[aprssig] Fill-in Digis

Tim Cunningham tim_cunningham at mindspring.com
Sat Mar 25 10:05:12 CST 2006

When selecting a packet controller to work as a packet decoder on our local 
voice repeater, I found the add-on TRUE-DCD board worked rather poorly with 
voice audio and it could not be utilized in muting the audio on the output 
of the repeater. This add-on board falsely triggered the mute control line 
to the point that it was very annoying to listen to a conversation on the 
output of the voice repeater. We then went to a Kantronics KPC-9612+ and it 
worked acceptably well. The add-on board for the TNC 2 clones may be 
adequate to work with open squelch radio outputs, but they are far inferior 
when using the DCD signal to mute audio on a voice repeater to prevent the 
packet data from being heard on the output of the voice repeater.

The point is that the DCD decoding works much differently on the TNC2 add-on 
(hardware decoding) versus the KPC (firmware decoding) units.


Tim - N8DEU
Huntsville, Alabama

----- Original Message ----- 
From: "Robert Bruninga" <bruninga at usna.edu>
To: <aprssig at lists.tapr.org>
Sent: Saturday, March 25, 2006 9:44 AM
Subject: Re: [aprssig] Fill-in Digis

>>I would assume that all schemes wait until end
>>of DCD and DCD works on valid bytes, not just
>>flag bytes...
>A true DCD detect tones not bytes, we are talking
>level 1 here, bytes  have no meaning, that is level 2.

I donno...  I am thinking of the Kantronics software
DCD and the add-on true-DCD chips for the TAPR
2 clones.  I thought they were looking for valid bit
transitions in the right places, not just tones.  I am
certain they are not just tone detectors.


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