Spectracom VelaSync 1225, Руководство пользователя

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Note: When the Timescale is set to “GPS”, the GPS to UTC
Offset must be set correctly. As of 26-Oct-2018, the offset
between UTC and GPS is 18 seconds.
2.10.7 NTP Reference Configuration
VelaSync's NTP Service needs to be setup such that it utilizes the time source ("input
reference") you want it to use. There are two options for an NTP Server to derive its
time from:
a.
The NTP Service uses VelaSync's System Time System Time is the time derived
from the internal Timing System. The Timing System is the time server's central
time processing engine. It consumes and processes time and 1PPS obtained from
an external input reference e.g., typically GNSS., i.e. typically the GNSS reference
(or IRIG, ASCII data input, etc.), and distributes that time over the NTP network.
This is called
Stratum 1 Operation , because VelaSync will be the Stratum 1 (or
primary) server. This is the most common configuration.
2.10.8 NTP Servers and Peers
VelaSync can be configured to receive time from one or more available NTP Servers
(VelaSyncs or different models). This allows for NTP Servers on a timing network to be
configured as potential (fallback) input time references for VelaSync System Time syn-
chronization. In the event that a current reference becomes unavailable, VelaSync can
fallback to the other NTP Servers available on the network.
A group of NTP servers at the same Stratum level (Stratum 1 time servers, for
example) are considered as
NTP Peers to each other.
NTP Servers at the same Stratum level
If VelaSync is configured to obtain time from other NTP Servers at the same Stratum
level (i.e., NTP Peers) but is currently using a different input reference as its selected ref-
erence, VelaSync will report to the network (via the NTP time stamps) that it is a
Stratum 1 time server. Should, however, all input references except the other NTP
server(s) become unavailable, VelaSync will then drop to a Stratum 2 time server (with
System Time being derived from the NTP time packets being received from the other
NTP Peers.
Holdover
If VelaSync is synchronized to another NTP Server or reference, and that server or ref-
erence subsequently loses sync or becomes unavailable (with no other higher priority
input references being present and valid), VelaSync will then go into the
Holdover mode.
2.10 Configuring NTP
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