________________________________
From: Jason Uher <jasonu...@gmail.com>
To: discuss-gnuradio@gnu.org; david.barto...@yahoo.com
Sent: Thu, April 22, 2010 7:51:41 AM
Subject: Re: [Discuss-gnuradio] DPSK Modulator and Demodulator
Thanks Jason. I have not delved into the code of the dbpsk demodulator
GRC block yet so I am unsure. I was hoping someone with experience using this
GRC block could answer quicker.
I believe the block has a root raised cosine filter in it so it would make
sense that it would have zeros to start but I am not sure why I get 13 bytes of
output data back from 2 bytes of input data.
Thanks,
Dave
>>> Hi,
>>>
>>> I am having trouble the the DBPSK mod and demod blocks. My flow graph is:
>>> file source -> DBPSKmod -> DBPSKdemod -> file sink
>>>
>>> If anyone knows why the output file of the whole graph would be 13 bytes
>>> or if I am missing something please let me know.
>>>
>>> Thanks,
>>> Dave
On Wed, Apr 21, 2010 at 9:46 PM, marcin_w <mwie9...@uni.sydney.edu.au> wrote:
>
> My mistake, i didn't realise you were using the available DBPSK block. The
> Packed to Unpacked block is already part of this Modulator, so disregard my
> comment.
Does the bpsk block you're using have some form of timing correction
in it? More than likely the data is being run through some sort of
filter (either explicitly or effectively) and the zeros at the
beginning are a warm up from the padding.
If you'd like the output to be 'nice' from a mathematical point of
view you will have to deconstruct the mod/demod blocks a little bit
and remove the timing correction stages and make sure that your
simulated channel does not introduce any timing corrections.
Jason
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