer is connected toa serial port you can enter CoM1 or COM2 etc provided you ve previously used the MODE command to set the baud rate and other communications parameters There are a few other special file names that don t do anything useful here and you should avoid using them NUL and con for instance If you re on a network under Windows you should be able to use network filenames using the Uniform Naming Convention UNC syntax as an alternative to mapping a network drive These filenames look like hostname dirl dir2 filename 40 InstantT rack If you specify a filename on a floppy disk like A PLAN OUT and you get one of those annoying Abort Retry Fail errors you can choose any of the three reponses If you choose Abort by typing AT InstantTrack will immediately exit If that s not what you want you should probably choose Fail instead by typing F In that case InstantTrack will tell you it failed but you kn
59. ecified in degrees minutes and seconds It must be converted to degrees before you type it in Use this formula decimal degrees degrees minutes 60 seconds 3600 Altitude is measured in meters above sea level You should try to find your latitude and longitude to at least two places after the decimal point Altitude is not nearly so important you can guess The US Geological Survey publishes detailed maps of the entire US which show latitude longitude and altitude to the required accuracy You can usually find these maps at your local major University library or a map store You can also find your location by using a GPS receiver 10 InstantT rack You can also type the D key for Delete on this screen This deletes the current station settings so this station will no longer appear on the station menu InstantT rack 11 6 Satellite Elements What Are The Orbits Satellite Orbital Elements are numbers that tell us the orbit of each satellite Elements for common satellites are distributed through the Internet on amateur packet radio bulletin boards and other means InstantT rack comes with elements for many satellites already defined but these elements are probably out of date by the time you install InstantTrack You can update these elements by telling InstantT rack to read in files containing new elements or by entering elements manually InstantT rack can read satellite element files in two common formats Entering
60. ect OSCAR 63 R Range 27 Rev 28 Right Acension 29 Right Ascension of Ascending Node 16 Riportella Vern 62 Rise Set 29 S Satellite Age 23 Schedule 21 42 Sky View 33 35 spin modulation 27 Squint 27 station 10 station elements 3 Subsatellite Point 28 Sun Angles 24 65 T Taff Laurence 62 time zone 3 6 7 8 Tyson Edmund 62 U UTC 8 V vernal equinox 17 Visibility 30 W Welch Roy 54 Williamson Paul 54 WWV 6 Y yellow 4 26 66 InstantT rack
61. ed by your setting of the TZ envi ronment variable or settings in the IT INI configuration file This is described earlier in this document The Info only line about your hardware realtime clock RTC is only printed if you have an IBM AT or a machine with an AT compatible BIOS The RTC is the device that remembers time of day when your computer is turned off InstantTrack reads the AT RTC but does not attempt to set it It makes no attempt to read or write the large variety of different third party aftermarket RTCs that are present in many IBM PC s and XT s The average phone call duration is about 20 seconds If there is phone line noise that garbles some of the characters it will take a little longer nstantTrack contains a timeout to prevent excessively long InstantT rack 45 phone calls This is initially disabled but may be enabled by setting the nist_maxt ime parameter in the IT INI file to some number of seconds other than zero NIST provides a timeout which hangs up the phone at their end after 55 seconds 12 3 What Can Go Wrong The most common thing that can go wrong is that your modem may require different commands than the one ve provided or you may have your modem on a different COM port You may edit the configuration file IT INI to correct these problems Please read instructions in ITINIDOC TXT before editing IT INI 12 4 Technical Notes on Dialing modems One of the challenges when writing any program
62. ee Understanding Satellite Parameters for a discussion of schedules Mode will only be displayed if a valid schedule has been entered for this satellite XYZ C oordinates These are the coordinates of the satellite and the observer in the cartesian geocentric inertial coordinate system These are called IJ K coordinates in some books The X axis points from the center of the Earth toward the vernal equinox The Y axis points 90 degrees to the east of the X axis The Z axis points straight up through the geographic North Pole Units are kilometers All the other numbers on this screen are calculated from the cartesian coordinates of the satellite and observer If this display bothers you you can turn it off by typing I for IJ K Next Rise Set This is the time at which the satellite is next expected to rise or set over the horizon This is only calculated if you have enabled this feature via the W for When command Skygazer s Information The following three parameters are related to the sky and to visual observation of the satellite These displays may be turned off by typing S for Sky R A Decl These are the Right Ascension and Declination of the satellite as viewed from your location Right Ascension and Declination are coordinates used by astronomers to locate objects in the sky They are similar to longitude and latitude except that they represent locations on the celestial sphere instead of the Earth R A and Dec ar
63. ent but which does not get entered into the permanent database More about visitors later Pick a station to edit The first time you run InstantT rack you should edit station 1 so that it represents your station s location Type the number of the station you picked then hit Enter The Edit Station Elements screen will appear and the present station name latitude longitude and elevation above sea level will be displayed Some computed information is also displayed to help you verify that you ve entered your station location correctly Editing station data is simple Use up arrow and down arrow keys to move the cursor to the line you want to change To change a value type the key followed by the new value Type the Enter key to enter the value To exit this screen type the Q key Most screens in InstantTrack exit when you type the Q key Q stands for Quit Latitude is entered in degrees North or South Longitude are entered in degrees East or West Not degr ees minutes seconds Latitude must be in the range 90N 90S Longitude must be in the range 180E 180W You may indicate North South East or West by typing N S E or W after the number or you may use negative numbers for South and East Positive numbers are assumed to be North or West Many other programs consider East to be positive Don t let that confuse you J ust use the letter E or W and you ll be safe Be careful if you have a latitude or longitude sp
64. er it does mean that if something goes wrong you might not notice Check your automation setup carefully and occasionally inspect the elements database manually to be sure the elements are up to date Since it s now possible for a second InstantTrack to come along and change the satellite database while a first InstantTrack is still running nstantTrack will warn you on the Update Satellite Elements screen if the database file IT ORB has been modified since the last time it was read or written When you see this warning be careful If you make changes to the database while the warning is displayed you will overwrite any changes that were made by the automated update To avoid this problem exit I nstantTrack and restart it There are some third party programs out there that update the I nstantTrack database directly Since the database format has changed since version 1 00 these programs probably won t work anymore Instead of updating those programs you are strongly encouraged to use the features of I nstantTrack described in this section to update the database 16 InstantT rack 6 2 Understanding Satellite Elements Seven numbers are required to define a satellite orbit This set of seven numbers is called the satellite orbital elements or sometimes K eplerian elements after J ohannes K epler 1571 1630 or just elements These numbers define an ellipse orient it about the Earth and place the satellite on the ellipse at a p
65. es for Drag but don t approve of them F eel free to substitute zero in place of any published negative Drag value 6 3 Understanding Satellite Parameters All the satellite parameters described below are optional They allow I nstantT rack to perform some of its more sophisticated and fun calculations so you are urged to read this section even though you are not required to enter these parameters NASA Designation This item consists of the year of launch a serial number within the year and a letter designating this object among the several objects placed into orbit by that launch As the name suggests it is assigned by NASA for reference Element Set Number This number labels a particular element set from a given source It is just copied from the element set file and displayed here for your reference Epoch Rev aka Revolution Number at Epoch This tells I nstantT rack how many times the satellite has orbited from the time it was launched until the time specified by E poch Epoch Rev is used by I nstantTrack to calculate the revolution number shown on the realtime screens and to calculate satellite age on the Satellite Elements Edit screen Don t be surprised if you find that orbital element sets which come from NASA have incorrect values for Epoch Rev The folks who compute satellite orbits dont tend to pay a great deal of attention to this number At the time of this writing elements from NASA had an incorrect Epo
