[aprssig] APRStt 4 digit grid squares...justification !!!

Dave B g8kbvdave at googlemail.com
Wed Feb 18 11:59:17 CST 2015


OK Bob, I missed the Sattelite connection.

However, have you listened to the racket on a downlink when a bird is over 
Europe?   There is no way on (or off) earth, that a simple handheld is going to 
get through that sort conjestion, especially if as you suggest, a large proportion 
of handie users attempt it at the same time..

Maybe its quieter when over the US?

What's possible, and what's practical, can sadly be at oposite ends of the 
spectrum.

Nice idea perhaps after all, but not convinced regarding the limited choice of 
available "squares".

73.

Dave G0WBX.



> 
> > "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 it.
> 
> 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.
> 
> Bob, Wb4APR
> 




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