[USRP-users] problem with USRP example on X310 with CBX-120

Jim Hunziker jhunziker at bcisensors.com
Thu Oct 23 13:40:06 EDT 2014


Marcus Leech responded to me off-list that I was using gain settings that
were too low. Setting them to 10 greatly improved my signal, though there's
still a carrier component that's bigger than my signal and not getting
removed. A colleague tells me he's working with Ettus regarding this
problem.


-- 
Jim Hunziker
BCI Systems and Software Engineering
(973) 348-9299
jhunziker at bcisensors.com

On Wed, Oct 22, 2014 at 4:42 PM, Jim Hunziker <jhunziker at bcisensors.com>
wrote:

> It looks like some of my problem was plotting abs(sig_c) rather than
> real(sig_c), but the signal still doesn't look great.
>
>
> --
> Jim Hunziker
> BCI Systems and Software Engineering
> (973) 348-9299
> jhunziker at bcisensors.com
>
> On Wed, Oct 22, 2014 at 12:15 PM, Jim Hunziker <jhunziker at bcisensors.com>
> wrote:
>
>> Hi. I have an X310 with a CBX-120 and a GPSDO, and I'm running the
>> txrx_loopback_to_file example with UHD version 3.7.3 like this:
>>
>> ./txrx_loopback_to_file --tx-args addr=10.10.10.90 --nsamps=250000
>> --tx-rate 2500000 --rx-rate 2500000 --tx-freq 56000000
>> 00 --rx-freq 5600000000 --rx-ant CAL --wave-type SINE --ref internal
>> --wave-freq 1000
>>
>> (It makes no difference if I use the RX2 antenna and a loopback cable.)
>>
>> With a sampling rate of 2.5 MHz and a sine wave of 1 KHz, I expect to see
>> a sinusoidal cycle every 2500 samples. I'm plotting them with GNU Octave
>> and the following commands:
>>
>> fid = fopen("~/uhd/host/build/examples/usrp_samples.dat", "rb");
>> [sig, count] = fread(fid, Inf, "int16");
>> sig_c = sig(1:2:end) + j * sig(2:2:end);
>> plot(abs(sig_c));
>>
>> The signal seems very noisy, and it's pretty much gone towards the end of
>> the capture. Am I doing something wrong?
>>
>> --
>> Jim Hunziker
>> BCI Systems and Software Engineering
>> jhunziker at bcisensors.com
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20141023/296a4e15/attachment-0002.html>


More information about the USRP-users mailing list