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seesats.doc
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SEESATS.DOC
Vers 0.9
30-Sep-87
Rich Bono, NM1D
7 Redfield Circle
Derry, New Hampshire 03038
Seesats and its companion files is being distributed as SHAREWARE.
This means that it is may be freely distributed to others as long as
there are NO CHARGES incurred. The author retains ALL COMMERCIAL
rights to all included programs and concepts involved. There is no
charge for this package, but in the spirit of the SHAREWARE concept, if
an end user finds this package useful, and would like to help fund
development of enhancements to this package, any amount that the end
user feels is appropriate for the value received in using this package
will be gladly accepted (ie: $25).
Please send all correspondence to the author at the above address. The
author also would also like to hear from end users about their use of
this program, including any ideas for enhancements.
If anyone makes changes to anypart of this program, they may
include their name, in the package as adding enhancements, but they
MUST send all changes to the author who will incorporate the changes into
the master archive copy. The author retains ALL RIGHTS to this code in
whole, or in parts.
The current version can be generated for MS-DOS, OS/2 or UNIX
systems.
This document describes the operation of 'SEESATS.EXE' and its
companion file, 'SEESATS.DAT'. Seesats grew out of a program
originally written for the IBM-PC in BASICA called 'orbits2' by W0SL.
This original software was VERY machine dependent. It was a very
'slick' program, as it used color and a lot of graphics. I tend to
think of software like this as a tool. Not something to impress my
friends, but something that is useful in different ways to different
persons. I converted the original 'slick' BASIC source code to the
language 'C'. In doing so, I also removed ALL traces of machine
specifics that I could find. This tended to change the flavor of the
original program from a 'slick' flashy graphics program, to a 'boring'
useful tool. Now you will find that this program should run on ANY
MS-DOS machine. This means that it should run on ANY machine that has
MS-DOS (version 2.0 or newer), not just the IBM family and its clones.
The only portibility problems that may come up is with the format of
your disks. But this can be solved by tranfering this software through
modems or a serial port (with the proper software).
The program (SEESATS.EXE) requires one companion file
(SEESATS.DAT) to operate. This file contains the raw data that varies
from time to time about the satelites you wish to track. This data is
usually refered to as KEPLERIAN ELEMENTS. The more acurate and up to
date this data is, the more acurate the outputs of seesats will be.
The file (seesats.dat) also contains some information about your earth
location, ie: latitude, longitude, altitude, identifier, and UTC
offset. This information should also be reasonably accurate if you
expect accurate predictions from seesats.
Remember that distances in this program are in METERS and
that time is in UTC (AKA GMT, and ZULU time). When you run this
program in 'realtime' mode, be sure that your DOS DATE and TIME is set
to UTC and that UTC offset is set to 0 or that your DOS DATE and TIME
is set to LOCAL time with UTC offset set to the difference between UTC
time and your local time zone. Remember that UTC offset needs to be
adjusted for local variations in seasonal Daylight Savings Time etc.
For prediction mode, you will enter the date and time desired. Again,
remember to enter UTC, not local time.
The program has an optional command line argument which
specifies the number of times it should calculate the positions of the
sateltites. For instance, if you start the program by typing:
SEESATS 2
The program will go through its calculations twice, and then exit to
DOS. This serves serveral purposes. First, if you just want a quick
update of new data, you would specify 1 (inplace of the 2 in the
example). This can serve a greater purpose in harmony with the MS-DOS
redirection facilities. For instance:
SEESATS >PRN Would send data to the printer in real
time until commanded to stop (with
CTRL-C).
SEESATS 1 >PRN Would send 1 calculation for each
satelite in realtime to the printer.
If the file PREDICT.SCR contained the following:
<--- Note: First line is blank!!! To get to menu.
1 <--- Select prediction mode from menu.
01/05/87 <--- Enter start date as DD/MM/YY.
13:00 <--- Enter start time as HH:MM (note no seconds allowed).
1 <--- Enter increment time in minutes
5 <--- Select continuous mode from menu.
<--- Note: Last line is blank!! To exit from menu.
Then the following would:
SEESATS <PREDICT.SCR Run in prediction mode (note:
this will have to be stopped
with a CTRL-C!)
