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Re: [Discuss-gnuradio] Problem in using trellis Error, correction en- an
Re: [Discuss-gnuradio] Problem in using trellis Error, correction en- and decoder
Fri, 5 Nov 2010 20:39:56 -0300
in the past Achilleas wrote:-------1) the trellis encoder outputs unpacked bytes. For example, if your FSM
has output cardinality 4 then it outputs 2 useful bits per byte.
There are a couple of potential problems with your flowgraph:
Are you sure you are handling this the right way at the packet encoder?2) You need to substitute the "trellis viterbi" by the "trellis viterbi
combo" block and input as parameters the kind of "distance" metric you
want and the corresponding constellation, etc. To do that you need to
know what is the output of the packet decoder...
I do not know how that block works but you should check it.
however, the main problem is the following
I have never worked with packet en/decoder so i cannot help with these.well, I first want to thank you, because it success. (The problem is solved).
-------------end of quote.
I did simplify the example: a source, a trellis and a viterbi combo.
Next, change the types for bytes.
Next use 'packed to unpacked' in the head.and 'unpacked to packed' in the tail of the flow.
i test with noise source the trellis, trellis-D8psk and trellis-DBPSK.
trellis-DBPSK in noise is better than trellis in noise .
but trellis in noise is better than trellis-D8psk in noise.
DBPSK Hamming distance=2.
trellis Hamming distance=sqrt(2).
the snapshot...where are the snapshot?
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Francisco Llaryora <=