Multi-constellation GNSS integrity check for detection of time signal manipulation
First Claim
1. A time distribution device for receiving and distributing a time signal, comprising:
- a time signal receiver suitable for concurrently receiving a plurality of Global Navigation Satellite System (GNSS) time signals including a first time signal from a first plurality of satellites of a first system of GNSS satellites and receiving a second time signal from a second plurality of satellites of a second system of GNSS satellites, the first system of GNSS satellites being different from the second system of GNSS satellites;
a time quality module configured to;
receive the first and second time signals from the time signal receiver;
calculate a phase error between the first and second time signals, wherein the phase error comprises a time difference between the first and second time signals; and
detect manipulation of one of the first and second time signals using the phase error; and
a time output for distributing a time signal to a receiving device separate from the time distribution device.
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Accused Products
Abstract
The present application discloses detecting manipulation of GNSS signals using a second time source. If two or more GNSS constellation signals are being detected, the phase error between the GNSS constellation signals may be monitored. When the phase error drifts, then manipulation is determined. The integrity of a GNSS constellation signal may be monitored using an internal time source such as a crystal oscillator by monitoring a slope of the free running counter at the detected rising edges of a pulse-per-second signal from the GNSS constellation. If more than two GNSS constellations are monitored, a voting scheme may be used to determine the manipulated GNSS constellation.
99 Citations
19 Claims
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1. A time distribution device for receiving and distributing a time signal, comprising:
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a time signal receiver suitable for concurrently receiving a plurality of Global Navigation Satellite System (GNSS) time signals including a first time signal from a first plurality of satellites of a first system of GNSS satellites and receiving a second time signal from a second plurality of satellites of a second system of GNSS satellites, the first system of GNSS satellites being different from the second system of GNSS satellites; a time quality module configured to; receive the first and second time signals from the time signal receiver; calculate a phase error between the first and second time signals, wherein the phase error comprises a time difference between the first and second time signals; and detect manipulation of one of the first and second time signals using the phase error; and a time output for distributing a time signal to a receiving device separate from the time distribution device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for receiving and distributing a time signal, comprising:
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a time distribution device concurrently receiving a plurality of Global Navigation Satellite System (GNSS) time signals including a first time signal from a first plurality of satellites of a first system of GNSS satellites and a second time signal from a second plurality of satellites of a second system of GNSS satellites, the first system of GNSS satellites being different from the second system of GNSS satellites; calculating a phase error between the first and second time signals, wherein the phase error comprises a time difference between the first and second time signals; detecting manipulation of one of the first and second time signals using the phase error; and distributing a time signal to a receiving device separate from the time distribution device. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A time distribution device for receiving a plurality of Global Navigation Satellite System (GNSS) signals and distributing a time signal, comprising:
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a time signal receiver suitable for concurrently receiving a plurality of GNSS time signals including a first time signal from a first plurality of satellites of a first system of GNSS satellites and receiving a second time signal from a second plurality of satellites of a second system of GNSS satellites, the first system of GNSS satellites being different from the second system of GNSS satellites; a time quality module configured to; receive the first and second time signals from the time signal receiver; determine a phase error between the first and second time signals, wherein the phase error comprises a time difference between the first and second time signals; and detect manipulation of one of the first and second signals using the phase error by comparing the determined phase error with a manipulation threshold and finding manipulation in response to the phase error exceeding the manipulation threshold, the manipulation threshold based on historical phase error data; and a time output for distributing a time signal to a receiving device separate from the time distribution device.
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Specification