66. es pokes out we will have the orbital plane fully specified The line of nodes pokes out two places of course We only need to specify one of them One is called the ascending node where the satellite crosses the equator going from south to north The other is called the descending node where the satellite crosses the equator going from north to south By convention we specify the location of the ascending node Now the Earth is spinning This means that we can t use the common latitude longitude coordinate system to specify where the line of nodes points Instead we use an astronomical coordinate system known as the right ascension declination coordinate system which does not spin with the Earth Right ascension is another fancy word for an angle in this case an angle measured in the equatorial plane from a reference point in the sky where right ascension is defined to be zero Astronomers call this point the vernal equinox Finally right ascension of ascending node is an angle measured at the center of the Earth from the vernal equinox to the ascending node know this is getting complicated Here s an example Draw a line from the center of the Earth to the point where our satellite crosses the equator going from south to north If this line points directly at the vernal equinox then RAAN 0 degrees By convention RAAN is a number in the range 0 to 360 degrees used the term vernal equinox above without re
67. ew that already and ask for a new filename If you can correct the problem such as by inserting a floppy disk do so and choose Retry by typing R If things are now working InstantTrack will pick up and continue as if nothing had gone wrong There is one other setting in the T INI configuration file pertaining to your printer The setting printer_formfeed_at_end controls whether I nstantTrack sends one last formfeed new page eject to the printer at the end of each job You probably need to set this to 1 under DOS because most printers will hold onto the last partial page of output until the computer sends a formfeed If you re running under Windows or OS 2 you probably want to set it to 0 J ust closing the file is enough to force the last page out of the printer under those environments If you find you re getting a blank sheet at the end of every job change this setting from 1 to 0 If you find you re not getting the last partial page of output until you print something else change this setting from 0 to 1 If you are moving rapidly from satellite to satellite using the arrow keys the capture file or printout will only contain as much of each satellite as InstantT rack had time to compute and put on the screen before you switched to ancther satellite The other lines on each screen though still blank will also appear in the output This function captures plain ASCII text in DOS format Exception
68. f the satellite across the sky for the next orbit or the next day for the Sun and Moon If you typea number 1 to 60 before typing G the sky track will span that number of orbits If you type G again the sky track will disappear The map is always drawn right side up so stars shown below the horizon line are in fact below the horizon Such stars are not blanked even though you cannot see them through the Earth because they will help you recognize constellations near the horizon As an aid in locating the correct portion of the sky on star charts etc the Right Ascension and Declination of the satellite are shown at the bottom of the screen RA and Dec are coordinates used by astronomers to locate objects in the sky They are similar to longitude and latitude except that they represent locations on the celestial sphere instead of the Earth Like the other maps the sky view is automatically updated as the Earth turns and the satellite moves 7 10 Commands on the Map Screen Whilein the realtime tracking map screen the following one character commands apply Space freeze unfreeze the display ees enable disable the City dots Eug look at orbital elements for this satellite Eat start stop fast forward mode Guinea enable disable ground track display EE enable n orbits of ground track display Ou a add delete an observer Poria change the map projection R geet change to cylindrical equidistant Seed chan
69. f them are Rather the extra digits are shown so you can visually estimate how fast the value is changing 26 InstantT rack Included on this screen are Azimuth and Elevation These are the angles you use to point an antenna at your station toward the satellite When Elevation is negative the satellite is below the horizon and is not visible from your station These figures along with the other figures on this line are colored green when the satellite is below your horizon and yellow when it is above your horizon Range dR dt and Doppler Range is the distance in km from your station to the satellite dR dt is the rate at which Range is changing in km second dR dt determines Doppler If you have entered a beacon frequency for the satellite the current Doppler shift for that frequency is shown in units of Hz Offpointing Angle Offp Many satellites use directional antennas Unfortunately the satellite antenna is seldom pointed directly at you This angle is a measure of how far away from you the satellite antenna is pointed It is O degrees when the satellite antenna is pointed directly at you If you know the beamwidth of the satellite antenna you can estimate how much degradation the link will suffer due to the offpointing For example if the satellite has an antenna with a 3dB beamwidth of 24 degrees e 12 degree half beamwidth then you will suffer 3dB of loss when the offpointing angle is 12 degrees When the offp
70. format is unknown Some old NORAD reports refer to this as T card format NASA documents often call it the 2 line format InstantT rack expects a file which contains groups of 3 lines One line containing the satellite s name followed by the NASA 2 lines of numbers Files of this format are distributed by T S K elso to nationwide computer networks and end up on BBS s and electronic mail systems around the country You can find T S K elso s element sets on http Awww celestrak com NASA leaves some fields out of some element sets The international designators for example are of ten missing nstantTrack checks for this and uses the new designator only if it s really there If there s a nonblank character in line 2 column 10 assume the designator is valid and read it in NASA format files look like this OSCAR 10 1 14129U 88230 56274695 0 00000042 10000 3 0 3478 2 14129 27 2218 308 9614 6028281 329 3891 6 4794 2 05877164 10960 GPS 0008 1 14189U 88230 24001475 0 00000013 0 5423 2 14189 63 0801 108 8864 0128028 212 9347 146 3600 2 00555575 37348 Each number is in a specified fixed column Spaces are significant The last digit on each lineis a mod 10 check digit which is checked by the program The program also checks the sequence numbers first column and checks each orbital element for reasonable range This is a very good set of checks so this format is very safe and robust have noticed recently files
71. g you know about the observer you d like to add and InstantT rack will try to use that information Because there are several options here the explanation begins to sound complicated Stay tuned It s very simple We ll take these one at a time If you know the name callsign of the station you d like to add and that station is in the station database you can just type the callsign InstantTrack will search the database and find the station information For example if you ve just started a conversation with KB5MU via your favorite satellite then you can just type KB5MU If you know the station you want to add is in the database but you can t remember the callsign then you can type s which gets you to the station selection menu which displays all the stations which you have defined and where you can pick the station you want If the station you want to add is not in the station database and you don t want to take the time to edit the database you can describe a visiting station This can be done several ways By city name gridsquare or latitude longitude If you know the gridsquare of the station you want to add you can just type the gridsquare For example if you ve started a conversation with someone who says he s at grid DM12 then you can just type DM 12 Either the four character or six character gridsquare will be accepted Most Amateur Radio operators know their gridsquare Asking What s you
