and this is the fft scope WITH TX (benchmark_tx.py -f 450e6 -A TX/RX)
as you can see, gain increased when TX is turned on.
However, it seems that benchmark_rx.py cannot catch those signals.
benchmark_rx.py -f 450e6 -A TX/RX
======================================================
linux; GNU C++ version 4.4.5; Boost_104200; UHD_003.004.000-eb11b05
>>> gr_fir_ccf: using 3DNow!
-- Opening a USRP1 device...
-- Loading FPGA image: /usr/local/share/uhd/images/usrp1_fpga.rbf... done
-- Using FPGA clock rate of 64.000000MHz...
No gain specified.
Setting gain to 25.750000 (from [0.000000, 51.500000])
UHD Warning:
The hardware does not support the requested RX sample rate:
Target sample rate: 0.050000 MSps
Actual sample rate: 0.250000 MSps
Symbol Rate: 25000.000000
Requested sps: 2.000000
Given sample rate: 250000.000000
Actual sps for rate: 10.000000
Requested sample rate: 50000.000000
Actual sample rate: 250000.000000
======================================================
it stops here and prints *NOTHING* whenever I set tx-gain and rx-gain with about 30 dB and 50 dB.
My assumption is that a demodulator does not consider signals as data.
Rather than, they are considered as noise whose signal strength is too weak compared to a certain threshold
which distinguish meaningful data and noise
Is my assumption is right?
Still I am curious because this situation occurs with very high tx-gain and rx-gain, also.
2011/11/19 Songsong Gee <address@hidden>:
> I'm currently testing UHD.
> I use two USRPs with one SBX on each.
> and I got GNU Radio 3.5.0rc0 on Ubuntu 10.10 and benchmark programs
> supporting UHD.
>
> When I run benchmark_tx/rx.py, however,
>
> address@hidden $ ./benchmark_tx.py -f 410M
> address@hidden $ ./benchmark_rx.py -f 410M
>
> I can see 'dots' representing a signal is transmitted on a transmitter side.
> but a receiver does give nothing on a screen.
>
> and the screens on the both side, I got this message.
> ====================================================
> No gain specified.
> Setting gain to 5.750000 (from [-20.000000, 31.500000])
>
> UHD Warning:
> The hardware does not support the requested TX/RX sample rate:
> Target sample rate: 0.050000 MSps
> Actual sample rate: 0.250000 MSps
>
> Symbol Rate: 25000.000000
> Requested sps: 2.000000
> Given sample rate: 250000.000000
> Actual sps for rate: 10.000000
>
> Requested sample rate: 50000.000000
> Actual sample rate: 250000.000000
> ====================================================
>
> What did I do wrong?
>
> 1. Wrong frequency option (either tx or rx)
> 2. Wrong/Unspecified sample rate option (either tx or rx)
> 3. Too weak signal strength to catch
> 4. Or...?
>
> --
> Seokseong Jeon, PhD Candidate
> Communication & Networks Lab
> IT Convergence Engineering (ITCE), POSTECH, Korea
> +82 10 8338 1229, gee.songsong at gmail . com
>
--
Seokseong Jeon, PhD Candidate
Communication & Networks Lab
IT Convergence Engineering (ITCE), POSTECH, Korea
+82 10 8338 1229, gee.songsong at gmail . com