Archana Ragothaman wrote:
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?
Try decreasing the bandwidth by increasing the interpolation and
decimation rates (and make sure the decimation is half the interpolation
value you use). The OFDM system takes quite a lot of resources right now
to run, so slowing things down may help.
Unfortunately, the output you've displayed there isn't really showing
anything wrong except you're not getting any packets. There's little to
go on to help you debug it. Try to run in verbose mode (-v), which will
output all of the settings of the (de)modulator.
Tom
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