Hi Jawad,
I believe that setting the USRP Sink block's setting to:
Clock: O\B GPSDO
Sync: Unknown PPS
is all that's needed but I do not have the hardware in front of me to
verify this at the moment. I hope someone will chime in with confirmation
or the correct settings, but I will check this when I get a chance, but it
may not be until Monday.
Regards,
Derek
On Fri, Jan 8, 2016 at 10:40 AM, Jawad Seddar <jawad.sed...@gmail.com>
wrote:
> Hello Derek,
>
> Thanks for your answer.
>
> Unfortunately, this is the method I was referring to when I was talking
> about setting the time manually in a python interpreter (the only
> difference is that I was using the functions from gr-uhd that translate to
> the method you mentioned).
>
> Is there a way of doing this directly from GRC?
> It used to work out of the box when using a usrp_source or usrp_sink block
> from gr-uhd.
>
>
> Regards,
> Jawad
>
> 2016-01-08 19:31 GMT+01:00 Derek Kozel <derek.ko...@ettus.com>:
>
>> Hello Jawad,
>>
>> The UHD 3.9 release changed the default GPSDO behavior. UHD does not
>> automatically synchronize device time to GPS time on initialization because
>> it's not reliable during device start-up. I'm not 100% sure about GNU
>> Radio's handling of these changes so will have to check before commenting
>> on the behavior there.
>>
>> Here is a method of reliably setting the time in your own code:
>> 1) Poll on usrp->get_mboard_sensor("gps_locked") until it returns true
>> 2) Poll on usrp->get_time_last_pps() until a change is seen.
>> 3) Sleep 200ms (allow NMEA string to propagate)
>> 4) Use
>> "usrp->set_time_next_pps(uhd::time_spec_t(usrp->get_mboard_sensor("gps_time").to_int()+1));"
>> to set the time
>> 5) Poll on usrp->get_time_last_pps() until a change is seen.
>> 6) Sleep 200ms (allow NMEA string to propagate)
>> 7) Verify that usrp->get_time_last_pps() and
>> usrp->get_mboard_sensor("gps_time") return the same time.
>>
>> Regards,
>> Derek
>>
>>
>> On Fri, Jan 8, 2016 at 4:50 AM, Jawad Seddar <jawad.sed...@gmail.com>
>> wrote:
>>
>>> Hi all,
>>>
>>> Yesterday, I decided to update from GNU Radio 3.7.7.1 + UHD 3.8.4 to GNU
>>> Radio 3.7.9 + UHD 3.9.1.
>>>
>>> I used pybombs and everything went well, my OOT modules compile and my
>>> blocks run just like they used to.
>>>
>>> My issue comes from the time that is set on the USRP. It seems like the
>>> time on the device is not set to use the GPSDO. After doing some digging, I
>>> noticed that this commit might be responsible :
>>> https://github.com/EttusResearch/uhd/commit/f4f3ce2550aba933b5f4d310d82a42a41ce3f6a1
>>> .
>>>
>>> So I tried setting the time source as GPSDO on my USRP source block (in
>>> GRC) but that doesn't seem to be working. I still get something (in the
>>> tens of thousands) that is way below what it should be (I get the time on
>>> the USRP by looking at the rx_time tag available at the beginning of a
>>> received sample stream).
>>>
>>> If I run a python CLI and setup a usrp_source then set the time manually
>>> to the gps_time, then the time is somewhat correct.
>>>
>>> Am I missing a step when setting up my usrp_source in GRC?
>>>
>>> Thanks,
>>> Jawad
>>>
>>> _______________________________________________
>>> Discuss-gnuradio mailing list
>>> Discuss-gnuradio@gnu.org
>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>>
>>>
>>
>
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