Circuit for a basic TNC (terminal node controller)
Hunter Sinclair
to find a circuit diagram or "how to build" a basic TNC.
I initially just want some basic functionality like send and receive
packets of text based data.
I have used my sound card and software on my machine to play around
with packet radio for a little bit and I would now like to build my
own device.
So I am looking for something that I can build to plug into my radio
that will do all the encoding/decoding of data for sending and
recieving. I would like it to either spit out the text data to either
a LCD or temporarily a computer/dumb terminal.
Please let me know if you have any information on this.
Thanks,
Hunter
Michael Black
Are we talking amateur radio packet? http://www.tapr.org
is the source of the most common ham TNC, and you used
to be able to buy a schematic (and software) from them.
By now, it might even be available online.
Their original TNC, the one that used a 6809, was described
in 73 magazine in the mid-eighties, but I don't have a specific
date and it used more obscure parts compared to their TNC II
which used a Z80.
I think Ham Radio might have run a schematic years ago.
For some strange reason, they never seemed to publish a
schematic in the ARRL Handbook.
Of course, the concept of a standalone TNC dates back 25 years,
at a time when few had computers and what they had might be limited.
It was easier to build a whole separate but limited computer, than
to write software for a bunch of computers and having to build USART
boards for all of them too.
More recently, that has been less need. Even before computers got
to the point where soundcards were used for the modem, there were
people adding USARTS to their computers (since many computers did
not have the synchronous feature, though MACs did) and doing the
rest in software. I don't have any pointers, but that's another
possibility at this point. If you scrounge up an old computer as
a terminal, likely you can scrounge one up that is good enough
to handle the TNC function.
Michael