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Configuring GPS Notification Alarm Thresholds

NetClock allows you to configure Minor and Major alarm thresholds for the GNSS receiver. This is done by setting the minimum number of satellites the receiver can track for a set time before an alarm is triggered. If both conditions are met, i.e. the reception quality falls below the set number of satellites for the set amount of time, an alarm is triggered.

The alarm notification feature described below allows you to be notified of a potential reception issue BEFORE the GNSS reference becomes invalid. This may be useful e.g., to notify system operators of a deteriorating signal reception before NetClock possibly losing the GNSS reference.

Note that NetClock itself has a pre-defined minimum number of satellites that must be tracked in order for GNSS to be considered a valid reference. The minimum number of satellites depends e.g., on your receiver mode (see Configuring the GNSS Receiver), the GNSS signal reception in the area where your antenna is located, and the receiver type. For SAASM units and in Stationary Mode, the minimum number of satellites is normally 4 (four). Hence, it would be suggested to set the Minor Alarm Threshold to 8, and the Major Alarm Threshold to 6.


Note: While GPS Notification Alarms can be used in Mobile GNSS Receiver Mode, it is not advisable.

To determine which GNSS Receiver Mode your NetClock is using, see Configuring the GNSS Receiver.

To determine how many satellites your NetClock unit is currently receiving, navigate to INTERFACES > REFERENCES: GNSS 0. See also Reviewing the GNSS Reference Status.

To set the GPS Alarm Thresholds:

  1. Navigate to MANAGEMENT > OTHER: Notifications, and choose the GPS tab.
  2. At the bottom of the window, locate the ALARM THRESHOLD panel:

  3. In the Minimum Satellites fields enter the minimum number of satellites that must be available before the alarm is triggered. The alarm will be triggered when the number of satellites available is BELOW this number.
  4. In the Duration Below Threshold (s) fields, enter the time in seconds that the system must be below the threshold set in the Minimum Satellites field before an alarm is triggered. The alarm will be triggered when this time is reached.

    By default, this timeout value is set to 0 seconds: As soon as the receiver drops below the minimum number of satellites, the associated alarm is triggered. A delay of e.g., 5 seconds, however, would not trigger an alarm if the number of received satellites drops below the specified number for only 3 seconds.

You can configure this event to cause either a Minor alarm, or a Major alarm, or both.

To learn more about Minor and Major alarms, see Minor and Major Alarms.

Note that the GNSS receiver must initially be tracking more than the configured number of satellites in order for this alarm to be triggered (the alarm is triggered when the receiver falls below the number of Minimum Satellites you specified above).