See last page for copyright and document info, File: Reeve_GpsNtp-Pi_Setup.doc, Page 25
It should not be necessary to reconfigure the NTP configuration file, ntp.conf, but the file should be checked
anyway. Be sure to backup the memory card before updating and upgrading. Using NTP v4.2.8p9 and later
may not work with the Raspbian Wheezy operating system on the RPi B+ but additional experimentation is
necessary. Note: To be informed of new versions of NTP, join the
NTP Hackers
mailing list at {
NTPHack
}.
Columns shown in NTP query with the –p option
Remote
: Peers specified in the NTP configuration (ntp.conf) file
*
Remote peer or server presently used as the primary reference
#
Source selected, distance exceeds maximum value
o
PPS peer; system synchronization is derived from a pulse-per-second (PPS) signal, either indirectly via
the PPS reference clock driver or directly via the kernel interface
+
Source selected, included in final set
x
Source false ticker, out of tolerance
.
Source selected from end of candidate list
–
Source discarded by cluster algorithm
blank Source discarded high stratum, failed sanity
refid
: Remote synchronization source
stratum
: Stratum level of the source
t
: Types available
l
local (such as a GPS, WWVB)
u
unicast (most common)
m
multicast
b
broadcast
–
netaddr
when
: When last polled (s)
poll
: Source polling interval (s)
reach
: Octal 8-bit left-shift shift register value recording polls (bit set = successful, bit reset = fail)
delay
: Round trip delay to the remote peer or server (ms)
offset
: Mean offset (phase) in the times reported between this local host and the remote peer or server,
positive for ‘remote time’ ahead of ‘local time’ (ms)
jitter
: Mean deviation (jitter) in the time reported for the remote peer or server, rms of difference between
multiple time samples (ms)
