[amsat-bb] Software Problems

Graham planophore at aei.ca
Sun Oct 23 15:25:30 UTC 2016

```Joe,

Back in the Oscar 7/8 and RS10 (et al) days, all I had was a simple
program written in BASIC for which I had to manually update the element
sets and which only provided a prediction rather than a "real time"
view. It all seemed so much simpler and to some degree more satisfying.

Skip forward 35 to 40 years and we have all these wonderful near real
time "ultra cool software programs", multiple computer platforms and
operating systems (Windows, Apple OS, Linux, Android) and the choices
are many, the learning curve can be steep, and it is easy to get frustrated.

From your list I have only first hand experience with Orbitron. The one
I decided on is not in your list - GPREDICT.

I quickly settled on GPREDICT because to me at least it was intuitive
and useable on at least Windows and LINUX. Generally I leave it running
on a Raspberry Pi 3 and a dedicated monitor showing the various Amateur
and Weather satellites in which I have an interest.  Predictions are
always spot on. I typically hear whatever satellite I am waiting for
within a few seconds of the indicated AOS.

To be fair, I also have own GPS disciplined NTP time server which serves
precise time to all of my networked computers plus I run NTP on each
computer on the network. I check them regularly to unsure that all are
correct.

Keeping you computer's time correct is the first hurdle. Having the
correct time to the a couple of seconds is more than adequate in this
case and if you have in interest in something like WSPR then within a
second is usually sufficient.

The next hurdle is to get your latitude, longitude, and altitude set
correctly in the program of your choice.  Latitude and longitude need to
have the correct quadrant be it specified as N S E or W or + for N, -
for S, - for W, and + for E, and as precise as you can. But this you
already know given your experience with the other modes you have listed.
Altitude is also important but needn't be that precise but ensuring the
right units is, i.e. ft or meters as required by the program. But again,
I think you are already aware of this. I am just being complete in my reply.

Once all of your configurations are set correctly, I can't see these
programs all giving different answers. It is possible  but the
underlying math is pretty much all the same for each of the programs.

cheers, Graham ve3gtc

On 2016-10-23 14:55, Joe wrote:
> I am really excited about getting back on the Birds after a 40+ year
> absence.
> I've done EME, MS, AU, and all sorts of weak signal stuff on 144Mhz.
> I've played the DX and contesting on HF.
> All has been fun, but none except for the EME has given the most
> happiness than the memories of playing with the birds in the late 70's
>
> Now let me know, I can take this off list if members here want me to,
> But This excitement is quickly turning into disgust. To the point I'm
> just about to say screw it and forget about Sat work again.
>
> I am in the need of help with prediction programs.
>
> Man in the late 70's it was the ARRL bulletin with keps etc. and a
> Oscar Locator.
>
> Now we got ultra cool software programs that all are incredible!
> Except for me, I can not trust ANY of them.  I have been testing
> several to see what I will make my primary program. BUT...... and
> there always is a "BUT" isn't there? I can not say what one to "Trust"
> The four I have installed are...
> SatLookDown1_28
> HRDSatTrack
> Orbitron
> SatPC32
>
> Now of course they all use the same computer clock. And it is accurate
> to less than a tenth of a second.
>
> Each one periodically ask to Up-Date the TLE's and I say "YES" and let
> them do it all on their own. I change NOTHING on where they get their
> data.
>
> The run them.
>
> The,
> SatLookDown1_28 & HRDSatTrack, both agree very closely. Almost to the
> second.
>
> But the Orbitron, is off, WAY off. like 15 minutes off.
>
> And the SatPC32 is even worse the sat is like 1/2 an orbit off!
>
> Now the ones that agree also match the page
>
> http://www.amsat.org.ar/pass.htm#
>
> So my guess they are the ones showing correct data.
>
> Now what to do about the other two. How can I make them show correct
> passes?
>