sleek daelite wrote:
Hey guys,
Could anyone help me with Garmin GPS 18lvc device that comes with PPS
output. I've been trying to configure the device to achieve about 1ms
accuracy. The specification of this device states it could achieve
about 1ns accuracy. Im quite puzzled as to why i can't achieve such
accuracy. My software include:
ntp-4.2.2p3-RC
Debian Kernel 2.6.16-2-486
gpsd 2.33
My content of ntp.conf is:
-------------------------------------------------------------
server 127.127.28.0
minpoll 4 maxpoll 4
fudge 127.127.28.0
time1 0.320 refid GPS
server 127.127.28.1
minpoll 4 maxpoll 4 prefer
fudge 127.127.28.1
refid GPS1
------------------------------------------------------------
My command line arguments for gpsd is:
gpsd /dev/ttyS0 -n -D 5 -N 2
When i run ntpq the output i get is:
ntpq> peers
remote refid st t when
poll reach delay offset jitter
======================================
*SHM(0) .GPS. 0 l
4 16 377 0.000 -6.006 6.758
SHM(1) .GPS1. 0 l
- 16 0 0.000 0.000 0.004
Your configuration seems OK but this display shows that your PPS pulses
are not being detected.
So, you are now synchronizing only on the serial messages, and 6ms
offset/jitter is normal.
gpsd expects the PPS pulses on the DCD line of the serial interface
(polarity is autodetected).
Are you sure this line is indeed providing the pulses?
Rob
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