Detection of manipulated satellite time signals
First Claim
Patent Images
1. A Global Navigational Satellite System (GNSS) receiver for providing a time signal to consuming devices, comprising:
- an antenna for receiving one or more GNSS signals from one or more GNSS satellites;
a processor;
a communications interface for communicating the time signal to the consuming devices; and
a non-transitory computer-readable storage medium comprising instructions that enable the processor to;
for a particular GNSS satellite of the one or more GNSS satellites, determine event times for a repeating event;
for the particular GNSS satellite, calculate an expected next event time from the determined event times;
for the particular GNSS satellite, determine an acceptable signal strength pattern for each event, wherein the calculated expected next event time comprises a time window based on the acceptable signal strength pattern;
detect a next event time for the particular GNSS satellite;
calculate a difference between the detected next event time with the calculated expected next event time for the particular GNSS satellite; and
indicate compromised signal integrity when the difference exceeds a predetermined threshold.
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Abstract
Disclosed herein is a system for detecting manipulation of a GNSS signal and mitigating against such manipulation. A GNSS receiver receives GNSS signals from a plurality of GNSS satellites, and calculates event times for each GNSS satellite. The GNSS receiver then compares a next event time for a particular GNSS satellite with an expected next event time for the particular GNSS satellite. If the difference between the expected next event time and the next event times exceeds a predetermined threshold, then the GNSS receiver indicates that signal integrity may be compromised.
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Citations
20 Claims
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1. A Global Navigational Satellite System (GNSS) receiver for providing a time signal to consuming devices, comprising:
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an antenna for receiving one or more GNSS signals from one or more GNSS satellites; a processor; a communications interface for communicating the time signal to the consuming devices; and a non-transitory computer-readable storage medium comprising instructions that enable the processor to; for a particular GNSS satellite of the one or more GNSS satellites, determine event times for a repeating event; for the particular GNSS satellite, calculate an expected next event time from the determined event times; for the particular GNSS satellite, determine an acceptable signal strength pattern for each event, wherein the calculated expected next event time comprises a time window based on the acceptable signal strength pattern; detect a next event time for the particular GNSS satellite; calculate a difference between the detected next event time with the calculated expected next event time for the particular GNSS satellite; and indicate compromised signal integrity when the difference exceeds a predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for detecting manipulation of satellite signals comprising:
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recording events associated with each of one or more Global Navigational Satellite System (GNSS) satellites by a GNSS receiver; generating, by the GNSS receiver, an expected time for a next event based on the recorded events; determining an acceptable signal strength pattern for the next event, wherein the generated expected time comprises a time window based on the acceptable signal strength pattern for the next event; detecting the next event; comparing an actual time of the detected next event with the expected time for the next event; and indicating a compromised GNSS signal in response to determining that the actual time of the detected event varies from the expected time for the next event by a defined threshold. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method comprising:
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recording events associated with each of one or more Global Navigational Satellite System (GNSS) satellites by a GNSS receiver; generating, by the GNSS receiver, an expected time for a next event based on the recorded events; determining, by the GNSS receiver, an acceptable signal strength pattern for the next event, wherein the generated expected time for the next event comprises a time window based on the acceptable signal strength pattern for the next event; comparing an actual time of the next event with the expected time for the next event; and distributing a precision time reference based on a signal from the one or more GNSS satellites, in response to determining that the actual time of the detected event is within a threshold time of the expected time for the next event. - View Dependent Claims (18, 19)
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20. A Global Navigational Satellite System (GNSS) receiver for providing a time signal to consuming devices, comprising:
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an antenna for receiving one or more GNSS signals from one or more GNSS satellites; a processor; a communications interface for communicating the time signal to the consuming devices; and a non-transitory computer-readable storage medium comprising instructions that enable the processor to; for a particular GNSS satellite of the one or more GNSS satellites, determine event times for a repeating event; for the particular GNSS satellite, calculate an expected next event time from the determined event times; for the particular GNSS satellite, determine an acceptable signal strength pattern for each event, detect a next event time for the particular GNSS satellite; calculate a signal strength difference between the signal strength pattern for the particular GNSS satellite during the event and the acceptable signal strength pattern for the event; calculate a time difference between the detected next event time and the calculated expected next event time for the particular GNSS satellite; and indicate compromised signal integrity when one or more of the time difference exceeds a predetermined threshold, and the signal strength difference exceeds a predetermined threshold.
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Specification