Adaptive equalizer and adaptive diversity equalizer

• US 5,644,597 A
• Filed: 04/22/1996
• Issued: 07/01/1997
• Est. Priority Date: 09/10/1993
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ueda, Koji
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): GHAYOUR, MOHAMMAD H
• Application Number:
  US08/636,061
• Time in Patent Office: 435 Days
• Field of Search: 375/229, 375/230, 375/231, 375/232, 375/233
• US Class Current: 375/232
• CPC Class Codes: H04B 7/082 selecting best antenna path
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2025/03541 Switching between domains, e.g. between time and frequency
• CPC Class Codes: H04L 2025/03573 between recursive and non-recursive
• CPC Class Codes: H04L 25/03038 with a non-recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence

Abstract

An adaptive equalizer which has a decision feedback adaptive equalizer and linear adaptive equalizer. A delay measuring circuit recieves an incoming signal and determines a multipath propagation characteristic for a channel. The delay measuring circuit includes a correlator which outputs a signal based upon a direct wave and a delay wave. Selection of the decision feedback adaptive equalizer or the linear adaptive equalizer is based upon the maximum delay time of the delay wave as determiend by the delay measuring circuit.

Claims

1. An adaptive equalizer comprising:

a decision feedback adaptive equalizer including an equalization filter part, a decision part having an input connected to the output of said equalization filter part and a tap-coefficient-update part which updates the tap coefficients of said equalization filter part in accordance with a tap-coefficient update algorithm, said equalization filter part having two linear transversal filters, that is, a feedforward filter and a feedback filter;

a linear adaptive equalizer including an equalization filter part having a linear transversal filter, a decision part and a tap-coefficient-update part which updates the tap coefficients of said equalization filter part in accordance with a tap-coefficient update algorithm;

a delay measuring circuit for measuring a multipath propagation characteristic of a channel; and

means for activating either said decision feedback adaptive equalizer or said linear adaptive equalizer based on the result of measurement by said delay measuring circuit.