Forum: GNU Radio BPSK modulatio

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9bf620728a30576ba2245d117c7cb8fb?d=identicon&s=25 mehdimolu (Guest)
on 2008-11-17 01:25
(Received via mailing list)
I am triying to implement a BPSK link between two USRPs. I had a look to
bench mark code and I tried to implement such a modulator and
except removing differential blocks in both RX and TX. the tx and rx
are as below :

RX  :

I have written a signal processing block which estimates the channel(by
correlating the received signal points by access code and estimating
on access code).
my problem is I can not receive properly, so, I don't have data in
first I thought it can be due to SPB, so,
I modified the RX above into a two parallel receivers which get the
signal from the same USRP, I mean, I removed the SPB that I had written

1-in the first chain I multiplied output of USRP_source by ( 1 )
2- in the second chain I multiplied output of USRP_source by ( -1 )

and the rest of receivers for both paths are the same as mentioned
above(again, I have removed SPBs in both receiving paths)
 I was thinking no matter what is the channel effect(BPSK modulation
based on sign of real part of signal) one of the chains will detect the
but still nothing in the output.
now i am really confused what can be the problem of the communication
I am trying to implement.

any hint is appreciated,
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