Dbpsk demodulation

GNU Radio
1

Hey,

  Apologies if this is a duplicate but i found this is my drafts

while
i thought i got delivered.

  I having been trying to debug my demodulator for a few days now

and
in due process i receive the following error message.

ValueError: itemsize mismatch : dbpsk_demod(5):0 using 1, sub_ff(15):0
using 4.

Now there are two things that i observed.

  1. With the connect statement of these two at hand , sub_ff is expecting
    4
    float bytes which is only connected to “1 byte/sample” output by the
    dbpsk_demod block.

  2. The output of the dbpsk_demod block (according to the line – >
    io_sig_out = gr.io_signature(1,1,gr.sizeof_char) … so its a
    dbpsk_demod_complex->character conversion where as the sub_ff is a
    "float
    –> float " .

My question is will a custom “gr_dbpsk_demod_cf” with a cosine
function(that possibly uses a certain kind of cosine table) be useful to
do
the following :

  1. keep the constellation in check (i.e 1 bit/symbol) at 0 and 180
    degrees
    respectively.
  2. ofcourse convert a complex to float.
  3. How effective would such a cpp block be as opposed to a full fledged
    python block ?

Thanks & regards,
Anay.

2

On Thu, Feb 9, 2012 at 12:47 PM, anay tuljapurkar <
[email protected]> wrote:

My question is will a custom “gr_dbpsk_demod_cf” with a cosine
Anay.

Anay,
It’s not clear what you really want to do here. If you want to work on
the
samples as floats, you could probably just edit the Python hier_block2
file
for what you want (or create a duplicate for your needs).

Tom