72. ge to orthographic E change to orbit view An change to sky view Risika enable disable antenna rotor control Sees toggle scroll mode for cylindrical map E set a specific time or return to realtime Uinton force an update of the map now VE toggle white on black vs black on white CGA and HGC only Wi enable disable next Rise Set time calculation amp display Qana quit tracking go back to main menu SR toggle between local UTC timezones Seah advance to next satellite Cad go back to previous satellite Ctrl gt advance to next satellite in this group Ctrl lt go back to previous satellite in this group When you initially start up the map screen it will be running in real time computing the position of the satellite Earth etc right now There are three commands that can be used to change this space F and T 36 InstantT rack The spacebar simply stops the screen like the freeze frame button on a VCR Typing the spacebar again pops you back to realtime The T command also produces a screen that stands still but T allows you to enter a specific time for which you want the calculations performed F or example if you are scheduled to use OSCAR 10 at 4pm today and you d like to see where the Satellite will be at that time you can type T then respond to the prompt by typing 16 00 followed by Enter InstantTrack will immediately calculate and display everything for that specific time At this time
73. he angle of the shadows that will be formed by mountains buildings etc in the pictures Many satellites that take pictures arein sun synchronous orbits i e orbits for which this angle has a constant value and in many cases this value is chosen to be around 20 degrees InstantT rack 25 7 Tracking a Satellite in Real Time When you choose either of the Realtime Track 1 Satellite items on the main menu you are immedi ately presented with a satellite selection menu After you choose a satellite all the information about that satellite appears 7 1 Choosing a Satellite The satellite selection menu appears whenever you enter any mode which will display information about one particular satellite Initially you see the first page of the menu which contains the first 50 satellites You can use the PgUp and PgDn keys to move between pages of the menu The satellite names are displayed in one of three colors white green or yellow with the following meanings White InstantTrack has not recently calculated this satellite s position Green This satellite is bd ow the horizon right now Yellow This satellite is above the horizon right now All are initially white of course While waiting for you to make your choice InstantTrack whips through all the satellites in the database calculating their position turning each name green or yellow This lets you know even before selecting a satellite whether or not it is above the
74. he display is a matrix Each row and column represents a satellite Thereis a small green dot at the intersection of any row amp column if the two satellites cannot see each other and a big yellow dot if they can Unfortunately only 20 rows and 58 columns of this matrix fit on the screen at any one time The four arrow keys scroll the display in various directions so you can see any part of the entire 200 x 200 matrix Two additional columns on the left are labeled O and S These stand for Observer that s you and Sun Dots in the O column indicate whether the satellite named to the left is visible to you at the present time Dots in the S column indicate whether the satellite named to the left can see the sun A dot next to the date and time in the upper left of the screen blinks once every time that the com puter has recomputed the positions of all the satellites and updated the display 11 2 Commands arrow keys cause scrolling so you can view selected portion of the covisibility display Zonet toggle between local UTC timezones E ais quit this screen 44 I nstantT rack 12 Setting Time via NIST 12 1 What is NIST ACTS NIST ACTS is the Advanced Computer Time Service provided by the US Government National Institute of Standards amp Technology The NIST Time Service presently uses an ordinary phone number in the 303 area code Colorado and there s an alternate number in the 808 area code Haw
75. icult for humans to read InstantT rack can read either format or any combination of the two Ideally you will find a source for elements in computer readable form and never be forced to typein elements by hand 12 InstantT rack To enter satellite elements select Housekeeping Functions on the main menu Then select Update Satellite Elements on the Housekeeping Menu This will take you to the U pdate Satellite Elements menu Here you can choose from a variety of satellite database update functions LAL LE whines Read in elements for ALL satellites in file ZONE ash Read in elements for ONE specific satellite 3 UPDATE Read in elements for ALL satellites EXCEPT those for which the program already has newer elements 4 OLD Delete satellites with old orbital elements 5 CRASH Delete satellites that have crashed 6 DELETE Deletea satellite manually 7 SQUISH Compact the satellite elements database 8 EDIT View Edit satellite elements by hand These functions are described below 6 1 1 Automatic Satellite Element Entry In most cases you will probably specify option 3 Under option 3 as nstantTrack reads in elements for each satellite it compares the E poch that is effective time of the element set in the database to the Epoch of the element set in the file The element set from the file is only read in if its Epoch is later than the Epoch of the element set you already hav
76. ill prompt you for a file name Enter the name of the file you want InstantTrack to create You may then page forward in time change satellites or whatever you like within the Satellite Position Table function and InstantTrack will capture everything you see except you can type C without capturing the old display If you want lots of output you can type S to enable Scroll mode When you re done capturing you may simply quit the function type Q as usual or you can type F or P again to toggle capture off When you type F for File nstantT rack puts one set of column headings just like the ones at the top of the screen at the top of the file It puts another set of column headings into the file when you ve changed a setting that invalidates the old column headings but otherwise the rest of the output flows seamlessly without any additional headings This mode is probably best for capturing to a file for later editing or analysis When you type P for Printer or Paged InstantTrack puts a set of column headings on each page of the captured data This is most appropriate if you are printing the output F or this to come out right you need to tell InstantT rack how many lines your printer can put on one page This setting is in the IT INI configuration file See the file ITINI DOC TXT for instructions on how to set this parameter The default value will probably work for you but it may l
77. in their orbits specified by Mean Anomaly Unfortunately when used this way it is common to specify MA in units of 256ths of a circle instead of degrees To minimize confusion when InstantTrack displays MA in units of 256ths of a circle it s called phaseinstead of Mean Anomaly When entering Mean Anomaly as an orbital element it must however be specified in degrees between 0 and 360 Example Suppose OSCAR 99 has a period of 12 hours and is turned off from Phase 240 to 16 That means it s off for 32 ticks of phase There are 256 of these ticks in the entire 12 hour orbit so it s off for 32 256 x12hrs 1 5 hours Note that the off time is centered on perigee Satellites in highly eccentric orbits are often turned off near perigee when they re moving the fastest and therefore difficult to use Drag aka Nu Drag caused by the Earth s atmosphere causes satellites to spiral downward As they spiral downward they speed up The Drag orbital element simply tells us the rate at which Mean Motion is changing due to drag or other related effects Precisely Drag is one half the first time derivative of Mean Motion Its units are revolutions per day per day It is typically a very small number Common values for low Earth orbiting satellites are on the order of 104 Common values for high orbiting satellites are on the order of 10 7 or smaller 20 InstantT rack Occasionally published orbital elements for a high orbiting satellite
78. itch i e IT M or ITNCP M See ITUPDATE TXT for information about recent changes etc As with any project this large the product is never complete There are more good ideas than time to implement them had to stop somewhere and the result is the present release make no commitment about future versions however do havea long wish list of ideas which hope can be implemented in future versions of InstantTrack Users have provided me with a long list of things could have done better Fixing isn t as much fun as implementing new features but some of this work might happen too Stay tuned InstantT rack 59 Appendix 3 Video Adapters MDA CGA HGC EGA VGA There are many different video adapter boards used in PCs these days Here is a discussion of how InstantT rack supports each of these InstantTrack automatically detects which kind of display you have so can usually run InstantTrack without worrying about what kind of display you have There are a few exceptions and these are noted below MDA Monochrome Display Adapter This is the oldest and simplest and doesn t support graphics You can use nstantTrack in any of the text screens but you won t get maps You might consider upgrading to an HGC or clone of same CGA Color Graphics Adapter This is the oldest kind of color graphics board for the PC InstantTrack does display maps on a CGA but they appear in a single color You can also use InstantTrack in a
