On 01/03/2019 02:18 PM, Sivan Toledo wrote:
Seems like we are getting closer.
The code I use to set the time source is
uhd_usrp_set_clock_source(usrp, "external", ALL_MBOARDS);
uhd_usrp_set_time_source(usrp, "_external_", ALL_MBOARDS);
Maybe it should not be _external_ by "external" without the "_"s? At
least on N200 _external_ works. I don't remember where I got the
string, maybe from reading the UHD sources or from the UHD
documentation (this was a few years ago).
Yeah, remove the "_"s
Regarding the ref_locked: no, I am not using the external reference
input but the GPSDO. So I will remove the test on this in my code. On
N200 it seems okay to test because I think there it tests whether the
PLL is locked to whatever clock source is selected. Is that right?
Indeed, the "ref_locked" behavior seems to be subtly different from
model to model.
Thanks, Sivan
On Thu, Jan 3, 2019 at 8:29 PM Marcus D. Leech
<patchvonbr...@gmail.com <mailto:patchvonbr...@gmail.com>> wrote:
On 01/03/2019 08:53 AM, Sivan Toledo wrote:
Hundreds of milliseconds, which I think imply that either the PPS
is arriving at a random time (not likely), or that the function
that sets the time at the next PPS actually sets it immediately.
The only thing i can think of is a setup error. Like not actually
requesting the time source be set to "external" for the B200 case.
Otherwise your assumptions about my setting is correct, an N200
and a B200 each with its own Ettus GPSDO.
I also noticed another thing that is strange, but maybe not the
cause of my problem; the ref_locked sensor returns false on the
B200 (even after I do all the procedure to set the clock at the
next PPS) but true on the N200. Maybe the B200 simply does not
have that hardware feature to check? Or does this indicates a
problem?
I think on the B200 "ref locked" refers to the external
front-panel reference in. BTW if you are using the external
REF-IN on a B200/B210
you have to remove the internal GPSDO, due to electrical
cross-talk on the REF lines.
On Wed, Jan 2, 2019 at 7:53 PM Marcus D. Leech via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>>
wrote:
On 01/02/2019 05:37 AM, Sivan Toledo via USRP-users wrote:
> Hi,
>
> I have a code that reads the GPS time and sets the time on
the next
> PPS using uhd_usrp_set_time_next_pps. The code is based on
advice from
> Ettus (we wait for PPS, wait 200ms, read the time, repeat 3
times, and
> then set the time correctly for the next PPS after checking
that there
> are at least 200ms left in the second) and it works fine on
N200 with
> GPSDO.
>
> The same code causes trouble on B200 with the TCXO based
GPSDO. The
> GPS seems fine and we get a fix, and the code works fine,
but the
> clocks are not synchronized with those of N200s.
>
> Is there a known problem with this function on N200s?
>
> Thanks, Sivan Toledo
>
Just to clarify the picture here, you have an N200 and a
B200, each with
their own GPSDO. You're trying your best to synchronize them
using the PPS pulse from their respective GPSDOS?
What scale is the lack-of-synchronization? Are we talking
nanosecond,
microsecond, millisecond?
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