Cross correlation detection in a satellite navigation receiver

• US 9,864,065 B2
• Filed: 09/08/2013
• Issued: 01/09/2018
• Est. Priority Date: 07/08/2013
• Status: Active Grant

• Current Assignee: Accord Ideation Private Limited
• Original Assignee: Accord Software & Systems Pvt. Ltd.
• Inventors: Rao, Vyasaraj Guru
• Primary Examiner(s): Burke, Sean P
• Application Number:
  US14/020,854
• Publication Number:
  US 20150009065A1
• Time in Patent Office: 1,584 Days
• Field of Search: 34235723
• CPC Class Codes: G01S 19/07 providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
• CPC Class Codes: G01S 19/08 providing integrity information, e.g. health of satellites or quality of ephemeris data
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver
• CPC Class Codes: G01S 19/42 Determining position

Abstract

A method and a system for detecting cross correlation in a satellite navigation receiver (SNR) in real time are provided. The SNR parallelly receives navigation signals from multiple satellites via multiple input channels. The SNR extracts ephemeris data from sub-frames of navigation data of each of the navigation signals. The SNR compares the ephemeris data of each navigation signal with the ephemeris data of another navigation signal. The SNR detects cross correlation between the navigation signals when the ephemeris data comparison results in a match and discards the navigation signal with low signal strength. The SNR also retrieves a ranging code from the sub-frames of navigation data of each navigation signal. The SNR compares the ranging code with a pre-programmed satellite identity code of a corresponding satellite. The SNR detects cross correlation when the code comparison results in a mismatch and discards the navigation signal with the mismatched ranging code.

Claims

1. A method for detecting cross correlation in a satellite navigation receiver in real time, comprising:

providing a system for said detection of said cross correlation in said satellite navigation receiver in real time, said system comprising;

at least one processor;

a navigation signal reception unit;

a non-transitory computer readable storage medium communicatively coupled to said at least one processor and storing modules of said satellite navigation receiver, said at least one processor configured to execute said modules of said satellite navigation receiver, said modules of said satellite navigation receiver comprising a data extraction module, a comparison module and a cross correlation detection module;

receiving navigation signals from a plurality of satellites, by said navigation signal reception unit, wherein said navigation signal reception unit comprises a plurality of input channels, wherein each of said plurality of input channels receives a navigational signal from one of said plurality of satellites, and wherein each of said received navigation signals comprises sub-frames of navigation data;

extracting ephemeris data from said sub-frames of said navigation data received via each of said input channels, by said data extraction module, wherein ephemeris data extracted from said sub-frames of said navigation data received via each of said input channels is stored separately in a database;

comparing ephemeris data extracted from said sub-frames of said navigation data received via each of said input channels with ephemeris data extracted from said sub-frames of said navigation data received via each of other of said input channels, by said comparison module; and

detecting said cross correlation between said received navigation signals, by said cross correlation detection module, when ephemeris data extracted from said sub-frames of said navigation data received via any of said input channels matches with ephemeris data extracted from said sub-frames of said navigation data received via another of said input channels.

2. The method of claim 1, further comprising discarding navigation data of a received navigation signal that has a lower signal strength of two compared navigation signals, whenever result of said comparison of received navigation signals results in a match.

3. The method of claim 1, further comprising verifying integrity of said navigation data in said sub-frames of said navigation data by said satellite navigation receiver for determining accuracy of said navigation data.