Method and apparatus for separating signals transmitted over a waveguide

• US 6,535,666 B1
• Filed: 01/18/2000
• Issued: 03/18/2003
• Est. Priority Date: 06/02/1995
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: Dogan, Mithat Can, Stearns, Stephen Deane
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): TAKAOKA, DEAN O
• Application Number:
  US09/484,567
• Time in Patent Office: 1,155 Days
• Field of Search: 333/125, 333/122, 333/114, 333/108, 333/137, 333/239, 333/248, 385/12, 385/31, 359/127
• US Class Current: 385/31
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14
• CPC Class Codes: G06F 2218/22 Source localisation; Inverse modelling
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04L 25/03993 Noise whitening

Abstract

Method and apparatus for separating signals transmitted over a waveguide using different propagation modes in overlapping frequency bands. The signals are received at an array of probes installed in an operative relationship to the waveguide, and are separated using a recovery system based on cumulants of the fourth or higher even order.

Claims

1. Communication apparatus for transmitting and receiving signals over a waveguide using different propagation modes in spectrally-overlapping frequency bands, the apparatus comprising:

a waveguide serving as a signal transmission medium;

a plurality of signal couplers for injecting modulated signals onto the waveguide in different electromagnetic propagation modes that are spectrally-overlapping;

a plurality of signal probes forming a probe array at one or more places in the waveguide separated from the signal couplers, such that the original propagation modes are subject to scrambling and distortion as a result of physical irregularities in the transmission medium; and

a recovery system coupled to the signal probes, to effect recovery and separation of the signals received at the signal probes, using cumulant computations based on cumulants of the fourth or higher even order.

2. A method of separating signals transmitted over a waveguide using different propagation modes in overlapping frequency bands, the method comprising the steps of:

generating multiple signals in overlapping frequency bands, modulated by respective information signals using modulation schemes that may be the same for all of the multiple signals;

transmitting the multiple modulated signals onto an electromagnetic waveguide, each signal being transmitted in a different propagation mode;

receiving the signals at an array of probes installed in an operative relationship to the waveguide; and

separating the received signals using a recovery system based on cumulants of the fourth or higher even order.