Version 2.22 of this document
Updated September 22, 2007
See the change history for details.

## The InstantTrack FAQ

### What is this FAQ?

This FAQ (Frequently Asked Questions) document answers many of the common questions asked about InstantTrack. It has been compiled by Paul Williamson, KB5MU, kb5mu@amsat.org, who is one of the contributors to the InstantTrack package (and currently the principal author of InstantTrack). The answers herein are believed to be correct, but if you have better information please send it to me for a future update of this document.

This document can be found on the AMSAT-NA Web pages at http://www.amsat.org/amsat/intro/itfaq.html. This document contains many Web links, so if you have only a printed copy you are missing some of the answers.

### What is InstantTrack?

InstantTrack is a satellite tracking program. That means that you feed it Keplerian elements (see this tutorial on Keplerian elements if you don't know what they are) and keep your computer's clock set accurately, and it gives you information about where the satellite is located right now. See also this explanation of satellite tracking programs. It can do a lot more, too. For more information, see the InstantTrack page.

### Who created InstantTrack?

InstantTrack 1.00 was written by Franklin Antonio, N6NKF. A few components (notably the OrbitDRV TSR) were written by Paul Williamson, KB5MU, who also developed version 1.50. See the authors. Many beta testers and other users contributed valuable ideas to the development. See the volunteers.

### How should InstantTrack be spelled?

OK, so nobody asks that question, but I wish they would. It should be spelled InstantTrack, with the Instant part in italics if possible. Don't leave out any letters, it's not InstaTrac or anything like that.

[index]

## Versions of InstantTrack

The latest released version is 1.50, released in October 2000.

A later version is currently in open beta testing release. See the Open Beta page.

### What are InstantTrack Patch #1 - #4?

InstantTrack Patch #1 through #4 (ITPATCH1.ZIP through ITPATCH4.ZIP) were bug-fix patches for InstantTrack version 1.00. They are now obsolete, and cannot be used with version 1.50.

### When will there be another new version of InstantTrack?

There are no immediate plans for another version. However, if bugs crop up, new versions may come out to fix them. Beyond that, there are plenty of additional features on the wishlist. A new version with minor improvements could come out any time.

Watch the Open Beta page for newer versions.

[index]

## Computer Compatibility

### What's the minimum computer that will run InstantTrack?

InstantTrack works very well on almost any IBM-type PC. You need:

• At least 512K of RAM (see memory hints below)
• DOS or any environment that can run DOS programs

That's all! But you will probably want:

• An EGA, VGA, or SVGA graphics display if you want to see the maps in color. A CGA or Hercules display will let you see the maps in monochrome. Any old video display (even monochrome) will work fine for the text screens. Tiny palmtop displays that can't display 80 columns by 25 lines may have trouble.
• A math coprocessor (8087 or 80287) will speed things up a lot if you have a really old, slow computer, but InstantTrack really is fast enough to be perfectly acceptable on the slowest old XT with no coprocessor. The fancier maps will take a while to redraw. If you have a 486 or a Pentium, your computer is so fast that you'll never have to wait for InstantTrack.
• A hard disk makes things faster, but you can run from a floppy if you must. A complete installation of everything takes up 1770K, but this includes all the documentation in two formats. A minimum installation for full function is about 707K. If you don't need maps, city names, stars, or online help, you can get by with just 284K.
• A mouse (any mouse with a DOS driver) can be used on the map screens.
• A modem on any standard serial port can be used to set your computer's clock.

### Does InstantTrack run with non-Intel CPUs like AMD, Cyrix, etc?

Yes. There are no known problems running InstantTrack on any PC-compatible CPU.

### Does InstantTrack run under Windows 3.1?

Yes. You will probably have to run InstantTrack in full-screen mode if you want to use the map screens.

If you run the Kansas City Tracker or similar rotor control device that is under the direct control of the computer, you will probably have timing problems running under Windows 3.1. You can reportedly live with this problem if you run InstantTrack using a PIF file, set the time slice setting under the Advanced Multitasking background section to a value higher than 20/100, and enable the Detect Idle Time checkbox.

### Does InstantTrack run under Windows 95?

Yes.

Depending on your video adapter, Windows 95 may automatically switch your InstantTrack window into full-screen mode when you use the map screens. As far as I know, the InstantTrack session is then stuck in full-screen mode until you exit InstantTrack.

