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
>>
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>>
>>
>
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