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RE:DSP-2232 and 400 baud TLM



Hi,

I haven't gotten P3T working yet, but I have gotten 3 e-mails from people
puzzling how to set the DSP-2232 up for 400 baud TLM.  The manual is
sometimes obscure, so here is my recipe:

The DSP-2232 does, after a fashion, decodes the 400 baud TLM.  It does it
from the DSP mode, using modem 44.  In order to get the unit to set up for
400 baud TLM, from your terminal program type DSP<CR>.  The LCD should say
"Loading Modem 44" and then show "DSPdat."  (It normally loads the correct
modem, 44, when you switch to DSP, but you can also load it with the normal
Modem 44 command if for some reasons it doesn't.)  The terminal will say
something like "Opmode was xyz, Opmode now DSPdata."

That's it!  The unit buffers the data and outputs it at the terminal TBAUD
baud rate.  Now select USB and tune in the signal by ear/meter.  There
should be a single light bar in the PORT 1 LCD, somewhere near the center.
Tune the radio, slowly, to center the bar.  Note that the LCD seems to be
updated every few seconds, so change the tuning and wait for a response.
Anywhere near the center, and you should be "printing" to your terminal
program.

This much will get you the ASCII strings in the message blocks.  There will
be a lot of non-printing control characters, etc.  You may, depending on
your program, be able to capture the data as 8 bit characters to a data
file.

That is as far as I have gotten.  Note that the DSP-2232 currently only
handles 512 bytes, not the current 514 bytes, including the 2 CRC blocks.
Someone is looking into modifying the modem code for this, but that is for
the future.  Also, a real G3RUH TLM modem generates a hardware handshake to
synchronize the data.  The DSP-2232 does not.  Any display software needs to
do the synchronization from the data stream.  (Does P3T do this?)


Hope this helps get people started.

Alan
WA4SCA


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