Adaptive line enhancer

• US 4,238,746 A
• Filed: 03/20/1978
• Issued: 12/09/1980
• Est. Priority Date: 03/20/1978
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Widrow, Bernard, Zeidler, James R., Hearn, Robert H., McCool, John M., Chabries, Douglas M.
• Primary Examiner(s): Nussbaum, Marvin L.
• Application Number:
  US05/888,266
• Time in Patent Office: 995 Days
• Field of Search: 333/17 R, 333/17 L, 333/70 R, 333/70 T, 333/28 R, 333/18, 333/29, 333/165, 333/166, 333/138-139, 333/174, 364/824, 364/862, 364/825, 364/819, 307/221 R, 307/221 C, 307/221 D
• US Class Current: 333/166
• CPC Class Codes: G01S 13/52 Discriminating between fixed and moving objects or between objects moving at different speeds
• CPC Class Codes: G11C 27/00 Electric analogue stores, e.g. for storing instantaneous values
• CPC Class Codes: H03H 21/00 Adaptive networks

Abstract

An input signal X(j) is fed directly to the positive port of a summing function and is simultaneously fed through a parallel channel in which it is delayed, and passed through an adaptive linear transversal filter, the output being then subtracted from the instantaneous input signal X(j). The difference, X(j)-Y(j), between these two signals is the error signal ε(j). ε(j) is multiplied by a gain μ and fed back to the adaptive filter to readjust the weights of the filter. The weights of the filter are readjusted until ε(j) is minimized according to the recursive algorithm: ##EQU1## where the arrow above a term indicates that the term is a signal vector. Thus, when the means square error is minimized, W.sub.(j+1) =W.sub.(j), and the filter is stabilized.

Claims

1. An adaptive line enhancer for spectral line enhancing, generally in an environment where significant noise is present, comprising:

means for delaying an input signal X(j) by a fixed time delay δ

;

weighted means, whose input is connected to the output of the delaying means, for adaptively filtering the delayed signal, using a least-means-square (LMS) algorithm, the output of the filtering means comprising a signal Y(j);

means, having as inputs the signals X(j) and Y(j), for subtracting the signal Y(j) from X(j), the output of the subtracting means being the error signals ε

(j);

means, having as an input the signal ε

(j), for multiplying the signal by a gain μ

, the output of the multiplying means being fed back to the filtering means, to cause the weights of the weighted means to be readjusted in a manner to minimize the difference between the signal X(j) and the signal Y(j), thereby minimizing the error signal ε

(j), wherein;

the weighted filtering means comprises a transversal filter.

2. The adaptive line enhancer, according to claim 1, wherein:

the transversal filter is a digital filter.

3. The adaptive line enhancer according to claim 2, wherein:

the digital filter comprises shift registers.