Hello, I'm currently trying to make your ofdm simulation work with two usrp rev4. The scripts benchmark_ofdm_tx.py and ...rx.py are modified in order to send (I looked on the examples in the directory "examples/python/digital/").
Decimation rate ist 160, interpolation rate 320. Frequency 2.4G, two Flex2400RF boards used. (Maybe my first faults lay here) I also recorded some seconds to a file so I can now replay the same scenario. The first thing I observe is that the synchronisation needs to know a value for the SNR. Fiddling around with that, the synchronizer starts the sampler even if no signal present (at high SNR-value), but no samples get through it if the value is lower than 8. The correlator block thinks to have found the known symbols sometimes in the noise. And, very confusing to me, the first ofdm symbol, after the correlation found a peak, is always the first known symbol - even in absence of a signal. The message "found at search delta..." appears very often, compared to your simulation. It looks like the following lines (I also edited some blocks to output debug info): found at search delta: 1, demod out: 38 e6 55 d1 21 93 6f d4 2b ea 3a e3 41 4f d2 9 bf f9 f5 16 73 45 9c a e2 len: 25 bin 1 h_sqrd = ( 37442.839844, 1714.728149 ) power = 42633.847656 real(h)/p = 0.878242 angle = 0.045764 This is repeated until I kill the process. There are also other outputs, with more "demod out" lines grouped together etc. e.g. the first lines after the gr_buffer warning bin 0 h_sqrd = ( 2.125927, 1.626051 ) power = 2.299746 real(h)/p = 0.924418 angle = 0.652948 found at search delta: 0, demod out: 38 e6 55 d1 21 93 6f d4 2b ea 3a e3 41 4f d2 9 bf f9 f5 16 73 45 9c a e2 len: 25 demod out: 18 3c 8d b3 e7 9 5b cf f4 d6 52 3d a0 d2 be 1a a8 9c 4a a7 a1 36 9a 85 19 len: 25 demod out: e9 9c 88 d9 c4 93 db c7 c6 9d 87 49 21 b1 3a 40 12 6f 27 30 de a5 c8 97 f2 len: 25 demod out: 7f a5 bb 14 54 b4 84 e5 e9 3f e9 9d f5 a5 44 54 0 fb 6 21 0 44 49 9f fa len: 25 Thank you very much in advance You did a great work on gnuradio!! Dominik _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
