Detecting and removing spoofing signals

Patent metadata

Field	Value
Publication number	US-2016146944-A1
Application number	US-201414551646-A
Country	US
Kind code	A1
Filing date	Nov 24, 2014
Priority date	Nov 24, 2014
Publication date	May 26, 2016
Grant date	—

Abstract

A method for detecting and removing spoofing signals may include receiving, by a navigation or communications device, a radio frequency (RF) signal and performing an anti-spoofing assessment to detect a presence of a spoofing signal associated with the RF signal. The method may additionally include generating a replica of the spoofing signal in response to the spoofing signal being detected and subtracting the replica of the spoofing signal from the RF signal to provide a residual non-spoofed signal. The method may further include decoding the residual non-spoofed signal by the navigation or communications device.

First claim

What is claimed is:

1 . A method for detecting and removing spoofing signals, comprising:
receiving, by a navigation or communications device, a radio frequency (RF) signal; performing, by the navigation or communications device, an anti-spoofing assessment to detect a presence of a spoofing signal associated with the RF signal; generating, by the navigation or communications device, a replica of the spoofing signal in response to the spoofing signal being detected; subtracting, by the navigation or communications device, the replica of the spoofing signal from the RF signal to provide a residual non-spoofed signal; and decoding, by the navigation or communications device, the residual non-spoofed signal.

2 . The method of claim 1 , wherein performing the anti-spoofing assessment comprises:
determining a measured angle of arrival of the RF signal by receiving the RF signal using an array of antennas; determining a predicted angle of arrival of the RF signal based at least on a predicted location of a source of the RF signal relative to the navigation or communications device; comparing the measured angle of arrival of the RF signal and the predicted angle of arrival of the RF signal; and detecting the spoofing signal in response to the measured angle of arrival and the predicted angle of arrival not being approximately equal each other.

3 . The method of claim 1 , wherein performing the anti-spoofing assessment comprises:
determining a measured angle of arrival of the RF signal by using an array of antennas to receive the RF signal; determining a predicted angle of arrival of the RF signal based on ephemeris data for a particular navigation satellite from which the RF signal is received; comparing the measured angle of arrival of the RF signal and the predicted angle of arrival of the RF signal; and detecting the spoofing signal in response to the measured angle of arrival and the predicted angle of arrival not being approximately equal each other.

4 . The method of claim 1 , wherein the spoofing signal comprises a counterfeit signal corresponding to a navigation code sequence from a particular navigation satellite, and wherein generating the replica of the spoofing signal comprises generating a cancellation waveform for the navigation code sequence of the particular navigation satellite.

5 . The method of claim 4 , wherein generating the cancellation waveform for the navigation code sequence of the particular navigation satellite comprises a product of an on-board replica of the navigation code sequence of the particular navigation satellite and a normalizing projection factor.

6 . The method of claim 4 , further comprising performing an iterative process to remove the spoofing signal in response to a magnitude of the spoofing signal not being known.

7 . The method of claim 6 , wherein performing the iterative process comprises performing the iterative process until a cross-correlation of a lagged and frequency shifted coarse acquisition pseudorandom noise code for the particular satellite is reduced to a level of correlation noise.

8 . The method of claim 6 , further comprising removing a multipath spoofing signal by performing the iterative process.

9 . The method of claim 1 , wherein receiving the RF signal comprises receiving a plurality of RF signals, each RF signal being received from a respective one of a plurality of GPS satellites, the method further comprising identifying a set of attributes of each RF signal, the set of attributes of each RF signal comprising a coarse acquisition pseudorandom noise code sequence (C/A PRN) for the respective one of the plurality of GPS satellites, a modulation for the C/A PRN, a time lag of the RF signal, and a Doppler shift of the RF signal.

10 . The method of claim 9 , wherein receiving the RF signal comprises receiving a plurality of RF signals, each RF signal being received from a respective one of a plurality of GPS satellites and each RF signal comprising a coarse acquisition pseudorandom noise code sequence (C/A PRN), and wherein generating the replica of the spoofing signal comprises:
removing the Doppler shift from each RF signal; correlating the C/A PRNs from each of the plurality of GPS satellites; adjusting the time lag of each RF signal; generating a cancellation waveform for the spoofing signal, the spoofing signal being a counterfeit signal corresponding to the RF signal from a particular GPS satellite being spoofed, wherein the cancellation waveform for the spoofing signal comprises a product of an on-board replica of the C/A PRN of the particular GPS satellite being spoofed and a normalizing projection factor; and performing an iterative process to remove any residual spoofing signal components and any spoofing signal multipath components.

11 . A method for detecting and removing a spoofing signal, comprising:
receiving, by a navigation device, an RF signal from each of a plurality of navigation satellites, each RF signal comprising a navigation code; performing, by the navigation device, an anti-spoofing assessment to detect a presence of a spoofing signal of at least one of the RF signals; generating, by the navigation device, a replica of the spoofing signal in response to detecting the spoofing signal of at least one of the RF signals; subtracting, by the navigation device, the replica of the spoofing signal from the RF signals received from each of the plurality of navigation satellites to provide a residual non-spoofed signal; and decoding, by the navigation device, the residual non-spoofed signal.

12 . The method of claim 11 , wherein performing the anti-spoofing assessment comprises:
determining a measured angle of arrival of each RF signal by receiving the RF signals using an array of antennas; determining a predicted angle of arrival of each RF signal based on ephemeris data for each satellite from which the RF signals are received; comparing the measured angle of arrival of each RF signal and the predicted angle of arrival of each RF signal; and detecting the spoofing signal in response to the measured angle of arrival and the predicted angle of arrival not being approximately equal each other.

13 . The method of claim 11 , further comprising identifying a set of attributes associated with each RF signal received by the navigation device, the set of attributes associated with each RF signal comprising the navigation code, a modulation for the navigation code, a time lag of the RF signal, and a Doppler shift of the RF signal.

14 . The method of claim 13 , wherein generating the replica of the spoofing signal comprises:
removing the Doppler shift from each RF signal; correlating the navigation code from each navigation satellite; adjusting a time lag of each RF signal; generating a cancellation waveform for the spoofing signal, the spoofing signal being a counterfeit signal corresponding to the RF signal from a particular navigation satellite being spoofed, wherein the cancellation waveform for the spoofing signal comprises a product of an on-board replica of the navigation code of the particular navigation satellite being spoofed and a normalizing projection factor; and performing an iterative process to remove any residual spoofing signal components and any multipath spoofing signals.

15 . A navigation/communications device, comprising:
a signal conditioning and digitization module configured to receive an RF signal and condition and digitize the RF signal; a signal processor for processing the digitized RF signal; a spoofing detector configured for performing an anti-spoo

Assignees

• Boeing Co

Inventors

• Geren William Preston
• Goodson Anthony

Classifications

• H04K3/228

  Elimination in the received signal of jamming or of data corrupted by jamming (interference suppression in receivers H04B1/10) · CPC title

• G01S19/215 Primary

  issues related to spoofing · CPC title

• H04K2203/32

  including a particular configuration of antennas · CPC title

• G01S7/36

  Means for anti-jamming {, e.g. ECCM, i.e. electronic counter-counter measures} · CPC title

• H04K3/65

  using deceptive jamming or spoofing, e.g. transmission of false signals for premature triggering of RCIED, for forced connection or disconnection to/from a network or for generation of dummy target signal · CPC title