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Troubleshooting GNSS Reception

If NetClock reports Holdover and/or Time Sync Alarms caused by insufficient GNSS reception:

When a GNSS receiver is installed in NetClock, a GNSS antenna can be connected to the rear panel antenna connector via a coax cable to allow it to track several satellites in order for GNSS to be an available input reference. Many factors can prevent the ability for the GNSS receiver to be able to track the minimum number of satellites.

With the GNSS antenna installed outdoors, with a good view of the sky (the view of the sky is not being blocked by obstructions), NetClock will typically track between 5-10 satellites (the maximum possible is 12 satellites). If the antenna’s view of the sky is hindered, or if there is a problem with the GNSS antenna installation, the GNSS receiver may only be able to a few satellites or may not be able to track any satellites at all.

When GNSS is a configured time or 1PPS input reference, if the GNSS receiver is unable to continuously track at least four satellites (until the initial GNSS survey has been completed) or at least one satellite thereafter, the GNSS signal will not be considered valid. If no other inputs are enabled and available, NetClock may not initially be able to go into time sync. Or, if GNSS reception is subsequently lost after initially achieving time sync, NetClock will go into the Holdover mode. If GNSS reception is not restored before the Holdover period expires (and no other input references become available) NetClock will go out of sync. The GNSS reception issue needs to be troubleshot in order to regain time sync.

For additional information on troubleshooting GNSS reception issues with NetClock, please refer to the GNSS Reception Troubleshooting Guide, available here on the Spectracom website.