hey, I am triying to implement a BPSK link between two USRPs. I had a look to the bench mark code and I tried to implement such a modulator and demodulator except removing differential blocks in both RX and TX. the tx and rx chains are as below : TX :message_from_string->bytes2chunks->symbol_mapper->chunks2symbols->rrc_filter->amlifier->USRP RX : USRP->pre_scaler->AGC->rrc_filter->rec_clock_recovery->Channel_estimator&equaliser->slicer->symbol_mapper->unpack->access_code_correlator->framer_sink I have written a signal processing block which estimates the channel(by correlating the received signal points by access code and estimating based on access code). my problem is I can not receive properly, so, I don't have data in sink_file. first I thought it can be due to SPB, so, I modified the RX above into a two parallel receivers which get the input signal from the same USRP, I mean, I removed the SPB that I had written and 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 works based on sign of real part of signal) one of the chains will detect the data but still nothing in the output. now i am really confused what can be the problem of the communication chain I am trying to implement. any hint is appreciated, Mehdi -- View this message in context: http://www.nabble.com/BPSK-modulatio-tp20531949p20... Sent from the GnuRadio mailing list archive at Nabble.com.
on 2008-11-17 02:25