Abstract: Methods and systems for cryptographically-secure autonomous detection of spoofed GNSS signals is provided. A method is provided that includes the steps of: generating a cryptographic code, controlling a motion of at least one antenna of a Global Navigation Satellite System (GNSS) receiver system according to the cryptographic code, detecting a plurality of satellite signals during the controlled motion of the at least one antenna, and determining, based on carrier phase variations of the detected plurality of satellite signals, whether the plurality of satellite signals originated from a spoofer transmitter.

Abstract: System and methods for a clock system disciplined to an external reference. In one embodiment, the clock includes a flywheel oscillator controlled by the external reference and a free running holdover oscillator. The holdover oscillator provides increased accuracy during periods of holdover when the external reference is not available. In a further embodiment, the flywheel oscillator is additionally controlled by a phase-locked loop with the holdover oscillator frequency as input, and a control switch for switching the flywheel oscillator to analog control if the phase-locked loop exhibits a fault.

Abstract: System and methods for a clock system disciplined to an external reference. In one embodiment, the clock includes a flywheel oscillator controlled by the external reference and a free running holdover oscillator. The holdover oscillator provides increased accuracy during periods of holdover when the external reference is not available. In a further embodiment, the flywheel oscillator is additionally controlled by a phase-locked loop with the holdover oscillator frequency as input, and a control switch for switching the flywheel oscillator to analog control if the phase-locked loop exhibits a fault.

Abstract: A satellite disseminated time and date code is received and converted into local time signal and displayed. The ground stations scan a frequency spectrum for signals from geosynchronous satellites. Once found, the position and time information from the satellites is used to compute the correct local time.