On 03/19/2014 12:25 AM, Jonathan Fox 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.
Maybe you're probably screwing up your tx signal by clipping, although I can't say for sure from your flow graphs (where exactly do you put the UHD sink?) See http://video.fosdem.org/2014/AW1125/Sunday/Tutorial_OFDM_Packet_Transceivers.webm, starting around ~27 mins for an explanation, or search the mailing list archive. Martin > > 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 > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
