Meinberg IMS-GNS181, Руководство по установке

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4.1.1.4 IRSA - Intelligent Reference Selection Algorithm
IRSA stands for an Intelligent Reference Selection Algorithm. In case that a master signal fails the IRSA takes
care that the switching to the next reference signal in the priority list runs automatically and smoothly. The
IRSA also takes into account the highly stable holdover performance of the local oscillator. It ensures that
switching from the superior reference signal to the less accurate one is delayed as long as the highly stable
oscillator can provide better accuracy in holdover than the next available reference signal in the priority list.
Figure: Activated IRSA mode with estimated precision values for available references.
To ensure that IRSA is working properly, follow these steps:
1. Configure a priority list of available reference signals in descending order from the superior to inferior
one in the MRS Settings menu (see chapter
MRS Source Priority ).
2. Activate IRSA in the IRSA menu. As per default the IRSA is deactivated.
3. Fill in the estimated precision values for the input reference signals in for this provided "Precision" column.
According to the estimated precision values the holdover time between current source and the next source from
the priority list will be calculated.
Here are some estimated precision values which you can load as defaults:
- GPS / GNSS as the first priority has the highest estimated precision :100 ns
- ext. Osc. (e.g. Rubidium): 120 ns
- PTP IEEE 1588: 100 ns
- PPS plus string: 100 ns
- NTP: 100 us
12 Date: 20th March 2020 IMS-GNS181 Setup Guide