[aprssig] APRStt 4 digit grid squares...justification !!!
bruninga at usna.edu
Tue Feb 17 08:37:59 EST 2015
> "why" we need another incompatible [APRS] locator specification...?
Its not APRS, it is DTMF uplink for satellite users
> Doesn't APRS report one's position anyway if needed?
Only 2% of Ham radio operators have APRS radios, so 98% do not experience
the APRS style of communications via satellite.
> Without GPS... program location with finger & key Lat/Long, or Maidenhead
Exactly. That is what this system implements for DTMF users.
> Most... hand helds... have keypads, that support alpha numeric format
But ALPHA doubles the length of the keys, making it impossible to fit both
the GRID and the CALLSIGN in the same DTMF memory.
> what happened to the KISS principle. Touch tones... Why?
This is KISS. It is a system designed to let the other 98% of ham
operators who do not own an APRS radio participate in ARISS and PCSAT
(NO44) style satellite communications.
> considering VHF range... why do we need another locator system
See original proposals. This is for a particular satellite mission. If
you dont want to use it, dont. It does not impact a single APRS user
anywhere on the planet.
> There are far more pressing things that need sorting with APRS,
> Look at what the [has been done] with advanced modulation
OK, let them build a satellite and see how many people will be able to use
Let me explain again... The #1 challenge with satellite communications is
congestion and collisions on the uplink. Thus, the uplinks should be as
short as possible. AND the entire users data MUST fit into a single
transmission burst so that any successful reception is complete.
Given that DTMF memories in most radios are 16 keys or less, then we must
have a DTMF system that can encode the callsign and GRID in a single DTMF
memory. This system does that.
And again, this is converted to STANDARD APRS at the satellite so everyone
who is concerned about yet another APRS format simply do not understand
this mission. This is a DTMF format and has nothing to do with APRS
formats. The dowlink will be normal APRS and Voice.
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