[Tetra] TETRA / PI/4 DQPSK Modulator

Christian Daniel -- maintech GmbH cd at maintech.de
Wed Jan 12 23:01:34 UTC 2011


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Hi everybody,

I haven written (and ripped :-) a PI/4 DQPSK modulator, which should be
able to transmit TETRA bursts. For compilation have a look into the
Makefile.

It reads data from stdin and expects one byte for every symbol. The
value should be 0, 1, 2 or 3. 0xff results in silence.

The symbol rate is 250000/14 on USRP1 which is 17857 symbols/s. A more
or less simple demodulator should work without problems (perhaps with
more selfnoise), but a MLSE based RX will most probably not work.

For more "professional" uses we will need an accurate resampler, but I
will throw that one in as time comes :-)

Have fun,
Christian

- -- 
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| maintech #      Dipl. Inf (FH) Christian Daniel |
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| http://www.maintech.de           cd at maintech.de |
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