Thanks Rob.
Actually, prior to tune the TwinRx I set the sampling rate.
Il lun 26 giu 2023, 17:33 Rob Kossler via USRP-users <
usrp-users@lists.ettus.com> ha scritto:
> Is there a chance that the issue is caused by the timed commands occurring
> prior to the "set_rx_rate" command (as indicated in the code provided in
> the issue tracker)? I don't know how the DDC responds to timed commands
> prior to knowing its output rate.
> Rob
>
> On Mon, Jun 26, 2023 at 11:22 AM Marcus D. Leech <patchvonbr...@gmail.com>
> wrote:
>
>> On 26/06/2023 11:12, Carlo Venier wrote:
>>
>> Good evening to everybody,
>>
>> I am trying to use an X300 with two TwinRX in a coherent setup.
>> After synchronization, in the case of fixed frequency operation (no
>> re-tuning) the phase differences among the channels are constant and
>> they remain constant over time.
>> However, if I re-tune the TwinRx on the exact same frequency, I expect
>> that the phase differences remain the same, but it does not happen. How
>> is it possible?
>>
>> The LO settings are the following:
>>
>> multi_usrp->set_rx_lo_export_enabled(true,
>> uhd::usrp::multi_usrp::ALL_LOS, 0);
>> multi_usrp->set_rx_lo_source("internal", uhd::usrp::multi_usrp::ALL_LOS,
>> 0);
>> multi_usrp->set_rx_lo_source("companion",
>> uhd::usrp::multi_usrp::ALL_LOS, 1);
>> multi_usrp->set_rx_lo_source("external", uhd::usrp::multi_usrp::ALL_LOS,
>> 2);
>> multi_usrp->set_rx_lo_source("external", uhd::usrp::multi_usrp::ALL_LOS,
>> 3);
>>
>> Moreover, by using the timed command before tuning all the channels
>> (code snippet at "https://files.ettus.com/manual/page_sync.html";, "Align
>> LOs in the front-end"), I get into the issue at
>> ("https://github.com/EttusResearch/uhd/issues/606";) and the X300 is not
>> usable until a power-cycle.
>> I get the same issues when using both the uhd3.15.0.0 and the uhd4.4.0.0.
>>
>> Hopefully this bug will get fixed.
>>
>> I think that without timed-tuning, even though you're sharing LOs, the
>> DDC phase-accumulators will be
>> "ticking over" between the individual (untimed) tuning commands. So
>> there will be unpredictable phase
>> between all the channels.
>>
>>
>> Should I expect the same phase differences when I re-tune to the exact
>> same frequency or is it okay for the phase differences to change and I
>> am missing something?
>> Do you have any suggestion on how to solve the issue?
>>
>> Thanks,
>>
>> Best regards,
>> Carlo Venier
>>
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