79. itude all cities gt 32 000 pop are included typed in the data for non U S cities from atlases and other reference books Gridsquares The Grid Locator System or gridsquares in Europe it s called the Maidenhead Locator System after the place where a meeting was held to standardize it is used by amateur radio operators It is simply an encoding of latitude and longitude into a four or six character string It s quicker to say DM 12it over the radio than I m at 32 817 degrees North latitude 117 267 degrees East longitude See Tyson s articlein QST It s listed in the bibliography Or see http Awww arrl org locate gridinfo html 48 InstantT rack 14 Files used by nstanfTrack Computer readable files used by I nstantTrack TEX GE This is the executable program ITNCP EXE nan Alternate executable program if you have No math CoProcessor ITOR Biia nik Library of satellite orbital elements ROTH ieia Library of station elements IT CTY GE Library of 1794 city locations worldwide TEM P ia aara aaia Maps of Earth ITST Ronaki Map of 920 bright stars IT HL EE Text for the online help screens Human readable files that come with nstantT rack ITMANUAL PDF The documentation file you are now reading formatted ITMANUAL TXT The documentation file you are now reading plain text ITUPDATE TXT Information about changes to I nstantTrack ITWISH TXT 000a Wish list of requested improvements
80. ll default to right now If you have asked for a single satellite schedule you will then select a satellite on the satellite selection menu If you have asked for a multiple satellite schedule you will be prompted for the name of a satellite group If you do not enter a group name the group will default to e all Satellites Groups are explained in the section on Satellite Parameters If you ve asked for the multiple observer schedule you will be prompted to select the observers The current observer list will be displayed and you will be allowed to edit it As with other places in InstantTrack where you can specify an observer this prompt accepts city names callsigns gridsquares lat lon or S or C to pull up the full station or city menus When you are done editing the observer list type the Enter key 10 1 Understanding The Display In the first form each day is shown as a row on the display Each column indicates a 20 minute period during the day A portion of the display looks like this Satellite Oscar 13 Station N6NKF Hours UTC DE 4B a At Be 6s ik Be 9 Oe ASE ED Se LA oe 23 01 21 90 OooBBBBBBJJJBBBBB 01 22 90 BJJJ B 01 23 90 BJ BBBB In the second form each satellite is shown as a row on the display A portion of the display looks like this Day 01 21 90 Station N6NKF Hours UTC OF L ar A ba Ge E TR 90 ZE TSA TA ee Sun eist Se ee KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK wee Tt Moon KK
81. ly related to mean motion by a simple equation Typically satellites have Mean Motions in the range of 1 rev day to about 16 rev day Mean Anomaly aka Mg or MA or Phase Now that we have the size shape and orientation of the orbit firmly established the only thing left to dois specify where exactly the satelliteis on this orbit ellipse at some particular time Our very first orbital element E poch specified a particular time so all we need to do now is specify where on the ellipse our satellite was exactly at the Epoch time Anomaly is yet another astronomer word for angle Mean anomaly is simply an angle that marches uniformly in time from 0 to 360 degrees during one revolution It is defined to be 0 degrees at perigee and therefore is 180 degrees at apogee If you had a satellite in a circular orbit therefore moving at constant speed and you stood in the center of the Earth and measured this angle from perigee you would point directly at the satellite Satellites in non circular orbits move at a non constant speed so this simple relation doesn t hold This relation does hold for two important points on the orbit however no matter what the eccentricity Perigee always occurs at MA O and apogee always occurs at MA 180 degrees It has become common practice with radio amateur satellites to use Mean Anomaly to schedule satellite operations Satellites commonly change modes or turn on or off at specific places
82. n 5 CRASH deletes all satellites where I nstantTrack computes a perigee which is below the surface of the Earth The object may have actually crashed or the element set you have may no longer be valid The files of NASA elements distributed by T S K elso often contain some very short lived objects It is not uncommon to find a couple of objects that crash within days after you get a new file of elements It is not necessary to delete these objects but I nstantTrack will find them and delete them for you if you wish Option 6 DELETE lets you delete a specific satellite InstantT rack 15 Option 7 SQUISH As you delete satellites from the database you leave holes In other words if you delete satellite number 33 then number 33 will show as blank on the satellite menu Option 7 slides all the satellites up in the database to fill in the holes This is also entirely optional 6 1 4 ITSORT Satellite Database Maintenance Utility In addition to the built in features of nstantTrack you may use the included program ITSORT to manage your satellite database See the file TSORT TXT for details 6 1 5 Automating Satellite Element Updates InstantTrack has two ways to further automate the updating of Keplerian elements One method or the other should be easy enough to integrate into any automation scheme you may want to use In the first method you specify F FILENAME on the command line when you run I nstantTrack like thi
83. n also work with a radio driver TSR program to tune your transceiver s to compensate for Doppler shift The status of the RotorDRV rotator driver the OrbitDRV background computation module and the RadioDRV radio interface driver can be obtained by selecting Option Status TSRs from the Housekeeping menu 38 InstantT rack 9 Satellite Position Table Ephemeris When you wish to view a table of the position of a satellite at times in the future which the astronomers call an Ephemeris select Satellite Position Table on the main menu by typing 3 This display is not realtime It allows you to examine future or past satellite passes The display has three formats The first format displays latitude and longitude Doppler and satellite mode information The second displays distance and direction to nearest city so you can visualize the path the satellite takes over the surface of the Earth during a pass The third format displays satellite visual observability information You can switch between them by typing C repeatedly 9 1 Entering Parameters You will be asked to select a satellite using the standard satellite selection menu After that you will be asked for a starting time and a time increment In each case the program provides a reasonable default value which you can select by simply typing the Enter key in response to each question Start time defaults to right now and the time increment defaults to 100 poi
84. n entered for this satellite in the database Satellites commonly operate on two or more frequencies simultaneously nstantTrack only displays the path loss at one frequency You can scale this number to produce path loss at a different frequency if you wish Path loss increases 1dB for every 12 2 increase in frequency For example InstantT rack 27 amateur radio satellites often use uplink downlink bands separated in frequency by a factor of 3 e g 145M Hz 435MH2z A factor of 3 in frequency corresponds to approximately 9 5dB changein path loss suggest you use path loss as a relative indication for a given frequency mode Earth station configuration etc of expected link quality Satellite communications links are almost always downlink limited The downlink signal power available at your receiver is all numbers in dB Transmitter power Transmit antenna gain Path Loss Receive antenna gain If all other things were constant receive signal power would vary directly with path loss Subsatellite Point If you draw a line from the satellite to the center of the Earth the point where this line intersects the Earth s surface is called the subsatellite point The coordinates of the subsatellite point are displayed three different ways Latitude Longitude This is the coordinate system in which the subsatellite point is traditionally displayed It is useful when comparing results against other programs Unfortunately
