Method of avoiding near-far interference problems in an array of navigation signal beacons having selected CDMA or GPS-like navigation signals

• US 6,160,837 A
• Filed: 11/21/1996
• Issued: 12/12/2000
• Est. Priority Date: 12/23/1994
• Status: Expired due to Term

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Engelbrecht, Lloyd, Bruno, Ronald, Schuchman, Leonard
• Primary Examiner(s): VO, DON NGUYEN
• Application Number:
  US08/754,406
• Time in Patent Office: 1,482 Days
• Field of Search: 375/200, 375/130, 370/319, 370/320, 370/321, 370/330, 370/335, 370/336, 370/337, 370/342, 370/344, 370/347, 370/436, 370/478, 455/256, 455/257, 455/63, 342/386, 342/419
• US Class Current: 375/130
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01S 1/68 Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
• 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 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04L 27/103 Chirp modulation for spread spectrum techniques H04B1/69
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

A method of avoiding near-far interference problems in a cellular ray of navigation signal beacons having selected CDMA or GPS-like navigation signals. The navigation signals from adjacent navigation signal beacons are pulsed so that adjacent navigation signal beacons do not broadcast navigation signals simultaneously and the multiple frequencies are coordinated in a time divisional multiplex manner. In another aspect, the near-far interference problem is avoided by using multiple frequencies in time division multiplexing and coordinating the use of the multiple frequencies and the time division multiplexing to assure avoidance of the near-far interference problem.

Claims

1. In a cellular array of navigation signal beacons having selected CDMA or GPS-like navigation signals, the method of avoiding near-far interference problems, comprising,

pulsing the navigation signals from adjacent navigation signal beacons so that adjacent navigation beacons do not broadcast navigation signals simultaneously, and

coordinating the broadcasts of the navigation signal beacons in a time-division multiplexed manner.