Hi All, (this might be a duplicate e-mail -- if so, sorry everyone!)
I am trying to generate on-off traffic patterns with high timing accuracy, so I decided to use the tx_timed_samples and tx_bursts examples to do so. To start, I tried to understand the examples by using tx_bursts to send constant samples of 0.3+0.3j to the USRP_A to send across a wire to another USRP_B. Then, I used rx_samples_to_file on the receiver end to pick up the signal and store it into a .dat file using type "short." Lastly, I used the following guide to import the samples into matlab using the read_short_binary and split_vect functions provided in gnuradio/gnuradio-core/src/utils/:
After I did that, I combined the two columns from the output after split_vect to make a complex number. I then plotted the magnitude of the samples because all I care about is to see if there is a signal or not. Although that came out successful, I am running into these spikes of high sample magnitudes separated by the size of the samples per buffer (spb or samps_per_buff) which is automatically set to 363 samples (to fit
in one ipv4 packet I presume). A picture of it can be seen by following the link below:
You can see the magnitude hovers over 30 which is good (noise hovers around 5). But, as you can see, there are two spikes with suppressed samples around it. These are exactly spaced 363 samples apart (this changes as I change the samples per buffer at the transmitter). Does anyone have an idea where this is coming from? I'm running out of ideas of where to look to figure out the problem. Any ideas
of what I can do to remove it (even manually)?
Regards,
Jason T.