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[aprssig] Did ICOM DSTAR ever take off ? can it be used for APRS ?

Gregg Wonderly gregg at wonderly.org
Tue Jun 21 13:50:09 UTC 2005


AE5PL Lists wrote:
> No, it is not "8 bit clean".  The radios use Xon/Xoff flow control and
> use CR/LF as line terminators for position reports.

Okay, that's unfortunate that it does that.  The devices that you would connect to the other end in text mode already do 
line termination.  I'm curious if its not the GPS's CR/LF that you are seeing.  The use of inband flow control is a 
problem as well.  They should have used out of band signaling.  Seems like the manufactures still haven't looked at the 
commercial RF network equipment such as that of FreeWave or others which provide an 8bit clean transport.

> While some clients do not support direct KISS interfaces, to my
> knowledge all do support TNC2 format interfaces.  It is actually much
> more compatible (and simpler to implement) if the clients think they are
> looking at a standard TNC2.

The problem is that this mode does not include a from call in the packet.  With KISS, the transported data is identified 
with a from call and a PATH so that it can be routed.

> Also, the D-Star radios don't allow RF routing as you describe.  In
> fact, there are no connections made with regards to this type of
> operation (broadcast, just like APRS was designed to use).

What I'm refering to is that in the KISS frame there is a 'source' device byte.  This can be used to allow multiple 
devices talk through a TNC.  Today, I am not aware of anyone using this.  But, what I would use it for is sending APRS 
vs GPS vs Weather packets through an 'APRS box' to a computer application that would then process the data correctly.

In the case of the DSTAR system, it could be used to select alternate processing by the software on the receive side of 
the DSTAR link.  In particular, it could be used to say "just send this to RF" instead of "read my path and do what it 
says".

I am thinking that this would be a form of DSTAR digipeating.  Everyone in an area could use DSTAR radios instead of 
radio + TNC to do APRS by hooking up their GPS through a little PIC assistance device that wrapped the data into a KISS 
frame (like the HAMHud does).

But, if it is not 8-bit clean, then KISS is not a choice and thus everyone can't share a single DSTAR receive site as a 
digipeater/translator.

Gregg Wonderly
W5GGW




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