Re: [Discuss-gnuradio] benchmark_ofdm_rx not working

[Kyle Jamieson]

Tom, Matt, Robert, and others,

Thanks for the OFDM implementation; it looks very cool.

Unfortunately I'm having the same problems running
gnuradio-examples/python/ofdm/benchmark_ofdm_rx.py from the svn trunk.
I've attached a screenshot of benchmark_ofdm_tx.py as seen from
usrp_fft, and it looks reasonable.

My commmand lines:
./benchmark_ofdm_rx.py -v -R A -f 2.5e9
./benchmark_ofdm_tx.py -v -T A -f 2.5e9 --tx-amplitude=1000

(have also tried --tx-amplitude=10,100,500,2000,4000, and played with
--rx-gain at the receiver, and tried -f 2.45, -f 2.4 at both.)

USRPs Rev. 4.2 (circa 2006).  I've tried both FLEX2400 and RFX2400/Rev
30 daughterboards.  My transmitter and receiver are two feet away from
each other.

Program output:

$ ./benchmark_ofdm_rx.py -v -R A -f 2.5e9
>>> gr_fir_ccf: using SSE
>>> gr_fir_fff: using SSE

OFDM Demodulator:
Modulation Type: bpsk
FFT length:      512
Occupied Tones:  200
CP length:       128
Warning: failed to enable realtime scheduling
gr_buffer::allocate_buffer: warning: tried to allocate
   20 items of size 1600. Due to alignment requirements
   64 were allocated.  If this isn't OK, consider padding
   your structure to a power-of-two bytes.
   On this platform, our allocation granularity is 4096 bytes.

----

Any pointers or suggestions why this isn't working would be much
appreciated.  Which daughterboards were used to develop/debug this?

Kyle Jamieson

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