InstantTrack does not support any of the Windows-specific rotator controller drivers, such as RR.DLL. DOS TSR-based rotator controller drivers may not work reliably under Windows 95.

### Does InstantTrack run under Windows 98?

Yes.

Depending on your video adapter, Windows 98 may automatically switch your InstantTrack window into full-screen mode when you use the map screens. It will stay in full-screen mode until you exit or until you hit Alt-Enter on a text screen to return to windowed mode.

InstantTrack does not support any of the Windows-specific rotator controller drivers, such as RR.DLL. DOS TSR-based rotator controller drivers may not work reliably under Windows 95.

In addition, there have been some reports of problems when the built-in screen saver kicks in. You might need to disable the screen saver while running InstantTrack to avoid a system lockup. It's also possible that another screen saver program might not have the same problem.

### Does InstantTrack run under Windows ME (Millenium Edition)?

Yes.

Windows ME is very similar to Windows 95/98, so all the comments in the question above about Windows 98 also apply to Windows ME.

I think.

### Does InstantTrack run under Windows NT?

Yes.

Depending on your video adapter, Windows NT may automatically switch your InstantTrack window into full-screen mode when you use the map screens. It will stay in full-screen mode until you exit or until you hit Alt-Enter on a text screen to return to windowed mode.

InstantTrack does not support any of the Windows-specific rotator controller drivers, such as RR.DLL. DOS TSR-based rotator controller drivers probably do not work at all under Windows NT.

### Does InstantTrack run under Windows 2000?

Yes.

Windows 2000 is very similar to Windows NT, so all the comments in the question above about Windows NT also apply to Windows 2000.

### Does InstantTrack run under Windows XP?

Yes.

Windows XP is very similar to Windows NT and Windows 2000, so all the comments in the question above about Windows NT also apply to Windows XP.

When Windows XP minimizes a DOS program like InstantTrack, the real time clock value seen by that program is frozen. When InstantTrack is reactivated, its notion of real time will be out of sync. XP will then speed up the real time clock until, eventually, InstantTrack is back in sync with reality. I'm sure this funny trick enhances compatibility with some programs, but it's not very helpful for a satellite tracking program! There is probably a way to turn off this feature of XP. If not, you should just avoid allowing InstantTrack to be minimized.

### Does InstantTrack run under Windows Vista?

With some caveats, yes. Windows Vista does not support running MS-DOS programs in all possible graphics modes, and InstantTrack uses a graphics mode that isn't supported. So, if you run InstantTrack directly under Vista, the text screens will work fine but Vista will refuse to let you enter the map screen. If you try, it will pop up a message that "This system does not support fullscreen mode. Choose 'Close' to terminate the application." and your only choice will be to close InstantTrack.

There is a viable workaround for this problem: you can run InstantTrack under an add-on DOS environment that is aware of Vista's limitations. One such environment is a program called DOSBox, a freeware DOS emulator that's designed specifically for running old DOS programs (mainly games) on modern computers. Simply download and install DOSBox and run it. You'll get a DOS window. Give the command mount c c:\it to give DOSBox access to your InstantTrack directory, and then change to that default directory by giving the command C:. You can then run InstantTrack as normal by giving the command IT. Now the map screens will work!

DOSBox is an emulator, meaning that the computer has to do a lot of extra work to run programs inside DOSBox. Luckily, InstantTrack is so fast that the extra work doesn't slow it down enough to matter on any modern computer. If this still worries you, virtualization environments such as VMWare will probably also work, without the extra overhead.

InstantTrack does not support any of the Windows-specific rotator controller drivers, such as RR.DLL. DOS TSR-based rotator controller drivers probably do not work at all under Windows Vista.

### Does InstantTrack run under 64-bit Windows?

Not natively. 64-bit Windows versions will refuse to even try to run 16-bit programs like InstantTrack.

There is a viable workaround for this problem: you can run InstantTrack under an add-on DOS environment that does work in a 64-bit environment. One such environment is a program called DOSBox, a freeware DOS emulator that's designed specifically for running old DOS programs (mainly games) on modern computers. Simply download and install DOSBox and run it. You'll get a DOS window. Give the command mount c c:\it to give DOSBox access to your InstantTrack directory, and then change to that default directory by giving the command C:. You can then run InstantTrack as normal by giving the command IT.

