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

[kb2scs at optonline.net]

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
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