SEESATS 1 <PREDICT.SCR Run in prediction mode for 1 set
of calculations.
SEESATS 1 <PREDICT.SCR >PRN As above, but send the results
the the printer.
SEESATS 100 <PREDICT.SCR >FILE Run in prediction mode for 100
calculations, sending the
output to 'FILE'. FILE could
be any legal MS-DOS file name.
This could be later printed, or
sent to another user via disk
or modem.
As you can see there are many things that could be accomplished
via the MS-DOS redirection facilities. Anything that can be done via
the menus can be done by placing the same keystrokes in a file and then
redirecting that file to take the place of the console input.
Of course this program could be started by another program that
waits for some event to occur. For instance: a CBBS could have this
program wait for a user to call the CBBS, upon the phone ringing,
another program could start 'SEESATS 1 >SATFILE.DAT'. This file
'satfile.dat' could then be made available to the user for downloading,
enabling the user to have the latest predictions for the satelites in
the SEESATS.DAT file!
The normal, day to day usage of SEESATS.EXE is not as
complicated as all this sounds! Just start seesats at your prompt by
typing:
SEESATS (hit RETURN)
If your DOS date and time is accuratly set and the UTC offset
is correct, you will see the locations of the satelites in the file
SEESATS.DAT at the very moment! To change some of the operational
characteristics of the program, hit ENTER (RETURN on some machines) and
a menu will be displayed on the screen that looks something like this:
Current Selections:
Mode is...realtime Print...all calculations Select...all satelites
Output is.paged
Seesats menu -
1 - Mode is prediction
2 - Print only when in view
3 - Select satelite of interest
4 - Print current element data for satelites
5 - Change output mode to continuous
0 - Quit.
Enter number for desired function ([ENTER] to continue) :
The line under current selections is showing that the
current calculations are being done in realtime (with the DOS date and
time), as opposed to prediction mode. All calculations will be printed,
as opposed to only when the satelite is in view from your location. All
satelites contained in the SEESATS.DAT database will be calculated, as
opposed to just one satelite chosen from the list of satelites in the
database.
The 1, 2, 3, & 5 entries in the menu will be the opposite of what
is being displayed in the current selection line. These will allow you
to toggle the modes of operation. The number 4 entry will allow you to
view the data in the ELEMENTS.DAT without stopping the program to print
out the file. Number 0 will cause the program to stop and return you to
MS-DOS. If you don't want to change anything, just hit return without
entering any selection, you will be returned to the same operating mode
that you were in.
The prediction mode will first ask you for a starting date and
time. Again, remember to enter UTC time! It will also ask for an
increment amount. This is the number of minutes to increment the clock
from the starting time for each batch of calculations. This is useful
to see when a satelite will be visable in the future. Remember that you
will get data for the current mode. If the program is set to show only
when in view, you will receive prediction data for only when the
satelite is in view from your location. Also, if the program is set to
show data from only one satelite, then you will receive predictions only
for the selected satelite. These modes can be changed while the program
is running to select various conditions as the needs arise.
Once the program is running, if you desire the data coming to
the screen to go to the printer, you could (if your machine supports
these features) hit the 'print screen' key to get a snapshot of the data
that is currently on the screen, or hit CTRL-P (toggle printer echo) to
have the data go to the printer at the same time as it goes to the
screen.
If you have the program 'SEESATS.EXE' and it's companion file
'SEESATS.DAT' in a directory that is pointed to by the MS-DOS PATH, then
the current directory will not have to contain a copy of these files.
The file SEESATS.DAT must be in a specific order and sequence.
Note that the earth station location must be before the satelite data.
There may be comments in the file as long as they start with either a
semicolen ';' or a vertical bar '|' in the first column. A line that
starts with a semicolen will be ignored. A line that starts with a
vertical bar will be output. This is used to send reminders to the user
of the program.
This program may be copied and distributed without charge to
others as long as all the files are intact and unchanged. The files
currently are SEESATS.EXE, SEESATS.DAT, PREDICT.SCR, and this file
SEESATS.DOC.
xxxx seesats.doc
Please keep me informed as to your progress
/**************************************************************************\
* Rich Bono (NM1D) rbono@necis.nec.com *
* (508) 635-6303 NEC Information Systems These are my own opinions *
\**************************************************************************/