NTP Performance

[Richard Laager]

On 11/23/19 1:53 AM, Richard Laager via devel wrote:
> 
> On ntp2 (again, this is the u-blox 6 eval kit), I'm getting duplicated
> sequence numbers, which doesn't seem quite right:
> 
> rlaager at ntp2:~$ sudo ppstest /dev/pps0
> trying PPS source "/dev/pps0"
> found PPS source "/dev/pps0"
> ok, found 1 source(s), now start fetching data...
> source 0 - assert 1574493759.100134288, sequence: 93299 - clear  1574493760.000155012, sequence: 93299
> source 0 - assert 1574493760.100134349, sequence: 93300 - clear  1574493760.000155012, sequence: 93299
> source 0 - assert 1574493760.100134349, sequence: 93300 - clear  1574493761.000138190, sequence: 93300

Okay, so upon further reflection, the timestamps seem to indicate that I
need to use the clear/falling edge. This also explains the duplication,
I think. This is despite the GPS being configured for rising edge. So as
Hal (I think) said, something is inverting the signal.

I thought I had tested with a "flag2 1" on the PPS driver, but I'll
retest that. I also want to test changing the GPS to falling edge, such
that the server should see it as rising edge.

-- 
Richard

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