DOSBox is an emulator, meaning that the computer has to do a lot of extra work to run programs inside DOSBox. Luckily, InstantTrack is so fast that the extra work doesn't slow it down enough to matter on any modern computer. If this still worries you, virtualization environments such as VMWare will probably also work, without the extra overhead.

InstantTrack does not support any of the Windows-specific rotator controller drivers, such as RR.DLL. DOS TSR-based rotator controller drivers probably do not work at all under 64-bit Windows.

### Does InstantTrack run under OS/2?

Yes.

Depending on your video adapter, OS/2 may suspend your session if you try to use the map screens in a DOS window. It displays the message

The system does not support this session's video mode in a window.

If this happens, you can hit Enter to dismiss the message, then hit Alt-Home to switch the session to full-screen mode. InstantTrack then resumes running normally. After you return to a text screen, you can hit Alt-Home again to return to windowed mode.

DOS TSR-based rotator controller drivers may not work reliably under OS/2.

### Does InstantTrack run under Linux or other Unix-like systems?

Sort of.

Under DOSEmu 0.66 on Debian Linux 2.0 with default options, I found that the text screens were usable but the non-ASCII characters (lines, degrees symbol, etc.) were not shown properly. The graphics screen was not available at all. Enabling console video made the text screens look right, but switching to a graphics screen confuses the video adapter (requiring a reboot unless you know a better way to re-initialize the video adapter under Linux).

I have not attempted anything adventurous like running a DOS TSR rotor controller under DOSEmu. If you have more information on running InstantTrack and friends under Linux, please let me know.

DOSEmu, like many Linux programs, is constantly improving. A newer version of DOSEmu may do a better job of running InstantTrack. Check the DOSEmu Home Page for news.

dosbox is another option worth trying, but I have not tested it yet.

### Does InstantTrack run on the Macintosh?

Amazingly, yes. Using one of several PC emulation programs available for the Macintosh, InstantTrack will work. It has been tested on an old 68K Macintosh under SoftPC (no longer available), and on an iBook running Connectix Virtual PC 5.0 (now available as Microsoft Virtual PC) under Mac OS X version 10.1.2. There are a few cosmetic imperfections, but it does work. It also works under dosbox, a free emulator for DOS games, which can be installed easily using fink, though there may be some problems with timekeeping in dosbox. It should also work under other emulation configurations. If you're a hard-core Macintosh fan, though, you'll probably want a native Macintosh program instead. Check the AMSAT-NA Software Catalog for Macintosh satellite tracking programs.

### Does InstantTrack run on a Windows CE palmtop?

Yes, under an emulator program such as XT-CE, as long as your screen is capable of displaying 80-column, 25-row text. If your screen is capable of emulating a CGA under XT-CE, you even get (monochrome) maps. XT-CE doesn't emulate the math coprocessor, so you'll need to run ITNCP.

### Does InstantTrack run on a Palm OS handheld?

No. There is no way to run an MS-DOS program on a Palm OS machine, as far as I know.

### Does InstantTrack run on a Commodore 64?

No. OK, so nobody asks this question either.

[index]

## Map Problems

### The text on the map screens is garbage.

There is a known problem with certain newer video adapters when run in EGA mode. With InstantTrack 1.50, this problem can be avoided by setting
vga_resolution = 2
in the IT.INI configuration file. This lets InstantTrack use VGA mode instead of EGA mode, and is the default setting. If you set
vga_resolution = 1
to use EGA mode, you will still run into this problem.

### The map screen doesn't show the map.

Probably you don't have enough free low memory. You should see the message Problem with map: not enough memory available. If you see Problem with map: can't open file instead, see the next answer.

If you have a recent version of DOS, you can type "mem" at a command prompt to find out how much memory you have available. The "largest executable program size" needs to be about 412000 or higher to use the EGA maps, or 444000 or higher to use the VGA maps. If this value is too low, the problem is probably that you have loaded too many resident programs, or TSRs. These are programs that pop up on demand, like Sidekick, or programs that supply services to other programs, like network drivers. Chances are you can get rid of some of these without missing them. Try looking in CONFIG.SYS or AUTOEXEC.BAT for stuff you're not using anymore. (Back up first, and be careful - you can end up with a machine that doesn't boot if you put the wrong things in these files.)

If you're running Windows 95/98/ME or Windows NT/2000/XP or OS/2, you shouldn't have this problem. If you do, you are probably running the program from a shortcut and you have messed with the memory settings in the shortcut's Properties.

