Thank you Ron, you are right: results look better at lower bandwidths. I'll
try experimenting more.
On Wed, Jun 5, 2019 at 4:53 PM Ron Economos via USRP-users <
usrp-users@lists.ettus.com> wrote:
> I wonder if the 2X master clock rate may be an issue. I use offset tuning
> all the time on my B210, but at smaller sample rates and offsets (10 Msps,
> 4 MHz offset and 4X master clock rate).
>
> Maybe a test with 10 MHz LTE versus 20 MHz would be useful?
>
> Ron
> On 6/5/19 16:34, Dario Fertonani via USRP-users wrote:
>
> Sorry, I wrote "coherent" meaning that the problems show up only with
> signal analyses that go beyond power spectrum.
> For example, the output LTE signal gives CQI=15 (max quality) with
> dsp_freq=0 and variable CQI (never 15) with dsp_freq = 11.52e6 (in all
> cases sampling rate is set to 23.04e6 and master clock rate is twice the
> sampling rate). I do know that LTE is robust to DC offset but this is a
> more general question on UHD/B210.
>
> On Wed, Jun 5, 2019 at 4:23 PM Marcus D. Leech <patchvonbr...@gmail.com>
> wrote:
>
>> On 06/05/2019 07:12 PM, Dario Fertonani wrote:
>>
>> Thank you Marcus. I should have mentioned that I tried removing that
>> line, with no success. With non-zero dsp_freq, the power spectrum looks OK
>> but the (coherent) signal quality is terrible.
>>
>> OK, that's a different level of problem.
>>
>> You're trying to maintain coherence across more than one B210?
>>
>>
>>
>> On Wed, Jun 5, 2019 at 2:25 PM Marcus D. Leech via USRP-users <
>> usrp-users@lists.ettus.com> wrote:
>>
>>> On 06/05/2019 05:20 PM, Dario Fertonani via USRP-users wrote:
>>>
>>> I'm trying to move the "DC offset" out of the main spectrum by using the
>>> dsp_freq field in uhd::tune_request_t. This doesn't seem to work on
>>> B210, meaning that the following code functions properly with DcOffset_Hz=0
>>> but not, for example, with DcOffset_Hz=10e6. In all these tests the master
>>> clock rate is large enough to fit DcOffset_Hz and the spectrum of interest
>>> easily. Anything obviously wrong?
>>>
>>> Thanks,
>>> Dario
>>>
>>> uhd::tune_request_t uhdTuneRequest( const double &CarrierFreq_Hz , const
>>> double &DcOffset_Hz )
>>> {
>>> uhd::tune_request_t tuneRequest( CarrierFreq_Hz - DcOffset_Hz );
>>> tuneRequest.args = uhd::device_addr_t( "mode_n=integer" );
>>> tuneRequest.dsp_freq_policy = uhd::tune_request_t::POLICY_MANUAL;
>>> tuneRequest.dsp_freq = DcOffset_Hz;
>>> return tuneRequest;
>>> }
>>>
>>>
>>> You shouldn't need to use POLICY_MANUAL at all, since the tune_request_t
>>> supports offset-tuning directly:
>>>
>>> https://files.ettus.com/manual/structuhd_1_1tune__request__t.html
>>>
>>>
>>>
>>> _______________________________________________
>>> USRP-users mailing list
>>> USRP-users@lists.ettus.com
>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>
>>
>>
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