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[aprssig] D-Star replacement for APRS: [Was: D710 GPS Port]

Gerry Creager gerry.creager at tamu.edu
Tue Aug 14 18:45:02 UTC 2007


There's already a lot of work that's gone into using D-STAR with APRS. 
Check out http://www.aprs-is.net/dstartnc2.htm

The initial work was done by AE5PL... the javAPRSsrvr mastermind.

gerry

Stephen H. Smith wrote:
> William McKeehan wrote:
>> Has anyone looked at D-Star as a potential replacement for APRS?
>>   
>> It seems to have a lot of the basic functionality.
>>   
> There are a LOT of technical, organizational and political obstacles to 
> this ever happening.
> 
> Partly as a result of the APRS founders shoe-horning and somewhat 
> kludging APRS into the protocols, hardware and infrastructure of the 
> preceding connected-packet era (do I dare use that over-used buzzword 
> "leverage"?), APRS has succeeded because it has allowed us to do a lot 
> of "neat stuff" with really cheap existing hardware.    This will *NOT* 
> be the case with D-Star.    A migration to D-Star will be a wrenching 
> total transition to *ALL NEW* base stations, mobiles, hand-helds and 
> repeater infrastructure.  
> 
> 
> D-Star is not a short-burst packetized transmission format. It's 
> primarily a digitized voice format that can carry a limited amount of 
> other data embedded in the main voice data stream.   As a result, the 
> simple single-frequency store-and-forward "digipeaters" we use on APRS 
> won't work with it.   You would be faced with coordinating a traditional 
> full-blown two-frequency "repeater pair", along with using a separate 
> receiver, transmitter and duplexer, just like present voice 
> repeaters.    Further , getting more than one repeater hop isn't a 
> matter of the second repeater hearing the first one, and then 
> retransmitting what it hears a moment later. It involves a complex 
> land-mobile-style backbone of links on another band, usually 1200 MHz to 
> connect repeaters together in real time.
> 
> Further, no manufacturer seems to have adopted it, except Icom.  
> 
> While the only mfr to officially support APRS is Kenwood, at least you 
> *CAN* add APRS hardware (TNCs, TinyTracks, Open Tracks, etc.) to other 
> radios.  This is not going to be the case with D-Star which is an 
> entirely digital modulation technique totally different from the analog 
> FM we use with APRS packet, that is built-into purpose-built radios.  It 
> is very unlikely you would be able to add D-Star to any existing radio, 
> especially hand-helds. 
> 
> Achieving anything remotely like the coverage of  the current 
> analog-FM-packet-based APRS network (where just about any FM radio made 
> in the last 30 years or so can be pressed into duty as a digipeater by 
> adding a $50 TNC). Duplicating this coverage with D-Star would require 
> literally tens of millions of dollars of brand-new infrastructure. 
> 
> Further, the present network reflects the sum total of a lot of small 
> steps made independently by clubs and individuals.  A nationwide D-Star 
> "APRS- replacement" infrastructure would require a degree of 
> coordination (and financial commitment) by clubs and individuals 
> unprecedented in amateur radio.
> 
> My guess is that we will get "islands" of D-Star activity in major 
> metropolitan areas (where the population density of hams is great enough 
> to support the major infrastructure investments required) , surrounded 
> by hundreds (or thousands) of miles of non-coverage.   I.E. the 
> individual ham or small club in a small mid-western town or rural 
> Kentucky that threw up an old hand-me-down 2-meter rig and a TNC to fill 
> in  the APRS network at almost no cost, is NOT going to lay out the 
> several thousand dollars minimum to put up a D-Star repeater, let alone 
> the backbone to link it to other D-Star systems.
> 
> Before they make this major investment, users are far more likely to use 
> Internet access from their cellphones to send/display GPS position 
> reports and send/receive short text messages.  (Envision an APRS-like 
> application overlaid on Google Maps running on an iPhone-like device.]
> 
> 
> --
> 
> Stephen H. Smith    wa8lmf (at) aol.com
> EchoLink Node:      14400    [Think bottom of the 2M band]
> Home Page:          http://wa8lmf.com  --OR--   http://wa8lmf.net
> 
> NEW!   World Digipeater Map
>   http://wa8lmf.net/APRSmaps
> 
> JavAPRS Filter Port 14580 Guide
>   http://wa8lmf.net/aprs/JAVaprsFilters.htm
> 
> "APRS 101"  Explanation of APRS Path Selection & Digipeating
>   http://wa8lmf.net/DigiPaths
> 
> Updated "Rev H" APRS            http://wa8lmf.net/aprs
> Symbols Set for UI-View,
> UIpoint and APRSplus:
> 
> 
> 
> 
> 
> 
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