Patent ID: 11906634
Assignee: NOVATEL INC.
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 9:
10. A receiver, comprising:
a first antenna and a second antenna configured to receive signals;
a processor configured to:
perform a carrier phase authentication procedure on the signals, wherein when performing the carrier phase authentication, the processor is further configured to:
measure a first double difference of a first carrier phase measurement of the signals;
determine whether a first value corresponding to the first double difference of the first carrier phase measurement exceeds a predefined carrier phase threshold;
in response to determining that the first value of the first double difference of the first carrier phase measurement exceeds the predefined carrier phase threshold, determine that the signals are authentic navigation signals; and
in response to determining that the first double difference of the first carrier phase measurement does not exceed the predefined carrier phase threshold:
initiating an observation window that lasts a predefined amount of time after determining that the first value of the first double difference does not exceed the predefined carrier phase threshold,
determining that the signals are the authentic navigation signals if (1) a signal difference variance value indicates that a current single difference, obtained during the observation window, it time variant in relation to a previous single difference of (2) a double difference variance value indicates that a current double difference, obtained during the observation window, is time variant in relation to a previous double difference, and
determining that the signals are spoofing signals if (1) the observation window has ended, (2) the single difference variance value indicates that the current single difference is not time variant in relation to the previous single difference, and (3) the double difference variance value indicates that the current double difference is not time variant in relation to the previous double difference.