### I see the message Problem with map: can't open file.

It's possible that you don't have the map files; check your InstantTrack directory (usually C:\IT) for the map files:

IT.MPX
Used for the orthographic (globe) map screen.
IT.MPY
Used for the rectangular map screen in EGA mode.
IT.MPZ
Used for the rectangular map screen in VGA mode.
IT.MPU
Used for the rectangular map screen in CGA mode.
IT.MPW
Used for the rectangular map screen in Hercules mode.

If they're missing, re-install them from the InstantTrack distribution diskette or downloaded distribution file. You may want to save a copy of IT.INI (if customized), IT.QTH (your locations), and IT.ORB (your Keplerian elements database) in case they get overwritten by the install.

More likely, the map files are there but InstantTrack isn't finding them. InstantTrack looks in two places for the map (and other) files. First, it checks for an environment variable named INSTANTTRACK that contains a directory path. If there is such a variable, InstantTrack looks there. Then, if that doesn't work, it looks in the current directory.

Running under plain DOS or a similar command-line environment, most often your current directory is the InstantTrack installation directory (where all the files are supposed to be) and there's no problem. If you move the executable file IT.EXE or ITNCP.EXE out of the installation directory, or if you add the installation directory to the PATH and type IT from another directory, or if you type an explicit path (such as C:\IT\IT) to run the program, the current directory won't be the same as the installation directory.

This case is best handled by using the environment variable. In your AUTOEXEC.BAT file, or at the top of a batch file you use to run InstantTrack, place a line like this one:

SET INSTANTTRACK=C:\IT

You may need to adjust the setting to match where you installed InstantTrack. Be sure there are no spaces before or after the equals sign or at the end of the line, or anywhere else except the one after SET. The word INSTANTTRACK must be all uppercase in the SET command.

Running under Windows, all the above still applies. Instead of AUTOEXEC.BAT you would use AUTOEXEC.NT, which is typically located in C:\WINDOWS\SYSTEM32. Note that every part of the path to InstantTrack's directory must comply with DOS naming conventions, so no spaces anywhere and no long names. Be sure to use a plain text editor (like NOTEPAD) to edit AUTOEXEC.NT or any batch file you may use.

Under Windows, you may find it convenient to run InstantTrack from a shortcut, perhaps on the desktop or in the Start menu. If you do so, you can use the shortcut's settings to control the current working directory, instead of using the INSTANTTRACK environment variable. To do so, right-click on the shortcut and select Properties, then find the Working: setting on the Program tab and set it to the installation directory. (The exact details of this procedure may vary in different versions of Windows, but it's generally similar.)

If you just double-click on the IT.EXE file in its installed location, it should just work (because the working directory is correct). If you have moved IT.EXE to the desktop or to the Start menu, move it back to the InstantTrack installation directory and create a shortcut in its place. To create a shortcut, right-click on IT.EXE and select Create Shortcut. The shortcut appears in the same directory. Now move it where you want it and rename it to something nice, like InstantTrack.

[index]

## Keplerian Elements

### Do I need to edit the elements file after I download it?

No. InstantTrack 1.50 is much more forgiving with Keplerian element files. Generally, you can feed any text file that contains NASA format or AMSAT format elements to InstantTrack and it will work fine.

One likely exception occurs if you receive an email where the element set has been "quoted" from an earlier email. Depending on which email programs were used, this generally puts some characters (often ">") at the beginning of each line. InstantTrack 1.50 doesn't handle that.

Another likely exception occurs if you accidentally save the element set in HTML format, perhaps by taking inappropriate default settings in your browser or email program. At least one program makes this mistake easy to make, and it puts <BR> at the end of each line. With either format, this results in satellite names with <BR> added to the end, like "AO-10<BR>". With NASA format files, these funny-named satellites will all show up with checksum errors, and won't be stored into the database. With AMSAT format files, they will be added to the database (with <BR> added to the object number as well), as long as there is room to add new satellites. Since this update appears to work if you don't look closely at the satellite names, it can be very confusing.

### I get checksum errors.

The NASA 2-line format has one digit on each line that's used to detect errors in the element set. It's the last digit on each line. If you want to try using the element set even though it might be corrupted, you can try changing the value of the last digit on the offending line until the error goes away. Beware that if you do this, you're asking for trouble, because the chances are good that the corruption is elsewhere in the line.

