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1994-04-30
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╔═════════════════════════════════════════╗
║ Satellite Orbital Prediction Software ║
║ By John A. Magliacane ║
║ « KD2BD Software - Copyright 1994 » ║
╚═════════════════════════════════════════╝
* INTRODUCTION *
----------------
PREDICT is a satellite orbital prediction program written in 'C' for the
MS-DOS operating system by John A. Magliacane, KD2BD in 1994. It was
designed specifically to assist in Amateur Satellite communications, and
contains features useful in making visual observations of larger satellites.
PREDICT was originally designed to run on a 1 MHz Commodore 64 computer
in 1992. As a result, the orbital tracking and prediction algorithms
contained in PREDICT have been optimized for high speed operation. During
its development, the program crossed over from the C64 environment to
several multi-user Unix and SunOS platforms, and then finally over to
MS-DOS. This version issued in 1994 is menu driven and supports a mouse.
* CONDITIONS OF USE *
---------------------
The files contained in this software package are the property of John A.
Magliacane, copyright 1994. You are welcomed to share this software with
others provided it is distributed in a complete and unmodified form and
that no fee or other consideration is charged or accepted. You are granted
the right to use this software for non-commercial purposes without further
permission. Commercial use of PREDICT without the expressed written
permission of the author is strictly forbidden. John A. Magliacane, the
author of this software, shall not be liable in any way for any damages
arising out of the proper or improper use of this software or its related
files.
* GETTING STARTED *
-------------------
The main program menu of PREDICT provides the following program options:
[F1] : Predict Satellite Passes
[F2] : Auto Update Keplerian Data Base
[F3] : Keyboard Edit Of Data Base
[F4] : Satellite Orbital Information
[F5] : Ground Station Information
[?] : Help!
[ESC] : Exit Program
The satellite ground station callsign and geographical location information
may be entered using the [F5] editing utility. Ground station location
should be entered in decimal degrees north latitude (south is entered as
negative), and decimal degrees west longitude. Your altitude above ground
should be entered in meters. The hour differential between your system
clock and UTC should also be entered.
All satellite programs require current Keplerian data for the satellites
of interest to the ground station operator. PREDICT holds orbital data
for 21 of your favorite satellites. Keplerian data is available from a
variety of sources in several different formats. The most popular is the
"NASA 2-line" format. This format is available through NASA and AMSAT
information sources on packet radio, telephone BBSs, and the Internet.
It contains the satellite name on a single line followed by two lines of
orbital data. Redundancy is incorporated into this format through the use
of a modulo 10 checksum digit on the end of each line:
MIR
1 16609U 86017A 94111.21750077 .00004090 00000-0 58434-4 0 5749
2 16609 51.6453 111.7160 0015230 167.5089 192.6283 15.58719614467153
PREDICT's "Auto Update" [F2] mode accepts orbital data in this form contained
in an ASCII text file and verifies the data against the checksum digits to
insure accuracy. It links object numbers between the 2-line element file
and the predict.dat file when the "Auto Update" program option is chosen.
This allows the user to label a satellite with a different name than what
is indicated in the 2-line element file.
When auto updating orbital data from a 2-line element source file, PREDICT
rejects all extraneous ASCII text, mail headers, etc., that may come either
before or after valid 2-line element data. In addition, it will only update
from Keplerian data that has a reference epoch time equal to or greater than
the data currently held in the predict.dat file.
Keplerian orbital data may also be entered through the keyboard using the
keyboard editing utility [F3]. In either case, the satellite program keeps
the old Keplerian data file as a back-up (predict.old).
Orbital data can be entered, changed, or edited manually using the [F3]
program option. New satellites can be added to PREDICT's orbital data
base by entering the new data into the program using the [F3] option.
This can be done automatically if a NASA 2-line element file is available.
Simply enter the satellite name and object name manually using the [F3]
utility. Accept the old orbital data by pressing ENTER at each line, then
run the "Auto Update" function [F2], and the orbital data for the new
satellite will be added to PREDICT's data file.
Once the program is loaded with Keplerian data and the ground station
location, it is ready to run.
* SATELLITE ORBITAL PREDICTION *
--------------------------------
The satellite orbital prediction mode begins by prompting the user for a
satellite selection from a list of 21 satellite names:
[A]: OSCAR-10 [H]: OSCAR-20 [O]: OSCAR-27
[B]: OSCAR-11 [I]: RS10/RS11 [P]: MIR
[C]: OSCAR-13 [J]: RS12/RS13 [Q]: UARS
[D]: PACSAT [K]: RS14/AO21 [R]: NOAA-9
[E]: DOVE [L]: OSCAR-22 [S]: NOAA-10
[F]: WEBERSAT [M]: OSCAR-23 [T]: NOAA-11
[G]: LUSAT [N]: ITAMSAT [U]: NOAA-12
Selection can be either via the keyboard or by clicking the mouse on
the satellite name displayed on the screen. The user is prompted for
a starting date and time to begin the orbital prediction calculations.
