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[Discuss-gnuradio] gr_trellis for DQPSK ISI channel equalization

From: fjans
Subject: [Discuss-gnuradio] gr_trellis for DQPSK ISI channel equalization
Date: Fri, 15 Jun 2007 13:49:49 +0200


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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