Once in a while you'll find an element set that was converted to the 2-line format without computing the checksum. (Please don't ever be guilty of this!) If you need to load this set into InstantTrack, you'll have to add the checksum. Computing the checksum by hand is extremely error-prone. You will probably find it easier to just try all ten possible values for each line.

If you get checksum errors on all the element sets in a file, you may have saved the file in a strange format, such as HTML. Open the file with a plain text editor (under Windows, you can use Notepad). Look at the element sets and see if anything funny has been added. If you're not sure what they should look like, see the Element Set Formats for examples.

It's hard to answer that question briefly for all cases, because there are many different sources of Keplerian elements and many different programs you might use to download them.

If you have access to the Web, the easiest way might be to go to the AMSAT Keplerian Elements page and download the file (NASA or AMSAT format) using your browser. The exact procedure depends on the browser, but in most browsers you can click on the file to bring it up on the screen, then select Save As from the File menu. In some older browsers, you may need to select "Load to disk" before you click on the file, then un-select "Load to disk" to continue. It is very important that you save the file in plain text format and not in HTML or any other funny format. This option may be well-hidden in some programs.

You can also FTP the files from FTP.AMSAT.ORG in the /amsat/keps/current directory. These are the exact same files you'll get from the Web page. Use ASCII transfer mode.

You can have the Keplerian elements bulletins emailed to you weekly. See the AMSAT Mailing Lists page for details. If you do this, with some email programs you can set it up to automatically update InstantTrack whenever a new element set comes in. See the Eudora tutorial for information on how to set that up with one particular program.

You may be able to find the elements on your local packet radio BBS.

### Where do I find Keplerian elements for non-amateur satellites?

There are several sources listed on the AMSAT Keplerian Elements page.

### Where do I find Keplerian elements for the Russian space station Mir or the International Space Station?

Mir is no longer in orbit.

Elements for the International Space Station are in the standard bulletins, see above. However, sometimes the ISS orbit changes more frequently than the weekly bulletins, so you might want to check another site (such as NASA) for fresh elements.

You may also wish to subscribe to the SAREX mailing list. See the AMSAT Mailing Lists page for details. Keplerian elements for the ISS are currently posted to that mailing list every day.

### Where do I find Keplerian elements for the Space Shuttle?

These elements change too often for AMSAT's regular weekly bulletins to keep up with. Possible sources are listed on the AMSAT Keplerian Elements page.

### Where do I find Keplerian elements for AO-40?

AO-40 is included in the regular weekly bulletins. See above.

### What about Keplerian elements for the Sun and Moon?

InstantTrack doesn't need (and can't use) Keplerian elements for the Sun and Moon. It has built-in models for the Sun and Moon that are far more accurate and don't need updating.

### InstantTrack can't seem to find my Keplerian elements file.

InstantTrack is a DOS program, so it can't understand filenames or directory names that contain spaces or are longer than 8.3 characters (that is, up to 8 characters, optionally followed by a period and 1 to 3 additional characters). If you're running under Windows 95/98/ME, Windows NT/2000/XP, or OS/2, you may well have directory names and path names with spaces or long names. Use the Windows Explorer (or whatever method you prefer) to move the file into a directory with a name that would be valid under DOS and/or to rename the file with a valid DOS filename, and InstantTrack should be able to read it.

Alternatively, under Windows you can give InstantTrack the DOS-compatible compressed filename, if you can figure out what it is. For example, if the Windows filename is
C:\Temporary Files\Junk I downloaded\amsat elements.txt
then you can (probably) tell InstantTrack to load
C:\TEMPOR~1\JUNKID~1\AMSATE~1.TXT

InstantTrack also imposes a maximum limit of 38 characters on the path, including drive letter and directory names if any. If the path to your Keplerian elements file is longer than that, you won't even be allowed to type it in.

[index]

## Timezone Difficulties

### I can't get my local time to be in the right time zone.

InstantTrack can get your timezone information in two different ways:

• from the DOS environment variable "TZ"
• from the setting "timezone" in the IT.INI configuration file.

Either way, the description of your timezone is a string of characters consisting of:

• Three letters, which is the normal name of your timezone,
• An integer number (which can be negative) indicating the offset in hours between your local time and UTC, and
• Optionally, three more letters, which is the name of your timezone when Daylight Saving Time is in effect.

