Today concerns arise around GPS spoofing capability which mean building a system that creates signals that would appear to a receiver to be from GPS satellites. Transmitting these false GPS signals to receivers may cause them to lock onto the false signals instead of the authentic satellite signals. This is called GPS spoofing.
Modern multi constellation GNSS receiver as the one embedded within the Timelink products are capable of detecting unconsistent satellite data and exclude them from the time calculation which makes it more difficult to spoof.
Nevertheless critical infrastructure tend not to rely on the GPS signal while critical synchronisation is required. Instead they rely on the internal pilot of their synchronisation system which garantee a low enough hold over to maintain the required accuracy.
This is made possible on the latest Timelink product line by excluding the synchronisation source (GNSS in our case) and let the disciplined Time & Frequency generator run on its internal pilot. The synchronisation source can then be included again once the mission critical events have been passed.
It is also recommended to monitor the time and the internal to GNSS PPS deviation by the remote control. Any spoofing activity would lead to a jump in time and PPS deviation which should be considered a critical alert.