The TS2000 has inbuilt AX.25 support. However, is it possible to use the TNC in a "transparent" mode so that I can view the on-air data without any decoding?

Upon basic searching, I came up with this page (http://www.waterfunrental.com/K0SWI/REVIEW/KW/KW_TS2000/KENWOOD%202000%20ALL%20MODELS%20COMMENTS.htm) which says that TS2000 does not support a "transparent" mode. Is it possible to see the on-air data in some other way?

EDIT: The real purpose is to try creating my own protocol and hence transmitting and receiving raw binary data. - My protocol does not use HDLC flags so I need the direct decoding of AFSK to binary and vice-a-versa.

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    $\begingroup$ When you say “without any decoding”, do you mean you want the analog AFSK signal, the bits of the AX.25 frame, or just the complete packet contents in any format as long as no information is lost? $\endgroup$
    – Kevin Reid AG6YO
    Jun 2, 2015 at 18:18
  • $\begingroup$ @KevinReidAG6YO want the direct binary conversion of the analog AFSK i.e. the result of g3ruh_scramble(nrzi_encode(0x7E ... frame ... 0x7E)) $\endgroup$
    – user80551
    Jun 2, 2015 at 18:45
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    $\begingroup$ Thanks for the clarification. I'm not familiar with the TS2000, but I'd suggest it'd overall be easier (and more reusable with different hardware) by putting the radio in FM mode and doing the AFSK demodulation in software. $\endgroup$
    – Kevin Reid AG6YO
    Jun 2, 2015 at 18:54
  • $\begingroup$ What @KevinReidAG6YO said. What you're looking for is software defined radio, not a radio with fixed demodulator to which you can find software... AFSK is a terrible choice, to be honest, if you actually want to communicate data. $\endgroup$ Jun 9, 2016 at 20:42

1 Answer 1


As noted in your linked article:

All is not lost, though, as there are two viable workaround solutions. The internal TNC does support KISS mode so all you need is a packet program that supports KISS (many packet programs do) and let the packet program handle the chore for you. This is by far the simplest and least painfull way of working around the limitations of the internal TNC.

When using KISS mode, the AFSK modem should send whatever you put into the KISS frame. There are command codes which must be escaped in the KISS wrapping function of your program, but it is quite simple and I would be happy to supply you with some skeleton Java code which is easily decipherable.

Once you send the KISS frame from your program to the AFSK modem which operates in KISS mode, it will send the HDLC across the link. Essentially, you will get a stream of bytes to deal with on the receive side. The receive modem in KISS mode sends those bytes to the controlling program in a KISS wrapper. So your limitations are few when using KISS and KISS enabled AFSK modems.

Note also that there are OTHER CODECs out there beside plain old Ma Bell AFSK used in typical packet. UZ7HO's sound modem makes use of another handful of CODECs, and provides a KISS mode via TCP port which is very convenient for programming. Similarly, the Direwolf packet modem provides a KISS TCP port as well. FLDIGI even has some limited support for KISS with many of it's modem CODECs.


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