If you include the last three letters, InstantTrack follows the Daylight Saving Time rules that applied in the United States from 1986 through 2006. Under these rules, Daylight Saving Time starts on the first Sunday in April and ends on the last Sunday in October. If you live in an area that follows these rules, simply include the last three letters and InstantTrack will take care of the time change automatically. If you leave off the last three letters, InstantTrack doesn't try to compensate for Daylight Saving Time automatically. If you live in an area that uses Daylight Saving Time but follows different rules (including most of the United States starting in 2007) you will need to change this setting manually at the beginning and end of the time change.

Typical values for North American locations through 2006:

 Pacific zone: PST8PDT Mountain zone: MST7MDT Central zone: CST6CDT Eastern zone: EST5EDT

If your area doesn't use Daylight Saving Time (summer time), leave off the last part. For example, users in Arizona probably use this:

MST7

and if you run your computer on Coordinated Universal Time (UTC), you can just use this:

UTC0

In 2007 and thereafter, in most of the United States, you will need to change the setting manually, whenever you change your clocks. Here are typical values:

 Pacific zone Winter: PST8 Summer: PDT7 Mountain zone Winter: MST7 Summer: MDT6 Central zone Winter: CST6 Summer: CDT5 Eastern zone Winter: EST5 Summer: EDT4

To use the environment variable method, use the SET command. Generally you'll want to put it in your AUTOEXEC.BAT file. A typical command looks like this:
SET TZ=CST6CDT
Be careful not to put any extra spaces in the SET command. The only space should be after the word SET. No spaces around the equals sign.

Under Windows 95/98/ME or Windows NT/2000/XP, SET commands in the AUTOEXEC.BAT file can be tricky or may not be convenient. You can still use the TZ environment variable by creating a batch file (named anything.BAT) that looks like this:
SET TZ=MST7MDT IT.EXE
and run the .BAT file instead of running InstantTrack directly. This method also works under DOS, and can be convenient for loading drivers too.

Alternately, you may find it more convenient to use the timezone setting in the IT.INI file. Follow the examples shown in the default IT.INI file.

Note: If InstantTrack doesn't find a timezone setting in the TZ environment variable or in the timezone entry in the IT.INI file, it defaults to PST8PDT, as if you were located in the Pacific timezone between 1986 and 2006. If you see InstantTrack doing that, it means your timezone setting isn't visible to InstantTrack for one reason or another.

### My time is ahead of UTC, not behind UTC like the U.S.

Just use a negative offset:

SET TZ=CET-1

### But where I live the timezone isn't an integer number of hours from UTC!

You can override the timezone offset by using the "timezone_offset_seconds" setting in the IT.INI configuration file. Set it to the number of seconds your timezone is behind UTC. For example, if you live in South Australia where the local time is 9.5 hours ahead of UTC, you would multiply 9.5 hours × 60 × 60 = 34200 seconds, and put this statement in your IT.INI file:
timezone_offset_seconds = -34200

NOTE: this feature seems to be broken in version 1.50. Download a later beta test version for a fix to this problem.

### My timezone is an integer number of hours from UTC, but we don't follow U.S. rules for summer time.

Since the U.S. rules are built into InstantTrack, you will have to take over manual control of your timezone. Whenever you go on or off summer time, you'll have to change your SET command or "timezone" setting. Leave off the letters after the number, so InstantTrack doesn't try to use the U.S. rules for Daylight Saving Time.

### Windows 95/98/ME/NT/2000/XP knows about my timezone, can't InstantTrack use that?

Sorry, no. Windows 95/98/ME and Windows NT/2000/XP don't make the timezone information available in the TZ environment variable so old DOS programs like InstantTrack can find it. I have no idea why they don't.

### Forget all that, I prefer to run my computer on UTC anyway.

Fine. Just use this command:

SET TZ=UTC0

### When Daylight Saving Time ends in the fall, InstantTrack seems confused for an hour.

Yes. After you set your clock back from 2:00 AM to 1:00 AM, for one hour InstantTrack has no way to know whether it is before the transition or after the transition. Don't let this worry you too much. Why are you operating satellites at that hour, anyway?

[index]

## Miscellaneous Problems

### I get a message that says Floating point exception has occurred. Is this a bug in InstantTrack?

Maybe so, but more probably you have a hardware problem. This is commonly caused by using a slow math coprocessor in a fast motherboard. Try running ITNCP.EXE (which doesn't use the coprocessor at all) instead of IT.EXE and see if the problem goes away. If it does, the problem is probably your coprocessor.

