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Re: [gpsd-users] Shared Memory: PPS timestamps not set?
From: |
Gary E. Miller |
Subject: |
Re: [gpsd-users] Shared Memory: PPS timestamps not set? |
Date: |
Thu, 4 Jul 2019 08:55:42 -0700 |
Yo Guido!
On Thu, 4 Jul 2019 17:31:03 +0200
Guido Gavilanes <address@hidden> wrote:
> Thank you Gary for taking time to answer.
> My ntpshm works on, I see the timestamps and ntp synch is working
> linke a charm (after a bunch of calibration runs).
Good. so gpsd works.
> the problem in fact is that in my program, when I read the pps
> timestamps I get:
> with socket:
> PPS clk: 1562247898.884325242 -> a realistic pps timestamp (UTC
> epoch in seconds, with subsecond information).
> and with shared memory:
> PPS clk: 0.1077805056 -> not comparable with the actual
> timestamp.
So the problem is in your program. Can't say much without seeing
your code.
> in fact with socket export i can know how much time has passed since
> the PPS hit, but with shared memory export i cannot compare my local
> UTC time with pps timestamp, since seconds part is missing.
A) Nothing missing.
b) You don't need it.
> So it
> makes me conclude that the same information decoded under two
> different export methods is in fact different. The only explanation I
> have is that PPS is not exported in shared memory export. Is it
> really that?
gpsd sends PPS time to ntpd over SHM. So we know that workx.
Look at the ntpshmmon code, and your code.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
address@hidden Tel:+1 541 382 8588
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"If you can’t measure it, you can’t improve it." - Lord Kelvin
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