GNSS spoofing is detected, GP-Blocker disconnects the GNSS antenna from the time server antenna port, and switches to “Hold Over” mode. This maintains the high accuracy of the PPS signal under GNSS spoofing.

The GP-Blocker is an RF switch with a remarkable 110 dB of RF isolation level and an embedded L-band GNSS jammer. The maximum output power of a standard GNSS antenna can reach up to 5 dBm. This may ensue in the case of military-grade spoofing or even when a low-power SDR is near the GNSS antenna. The typical receiver sensitivity level is about minus 145 dBm in a tracking mode. Hence, to block spoofing, an RF switch with an isolation level of at least 150 dB is necessary. However, commercially available switches do not provide more than 90 dB. And even if two switches are used, the required blocking level will not be accomplished due to RF cable leakage.

The GP-Blocker with a high level of RF isolation combined with the built-in GNSS jammer can block the most powerful military-grade GNSS spoofing.