InstantTrack may be the only program you run that really exercises the coprocessor extensively. Even if you run other floating-point programs, InstantTrack may be the only program you have that will actually notice when the coprocessor has a problem.

### Fast forward mode is much slower!

InstantTrack 1.00 ran fast-forward mode as fast as the computer could go, which can be way too fast on modern computers. InstantTrack 1.50 runs fast-forward mode at a regulated pace instead. This makes fast-forward mode much easier to use, though perhaps not as dazzling. You can adjust the speed of fast-forward mode by changing the "fast_forward_delay" setting in the IT.INI configuration file.

### What happened to InstantTrack in the Year 2000?

There were several known problems with InstantTrack 1.00 and Keplerian element sets with epoch times in the 2000's. There was also a problem with the Update Time (NBS via modem) function. InstantTrack version 1.50 corrected these problems.

### I can't get the Update Time (NBS/NIST via modem) function to work.

Try changing the settings in the IT.INI configuration file. If you still can't get it to work, your best bet is probably to obtain a separate standalone program to set your computer's clock using your modem. Most of these programs are easier to get working than the feature in InstantTrack.

If your InstantTrack computer is on the Internet regularly, you might consider using an NTP (Network Time Protocol) or SNTP (Simple Network Time Protocol) program to set your clock over the net instead of dialing direct to a time server. For Windows 95/98/ME/NT/2000, check out Dimension 4, an easy-to-use freeware SNTP client.

For Windows XP, you have a built-in Internet time function. Right-click on the time in the lower right corner of the screen, and choose "Adjust Date/Time". Choose the "Internet Time" tab on the resulting dialog box. Check "Automatically synchronize with an Internet time server" to enable automatic updates, or click on "Update Now" to update once.

### Where do I get Attitude information for satellite X?

First of all, make sure that Attitude makes sense for the satellite you're interested in. InstantTrack can only do attitude (antenna off-pointing or "squint" angle) calculations for two types of spacecraft:

• Spacecraft that maintain a fixed orientation in inertial space. These spacecraft are almost always spin-stabilized. The fixed orientation is described by two numbers, called Bahn latitude and longitude (BLAT and BLON, or ALAT and ALON).
• Spacecraft that keep their antennas oriented to local vertical. Usually this is achieved by gravity-gradient stabilization, as on the UoSAT satellites.

InstantTrack cannot calculate the attitude of either of these types of spacecraft:

• Magnetically stabilized spacecraft like AO-16, DO-17, WO-18, LO-19, IO-26, AO-27, or MO-30, because they tumble in the Earth's magnetic field,
• AO-40 in its intended final orbit, assuming its 3-axis stabilization system had worked, or almost any commercial communications spacecraft, because it actively controls its attitude to whatever it pleases.

At this writing (January 2002) the only spacecraft in the amateur radio fleet for which Bahn Attitude makes any sense are AO-10 and AO-40. Attitude information on AO-10, such as it is, is available in this article by G3RUH. Updated information is available on W4SM's AO-10 page. See the next question about AO-40.

### What about the Attitude of AO-40?

During AO-40's working lifetime, attitude parameters for AO-40 were available on the its telemetry beacon and (usually) in the AMSAT News Service weekly satellite report.

There's a problem, though. InstantTrack 1.50 assumes that the high-gain antennas on the spacecraft are pointing in the +Z direction (that is, away from the kick motor). However, on AO-40 the antennas are mounted on the kick motor side, and point in the -Z direction. This means that if you put the regular Bahn coordinates into InstantTrack, it will get the squint angles wrong.

To compensate for this problem using InstantTrack 1.50, you can convert the Bahn coordinates to point in the opposite direction. To convert the Bahn longitude, add 180. If that number is 360 or larger, subtract 360. To convert the Bahn latitude, simply negate it.

For example, recently as I write this (December 8, 2000) the attitude was reported in the beacon as "267/-3". That's a longitude of 267, and a latitude of -3. The converted longitude for InstantTrack 1.50 is 267 + 180 - 360 = 87, and the converted latitude is +3. So the attitude should be entered on the Manual Edit Satellite Elements screen as "3,87". Notice that InstantTrack 1.50 wants the latitude first, and a comma between them, whereas the beacon lists the longitude first and uses a slash between them.

