On 17/11/2022 10:23, Al Amiri, Wesam (waalamiri42) wrote:
Hello,
I am working on the implementation of OFDM TX and RX using USRP N210
and GNURadio.
I used the the grc flow graphs done by GNURadio workshops and I was
able to receive the OFDM signal and demodulate it.
Also, I connected a constellation sink to the Palyoad Stream Virtual
Source at the RX side (after demodulation), and I got 4 constellation
points which is corresponding
to the QPSK similar to the Tx cosntellation.
However, when I removed the Smidl and Cox synchronization to check the
phase rotation from the CFO (please see attached) , I still have the
same 4 constellation points without phase rotation. Do you know why
this happens?
You haven't described your physical setup, but if you have TX
looped-back to RX, there won't be any phase rotation since
the TX and RX are both phase-locked to the same master oscillator
on-board the N210. In "real-life" scenarios, of course,
there will be phase rotation between the TX and RX.
One more thing please, is there any way to extract a certain
subcarrier from the FFT at the receiver side. I need to do some post
processing on one of the subcarriers?
Regards,
Wesam Al Amiri
