US 11,994,597 B2
Systems and methods using chip-scale atomic clock to detect spoofed GNSS
Michael Ray Elgersma, Plymouth, MN (US); and Ruth Dagmar Kreichauf, River Falls, WI (US)
Assigned to Honeywell International Inc., Charlotte, NC (US)
Filed by Honeywell International Inc., Charlotte, NC (US)
Filed on Nov. 8, 2021, as Appl. No. 17/521,693.
Claims priority of provisional application 63/135,607, filed on Jan. 9, 2021.
Prior Publication US 2022/0221589 A1, Jul. 14, 2022
Int. Cl. G01S 19/21 (2010.01)
CPC G01S 19/215 (2013.01) 20 Claims
OG exemplary drawing
 
1. A system, comprising:
a Global Navigation Satellite System (GNSS) receiver communicatively coupled to an antenna, wherein the GNSS receiver is configured to receive GNSS signals from GNSS satellites via the antenna, wherein the GNSS receiver is configured to output a GNSS time signal;
a chip-scale atomic clock configured to output a chip-scale atomic clock time signal;
at least one processor coupled to a memory, wherein the at least one processor is communicatively coupled to the GNSS receiver and the chip-scale atomic clock, wherein the at least one processor is configured to:
determine whether a difference between the GNSS time signal and the chip-scale atomic clock time signal exceeds a threshold, wherein the threshold is based on error bounds of the chip-scale atomic clock and increases nonlinearly over time until the chip-scale atomic clock is reinitialized;
when the difference between the GNSS time signal and the chip-scale atomic clock time signal does not exceed the threshold, estimate a system time signal using the GNSS time signal or the GNSS time signal and the chip-scale atomic clock time signal;
when the difference between the GNSS time signal and the chip-scale atomic clock time signal exceeds the threshold, estimate a system time signal without using the GNSS time signal and output an alarm indicating that GNSS spoofing has been detected; and
output the system time signal or a signal indicative of a system time error.