[USRP-users] B200 cannot output a sine wave

Alex Humberstone alex.m.humberstone at gmail.com
Tue Jul 28 09:29:49 EDT 2020


What you're trying to do is pretty straight forward. I do this here in my
lab all the tiem. Can you show us your flowgraph? How are you running
tx_waveforms? Are you using a USB 3 port? How's the B200 connected to the
oscilloscope?



On Mon, 27 Jul 2020 at 21:58, Aaron Smith via USRP-users <
usrp-users at lists.ettus.com> wrote:

> Marcus,
>
> I have tried frequencies ranging from 75-450 MHz. My scope is good to 500
> MHz. I have tried gain settings betweeb 30 and 60. I am using RG-174, which
> is good to 1000 MHz.
>
> In my custom code I generate tones by sending repeating samples with a
> value of 0.8. In the past this caused tones to appear at B200's center
> frequency. This should work regardless of the clock rate or sample rate,
> but in this case I'm using a 48 MHz master clock rate and a sample rate of
> 8 MHz.
>
> I also followed a gnuradio companion tutorial to generate a tone and it
> produced something ugly too.
>
> The only thing in my setup that changed is the host laptop. I switched to
> a new laptop and had to build UHD from scratch. However, gnuradio companion
> appears to use a different UHD version, so I'm skeptical that is the
> problem.
>
> Thanks for your help.
>
> On Mon, Jul 27, 2020, 7:45 PM Marcus D. Leech via USRP-users <
> usrp-users at lists.ettus.com> wrote:
>
>> On 07/27/2020 09:05 PM, Aaron Smith via USRP-users wrote:
>>
>> Hello all,
>>
>> I am trying to output a sine wave from a B200 using custom code, or the
>> UHD tx_waveform example. In either case, when I view the output on an
>> o-scope, there is not a pure sine wave. The output looks more triangular
>> wave. I have used this scope with other B200s and the same code to get a
>> pure sine. Is the radio damaged? Is there some sort of calibration
>> required? I am using UHD 3.15.0.
>>
>> Thanks
>>
>>
>>
>> _______________________________________________
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>>
>> What frequency?  What gain settings? What is your baseband bandwidth?  Is
>> your coax cable known to be "good" at the frequency of interest?
>>   What sample rate?  Is the baseband signal well within the Nyquist
>> limits?
>>
>>
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-- 
Sincerely,
Alex-M-Humberstone
PhD Student
Klipsch School of Electrical Engineering
New Mexico State University
Las Cruces, New Mexico
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