85. n read the file TINIDOC TXT for details on how these settings should be used 4 3 How Time is Displayed and Entered Many InstantTrack screens display date and time These dates and times may be displayed as athe UTC or local time You get to choose Some users prefer to think in UTC others become totally confused trying to mentally convert back and forth between UTC and local time Most of us are somewhere in between When InstantTrack starts up time display is in UTC At any time on most screens you can type the Z command which toggles the time display mode between UTC and Local Z stands for Zone as in timezone You can always tell which mode you re in A realtime time display appears at the top left corner of most screens and it contains the timezone name For example the time displayed might be 03 01 92 06 22 37 UTC If then type Z the display will instantly become 02 29 92 23 22 37 PDT 8 InstantT rack What about time entry A few InstantTrack screens will prompt you to enter a time In most cases you can just respond by typing the Enter key InstantTrack will accept this to mean right now If you need to enter some other time InstantTrack will accept any of the following formats mm dd yy hh mm ss fully specified date amp time mm dd yy hh mm seconds default to 00 mm dd yy time defaults to 00 00 00 hh mm ss day defaults to today hh mm and seconds default to 00 The exam
86. n your screen It looks like this Assertion failed satp NULL in file keprmenu c at line 329 Stackdump Follows keprmenu c set_sat_elem keprmenu c elem_manual_set actmenu c action_menu it c main Abnormal program termination The first line tells me what assertion failed exactly wherein the program and the stackdump tells me how got there InstantT rack 51 If you stumble onto a bug in InstantTrack and a stackdump like this appears on your screen please hit the Shift PrtSc or whatever key on your computer makes a screen dump on the printer slip it into an envelope and send it tome If you re one of the first to report a bug your name or callsign will appear next to the bug description in the I1T UPD filein future versions Question My modem doesn t hang up the phone after InstantTrack calls NIST to update time What do do to fix this Answer nstantTrack does two things to hang up the phone Get either one of these mechanisms working right and the modem should hang up properly First InstantTrack sends a command to your modem to tell it to hang up the phone By default this command is ATH Some modems need this command changed to ATHO Some modems may need yet a different command Read the documentation that came with your modem If your modem didn t come with any technical documentation complain to the manufacturer or check the manufacturer s web site You can then edit thelT INI fileto
87. ng Started There are only three things you must do to get started 1 Set your time zone 2 Enter your station elements or location 3 Update the Keplerian elements database These procedures are described in the sections titled Setting Your Time zone Station Elements Where Are You and Satellite Elements What Are The Orbits which follow You then run one of the following two programs IT if your computer has an 8087 80287 or 80387 numeric co processor or uses a 486DX Pentium or any other modern Pentium class CPU ITNCP if your computer has an older processor and does NOT have a numeric coprocessor the letters NCP stand for No Co Processor A few of you with unusual hardware configurations may need to set a few more parameters These are described in the file ITINI DOC TXT If InstantT rack s use of your mouse causes problems you can tell InstantTrack not to use the mouse by adding M on the command line This can be helpful under certain older multitaskers InstantT rack 3 2 The Main Menu Screen The main menu is the first screen to appear when you fire up InstantT rack This screen is a simple menu which allows you to pick among the basic functions that I nstantTrack performs Each of these functions is described in a later section At the bottom of the main menu screen there is a horizontal red line below which appear your present pointing angles azimuth elevation to up to se
88. nstantT rack is copyrighted software See the copyright and distribution information later in this document InstantT rack 1 00 introduced in 1989 several features that made it unique among satellite tracking programs and a few features which while not unique were relatively uncommon among low cost satellite tracking programs While many of these features have been added to other programs no other program matches I nstantTrack s combination of speed small size ease of use and wide compatibility with many different computers I ve taken the liberty of listing a few of these here Speed nstantTrack is still faster than any other tracking program Humans should never wait for computers I nstantTrack is fast even on ancient slow computers Ease of use Most commands area single keystroke Usually tedious functions are fully automated Automated orbital element entry nstantTrack reads the popular NASA and AMSAT format satellite element files and updates its database automatically You need never again manually enter dozens of 10 digit numbers Automated time setting nstantTrack automatically sets the time on your computer by accessing the NIST time service via your modem Instant Visibility mstantTrack shows you the positions of your favorite Satellites even before you issue the first keystroke The menu of 200 satellites shows you which are visible from your location even before you select a satellite Th
89. ntT rack rapidly computes the time at which a satellite will rise over the horizon Tracking Multiple Stations You can see the computed parameters azimuth elevation squint etc both from your perspective and from the perspective of the station at the other end of the satellite link Documentation Extensive and Tutorial Online Help nstantT rack contains a context sensitive online help facility which can be entered from almost any screen InstantT rack 1 1 Required Hardware Any IBM PC or AT PS 2 clone etc with at least 512K memory running DOS or a compatible environment such as OS 2 Windows 3 1 Windows 95 Windows 98 Windows NT or Windows 2000 Any display type is OK for the text mode screens Color maps require EGA or VGA display Minimal monochrome maps are supported on HGC and CGA I m not particularly fond of the ancient CGA boards if you have one of those beware that have taken no steps to avoid CGA snow A numeric coprocessor 8087 or 80287 or 80387 is NOT required but it is recommended InstantTrack isn t really Instant on an old computer without a coprocessor but it will still probably be faster at most things than any other tracking program If you havea Pentium or faster CPU you have a numeric coprocessor built in and don t need to worry about it A mouse is NOT required but can be used on the map screens Due to the large file sizes involved a hard disk is recommended 1 2 Getti
90. nts per orbit which means the time increments will be smaller for faster moving satellites InstantT rack displays the timezone in the Starting at prompt but you aren t allowed to enter it yourself You must use the timezone nstantT rack displays There is no means to switch timezones at this prompt 9 2 Understanding The Display The numeric information presented on this display is a subset of the information on the realtime text display See explanations in the text display section 9 3 Commands While a table of satellite positions is displayed you can use the following commands Enter display the next page of the table Eise quit tracking go back to main menu Lee advance to next satellite nia go back to previous satellite Ctrl gt advance to next satellite in this group Ctrl lt go back to previous satellite in this group Coie toggle the display format Lat Lon vs Cities vs Visual Eau begin end capturing output to a file no page headings Pies eitiseeste begin end capturing output to a file with page headings Stes toggle the scroll mode Page at a time vs Scrolling WW Gein toggle the fast rise time finder on off EA toggle between local UTC timezones Most of these commands are self explanatory The W command is here only to help me verify InstantT rack s fast satellite rise time finding algorithm When this is disabled the indicator SLO will appear in the upper left corner
91. ny of the text screens If you have one of the old CGA boards that makes snow when a program writes to it quickly be prepared for snow with I nstantT rack HGC Hercules Graphics Card HGC or HGC This is a monochrome graphics card Clones of the Hercules card are sometimes called MGC s in fact InstantT rack supports Hercules cards You will get all the text and all the maps but of course you wont get any color Touse InstantTrack with a Hercules card you must first load Microsoft s Hercules graphics driver program MSHERC COM which is provided with InstantTrack MSHERC is a TSR i e a program that stays resident so you need only load it once each time you reboot your computer You may wish to load it from within your AUTOEXEC BAT file Because of a quirk in MSHERC COM it must be loaded after your mouse driver if you have a mouse that is InstantTrack was designed assuming a color display and the documentation repeatedly refers to the colors of various objects on maps If you are using a monochrome card you ll have to simply ignore the references to color More difficult to ignore InstantTrack relies heavily on color to help you distinguish various objects on map screens so nstantTrack is more difficult to use on a monochrome display urge you totry InstantTrack on a color display if you have a chance because the difference is like the difference between night and day EGA Extended Graphics Adapter
