HP41 code to compute satellite position from TLE/keplers?
12-24-2014, 12:30 AM
Post: #1
 twdeckard Member Posts: 94 Joined: Dec 2013
HP41 code to compute satellite position from TLE/keplers?
Does anyone know of an HP41 routine to calculate satellite look at angles from the TLE descriptions? Google claims one existed?

Thanks
Todd
12-24-2014, 07:02 AM
Post: #2
 Ángel Martin Senior Member Posts: 1,317 Joined: Dec 2013
RE: HP41 code to compute satellite position from TLE/keplers?
(12-24-2014 12:30 AM)twdeckard Wrote:  Does anyone know of an HP41 routine to calculate satellite look at angles from the TLE descriptions? Google claims one existed?

Thanks
Todd

May be worth a check to JM Baillard's "Astronomy" section at:
http://hp41programs.yolasite.com/
12-24-2014, 05:59 PM
Post: #3
 twdeckard Member Posts: 94 Joined: Dec 2013
RE: HP41 code to compute satellite position from TLE/keplers?
Excellent suggestion, I skimmed thru it quickly and didn't find it.

Its specifically a program called ORBIT 1, or ORBIT two for the -cx. It was the calculator version of a BASIC program for predicting satellite look at angles from keplers you get from NORAD.

I am interested in the HP version because if you are going to try to send morse code to an antique amateur radio satellite you might as well plot its position with your '41!

Also, I only need approximate azimuth/elevation and would like to investigate the simplifications they used over the more elaborate models available in any flavor of source code desired.

I sent a note to the amateur satellite radio association to see if they have it in the archives.
12-24-2014, 06:34 PM
Post: #4
 Allen Member Posts: 146 Joined: Aug 2014
RE: HP41 code to compute satellite position from TLE/keplers?
Does Wolfram|Alpha display it?
12-24-2014, 07:30 PM
Post: #5
 kkapkin Junior Member Posts: 6 Joined: Dec 2013
RE: HP41 code to compute satellite position from TLE/keplers?
Todd, perfect timing, I have been searching such program recently. Let me know if you find that program, as an operator I would be very interested in as well.
Cheers,
Kerem
KK6RDB
12-25-2014, 01:02 PM
Post: #6
 SlideRule Senior Member Posts: 1,324 Joined: Dec 2013
RE: HP41 code to compute satellite position from TLE/keplers?
(12-24-2014 05:59 PM)twdeckard Wrote:  ... program called ORBIT 1, or ORBIT two for the -cx ... calculator version of a BASIC program ...

This excerpt from AMSAT may be of interest.
AMSAT
PROGRAM AVAILABILITY NOTICE

16. HP-41 PROGRAMMABLE CALCULATOR - ORBIT 1 - This program will output AZ
and EL in real-time or all W3IWI parameters in the prediction mode. Special
but not essential). ORBIT II - The same as ORBIT I with the addition of
functions from the Time Module for output of time and input from the time
clock in real time-mode. Please specify ORBIT I or ORBIT II.

-----------------------------------------------------------------------------

ORDER FORM

Program Desired/Computer Type________________________________________________

Enclosed find my check for $_________ OR Charge my Visa or MasterCard________ Card No. _______________________________________ Exp. Date _________________ AMSAT Member No.____________ (If you don't include your number, you will be charged non-member prices!! Name ________________________________________________________________________ Address _____________________________________________________________________ City/State/ZIP ______________________________________________________________ Send directly to: AMSAT PO BOX 27 WASHINGTON, DC 20044 OR CALL 301-589-6062 AND CHARGE IT FOR FASTER DELIVERY!!! as well as theses attachedments. Track Satellites (67)- [attachment=1352] Orbital Programs (excerpt from) - [attachment=1353] SlideRule 12-25-2014, 04:46 PM Post: #7  SlideRule Senior Member Posts: 1,324 Joined: Dec 2013 RE: HP41 code to compute satellite position from TLE/keplers? (12-24-2014 05:59 PM)twdeckard Wrote: ... a BASIC program for predicting satellite look at angles from keplers you get from NORAD ... Orbit tracking programs The best general purpose orbit tracking program available for free public use was originally written in BASIC by Dr. Thomas A. Clark. A listing of his program appears in the AMSAT publication ORBIT magazine issue #6. You can get a copy of this issue by sending$2 to
AMSAT PO Box 27
Washington, DC 20044
(This address is also good for general inquiries about AMSAT and its programs)
Tom's program has been translated into a number of dialects of BASIC, PL/1, HP-41C, etc, and are available from
Amsat Software Exchange (ASE) Box 338
Ashmore, IL 61912
(for small donations ($5-$15) to cover costs)
One of the guys running the ASE, Bob Diersing, N5AHD, runs a CBBS on (512)852-8194 where you can read some info about the available programs and get Keplerian elements for a number of satellites. Tom's article includes a very good discussion of the theory behind his program, which is a general one handling elliptical orbits as well as circular ones. It uses the "Keplerian Element" sets derived by the North American Air Defense Command (NORAD)
Source file

as well as
ORBIT magazine issue #6

BEST!
SlideRule
12-26-2014, 04:58 PM
Post: #8
 twdeckard Member Posts: 94 Joined: Dec 2013
RE: HP41 code to compute satellite position from TLE/keplers?
Excellent thank you.

Regards and Happy Holidays
Todd
12-27-2014, 02:59 AM
Post: #9
 twdeckard Member Posts: 94 Joined: Dec 2013
RE: HP41 code to compute satellite position from TLE/keplers?
Here is the program from Ham Radio Magazine, March 1981 (P. Bunnell)

Attached File(s)