[aprssig] ISS Tracking & Pass Information

[Bob Bruninga]

Great project!

But the format for zulu time is HHMMz.  there is no colon.  And it saves bandwidth too.

> send an APRS message to ISS... The response will be:
> Az: aaa El: lll LOS:xx:yyz - If you are in a pass
> AOS: xx:yyz+aa:bbc - If you are not in a pass
> AOS: NONE - If... no passes... in... two days.

I wonder if we could tweak the format to not be so choppy or to better match some radios small 12x12x12x10 display windows... (D7).   I'd suggest:

AZ/EL aaa/LL LOS: X min

AOS ISS in HH:MM MaxEL yy deg

Duration is always going to be in minutes and I'd rather see a relative time, rather than try to think in zulu and not be sure.  This tells you how long till the next pass and what its max elevation will be.  Anyone who operates the satellites can infer how long it will last from the maximum elevation angle and whethter it is a pass worth listening to or not...

> You can send an APRS message to "AO-51" 
> to find out when that satellite will pass within
> range.

You might consider dropping the requirment for the HYPHEN.  In all my earlier APRS/space applications I truncated the names to 4 bytes and eliminated hyphens... mostly because they are wasted characters and take a lot of button pushing to get the "-" character...

> Give the service a try...

It is a great concept!!!

One disadvantage of the time-to-go approach is that the message sits in your message buffer and for use later,  you haev to mremmebr when it came in.  Maybe it is better your way.  In that case, I'd suggest:

AOS ISS_ at HHMMz MaxEL yy deg

Notice that you need the satellite name (typically truncated to 4 bytes) so that these messages make sense later.

Great work!
Bob, WB4APR