92. o back to main menu Enter go to next day InstantT rack 43 11 The Satellite Covisibility Display Some satellites have the capability of establishing a communications link directly with another satellite This is called a crosslink Crosslinks are only possible when one satellite can see the other i e when the Earth doesn t get in the way of the direct line of sight path from one satellite to the other satellite This display shows you in realtime which satellites see which satellites i e where crosslinks are theoretically possible Crosslinks are possible an amazingly large fraction of the time There is growing interest in recent years in very small communications satellites in low Earth orbit LEO These are cheaper to build and launch than large satellites and many can be launched at one time The AMSAT Microsat project has designed a very small 9 cube amateur radio digital communications satellite A disadvantage of low Earth orbit is that any one low satellite can seea very small fraction of the Earth s surface at any time making long distance communication impossible The AMSAT Microsat overcomes this difficulty by operating in a store and forward mode An alternative solution would be to design microsats with crosslink capabilities Looking forward to the day when amateur satellites will support crosslinks this display tells you when such crosslinks are possible 11 1 Understanding The Display T
93. of almost NASA format elements on some BBSs Specifically some peo ple have been leaving off the check digits and adding commentary to the first line There is no excuse for this We can only exchange data if we adhere to standards An almost NASA format file is no better than a diskette that s almost the right size to fit in that little slot in the front of your computer The following description which obtained from T S Kelso describes the NASA format in detail Data for each satellite consists of three lines in the following format AAAAAAAAAAA 1 NNNNNU NNNNNAAA NNNNN NNNNNNNN NNNNNNNN NNNNN N NNNNN N N NNNNN 2 NNNNN NNN NNNN NNN NNNN NNNNNNN NNN NNNN NNN NNNN NN NNNNNNNNNNNNNN Line 1 is a eleven character name InstantT rack 55 Lines 2 and 3 are the standard Two Line Orbital Element Set F ormat identical to that used by NASA and NORAD The format description is Line2 Column Description 01 01 Line Number of Element Data 03 07 Satellite Number 10 11 International Designator Last two digits of launch year 12 14 International Designator Launch number of the year 15 17 International Designator Piece of launch 19 20 Epoch Year Last two digits of year 21 32 Epoch J ulian Day and fractional portion of the day 34 43 First Time Derivative of the Mean Motion divided by 2 or Ballistic Coefficient Depending of ephemeris type 45 52 Second Time Derivative of Mean Motion divided by 6 Blank if N A 54 61 B
94. of the screen and the program will use the simpler but slower method of stepping time and recalculating satellite position until the satellite appears above the InstantT rack 39 horizon Results should always be the same either way The times displayed will be slightly different because the slow method has a fixed time granularity of one time step When the default fast algorithm is used the first line of each pass may show the satellite as slightly below the horizon even with an elevation of 0 This is due to slight precision errors in the calculation You can assume that this error is negligible and that this represents the moment when the satellite comes over the horizon In the default Page at a time scroll mode type Enter to see the next page Switching from satellite to satellite doesn t change the other settings So if you start with a large time increment because you started on a satellite with a high orbit and then move to satellite with a low orbit the results won t be very useful 9 4 Printing or Capturing to a File The table of satellite positions can be printed or captured toa file for later study Enter your parameters as usual to bring up the first screen of the table Type C if you like to set the display format to the one you want Type Z if you want to change the timezone When you re satisfied that the screen displayed is where you want to start the capture type F or P InstantTrack w
95. ointing is more than twice the half beamwidth it becomes difficult to predict the satellite antenna s performance because you re in the region where antenna sidelobes begin to appear OSCAR 10 and OSCAR 13 both had considerable asymmetries in some of their directional antennas Because the satellites were spinning these antenna asymmetries cause the signal to vary in amplitude This is often called spin modulation The spin modulation should be least when the offpointing angle is small Some satellites have antennas purposefully designed to radiate in directions other than their axis of symmetry For example OSCAR 10 and OSCAR 13 were equipped with high gain antennas that behaved as described above and an alternate set of low gain antennas which performed best when the offpointing angle is near 90 degrees These satellites were normally commanded to switch between the two types of antennas at appropriate points in their orbits The offpointing angle is only calculated when you have entered attitude coordinates or Local Vertical for the current satellite This angle is sometimes called squint Path Loss Path Loss is the amount by which a signal is attenuated as it travels from your station to the Satellite or vice versa This is a function of frequency as set in the satellite element database and range from your station to the satellite Path loss is only displayed if the current satellite is above the horizon and a frequency has bee
96. or a new filename If you can correct the problem such as by inserting a floppy disk do so and choose Retry by typing R If things are now working I nstantT rack will pick up and continue as if nothing had gone wrong Examples of the file formats can be found in an appendix at the end of this document I nstantTrack doesn t care about extra stuff at the beginning or end of the file or even between sets of elements but it is fairly picky about the element sets themselves It checks most of the numbers for plausibility In NASA format files it checks the checksum digit at the end of each line In AMSAT format files if there is a checksum at the end of the element set InstantTrack checks that unless this has been disabled in the IT INI configuration file If anything doesn t seem right I nstantTrack skips over that element set There is a parameter in the IT INI configuration file that controls how InstantTrack interprets the checksum in a NASA format file See ITINIDOC TXT for details InstantT rack 13 InstantT rack reads the elements file very quickly almost instantly on modern computers It tells you what it found in the file element set by element set coded by color If the screen fills up InstantT rack waits for you to type any key to continue You can also type Esc at this prompt which causes nstantTrack to continue through the file without waiting again After updating satellite elements the database file stored in a
97. ords and a correctly formatted number One nice implication of this is that additional information as long as it is carried on additional lines commentary information about satellite schedule etc can be added to these files and it will not bother InstantTrack Each orbital element is checked for correct range and element sets containing out of range elements are discarded InstantT rack expects a blank line to appear between the information for each satellite and the next satellite That s how it knows when the information for each satellite is finished First example AMSAT format as distributed by Conrad Kirksey W5BWF Satellite AO 10 Int l Object Number 14129 NASA Designation 1983 058B Epoch Time TO 88239 30510271 Fri Aug 26 1988 Epoch Rev KO 1114 ean Anomaly MO 6 0030 deg ean Motion NO 2 05882335 rev day Inclination 10 27 1492 deg Eccentricity EO 0 6027104 Arg Perigee W0 331 5568 deg RAAN O0 307 6972 deg Period 699 428632 min rev Increment 174 857158 deg rev Beacon Fl 145 8100 MHz Decay Nl 1 38E 06 rev day 2 Element Set 352 Second example AM SATish format as distributed in an ARRL bulletin KEPLERIAN BULLETIN 77 ARLKO77 FROM ARRL HEADQUARTERS NEWINGTON CT SEPTEMBER 24 1988 TO ALL RADIO AMATEURS Satellite oscar 10 Catalog number 14129 Epoch time 88248 53312992 Element set 3 53 Inclination 27 1605 deg RA of
98. ould define a DOS environment variable named INSTANTTRACK and make it point at the directory containing the nstantT rack files Example SET INSTANTTRACK D it You may also wish to put the directory containing the nstantTrack EXE files in your PATH definition sothat DOS will know where to find them when you type IT or ITNCP Example SET PATH C bin D it 50 InstantT rack Common Questions and Answers These are questions and comments often receive about I nstantTrack and the associated answers Question Why don t you interface to the Heathkit Most Accurate Clock Answer Calls to NIST cost me about 0 15 each from San Diego to Colorado in the evening Soif called NIST every day of the year for a period of five years the total cost would be 273 75 Of course would never expect you to call that often The Heath clock costs over 400 so it won t pay for itself even after five years of daily use Question can t afford the memory space for the TSRs What can do Answer Here are some ideas 1 There are several public domain programs that will allow you to load and unload TSRs at will Possibly one of those could help you 2 If you re running a 286 based machine and you have EMS expanded memory there are utilities such as Headroom commercially available which can move some TSRs intoEMS memory Some InstantT rack users have successfully used Headroom to move TSRs including OrbitDRV to EM
