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Re: [Discuss-gnuradio] need help for digital.constellation_decoder_cb in

From: Arturo Rinaldi
Subject: Re: [Discuss-gnuradio] need help for digital.constellation_decoder_cb in release 3.5.0
Date: Fri, 09 Mar 2012 04:19:43 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2

Nella citazione in data ven 09 dic 2011 05:55:57 CET, Ben Reynwar ha scritto:
On Thu, Dec 8, 2011 at 5:33 PM, Arturo Rinaldi<address@hidden>  wrote:
I noticed dramatic changes in the 3.5.0 release in the generation of the
constellation points of digital modulations. So, if the easy part is to
again modify the source code to match my needs, i need some help in using
the new block :


instead of


I usually used the last one where arg1 is a list containing the complex
values of a generic digital modulation and arg2 is the symbol mapping (Gray
Coding for instance). Which blocks do i need to put together to get the same
result ?

Regards, Arturo

Discuss-gnuradio mailing list

Simplest solution is probably:

constell = digital.digital_constellation(list_of_complex_points, [], 1, 1)
decoder = digital.constellation_decoder_cb(constell)

To get the symbol mapping you want, just choose the appropriate order
of the complex points in the list.

The 2nd, 3rd and 4th arguments to the constellation constructor while
not relevant to this example are:
  - a mapping to be applied before differential encoding.
  - the rotational-symmetry of the constellation
  - the dimensionality of the constellation (i.e. number of complex
points that together map to one symbol)

Functions to simplify the creation of commonly used constellations can
be found in digital.bpsk, digital.qpsk, digital.psk, and digital.qam.


i made some progress in simplyfing the creation of the constellations but i still need help in the decoding part.

I'm trying to calculate the modulation BER by using this flow graph :


i removed all the unnecessary parameters to my study (excess bw , differential coding etc.) because i need only gray coding. and the decoding part is this one


could you please help me ? the grc blocks are made by invoking only the psk_new.py source


modified by me. please help me. thx in advance

Regards, Arturo.

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