And if you are running over the air, try setting the TX and RX sampling rate to have the same value.
In any case, I would first run in loopback mode (as shown in your png file) and save the over-the-air transmissions for later. On Tue, Mar 18, 2014 at 7:51 PM, Aditya Dhananjay <adi...@cs.nyu.edu> wrote: > Hi Jon, > > Disclaimer: I haven't run your code, but based on eyeballing the png file: > > It looks like your "delay" block is not configured properly. The delay > should be fft_len + cp_len which is 80 (instead of 72). > > Best, > Aditya > > > > On Tue, Mar 18, 2014 at 7:25 PM, Jonathan Fox > <31...@cardinalmail.cua.edu>wrote: > >> So I have the stock python scripts (tx_ofdm and rx_ofdm) located in the >> gr-digital examples and put USRP sources and sinks in the appropriate >> spots. I left sampling alone (100K for TX, 3.2M for RX) and had the TX/RX >> frequency at 500 MHz. The USRPs used are N210s with WBX daughterboards. I >> tested the USRP used for TX out by outputting a signal to another and >> looking at it on the GNU Radio spectrum analyzer. Also, this is through SMA >> cables and a 30 dB attenuator, no over the air transmission. I placed file >> sinks after each block in the process; each file is a binary file. After >> multiple runs I felt like something wasn't working after looking at the >> binary files. >> >> When I execute, only the file sinks placed after the Schmidl & Cox OFDM >> Synchronizer freq_offset and detect have data in them, at least their files >> have some size to them, implying something has been written. The file sinks >> after FFT (or the header/payload demux) have no data, 0 KB. >> >> When I discovered that the receive didn't work, I took the grc file >> another user made back in October with both TX mod and RX demod in the same >> flowgraph to see if that would work (files attached). Again same issue, all >> the binary files after the FFT have no data so something is getting screwed >> up in my demod. >> >> Has any user on this list run into this issue before or can offer some >> insight to why the receiver is failing? >> >> Thank you, >> >> Jon >> >> Attached is the python script, grc file, and screen shot of the TXRX >> combo in GRC. >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >
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