99. ount of area which will reflect light If the satellite is shaped like a sphere or cube or other symmetrical shape then diameter means exactly what you think If on the other hand the satellite is long and skinny you have to come up with a number which you hope will be representative I ve used 10 meters for Mir 1 meter for OSCAR 10 OSCAR 13 0 25 meters for the AMSAT microsats etc Groups Because I nstantTrack contains such a large database of satellites it is convenient to categorize satellites in the database so that some functions can operate on a subset of the database There are 27 groups of satellites that you are allowed to define They are named A through Z and There are also two predefined groups named and Each satellite and the Sun and Moon may bea member of up to eight user defined groups The following groupnames have special meaning This group contains all satellites Your favorite satellites group Displayed on the bottom row All satellites that do not belong to any A Z group InstantT rack 23 Here are some groups that have defined You may use these same meanings for these letters or any other meanings you choose A Amateur Radio Satellites OSCARs G GPS Navstar Navigation Satellites L Low Earth Orbiting Satellites P Pacsats Amateur Packet Radio Satellites R Russian Satellites W Weather Satellites You specify which groups a satellite is in by entering a
100. ples above show a 2 digit year That s all that you normally need to type For example 90 means 1990 IT will assume that a 2 digit year is in the range 1950 2049 which is of course what you normally want You may type the full 4 digit year if you wish You may also omit leading zeros For example 3 2 89 22 0 isa legal entry Time entry always assumes the same timezone as time display In other words if you have InstantT rack displaying times in UTC it assumes you will enter times in UTC InstantT rack 9 5 Station Elements Where Are You Totell InstantTrack where you are located or where your friends are located select Housekeeping Functions by typing the 6 key at the main menu Then select U pdate Station Elements by typing the B key at the Housekeeping Menu You will then be presented with a Station Selection Menu InstantTrack contains a database which remembers the locations of up to 50 stations The first station station 1 in this database is special InstantT rack expects the first station to be where YOU are located The other 49 entries can be used to specify the location of stations you often communicate with The parameters of the stations you enter in the station database will be saved on disk in the file IT QTH and will be available next time you run InstantTrack The program also understands the concept of a visiting station A visiting station is one you may want to define for the mom
101. r months of time in orbit For these satellites all you have to dois enter these two numbers latitude first then a comma then longitude For highly elliptical orbits OSCAR 10 OSCAR 13 etc these numbers are usually in the vicinity of 0 180 This means that the antennas point directly toward Earth when the satellite is at apogee Note that some sources list the coordinates in the opposite order usually with a slash between them Example 180 0 These two numbers describe a direction in a spherical coordinate system just as geographic latitude and longitude describe a direction from the center of the Earth In this case however the primary axis is along the vector from the satellite to the center of the Earth when the satellite is at perigee An excellent description of Bahn coordinates can be found in Phil Karn s Bahn Coordinates Guide See the bibliography Other spacecraft use attitude control mechanisms that InstantTrack can t handle These include magnetic stabilization AO 16 and similar microsats and 3 axis stabilization Phase 3D after its successful commissioning For these satellites enter None for the attitude Diameter This parameter gives I nstantTrack a rough idea of the size of the satellite Diameter is specified in units of meters Diameter is used to estimate the brightness which stargazers call magnitude of a satellite for visual observation nstantTrack is only interested in knowing the rough am
102. r gridsquare then typing it into InstantTrack is usually a very convenient way to get the station at the other end of the satellite link into your computer The gridsquare will be displayed with all six characters even if you entered only four If you know the name of a reasonably large city large enough to be in InstantTrack s database of 1794 cities near the fellow you want to add you can just type the name of the city or any part of the name InstantTrack will search the city database and display a menu of cities that matched the string you typed allowing you to select which one you want For example if you type Fort the menu will have several entries including cities such as Fort Worth TX and Fort de France Martinique If you have trouble spelling the name of the city Is it Gdansk or Gadansc or Gedansik you can just type Poland All the cities I nstantT rack knows about in Poland will be displayed and you can pick the one you want 32 InstantT rack Or if you can approximate the spelling type followed by any spelling that would sound more or less similar to the actual city name InstantTrack will search phonetically Typing gdnsk for instance will match Gdansk hewstin will match Houston You can also use a menu of all cities Known to I nstantTrack by typing c Once in this menu you may then scroll among the menu s 50 pages using the Pg
103. s C gt it f c download nasa all The F part tells InstantTrack to look for a filename and the next part is the filename itself When you invoke nstantTrack this way it doesn t display the menu or do any of the normal functions Instead it just reads the file you specified in Update mode and then exits This method is ideal for situations where you can easily run a program as part of the download process For example if your email program has filters you can program a filter to detect a message containing K eplerian elements and let the filter automatically run InstantTrack with the F switch to instantly load the new elements into the database In the second method you specify the filename using the auto_read_kepsfile parameter in the IT INI configuration file see ITINI DOC TXT for details In this case nstantTrack reads the file on startup but it then proceeds to display the main menu and run normally With this method you don t need to run a program as part of your automation J ust arrange for the elements file to be in a predictable place and InstantTrack will find it there next time it is run With either method InstantTrack doesn t stop for anything during the Keplerian file update Even if there are errors InstantT rack rushes along at full speed The idea is that you don t want to be bothered with any interaction during the fully automated update You might not even be at the computer Howev
104. t of orbital elements is a snapshot at a particular time of the orbit of a satellite E poch is simply a number which specifies the time at which the snapshot was taken Orbital Inclination aka Inclination or To The orbit ellipse lies in a plane known as the orbital plane The orbital plane always goes through the center of the Earth but may be tilted any angle relative to the equator Inclination is the angle between the orbital plane and the equatorial plane By convention inclination is a number between 0 and 180 degrees Some vocabulary Orbits with inclination near 0 degrees are called equatorial orbits because the satellite stays nearly over the equator Orbits with inclination near 90 degrees are called polar because the satellite crosses over the north and south poles The intersection of the equatorial plane and the orbital plane is a line which is called the line of nodes More about that later InstantT rack 17 Right Ascension of Ascending Node aka RAAN or RA of Node or Og and occasionally called Longitude of Ascending Node RAAN wins the prize for most horribly named orbital element Two numbers orient the orbital plane in space The first number was Inclination This is the second After we ve specified inclination there are still an infinite number of orbital planes possible The line of nodes can poke out the anywhere along the equator If we specify where along the equator the line of nod
