On 06/09/2016 10:04 PM, Gary E. Miller wrote:
Yo Mike!
Back on list since I think I see a real problem here.
On Thu, 9 Jun 2016 21:41:32 -0400
Mike <bellyac...@gmail.com> wrote:
On 06/09/2016 09:26 PM, Gary E. Miller wrote:
Yo Mike!
On Thu, 9 Jun 2016 21:22:29 -0400
Mike <bellyac...@gmail.com> wrote:
Yes, one GPGGA and one GPRMC each second, but they are both for the
same fix, one fix per second, always ending in 0.940.
That is bad.
gpsd assumes that the fix data for each second starts to arrive just
after the beginning of the second. But yours starts so close to the end
of the second that data will still be spilling into the next second, before
anything is computed.
Some of your lines are 78 chars long. At 9600 each char takes 0.001
seconds. 78 chars is 0.078 seconds. So even if the GPGGA is started
at exactly 0.940 into the second, the sentence can not be received, and
checksum checked, before the next second starts. 0.940 + 0.078 is 1.018
seconds.
gpsd may then pair the PPS with the wrong second. Which is the sypmtom
you see.
Groan... I'm gonna have to sleep on this one...
RGDS
GARY
Okay so I can understand that explanation. Thank you for the detail.
What I fail to understand is why this just seems to have appeared out of
thin air. It's not like I just hooked this up yesterday. I have toyed
with this thing for probably three years off and on, never had anything
like the offset I'm seeing. Of course there is no saved data from times
when it was running well.
Mike
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