[aprssig] RE TH-D7 and Group Code (SPCL/AlterNet)

[Andy AB9FX]

----- Original Message ----- 
From: <kb2scs at optonline.net>
To: <aprssig at lists.tapr.org>
Sent: Sunday, March 05, 2006 06:38
Subject: [aprssig] RE TH-D7 and Group Code (SPCL/AlterNet)


> Hi Steve
>               I do not know how the TH-D7 program code is coded to
> handel SPCL and AlterNet. But  I do know how APRS software is
> supposed to work with SPCL and ALterNet.
>
> How SPCL is supposed to work according to the APRS Spec.
> APRS Software is supposed to allow the user to change his ToCall to
> "SPCL". When the user does so his APRS software is supposed to filter
> out all other Stations that do not have "SPCL" as there ToCall. Which
> would cause only the stations with the ToCall of "SPCL" to show up on
> their Maps.
> Note all other stations running APRS software  on 144.390 would see
> the "SPCL" stations on their map.
>
> How AlterNet is supposed to work according to the APRS Spec.
> APRS Software is supposed to allow the user to change his ToCall to
> any valid AX25 ToCall. When the user does so his APRS Software is
> supposed to filter out all other Stations that do not use this
> AlterNet ToCall. Which would cause only the stations with the same
> AlterNet ToCall to show up on their maps.
> Note  all other stations running APRS software on 144.390 are not
> supposed to see the stations using the AlterNet ToCall.
>
> The above "Note" sentence is supposed to be the difference between
> "SPCL" and "AlterNet" according to the APRS Spec.
>
> I do not know if the TH-D7 has implemented this part of the APRS
> Spec.
>
> APRSDos and APRS-SCS do adhere to the APRS Spec. So "SPCL" and
> "AlterNet" do work in APRSdos and APRS-SCS.
> There are probably other APRS Software that adhere to the APRS Spec
> in this manner but I have only used APRSdos and APRS-SCS.
>
> I hope this has been of some help.
>
> Let us hope we never witness the "Silence Of The Hams"
> 73 DE John  KB2SCS
>       E-Mail:            kb2scs at arrl.net
>       APRS-SCS     http://www.tapr.org/~kb2scs
>       Web Page:     http://www.qsl.net/kb2scs
>

Only explanation of SPCL I've found for TH-D7 is in the PG-4W manual. 
Although manual seems to be for TH-D7A not TH-D7A(G), is still on the 
market. After some tests with my TH-D7A(G), SPCL works the same way as 
explained on page 22, PG-4W manual.
SPCL in the TH-D7 is implemented only for some uncompressed APRS data 
formats.
You can filter out packets other than addressed to GPSxyz, SYMxyz and other 
then in Mic-E format.
In other words, setting SPCL in your TH-D7 you see all SPCL, all Mic-E, all 
GPSxyz, all SYMxyz. You filter out packets such as addressed to APRS, 
APU..., APT... etc. and are not compressed in Mic-E.
73!
Andy