On Thu, Jul 24, 2008 at 12:30 PM, Nikhil <[EMAIL PROTECTED]> wrote: > Are you trying to measure the impulse response of the channel? If so, then > one technique would be to transmit a known pseudo-random bit sequence (an > m-sequence) using BPSK modulation at the carrier frequency of interest. The > chip rate of the sequence determines the measurement system bandwidth, while > the sequence length determines the 'dynamic range' of the measurement. > > At the receiver set the LO to the same carrier frequency as that at the > transmitter. Here you need to cross-correlate the equivalent low-pass > received signal with the known m-sequence to give the (complex) impulse > response of the channel. Any 'peaks' that exceed your definition of a > threshold noise level would be your channel coefficients in the time domain.
This is actually implemented in gr-sounder. Unfortunately, the cross-correlation done on the very limited space FPGA has no frequency offset compensation, so the resulting impulse response vectors "roll" in the time domain. -- Johnathan Corgan Corgan Enterprises LLC http://corganenterprises.com/ _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
