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8.4
Stratum handling
Stratum in synchronized operation:
The Stratum value behaves as follows for synchronization from the time source:
- When a fix stratum is configured, the system will always have this configured Stratum.
- If the system has auto stratum configured then the system will have the Stratum of its
source plus 1. GNSS has Stratum 0 => DTS therefore Stratum 1. A PTP master clock
may have Stratum 1 => DTS therefore has Stratum 2.
Stratum in case of time source loss:
The Stratum value behaves as follows in the case of external time source loss:
When a fix Stratum is configured, the system will always have this configured Stratum.
When the Stratum is set to auto mode the Stratum is calculated as follow:
The Stratum can count from 1 up to 16, which means 15 steps
1 hour => 60 minutes => 3600 seconds, 3600 / 15 steps = 240 s/step
E.g. the Stratum timeout is configured to 2 hours, the Stratum is increasing:
2h => 120min => 7200 sec
7200 sec / 15 = 480 s/step (
8 min/step
)
Stratum increase is stopped at configured Stratum limit.
E.g. the Stratum timeout is like before 2 hours (increasing of the Stratum every 8
minutes), the Stratum limit is set to 12. These means after 8 minutes of synchronisation
loss the device will increase the Stratum from 1 to 2. 8 minutes later the device will
change the Stratum from 2 to 3 and so on. After 11 steps * 8 minutes = 88 minutes the
Stratum of the device is 12. From now on the device will have the Stratum 12 until it is
synchronized again. The Stratum stops increasing, because the device has from now
on the synch alarm (as configured).
Technical description of the stratum functionality:
Stratum_Fix > 0
Stratum =
Stratum_Fix
Synchronisation
(GPS) = ok
Stratum = 1
Stratum = (current time – last synch time) / (stratum timeout * 15);
(Max stratum value = St_max)
Yes
Yes
No
No
Legend:
Stratum timeout:
Stratum TO <0-16>, Stratum error timeout time 1-999 [h], for loss
of the external source
St_fix:
0..15, configurable fix stratum, 0 = auto
Max Stratum value: 1..16, configurable stratum limit
current time [s]:
current time (can be found in the overview => time state)
last synch time [s]: time of the last synchronization (can be found in the overview =>
time state)
