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Message: 6
Date: Mon, 22 Oct 2007 10:43:50 +0100
From: Tom Rondeau <
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Subject: Re: [Discuss-gnuradio] benchmark_ofdm_rx not working
To: GNU Radio Discuss <address@hidden>
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Archana Ragothaman wrote:
> Hello,
>
> I am using two USRPs rev 4 and two RFX2400. I am basically trying to
> make the USRPs communicate with each other using the
> benchmark_ofdm_tx.py and benchmark_ofdm_rx.py scripts. The commands I
> am executing are
>
> ./benchmark_ofdm_tx.py -f2.4e9 -T A (at one USRP connected to laptop)
>
> ./benchmark_ofdm_rx.py -f2.4e9 -R A (at the other USRP connected to
> another laptop)
>
> The benchmark_ofdm_tx.py script is working as I can see the packet
> number displayed(I wrote a print pktno in the script)
>
> However the benchmark_ofdm_rx.py script does not give any output. I
> don't think the rx_callback function is being executed(as the packets
> are printed in that function).
>
> Can anyone please help me out and give suggestions as to what the
> problem could be?
>
> Thank you.
First, try running the benchmark_ofdm_tx on one side and tht usrp_fft to
display the received power at the receiver. What does this look like?
The problem is likely that you are not transmitting enough power. There
is a --tx-amplitude flag to adjust this. Set it to 2000 - 4000.
Tom
Hello,
I increased the amplitude to around 3000 on the tx usrp. I also ran the usrp_fft.py on the rx side. I could observe the spectrum of the rx signal which was around 30 dB. So I know that the rx side usrp is able to receive the packets trasnmitted. However, now when I run the benchmark_ofdm_rx.py script on the rx side, I do not see any output. The output that I get is
After rx_callback( ) definition
>>> gr_fir_ccf: using SSE
>>> gr_fir_fff: using SSE
INIT Completed Successfully!!!!
fg=usrp_graph(....) called (comment added for debugging)
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.
fg.start() (comment added for debugging)
Inside RX _Callback pktno (comment added for debugging)
ok: False pktno: 58626 n_rcvd: 1 n_right: 0
Only one packet is received after a long time. Could you suggest as to why the output is not displayed?
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