Copyright © Sigicom AB 2021
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6.3.
GPS time synchronization
It is possible to enable a function that marks each transient with a time
difference
10
to the exact (whole) second. This makes it possible to use two
or more INFRA C22 to measure the ground wave, for example caused by
railway traffic. It is here recommended that the units are placed with a
distance of at least 50 meters between them, and that their Trigger level is
so low that they each trigger a transient. If needed, contact Sigicom for
further details.
Note! With Time synchronization activated the needed power
increases with at least five times, and time to battery is empty is thus
shortened with the same factor.
6.4.
Time Synchronization through Internet
The C22 automatically synchronizes its clock to an NTP (
N
etwork
T
ime
P
rotocol) server on Internet. SNTP according to RFC 4330 is used. No
user configuration of the NTP server can be made.
An NTP request with subsequent difference calculation is performed at
every INFRA Net communication, but not more often than once every 60
minutes. The calculated difference is stored with each data timestamp.
The internal clock is gradually adjusted while monitoring is running. Any
remaining difference is adjusted at power off.
Expected time diversion is below 1 minute per month.
Note! All data from C22 is always time stamped with UTC time. Time
zone only affects the presentation of time.
10
This time difference is defined as:
(internal instrument time) – (GPS time)
