Hi all,I've been trying to figure out the frequency offset of USRP recently. So I run the OFDM benchmark program and output the compensation value of fine offset.For detail,in benchmark.rx.py, we import ofdm_receiver,and ofdm_reciver import ofdm_sync_pn to calculate the fine offset and do time synchronization.The main procedure of ofdm_sync_pn(using Schmidl and Cox algorithm) is as following:
And I output the S/H(sample and hold) block to file sink block to record the fine offset.However,the result figure are as following:
X label can be regarded as time,Y label is the output fine offset by angle between -Pi to Pi.It is fiercely different from my expectation in which the figure should be a straight line approximately.I wonder why this happens.Thank you so much!