[aprssig] Possible auto-reply bug in the Kenwood TM-D700 and/or TM-D710

Guido Trentalancia iz6rdb at trentalancia.com
Sat Jul 23 17:27:08 EDT 2011

On Sat, 2011-07-23 at 22:28 +0200, la3qma at aprs.la wrote:
> >> I can check the TM-D700 tomorrow if no one else is testing this before me.
> >
> > I think it's pointless to do that. It should be a TM-D710 because
> > sometimes it is identified by aprs.fi as "TM-D710" and other times as
> > "TM-D700 version 02", exactly as my TM-D710. See my second message about
> > this...
> Check the raw data. If the last character is a "=" then it's a TM-D710
> Both TM-D700 and TM-D710 use APK102 so that the TM-D700 is identifying  
> a TM-D710 as a TM-D700 to be backward compatible. So the "=" is used  
> to identify it as an TM-D710.

The last character of the whole packet is "=" when the format is
compressed. When it's not compressed (i.e. is using "APK102"), the last
character is part of the payload (for example, it is the last character
of the comment field or the last character of any other APRS field).

Otherwise, people would get the "=" in the comment text as well....

So, it should be a TM-D710 for sure, because all compressed packets end
with "=".

> > It's not just sending back an ACK. It's sending back a full
> > pre-determined text message similar to "I am not available now, i will
> > call you later".
> I have tested from two of my TM-D710 and no one is sending the  
> autoreply to either bulletin or messagegroup.
> Using the latest firmware.

Could it be that such station is using a previous version of the
firmware (not everybody does carry out updates) ? Can you tell for sure
that no previously released firmware version has ever suffered such
problem ?

> > Because it identifies as TM-D710 (e.g. "APK102" and see also above), it
> > shouldn't be APRS packets generated by an external software, but rather
> > APRS packets generated by the APRS mode of the Kenwood transceiver
> > itself.
> >
> > Of course, it could still be that the user is generating the APRS
> > packets with a computer and using the "APK102" string instead of using
> > something else which is unique, but that's very unlikely !
> I have seen more strange things ;o) so i would not bet on that people  
> have not changed it to APK102

I really doubt that station is using packets generated with a computer.
Most likely those packets have been generated by the APRS functions of
the Kenwood itself...

It seems it's replying to bulletins from other stations too. Just before
sending out the predefined text, it is sending a "rejX" (should be for
rejection of message X, i.e. some sort of negative acknowledgement). I
am not sending out any message at all.

> Kai Gunter



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