Meinberg LANTIME/GPS Operating Instructions Manual page 21

For the synchronisation of the NTPD with the GPS it is necessary that the GPS
receiver is synchronous with the GPS time (LOCK LED is turned on). In this case the
following message is monitored on the display:
GPS: NORMAL OPERATION
NTP: Sync
The second line shows the user that the NTPD is synchronized with the GPS with an
offset of -1 ms. Because of the internal time of the NTP which is adjusted by a
software PLL (phase locked loop) it takes a certain time to optimise this offset. The
NTPD tries to keep the offset below ±128 ms; if the offset becomes too large the
system time is set with the GPS time. Typically values for the offset are +-5 ms after
the NTPD has already synchronized. If NTPD is not synchronised and GPS receiver
is then, the green LOCK-LED is blinking.
Wed,
Offs: -1ms MEZ
21
18.11.1998
10:04:10