Dears,
I am working on the implementation of OFDM TX and RX using
GNURadio 3.10.3 and USRP N210 (with UHD_4.2.0). In the
implementation, I followed the GRC flow graph provided by GNU
Radio Workshop (Slides 259 - 260) with changing the carrier
frequency to 2 GHz, Sampling rate 1MHz at TX, and 10 MHz for
Rx.
The Tx USRP is connected to a Log Periodic antenna and similarly
for the Rx USRP. There is no LOS between the TX and Rx antennas.
They directed toward a reflective board so that the transmitted
signal will be reflected by the board and received by the
receiver. The implementation works fine, and I was able to
receive the OFDM signal by the RX USRP.
What I am trying to do is to extract some carriers from the
FFT bins at the demodulator to do phase measurements on each
one of the extracted carriers.
I tried to create my own block to do that, but that didn't work
and caused the GRC graph to freeze. Then, I tried to do that
offline using Matlab, where I attached the FFT block to a file
sink.
In Matlab, I plotted the absolute of I/Q samples of the file
sink as shown in the attached figure. But still, I am not able
to distinguish between the subcarriers.
Could anyone please give me advice how to extract certain
carriers from the FFT bins of the demodulator?
Regards,
Wesam Al Amiri
Without completely dissecting your flow-graph, if this were MY
problem, I might make an embedded Python block that allows me