[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: AO16/LO19 Traknet Operational!



    MANCHESTER TNC*:  Although any Satellite TNC/Modem can be used, 99% of
    most mobile operators would be left out.  BUT as I pointed out in the
    original Traknet Paper, ANY TAPR-2 TNC CLONE can generate Manchester
    with the simple addition of an 89 cent XOR gate and a switch.  THus,
    almost anyone can transmit from his mobile 2m FM rig...  For details
    see my TRAKNET.TXT in any of the APRSdos docs, or AMSAT Journal, or visit

       http://web.usna.navy.mil/~bruninga/traknet.html

I'm still trying to figure out how to receive 1200 PSK, but i've gone
through and carefully commented the 1200 AFSK 'soundmodem' code for
LINUX and am ready to make a similar mod in software.  However, my 1992
ARRL Handbook disappeared and its recent replacement while providing
good overviews of a wider range of topics, often no longer contains
information necessary for implementation by those not already familiar
with a topic.  *Sigh*  That may be appropriate given a marked decrease in
homebrewing and an increase in 'appliance operators', but also tends to
perpetuate the comparative lack of innovative work by amateurs.  For
example, i have neither the interest (nor the money right now) to go out
and purchase the relevant books on communication theory containing the
information in previous handbooks.

So, let's see if i remember this coding correctly.  Is this the scheme that
has a transition at every bit cell boundary, and another in the middle of
the bit cell if the signal is a '1'?

         _________                    ________           __________________
 Data   |         |__________________|        |_________|                  |_


         ____      ________           ____     _________      ___      ____
 Signal |    |____|        |_________|    |___|         |____|   |____|    |_


which is self-clocking (as opposed to the scheme which has a transition at
the beginning  of a bit cell if it's a '1' and not if it's a '0', which is
not self-clocking).

So, does that represent what your inexpensive mod to certain existing TNCs
do?
                             -- KD6PAG  (Networking Old-Timer, "RF newbie")
----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home