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[aprssig] TS-2000 TNC Question

Steve Noskowicz noskosteve at yahoo.com
Fri Dec 3 07:08:47 UTC 2010


 
 
The following was on the Yahoo TS-2000 Group.  Can anyone comment/correct?
 
I only kjnow that the Tasco has no/insufficient buffering and no flow control.
Yea, I know this a Packet issue, but I know there are several of you who know.
73, Steve
 
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 I hope the programming behind the chip in the TS2000 is better than in the D700.

The TM-D700A TNC doesn't properly implement the AX.25 Ver 2 protocol and
Kenwood doesn't plan to provide a fix. It will not acknowledge packets
received in the connected state unless the poll bit is set. That means you
send a packet to it (over the air) which is received, but not
acknowledged. The sending TNC then gets tired of waiting for an
acknowledgement and "inquires" whether the TM-D700A got the earlier packet by
sending an inquiry frame with the poll bit set. The TM-D700A will only then
acknowledge the previously received packet as properly received. For this
reason it isn't a good choice for widespread use on a crowded packet network
because that behavior slows thruput considerably. But then there aren't too
many crowded packet networks these days. It's not a problem for APRS since
that's all UNPROTO (unconnected) packets that don't require acknowledgement.

73 de Jim, KB3PU

 
 
 


      
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