Agreed on all parts. I already have the loopback cables as same type, same
length. The plan is to tweak the phase offset to 0 using some high precision
equipment, then see what degree of control can be obtained once the channels
are phase aligned.
Gonna look and see if the Python API supports the splitter control, snippet may
work!
<end transmission>
> On Jan 14, 2022, at 18:58, Marcus D. Leech <patchvonbr...@gmail.com> wrote:
>
>
> On 2022-01-14 18:10, Paul Atreides wrote:
>> Ok thanks. In my haste I was mistaken in assuming that the LO gain would
>> track with the RF output gain. Silly mistake. I’m still getting used to
>> separating out the LO.
>>
>> I can put this on a SpectrumAnalyzer (with an attenuator in line) on Monday.
>>
>> I’m trying to take channel to channel phase measurements to determine what
>> level of phase control I can have over one channel.
> My guess is that if you extrude the LO out and then loop it back in, with
> equal-length, equal-type cables, the channel-to-channel phase error will be
> quite small.
>
> If the phase-error that results is *fixed* and *characterized*, you can
> simply rotate the phase of one of the baseband signals to compensate.
>
>>
>> It’s not critical that I use GNURadio but it seemed like the logical option
>> as it’s very easy to make those adjustments.
>>
>> I will look at the python API and see if the commands Rob was talking about
>> can be invoked using Python instead of writing a C++ application.
>> Then I’ll see if that is included in gr-uhd. If not, I can submit a pull
>> request with any changes.
> I think the only "missing piece" is the control for the splitter module, and
> with GR3.9+ you can use a code snippet to insert that, I think.
>
>
>>
>> I’ll ping the gnuradio chat later tonight.
>>
>>
>> Thanks for the help guys are in
>> <end transmission>
>>
>>> On Jan 14, 2022, at 17:43, Marcus D. Leech <patchvonbr...@gmail.com> wrote:
>>>
>>>
>>> On 2022-01-14 17:35, Paul Atreides wrote:
>>>> Using a B210 at f_c of the N321. TX LO OUT0 is plugged into RX2 of the
>>>> B210
>>> You might want to put an attenuator inline, since the LO output is a couple
>>> of dBm, which is
>>> "loud as a heavy metal concert" from the perspective of a receiver input.
>>>
>>> If the splitter isn't enabled in this test, then what you're seeing is the
>>> leakage through the RF
>>> switch that enables the splitter, which means that once the splitter is
>>> turned on, the
>>> signal will be even louder...
>>>
>>>
>>>>
>>>>
>>>>
>>>> On Fri, Jan 14, 2022 at 5:32 PM Marcus D. Leech <patchvonbr...@gmail.com>
>>>> wrote:
>>>>> On 2022-01-14 17:30, Rob Kossler wrote:
>>>>>> These thare the UHD commands. I don't know how these translate to
>>>>>> gnuradio.
>>>>>>
>>>>>> % set both LO sources to use external
>>>>>> set_tx_lo_source(“external”, “lo1”, 0)
>>>>>> set_tx_lo_source(“external”, “lo1”, 1)
>>>>>>
>>>>>> % export the internal LO to the 1:4 splitter
>>>>>> set_tx_lo_export_enabled(true, “lo1”, 0)
>>>>>>
>>>>>> % enable the 1:4 splitter output port
>>>>>> get_device()->get_tree()->access<bool>("mboards/0/dboards/A/tx_frontends/0/los/lo1/lo_distribution/LO_OUT_0/export").set(true)
>>>>>>
>>>>> I don't think the current GR code has support for controlling the
>>>>> splitter, so a "code snippet" would likely be required.
>>>>>
>>>>>
>>>>>>>> To unsubscribe send an email to usrp-users-le...@lists.ettus.com
>>>>>
>>>
>
_______________________________________________
USRP-users mailing list -- usrp-users@lists.ettus.com
To unsubscribe send an email to usrp-users-le...@lists.ettus.com
