[USRP-users] calibration on Wifi bands for X310/UBX

Derek Kozel derek.kozel at ettus.com
Tue Jul 4 06:00:29 EDT 2017


Hello Sanjoy,

Your initial calls to set_center_freq are all correct and use the command
time. However the other call to set_center_freq must also the
set_command_time call.

Regards,
Derek

On Tue, Jul 4, 2017 at 10:09 AM, Sanjoy Basak <sanjoybasak14 at gmail.com>
wrote:

> Hi Derek,
> I am not using Rfnoc. The time and clock sources are set to external and
> motherboard time is also set correctly. Please have a look in the code.
>
> Right now I am using simple flowgraph and python codes to check the
> calibration. Please have a look. I am not getting the repeated offset
> phase. It is changing with every tuning.
>
> Best regards
> Sanjoy
>
>
>
>   <https://mailtrack.io/> Sent with Mailtrack
> <https://mailtrack.io/install?source=signature&lang=en&referral=sanjoybasak14@gmail.com&idSignature=22>
>
> Sanjoy Basak
> Researcher
> Royal Military Academy
> Dept. Communication, Information Systems & Sensors (CISS)
> 30, Avenue de la Renaissance
> B-1000 Brussels
> BELGIUM
> Tel : +32-2441 4162
> email: Sanjoy.BASAK at mil.be
>
> On Mon, Jul 3, 2017 at 7:53 PM, Derek Kozel <derek.kozel at ettus.com> wrote:
>
>> Hi Sanjoy,
>>
>> Timed commands will definitely be required in order to have repeatable
>> phase offsets. To check, you are (re)setting the time on each X310 at the
>> start of your program and have set the clock and time sources to external?
>>
>> Are you using the multi_usrp API and creating a single rx_streamer with
>> all four channels? If you are using the RFNoC API then timed commands must
>> be used to set the DDC frequency (if non-zero) as well since that has an
>> effect on the phase which is stateful.
>>
>> Can you please paste your code for setting the rx frequency? Also for
>> setting the motherboard time?
>>
>> Thank you,
>> Derek
>>
>> On Mon, Jul 3, 2017 at 6:20 PM, Sanjoy Basak <sanjoybasak14 at gmail.com>
>> wrote:
>>
>>> Hi Derek,
>>> I am referreing to phase calibration. I am taking one transmit signal
>>> (sine/cosine wave) from one x310 and distributing the signal through a 1x4
>>> power divider and feeding it to 4 receivers of 2 other X310s. All the X310s
>>> are connected to the octoclock. Afterwards I am comparing the phase of 4 RX
>>> signals.
>>>
>>> For calibration, I take one rx signal as the reference signal and find
>>> the phase differences of other 3 rx signals compared to the reference
>>> signal. I save the offset (initial) phases and use it further for
>>> calibration.
>>>
>>> As I mentioned earlier, for 2.4 GHz, 2.45 GHz and 2.5 Ghz, I find the
>>> phase calibration remains even after restarting (or retuning) the USRP.
>>> However, for other Wifi bands (for example 2412 MHz or 2452 MHz ...) the
>>> phase calibration does not remain. After retuning, I find the calibration
>>> is gone.
>>>
>>> I also used set_command_time method. But the result was the same.
>>>
>>> Best regards
>>> Sanjoy
>>>
>>>
>>>
>>>   <https://mailtrack.io/> Sent with Mailtrack
>>> <https://mailtrack.io/install?source=signature&lang=en&referral=sanjoybasak14@gmail.com&idSignature=22>
>>>
>>> Sanjoy Basak
>>> Researcher
>>> Royal Military Academy
>>> Dept. Communication, Information Systems & Sensors (CISS)
>>> 30, Avenue de la Renaissance
>>> B-1000 Brussels
>>> BELGIUM
>>> Tel : +32-2441 4162
>>> email: Sanjoy.BASAK at mil.be
>>>
>>> On Mon, Jul 3, 2017 at 6:29 PM, Derek Kozel <derek.kozel at ettus.com>
>>> wrote:
>>>
>>>> Hello Sanjoy,
>>>>
>>>> What calibration are you referring to? Frequency, amplitude, phase? How
>>>> are you doing your calibration and how are you checking it? The more you
>>>> can tell us about your method and the results you are seeing the better we
>>>> can answer.
>>>>
>>>> Regards,
>>>> Derek
>>>>
>>>> On Mon, Jul 3, 2017 at 4:46 PM, Sanjoy Basak via USRP-users <
>>>> usrp-users at lists.ettus.com> wrote:
>>>>
>>>>>
>>>>> Hello Experts,
>>>>> I am trying to calibrate X310/UBX on the whole wifi bands (the
>>>>> complete 2.4 GHz band).
>>>>> 2.412,2.417,2.422,....,2.484 GHz
>>>>>
>>>>> I am doing direction finding tests and need to calibrate 4 channels of
>>>>> 2 X310s on the specified frequencies. Both X310s are connected with
>>>>> Octoclock. However, I could only have calibration on 2.4 GHz, 2.45 GHz, 2.5
>>>>> GHz. For other bands, calibration does not remain after retuning. Is there
>>>>> any specific reason why the calibration only works for every 50 Mhz channel
>>>>> after retuning. I tested with different sampling rates, but the result is
>>>>> the same. Calibration does not remain after retuning.
>>>>>
>>>>> I am using UHD_003.009.002 (installed from synaptic) and ubuntu 16.04.
>>>>> Is there any specific way how I can make it work?
>>>>>
>>>>> Best regards
>>>>> Sanjoy Basak
>>>>>
>>>>>
>>>>>
>>>>>   <https://mailtrack.io/> Sent with Mailtrack
>>>>> <https://mailtrack.io/install?source=signature&lang=en&referral=sanjoybasak14@gmail.com&idSignature=22>
>>>>>
>>>>> _______________________________________________
>>>>> USRP-users mailing list
>>>>> USRP-users at lists.ettus.com
>>>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>>>
>>>>>
>>>>
>>>
>>
>
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