D700 Head protocol


Bob
 

Has anyone figured out the protocol between the radio and the head?

My idea was to use a D700 body and plug in a custom interface that I could emulate the control head.  I am aware I can control the radio via serial port but I do not want to use that and I do not want to use the D700 Head.  Think of it as a "Software Defined" type of radio.

Thanks
boB - W5EVH



Brian Beuershausen
 

I've thought about it, but haven't pursued it just yet.  My thought experiment originated with wanting to put the radio at the top of a tower and the head in the shack for maximum ERP with no coax cost.  For that, you just need suitable digital line drivers & receivers between the rig & the head (and power, of course).  The downside is that it would expose the rig to temperature swings & potential water ingress.  And since I don't have a tower, well . . .

But that doesn't really get to your question.  I think the real fun & reward of such a project would be the very process of reverse-engineering the protocol.  It's a bit beyond me for now, but I doubt that it's super duper rocket surgery.  With the rig on the bench, you could monitor the data lines with a logic analyzer.

The serial protocol (RS-232 side) is well documented and I am 99% certain that same protocol is used for control signals in the head's data link, but also with the digital audio stream (2 speaker channels + a mic channel) either multiplexed in or packetized among the control signals.

The head protocol could theoretically be packetized over ethernet and therefore handled through a LAN or the internet.  That would let you create multiple endpoints for the speaker audio too.

Sounds like fertile ground for endless fun!  If I ever get a logic analyzer (I've been agonizing over the selection process for over a year now), I'll give it a shot.  But if you make any progress, please be sure to share!

-- Brian / KB5EO


David Ranch
 


Hello Bob,

 

Has anyone figured out the protocol between the radio and the head?

My idea was to use a D700 body and plug in a custom interface that I could emulate the control head.  I am aware I can control the radio via serial port but I do not want to use that and I do not want to use the D700 Head.  Think of it as a "Software Defined" type of radio.


I'm aware of a one project that figured out aspects of the D700:

   - W2FS Keyboard interface for Kenwood Tm-d700a : (EOLed) - www.rhuss.cncfamily.com/D700_Manual.pdf

   - There is also the Remote Rig system - http://www.remoterig.com/wp/?page_id=362 - but I don't know if those devices really understand the protocol itself or if they just blindly shovel bits around (I suspect the later)

As for the display control and what not, I haven't seen anything.

--David
KI6ZHD


agcme2002
 

The keyboard interface actually plugged into the microphone jack.  It emulated the button presses of the DTMF keypad using the T9 based entry system like standard cell phones (press 2 repeatedly for A, B, C and 2; 3 for D, E, F and 3; etc.)

The Remote Rig does not analyze the protocol, it simply echos the data from one side to the other.  It still requires an actual head installed on the other end.

The display itself is using a 115,200 baud serial communication but from the schematic it is depending on the processor in the head to receive data and turn that into a rendering of pixels on the display.


agcme2002
 

The serial protocol for the body isn't the same as the head (different baud rates to start) but there's also no audio over the head cable.  The speaker is independent (in the body) and the microphone comes in via an analog connection on the microphone port.

It's possible to reverse engineer the protocol with some careful monitoring and control (for example, changing the frequency by one step to see how the frequency is transmitted back to the head to update the display) but I don't think many people have bothered because the equivalent data was always available via the body mounted serial port using the Kenwood CAT protocol.