[Discuss-gnuradio] OFDM benchmark transmit signal bandwidth

[Guanbo Zheng]

Hi all

I am currently using OFDM benchmark to generate OFDM signal under the setting of FFT len, CP length, occupied-tones and something.
But I can not find out what is the real bandwidth of signal it generated. 
Because when I changed the Interpolation rate (sampling rate), the bandwidth at RX changed as well.
Ideally we know that setting enough large sampling rate ( In USRP2, the max fs = 25MHz), I should observe the constant signal with fixed BW. 
It seems to me that BW of the generated signal is too large.

My question is: how to determine the BW of transmit signal in the codes? where I can change it.
All I found is actual bit rate =  (converter_) / xrate / samples_per_symbol = 100MHz/4/2. But this one seems not related to the BW of signal itself.

Thanks for any suggestions!
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Regards,
Guanbo