Hi, I am trying to use benchmark_ofdm_tx.py and benchmark_ofdm_rx.py to test the OFDM communication between two usrp nodes. While the transmitter is sending data, I use a sprctrum analyzer to observe the spectrum, and find the signal bandwidth far beyond my calculation, which is 330kHz around with the --fft-length/--occupied-tones=512/256. With my calculation, the sampling rate of DAC is 128Msamples/second, and each sample has 14bits, so the with the interpolation setting to default(256) the bandwidth of signal should be 128M*14/256=7MHz. Is that correct? If not could anyone tell me how to calculate in a right way?
Another problem is when I change the occupied-tones to 64, the bandwidth of signal will drop to 180kHz. I think the bandwidth of signal should be fixed to some bandwidth if you don't change the interpolation, and the occupied-tones should only affect the bandwidth of each sub-carrier. Is that a correct understanding? I also tried changing packet size, seemed it also affected the bandwidth of ofdm signal. I am really confused. By the way, the bandwidth I mentioned above with out specified are all null to null bandwidth. Thanks, Best regards, Yan _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
