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[aprssig] ISS Tracking & Pass Information UPDATE

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Sat Oct 15 01:18:29 UTC 2011

On 10/14/2011 9:05 PM, Bob Bruninga wrote:
> Again, I'm glad to hear the message is ORIGINATED by the Satellite Callsgin,
> This is GREAT!  It means that the nearby IGate will not only relay the
> response back to the queryer, but if the IGate is doing its job, it will
> also send out a local courtesy copy of the ISS actual APRS-IS POSIT.

Um, not quite.   There is no "station" acting as the satellite 
transmitting any position updates.  The ISS that's "flying" in the 
APRS-IS right now is the same as all other satellites that I've seen 
"flying" in APRS before from other tools.  It's an APRS object.  An 
object originated by KJ4ERJ-15.  As far as I know, the "courtesy" posit 
copy gated for messaging-active stations is for just that, stations.  I 
don't believe the IGates will pick up an object posit and associate it 
with a message for the same name.  I could be wrong about this, but I 
don't think so.

Now, when Item-In-Message gets more universally supported, I can 
followup the pass information with an Item describing the current 
location that the current APRS-IS system and IGates should gate just as 
effectively as the response message.  But as far as I know, that's all 
we've got to hope for right now.

> > From that Posit, the HT or Mobile radio will not only show DISTANCE and
> DIRECTION to the satellite, but also which direction it is moving!  The
> operator can instantly visualize the 3D geometry of the pass.

Wait, how is the radio going to know the direction the satellite is 
moving from a single courtesy posit?  The course/speed in a packet can't 
quite handle the speed of a satellite (I tried, 3 digits doesn't cut 
it).  And, as I stated above, as long as the satellite is an object, I 
don't think the posit will get out after the message, even if I was 
injecting positions for all of the queriable satellites, which I'm not.  
Just the ISS.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

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