In the clock recovery, the useful term in the output of the M&M error detector becomes small for long sequences of identical symbols. This affects the sampling instant, and I suspect is related to what you are seeing. You can modify the gain_mu value to get these and similar effects.
-TT On 8/13/07, Shyamnath <[EMAIL PROTECTED]> wrote: > > Hi guys, > I am trying to analyze the functionality of each of the blocks in the dbpsk > mod/demod when I noticed the following behavior. > > The high level modulator flow control is as | Symbols |-> | RRC filter | > -> |amplifier | -> channel > and that for the demodulator is channel -> | Pre-scaler| -> > |agc| -> |RRC | -> |clock recovery| -> |slicer| > > My understanding is that the real part of the output of the clock recovery > must be close to that of the symbols or some scaled version of it(+a, -a in > case of bpsk). > > However, my observations (in the link below) show that the output of the > clock recovery depends a lot on the bit pattern, i.e., for the bit pattern > 1010 the peaks of the 1s and the 0s are way smaller than those of the bit > pattern 1111110000. > > http://nms.csail.mit.edu/~gshyam/data/clock.pdf > > > Since we are using a RRC I would doubt it is due to ISI . and since the > radios are close to each other and there is a direct LOS I donot think this > is due to multi-path (or is it?). Is this behavior due to some component on > RFX 2400/USRP or something else? > > thanks > Shyam > -- > View this message in context: > http://www.nabble.com/Weird-Behavior-of-BPSK-on-RFX-2400-tf4264711.html#a12137123 > Sent from the GnuRadio mailing list archive at Nabble.com. > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