The starting time must be entered in UTC using the format:
DDMonYR HH:MM:SS
such as: 01May94 02:00:00
The default starting date and time is the current date and time and may be
accepted simply by pressing the [ENTER] key and not entering any time.
If the satellite is in range at the time entered, PREDICT will move back
in time to find the time of AOS, and start printing an orbital calendar
starting at AOS. Tracking data is displayed one screen at a time. A typical
satellite pass might look something like this:
KD2BD's Orbit Calendar For RS14/AO21
Date Time El Az Phase Lat Long Range Orbit
-------------------------------------------------------------
01May94 02:01:08 0 172 110 10 70 3659 16311
01May94 02:02:58 7 169 114 16 69 2982 16311
01May94 02:04:47 16 165 119 22 69 2328 16311
01May94 02:06:33 28 158 123 28 68 1745 16311 +
01May94 02:08:10 45 140 127 34 68 1325 16311 +
01May94 02:09:29 56 103 130 38 67 1159 16311 +
01May94 02:10:31 54 64 133 42 67 1191 16311 +
01May94 02:11:36 42 39 135 45 66 1371 16311 +
01May94 02:12:58 29 26 139 50 65 1734 16311 +
01May94 02:14:35 17 18 143 55 64 2262 16311 +
01May94 02:16:20 8 14 147 61 62 2888 16311 +
01May94 02:18:08 1 12 151 67 58 3558 16311 +
01May94 02:18:36 0 11 153 68 57 3731 16311 +
The information displayed is defined as follows:
Date : Date in UTC
Time : Hours, minutes, seconds UTC in 24 hour format
El : Satellite elevation above the ground station horizon in degrees
Az : Satellite azimuth heading (North = 0 degrees)
Phase : Modulo 256 orbital counter. Perigee = 0, Apogee = 128
Lat : Sub-satellite point latitude in degrees North
Long : Sub-satellite point longitude in degrees West
Range : Distance between the satellite and the ground station in kilometers
Orbit : Orbit number. Number of perigees that have occurred since launch
A '*' symbol at the end of the line indicates the satellite is in sunlight.
A '+' symbol indicates it is in sunlight while the ground station is in
twilight. Some larger satellites are visible under these conditions as
reflected sunlight causes them to appear as "stars" moving across the sky.
If the end of the line is blank, the satellite is not in sunlight.
Each screen is concluded with the prompt:
More? [y/n] >>
Entering the letter 'n', hitting the ESCAPE key, or clicking the right
mouse button ends the orbital prediction calculations, while entering a
'y', pressing the ENTER key, the space bar, or clicking the left mouse
button causes the program to advance to the next screen of orbital
predictions.
* LOGGING SCREEN OUTPUT TO A FILE *
-----------------------------------
A screen logging feature is available in PREDICT and is activated by
pressing CTRL-BACKSPACE while in the orbital prediction mode. Orbital
predictions displayed on the screen can be logged to a file for future
reference or printing using this feature. Once activated, the current
screen and all subsequent orbital prediction screens are copied to a file
named "satname.txt". Invalid filename characters are replaced with an
underscore ('_') character.
The file logging feature is de-activated by pressing CTRL-BACKSPACE once
again, or by exiting the orbital prediction mode. If it is re-activated
once again at a later time for the same satellite, the orbital data will be
appended to the older data using the same file name. The file may be
edited at a later time using the DOS text editor and printed on a printer.
* CONTRIBUTIONS WELCOMED *
==========================
A considerable amount of time and effort has gone into the development
of PREDICT. If you find this software useful, a reasonable contribution
would be appreciated. Not only would a contribution help compensate for the
hard work and long hours that have gone into the development of this accurate
and easy-to-use satellite orbital prediction program, but your financial
support would also serve as encouragement for the author to pursue enhanced
versions of PREDICT and other related software.
Checks should be made payable in US funds to the author and sent to the
following address:
John A. Magliacane, KD2BD
1320 Willow Drive
Sea Girt, New Jersey 08750-2315
Comments and suggestions regarding PREDICT are also welcomed with your
payment.
Thank you!
73, de John, KD2BD