Forum: GNU Radio gr_trellis for DQPSK ISI channel equalization

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unknown (Guest)
on 2007-06-15 15:50
(Received via mailing list)

I am new at dsp and I hope that I do not bother you which a
stupid question:

I want to use the gr_trellis block as an ISI equalizier for a
burst type (pi/4)-DQPSK system. Therefore I have two questions:

1) I think that I know how I have to expand the fsm_utils.
make_isi_lookup() function to deal with PSK and how to expand
the function for this two-dimensional case.

But where and how do I have to consider that in DQPSK not every
symbol transition is possible (depending on the current state) ?

2) Due to the burst structure of the signals I have 10 known
bits (= 5 known symbols) at the beginning and at the end of each

Where and how do I have to consider that ? I see only a beginning
and an end state that could be specified.

Any hints are appreciated.

Thank you very much in advance.

Best regards,
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