Hi Folks,
I wonder, if a SHM(1) disciplined NTPd can reach the same accuracy than
one with the ATOM(PPS) Driver.
[1] says, that SHM(1) is used for "PPS from GPS". SHM(0) is sourced
from NMEA-Messages.
I'm currently parsing very precise timestamps via SHM(1) to NTP
(Operation mode=0). Every timestamp in SHM(1) is derived from a
pps-source and tweaked individually. Up to here everything works fine,
including Nanosecond resolution. See ntpshmmon output:
ntpshmmon version 1
Name Seen@ Clock Real
L Prec
sample NTP0 1434023966.919852901 1434023966.105478000
1434023966.000000000 0 -1
sample NTP1 1434023967.094973227 1434023966.999997298
1434023967.000000000 0 -20
sample NTP0 1434023967.920931333 1434023967.099366000
1434023967.000000000 0 -1
sample NTP1 1434023968.096867651 1434023967.999997890
1434023968.000000000 0 -20
Unclear is, whether NTP accounts SHM(1)-timestamps with the same weight
as ATOM(PPS)-timestamps. Any experiences with this?
BR, fran
[1] www.support.ntp.org/bin/view/Support/ConfiguringSHMRefclocks
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