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InstantTrack Tutorial:
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InstantTrack provides a mechanism that makes it easy to let another program update the Keplerian elements database maintained by InstantTrack. This tutorial shows you exactly how to set this up using cURL to download elements from the AMSAT.ORG web site.
cURL is a command-line program that can fetch from the Internet
nearly any file that a web browser can, given just its URL (that is, its
web address). cURL is available from http://curl.haxx.se/
for Windows (95, 98, ME, NT, 2000, or XP, but not 3.1) and for many
other operating systems. Go to the download
page and get the version you need. Assuming you're running Windows,
get the Win32 version without SSL support (for simplicity). Either way,
you'll download a zip file. When you open the zip file (using WinZip or
whatever you usually use) you'll find a single executable, and some
auxiliary files you won't need. Just extract the CURL.EXE file into your
InstantTrack directory (usually, that's C:\IT).
Here's a local copy of cURL 7.9.7 for Windows (no SSL) in case you have trouble getting it from the cURL site. This may not be the latest or best version of cURL.
If you're running plain MS-DOS, there is even a version of cURL for you. It does require some additional components. If you have trouble with that solution, try the WATTCP tutorial instead.
You'll need to create a batch file to take care of some of the details of the automatic update. Use a text editor (such as Notepad) and type in the following:
@echo off c: cd \it copy it.orb itorb.bak curl http://www.amsat.org/amsat/ftp/keps/current/nasa.all >nasa.all it /f nasa.all
Save the file with a suitable name, such as GETKEPS.BAT (it must end with
.BAT), in your InstantTrack directory. Or, to save the step of building
the file, just download my GETKEPS.BAT and save it in
your InstantTrack directory.
I've assumed that your InstantTrack directory is C:\IT. If you have
installed InstantTrack elsewhere you'll need to change lines 2 and 3 to
reflect the correct drive and directory.
If you're interested in the technical details, see this explanation of the batch file.
The batch file we used also creates a backup copy of the database in
ITORB.BAK. This can rescue you from ONE bad update. To restore the database to
the way it was before the update, delete the file IT.ORB and rename ITORB.BAK to
IT.ORB. Note that this will also eliminate any manual changes you have made
since the update.
If you don't need a backup file, you can delete the copy command from the batch file.
You'll need to be connected to the Internet for this to work. If you're lucky enough to have an always-on connection (cable modem, DSL, satellite, etc.) you won't need to worry about this. If you dial up using a modem, you can either do so manually before running the batch file, or (I think) you can configure Dialup Networking to dial automatically whenever a program tries to access the Internet.
You can run the program from the command line, if you like. Just CD
to the InstantTrack directory and type the name of the
batch file, GETKEPS. The program will quickly download the
NASA-format elements file and feed it to InstantTrack. If you
have a fast connection and a fast computer, this will all happen so fast
it seems, well, Instant. Even on a dialup, it shouldn't take more
than a few seconds, unless it has to dial the modem.
If you expect to run the update manually, you will probably want to
create a shortcut. Open the Windows Explorer and navigate to the InstantTrack directory, C:\IT. Right-click on the batch
file (it may look like GETKEPS or like GETKEPS.BAT, depending
on how you have Windows Explorer set up). Choose Create Shortcut
and let it create a shortcut for you. Find the shortcut at the bottom of
the files. It will be named Shortcut to GETKEPS.BAT. Right-click
on it, choose Rename and give it a better name, such as Get
Keps. Right-click on it again, choose Properties, choose the Program
tab, and check the Close on exit box. Now drag the renamed
shortcut onto the desktop. You can run it from there, anytime, by just
double-clicking the icon.
If you prefer a clean desktop, move the icon into your Start menu.
Try it now. Did it work? Check for a NASA.ALL file on your disk with
today's date. If there's a problem with cURL, that file won't show up.
In that case, add a PAUSE command after the CURL command in the batch
file, and try again. This will give you a chance to see whatever error
message cURL is reporting.
Note: the IT.ORB file will be updated only if there are newer
elements in the downloaded file. Don't let this confuse you when testing
out your batch file. The date and time on the IT.ORB file won't change
every time you run the batch file. You can force it to change by running
InstantTrack and deleting the elements for one of the satellites in the
downloaded set. That way, the automatic update will need to re-add that
satellite, forcing it to update the IT.ORB file.
The elements on AMSAT.ORG are updated once a week. There's no need to download it more often than that. Wouldn't it be nice if that could just happen automatically without you doing anything? Here's how.
Windows 2000: From the Start menu, choose Settings, then Control Panel.
Windows 98SE: Double-click on My Computer.
Windows (others): find Scheduled Tasks wherever they've hidden it this time.
Double-click on Scheduled Tasks. Double-click on Add
Scheduled Task. Click Next> to begin the wizard. Your
batch file isn't an application that Windows knows about, so click Browse,
navigate to C:\IT, and double-click on the batch file.
Choose Weekly and enter a suitable name, such as Update Keps
using cURL. Click Next> again, and choose your time. It
doesn't matter when during the week you choose, as long as your computer
is switched on and has Internet access at the time you choose. Choose only one day of
the week, and Every 1 weeks. Complete the rest of the wizard
until it lets you click Finish.
That's it! You should never have to worry about loading new Keps
Last updated 04 December 2003. Comments to KB5MU, kb5mu@amsat.org
Copyright 2002 Paul Williamson. All Rights Reserved.