On 10/27/2010 02:11 PM, Hongliang Zhang wrote: > Hi everyone, > > I made a test for UHD blocks today, and I found a problem as follows: > > I take two USRP2 boards for my test. One is used as transmiter and the other > board is set to be receiver.And I use UHD Simple Sink and UHD Simple Source > blocks for transmiting and receiving respectively. > > sampling frequency = 195.312K (which is the minimum sampling frequncy of the > system). > gain=0 > The transmitted signal is a AM modulated sine signal. > The frequency of orignal sine wave (the message signal) is 10K Hz. > The frequency of carrier signal (center frequency for modulation at > transmitter board) is 2.42 GHz, and I use the same frequency at the receiver > board for demodulation. > Amplitude of transmitted signal is 0.05. > > I connect the two boards together, and I add a scope to observe the period > of the received demodulated signal. The problem is the period is about > 0.000045, which means the frequency of the signal I received is not 10 KHz, > but about 2.2 KHz. > > I have used the same external reference clock and PPS signal for both of the > boards, so I think they are set up correctly. Why do I get a received signal > with different frequency from what I transmit? > > Does anyone meet the similar problem before? How may I solve the problem? > > Thanks so much for every help and suggestions in advance. > > Best regards, > Hongliang > > > > What daughterboards are you using?
Can you share your (GRC) flow-graphs with us--makes it easier to spot problems. I hope that you're using an attenuator between the transmitter side and receiver side. My guess is that there's a sample-rate issue somewhere on the receive side, like the scope sink hasn't been told the correct sample rate, so it's displaying incorrectly, etc. -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
