[USRP-users] help: USRP1 + WBX 50-2200

Marcus Müller marcus.mueller at ettus.com
Thu Dec 11 12:25:48 EST 2014


Hello SKA15!

A few ideas,:

* This is getting a GNU Radio-related discussion; there's a very active
mailing list [1] for GNU Radio.
* The 96k sampling rate is not supported by every audio device; try 48k
and match the interpolation.
* The GNU Radio companion has a nice screenshot feature which will
export PNG images that are easier to read ;)
* Make sure the antenna is connected to the right port (RX2)

But most importantly, you forgot to share the output of uhd_usrp_probe.
This would be nice to have, because it might explain why you can't set
the 88.1MHz, which is the gravest problem so far.

Greetings,
Marcus

[1] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
On 12/11/2014 06:15 PM, Thesis 2015 wrote:
> oh...thank you for your reply...
>
>
> The sampling rate of the usrp_source block is 5Msps. The picture attached
> is a screenshot of the flow graph:
>
>
>
> On Thu, Dec 11, 2014 at 1:27 AM, Marcus Müller <usrp-users at lists.ettus.com>
> wrote:
>
>>  Hello SKA15,
>>
>> nice meeting you here :)
>>
>> There is one thing that is most probably easy to solve: We're seeing a lot
>> of 'O', meaning overflow, which means that your system can't cope with the
>> samples that the USRP1 is producing fast enough. What is the sampling rate
>> you use in the usrp_source block? The USRP1, bound by USB2 speeds, can't
>> really produce very high sampling rates, so unless the PC you are using to
>> do this is really slow, this points to your sound card's sampling rate
>> being significantly slower than the sample rate the USRP pushes through the
>> flow graph. Do you resample to match your sample rate to the one you use
>> for your alsa sink? Which one is that?
>>
>> The "not being able to tune to 88.1MHz" warning is indeed strange; could
>> you run "uhd_usrp_probe" on a console and attach the textual output of that
>> command?
>>
>> Greetings,
>> Marcus
>>
>>
>> On 12/10/2014 03:53 AM, Thesis 2015 via USRP-users wrote:
>>
>> Good day,
>>
>> We are beginners using the USRP1 with WBX v.3 50-2200 daughterboard and GNU
>> radio Companion version 3.7.5.1 with UHD_003.008.000-18-g864f84b5 installed
>> on Ubuntu 14.04 LTS operating system. Our goal in using these is to create
>> an SDR WBFM receiver.
>>
>> We have followed what was done in the video posted by the ettus research (http://www.ettus.com/kb/detail/sdr-for-beginners-building-an-fm-receiver-with-the-usrp-and-gnu-radio)
>> but have encountered some problems. As we ran the GRC file, both the fft
>> plot and scope plot appeared but all we could hear are static sounds
>> together with the script shown below:
>>
>> Executing: "/media/thesis/Data/Downloads/Thesis/FM Reciever using
>> GRC/fm_example.py"
>>
>> linux; GNU C++ version 4.8.2; Boost_105400; UHD_003.008.000-18-g864f84b5
>>
>> Using Volk machine: sse4_1_64_orc
>> -- Opening a USRP1 device...
>> -- Loading FPGA image: /usr/local/share/uhd/images/usrp1_fpga.rbf... done
>> -- Using FPGA clock rate of 64.000000MHz...
>> WARN: Sensor 'lo_locked' failed to lock within timeout on channel 0.
>>
>> UHD Warning:
>>     Tune Request: 88.100000 MHz
>>       The requested RX frequency is outside of the system range, and has
>> been clipped:
>>         Target Frequency: 88.100000 MHz
>>         Clipped Target Frequency: 0.000000 MHz
>>       Successfully tuned to 0.000000 MHz
>> INFO: Audio sink arch: alsa
>> OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
>>
>>   Done
>>
>>   We are hoping that you could help us with this problem. Thank you.
>>
>> -SKA15-
>>
>>
>>
>>
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>>
>>
>>
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>>





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