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

Sanjoy Basak sanjoybasak14 at gmail.com
Tue Jul 4 10:02:15 EDT 2017


I used timed command once.

now = self.receiver.get_time_now()
cmd_time=now+uhd.time_spec(0.5)

self.receiver.set_command_time(cmd_time)

        self.receiver.set_center_freq(freq, 0)
        self.receiver.set_center_freq(freq, 1)
        self.receiver.set_center_freq(freq, 2)
        self.receiver.set_center_freq(freq, 3)

        self.receiver.clear_command_time()

Isn't this enough?

How do I add timed command before set_f function (for receive only
cal_test_try.py file)?



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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 Tue, Jul 4, 2017 at 3:52 PM, Derek Kozel <derek.kozel at ettus.com> wrote:

> The transmitter will not have a meaningful phase value. You are comparing
> the offsets between the four receivers. Looking at your cal_test4.py file
> we can see that the set_f function tunes the transmitter and receivers and
> does not use timed commands. This is also true for your receive only
> cal_test_try.py. You will need to add timed commands to those so that all
> four channels tune simultaneously.
>
>     def set_f(self, f):
>         self.f = f
>         self.transmitter.set_center_freq(self.f, 0)
>         self.transmitter.set_center_freq(self.f, 1)
>         self.receiver.set_center_freq(self.f, 0)
>         self.receiver.set_center_freq(self.f, 1)
>         self.receiver.set_center_freq(self.f, 2)
>         self.receiver.set_center_freq(self.f, 3)
>
>
> On Tue, Jul 4, 2017 at 1:51 PM, Sanjoy Basak <sanjoybasak14 at gmail.com>
> wrote:
>
>> Hi Derek,
>> I am using transmitter on continuous mode and then testing the phase of
>> the receivers with that python file. So, I am not retuning the transmitter
>> again. It's tuned once and then I am retuning the receiver and testing if
>> the phase is the same or different. So, with different retune the receivers
>> are having different offset phases at these frequencies.
>>
>> I also tested with transmitter and receiver together, transmitting and
>> receiving at the same time and also tuning at the same time (with the
>> attached python file). However, I am getting the same result. The offset
>> phases is different at different retunes.
>>
>> Best regards
>> Sanjoy
>>
>>
>>
>>
>>
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>>
>> 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 Tue, Jul 4, 2017 at 12:00 PM, Derek Kozel <derek.kozel at ettus.com>
>> wrote:
>>
>>> 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
>>>>>>
>>>>>>
>>>>>>
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>>>>>>
>>>>>> 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
>>>>>>>>
>>>>>>>>
>>>>>>>>
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>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> 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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