I am trying to use benchmark_ofdm_tx.py and benchmark_ofdm_rx.py to test
OFDM communication between two usrp nodes.
While the transmitter is sending data, I use a sprctrum analyzer to
the spectrum, and find the signal bandwidth far beyond my calculation,
is 330kHz around with the --fft-length/–occupied-tones=512/256. With my
calculation, the sampling rate of DAC is 128Msamples/second, and each
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
anyone tell me how to calculate in a right way?
Another problem is when I change the occupied-tones to 64, the bandwidth
signal will drop to 180kHz. I think the bandwidth of signal should be
some bandwidth if you don’t change the interpolation, and the
should only affect the bandwidth of each sub-carrier. Is that a correct
I also tried changing packet size, seemed it also affected the bandwidth
ofdm signal. I am really confused.
By the way, the bandwidth I mentioned above with out specified are all