105. tellites They have a variety of materials useful to anyone learning about amateur radio satellite operation They publish the bimonthly AMSAT J ournal Please consider becoming a member of AMSAT NA AMSAT UK gt AMSAT UK 40 Downsview Small Dole West Sussex BN5 9YB U K Phone 44 0 1273 495733 This is a U K non profit group similar in purpose to AMSAT NA They publish a very good newsletter OSCAR News once every two months and publish other material useful to beginners AMSAT Australia gt AMSAT Australia G P O Box 2141 Adelaide 5001 AUSTRALIA Phone 08 297 5104 This is an Australian non profit group similar in purpose to AMSAT NA Project OSCAR gt Project OSCAR P O Box 6700 San Mateo CA 94403 This group publishes The OSCAR Letter containing information about amateur radio satel lites and also distributes amateur satellite related software written by hams in other countries Subscribe by sending 10 and six 10 SASE to Project OSCAR OSR gt Harlan Technologies 5931 Alma Dr Rockford IL 61108 2409 These folks publish OSCAR Satellite Report a four page newsletter which comes out every two weeks Best print source for up to the minute information about status of Amateur Radio satellites InstantT rack 63 NIST gt NIST ACTS National Institute of Standards amp Technology Time and Frequency Division Mail Stop 52 325 Broadway Boulder CO 80303 These people run the NIST
106. that attempts to dial and interact with a modem is the very large variety of different brands and models of modems in use They all support a slightly different set of commands and handle the various RS 232 modem control signals in a slightly different way Furthermore there are an amazing number of different ways that RS 232 cables can be wired Most commercial communications programs for DOS Crosstalk MIRROR ProComm solve this problem by providing a large number as many as 20 different configuration files which tell the program how to interact with each different kind of modem These differences include the command set handling of modem control signals which are required and which are provided by the modem handshake timing call progress indications etc I ve taken a different approach I ve written serial I O routines which are completely oblivious to the state of the RS 232 modem control signals If your modem happens to not provide one of the modem control signals or uses one of them in an unusual way InstantTrack doesn t care The standard IBM BIOS on the other hand requires that the modem raise DSR and CTS For outgoing modem control signals raise DTR and RTS which hopefully will satisfy all modems that care The standard IBM BIOS raises DTR but then toggles RTS depending on whether you are reading or writing to the serial port ve also provided an initialization file IT INI where you can specify th
107. to I nstantT rack ITINIDOC TXT Documentation describing the IT INI file RSV Configuration parameter file INTSPEC TXT Information for programmers on interfacing to nstantTrack SINCE100 HTM Web page describing the changes since Version 1 00 SINCE100 PDF PDF file describing the changes since Version 1 00 Related programs DUMMYKCT COM Sample dummy rotor driver TSR program ITRACK EXE Command line user interface for OrbitDRV ITSORT EXE Utility for manipulating the nstantTrack satellite database ORBITDRV EXE Background tracking TSR option for InstantTrack ORBITNCP EXE Alternate background tracking TSR if you have No math CoProcessor TEST63 EXE Test program to evaluate Interrupt 0x63 on your computer Documentation for related programs ORBITDRV TXT The documentation file for OrbitDRV ORBITDRV UPD Information about changes to OrbitDRV ITRACK TXT ee The documentation file for ITRACK ITRACK UPD Information about changes tol TRACK ITSORT TXT eee The documentation file for TSORT ITSORT UPD Information about changes to TSORT InstantT rack 49 Generally all the computer readable files should be placed in the same directory and IT should be run while connected to that directory If you wish to run InstantTrack while connected to directories other than the one in which you have placed these files you sh
108. un s ascending node as the place from which all ascending nodes are measured The RAAN of your satellite s orbit is just the angle measured at the center of the Earth between the place the Sun s orbit pops up past the equator and the place your satellite s orbit pops up past the equator Argument of Perigee aka ARGP or Wer Argument is yet another fancy word for angle Now that we ve oriented the orbital plane in space we need to orient the orbit ellipse in the orbital plane We do this by specifying a single angle known as argument of perigee 18 InstantT rack A few words about elliptical orbits The point where the satellite is closest to the Earth is called perigee although it s sometimes called periapsis or perifocus We ll call it perigee The point where the satellite is farthest from Earth is called apogee aka apoapsis or apifocus If we draw a line from perigee to apogee this line is called the line of apsides Apsides is of course the plural of apsis know this is getting complicated again Sometimes the line of apsides is called the major axis of the ellipse It s just a line drawn through the ellipse the long way The line of apsides passes through the center of the Earth We ve already identified another line passing through the center of the Earth the line of nodes The angle between these two lines is called the argument of perigee Where any two lines intersect they form two complementary
109. uration file And if you have problems with text on the map screens you can try the force bios chargen_g setting in the I T INI configuration file See the file TINIDOC TXT for details Advantages 480x640 resolution maps look nicer Disadvantages 480x640 resolution maps area bit slower to draw and they require about 32K more memory If you have a slow computer or are short of memory you might want to stick with the lower resolution maps InstantT rack 61 Bibliography The Radio Amateur s Satellite Handbook by Martin R Davidoff K2UBC 1998 published by ARRL 225 Main St Newington CT 06111 This is an excellent introduction to amateur radio Satellites basic orbital mechanics operating procedure etc and is highly recommended Methods of Orbit Determination by Pedro Escobal 1965 corrected reprint 1973 published by Krieger Publishing and J ohn Wiley amp Sons ISBN 0 88275 319 3 This is the best orbit mechanics book have found Fairly technical and expensive but logically organized un derstandable and complete This book piqued my interest in Celestial Mechanics again after many years of neglect Celestial Mechanics A Computational Guide for the Practitioner by Laurence Taff 1985 published by J ohn Wiley amp Sons ISBN 0 471 89316 1 This book provides a refreshingly candid assessment of computational techniques Taff makes his opinions clearly known in a style atypical of most textbooks Lots of good m
110. ven selected satellites The Sun and Moon also appear if five or fewer satellites are selected Each pair of angles is displayed in yellow if the object is now above your horizon and green if it is below These colors are consistent in displays throughout I nstantT rack On very slow computers it may take a couple of seconds for these numbers to appear On faster machines they appear instantly It is important for you to realize that you do not have to wait for these numbers to appear before making your menu selection As soon as you type a key this program will jump instantly to the desired function That s how I ve tried to make I nstantT rack work you almost never wait for anything 4 I nstantT rack 3 Online Help Screens InstantTrack contains a modest online help facility Select Help at the main menu by typing to get a menu of help screens or type while in any of the major function screens to jump instantly to the help screens that describe that particular function You may then navigate among the help pages using the PgUp and PgDn keys Return from a help screen by typing Q or using the H ome or Esc key Using online help you can almost use nstantTrack without this manual This is a great help when you need a quick answer but there s still no substitute for actually reading the manual You d be surprised at the number of people who ask questions when the answer is right herein the
111. veral ways to set your computer s clock You can do it by hand of course getting time in formation from the phone company or WWV or a GPS receiver This works very well InstantTrack can also set your computer s clock for you by accessing the National Institute of Standards amp Technology formerly known as the National Bureau of Standards telephone time service Your computer uses your modem to make a very quick long distance call to a modem at NIST This feature is described in more detail in a later section If your computer is connected to the Internet you may want to consider obtaining a program that sets your computer s clock using Network Time Protocol NTP or Simple Network Time Protocol SNTP This will allow your computer to keep its own clock set automatically 6 InstantT rack 4 2 Setting Your Time Zone There are two ways to tell InstantTrack your time zone e theDOS environment variable TZ e inthelT INI configuration file 4 2 1 Setting Your Time Zone using TZ You can tell InstantTrack the name of the local time zone by setting a DOS environment variable called TZ short for Time Zone This is the standard DOS method and may have already been done on your computer You should put the command to set it in your AUTOEXEC BAT file so that you never forget You must set TZ to your time zone by executing a DOS command like this SET TZ PST8PDT The first three letters PST in this case are the nam

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