Version 1.51 and later of InstantTrack (currently in open beta testing) provide a better solution. These versions take the attitude in the same format as published in the beacon and elsewhere, with the longitude first and a slash separator. In addition, for satellites like AO-40 with the antennas on the -Z face, you can add a "-" after the coordinates to inform InstantTrack of this fact. So in the example above, you'd enter "267/-3 -" the first time. On subsequent updates, you can leave off the extra "-"; it becomes the new default for that satellite. See the open beta page for more information and to obtain the newer version.

Note that this type of attitude calculation will only work as long as AO-40 is in spin mode. After the orbital maneuvers were completed, AO-40 was supposed to go into a 3-axis stabilized mode. InstantTrack 1.50 can't handle that type of attitude mode. Perhaps there will be a new version that can, someday.

### How do I make InstantTrack print out a report of satellite passes?

Bring up the ephemeris display you want on-screen, then hit "P" or "F" to initiate the capture. See the user manual for full details.

If all you need for each pass is the beginning and ending time and the maximum elevation, you can use the program ITPASS that comes on the InstantTrack Utilities Disk, available for a donation from AMSAT HQ. ITPASS works with InstantTrack's satellite database, so it's almost like adding a feature to InstantTrack. ITPASS is now available for free download.

### Does InstantTrack use true North or magnetic North?

True North. All tracking programs use true North.

For information about the difference, and how to use a magnetic compass to find true North, search the web for magnetic declination.

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## Programmer's Details

### What language is InstantTrack written in?

C, with just a little bit of assembly language.

### Can I get the source code?

The source code is not distributed. If you have a serious commercial requirement for the source code and are willing to pay serious money for an as-is license under non-disclosure with absolutely no technical support, you may contact InstantTrack's authors to negotiate a license.

### What's the format of InstantTrack's database files?

The format of these files is not documented. It may change from version to version of InstantTrack. It did in fact change with version 1.50.

If you want to automate changes to the IT.ORB database of satellite elements, consider using the new automation features in InstantTrack 1.50 instead of writing your own program. It is now possible to have InstantTrack read an element file under command-line control, or look for an element file named in IT.INI on startup.

### What's the interface for rotator controllers?

InstantTrack uses a version of the software interface defined for the Kansas City Tracker, based on software interrupts. The details of which functions are used are provided in the file INTSPEC.TXT, which is also included with InstantTrack.

### What's the interface for Doppler tuning?

InstantTrack uses an interface for Doppler tuning similar to the Kansas City Tracker interface for rotator control. The details are provided with InstantTrack in the file INTSPEC.TXT. One extra hint: your radio driver interrupt handler must copy the range rate information into its own memory space, since the information is overwritten immediately after the interrupt handler returns.

An example program (rrdemo) is available to demonstrate the technique.

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## Obtaining InstantTrack

### Where can I get InstantTrack?

InstantTrack is available for a donation to any of several AMSAT organizations, including:

AMSAT-NA
850 Sligo Avenue, Suite 600
Silver Spring, MD 20910-4703
Phone: +1 (301) 589-6062.
Fax: +1 (301) 608-3410.

AMSAT-Australia
G.P.O. Box 2141
Phone: (08) 297 5104

AMSAT-UK
40 Downsview
Small Dole
West Sussex, BN5 9YB
U.K.
Phone: +44 (0) 1273 495733
Fax: +44 (0) 1273 492927

AMSAT-DL-Warenvertrieb
Martin Blanz, DL9SAT
Liegnitzer Str. 70
D-71701 Schwieberdingen
Fax: +49 7150 397978

AMSAT-ZL
c/o 20 First View Ave.
Beachlands 1705
Auckland
New Zealand
email: jpsl@ihug.co.nz

AMSAT-OZ
IHK
EIT-sektoren
Lautrupvang 15
DK-2850 Ballerup
Denmark
email: oz1my@amsat.org

See the Get It Now page for InstantTrack.

You can obtain InstantTrack online and download it immediately. See the InstantTrack page for details.

InstantTrack should not be offered for free download on any Internet site or BBS. InstantTrack is offered by various AMSAT organizations for a donation to raise funds for the amateur radio satellite program. It is not free.

### I saw InstantTrack on the Net, or on a CD-ROM, or in a shareware bin at a hamfest.

Please notify AMSAT HQ so we can follow up. Usually it's just an honest mistake (or honest carelessness), and we have had fairly good luck getting the unauthorized copies removed.

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