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[aprssig] Satellite positions: FREQUENCY

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Tue Oct 18 23:03:55 UTC 2011


On 10/18/2011 12:49 PM, Bob Bruninga wrote:
>
> The HUMAN interface to the HT/Mobile FM satellite operator is just to see
> the "object" in his POSITION LIST and there it is displayed with a DISTANCE
> and BEARING and ELEVATION and FREQUENCY.

Nope, no ELEVATION in a position object.  Distance and Bearing might be 
calculated from the Lat/Lon of a position packet, but position packets 
are globally visible and have NO observer information, so no Elevation 
makes sense to all possible receivers.

The Bearing is in the existing APRS message, which is also in his 
message list.  Distance, IMHO, is meaningless, it's Azimuth (bearing) 
and Elevation (observer specific) that matter, so the only thing missing 
in the message is the frequency which is invariant for any given satellite.

So, I ask again, why TWO packets for every query instead of just ONE 
that conveys all of the useful dynamic information specific to the 
observer's location?

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




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