There are two forms of GPS signals that can be received, civilian and military. Military GPS uses encrypted GPS signals, and requires special receivers that support the use of military GPS, while civilian GPS does not use any form of encrypted signals. Additionally, military GPS is restricted by the U.S. Government and requires authorisation to use it.
Tekron clocks use civilian GPS, where encryption of the GPS signals is not available, meaning that Tekron do not have any encryption or authentication to determine valid GPS signals. Although we do not use the encrypted GPS, our clocks will perform internal checking of valid GPS signals. If the clock detects an invalid GPS signal, then the clock would temporarily stop trusting the GNSS source and will either go into a Holdover state or synchronise to the next best time sync source, based off the Clock Source Priorities configuration setting.
Our GNSS receiver has it's own proprietary firmware, written and updated by the GNSS receiver manufacturer. The GNSS receiver firmware includes anti-spoofing and jamming features, which we do not have detailed information on. Tekron's firmware enables the GNSS manufacturers anti-spoofing and jamming mode by default.