Adaptive noise canceling system and FM radio communication receiver using said system

• US 5,710,996 A
• Filed: 05/26/1995
• Issued: 01/20/1998
• Est. Priority Date: 09/30/1994
• Status: Expired due to Term

• Current Assignee: ICOM Incorporated
• Original Assignee: ICOM Incorporated
• Inventors: Sun, Weimin, Kajimoto, Shigeki
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Kincaid, Lester G.
• Application Number:
  US08/452,282
• Time in Patent Office: 970 Days
• Field of Search: 455/205, 455/296, 455/303, 455/304, 455/305, 455/306, 455/307, 455/309
• US Class Current: 455/309
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising

Abstract

An adaptive noise canceling system for improving a S/N ratio and clarity of a output signal includes a delay for delaying the input signal X(j) by a fixed time delay a, a filter for filtering the delayed signal D(j), a subtracter for subtracting the filtered signal Y(j) from the input signal X(j), a coefficients adjuster for adaptively adjusting coefficients of the filter using a least-means-square (LMS) algorithm, a level adjuster for adjusting a level of an error signal ε(j) which is obtained by subtracting the filtered signal Y(j) from the input signal X(j), and an adder for adding the level adjusted signal ε(j) to the filtered signal Y(j).

Claims

1. A frequency modulation radio communication receiver using an adaptive noise canceling system for improving clarity of an output signal, said receiver comprising:

a radio receiving means for receiving a radio frequency signal;

a demodulating means for demodulating the radio frequency signal, an output of said demodulating means being a signal X(j);

an adaptive noise canceling system for improving a S/N ratio and clarity of an output signal Z(j);

an audio frequency signal outputting means for outputting an audio signal of the output signal Z(j) of said adaptive noise canceling system;

wherein said adaptive noise canceling system includes;

a delaying means for delaying the demodulated signal X(j) by a fixed time delay δ

, an output of said delaying means being a signal D(j);

a filtering means, having as an input the signal D(j), for filtering the delayed signal D(j), an output of said filtering means comprising a signal Y(j);

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

(j);

a coefficients adjusting means, having as an input the error signal ε

(j), for adaptively adjusting coefficients of said filtering means using a least-means-square (LMS) algorithm, an output of said coefficients adjusting means being the coefficients of said filtering means;

a level adjusting means, having as an input the error signal ε

(j), for adjusting a level of the error signal ε

(j), an output of said level adjusting means being a signal ε

'"'"'(j);

an adding means for adding the level adjusted signal ε

'"'"'(j) to the output signal Y(j) of said filtering means, an output of the adding means being the output signal Z(j).

2. A frequency modulation radio communication receiver using an adaptive noise canceling system for improving clarity of an output signal, said receiver comprising:

a radio receiving means for receiving a radio frequency signal;

a demodulating means for demodulating the radio frequency signal, an output of said demodulating means being a signal X(j);

an adaptive noise canceling system for improving a S/N ratio and clarity of an output signal Z(j);

an audio frequency signal outputting means for outputting an audio signal of the output signal Z(j) of said adaptive noise canceling system;

wherein said adaptive noise canceling system includes;

a delaying means for delaying the demodulated signal X(j) by a fixed time delay δ

, an output of said delaying means being a delayed signal D(j);

a filtering means, having as an input the delayed signal D(j), for filtering the delayed signal D(j), an output of said filtering means comprising a signal Y(j);

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

(j);

a coefficients adjusting means, having as an input the error signal ε

(j), for adaptively adjusting coefficients of said filtering means using a least-means-square (LMS) algorithm, an output of said coefficients adjusting means being the coefficients of said filtering means;

a level adjusting means, having as an input the demodulated signal X(j), for adjusting a level of the demodulated signal X(j), an output of said level adjusting means being a signal X'"'"'(j);

an adding means having as inputs the signals Y(j) and X'"'"'(j), for adding the signal X'"'"'(j) to the signal Y(j), an output of said adding means being the output signal Z(j).

3. A frequency modulation radio communication receiver using an adaptive noise canceling system for improving clarity of an output signal, said receiver comprising:

a radio receiving means for receiving a radio frequency signal;

a demodulating means for demodulating the radio frequency signal, an output of said demodulating means being a signal X(j);

an adaptive noise canceling system for improving a S/N ratio and clarity of an output signal Z(j);

an audio frequency signal outputting means for outputting an audio signal of the output signal Z(j) of said adaptive noise canceling system;

wherein said adaptive noise canceling system includes;

a delaying means for delaying the demodulated signal X(j) by a fixed time delay δ

, an output of said delaying means being a signal D(j);

a filtering means, having as an input the delayed signal D(j), for filtering the delayed signal D(j), an output of said filtering means being a signal Y(j);

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

(j);

a coefficients adjusting means, having as an input the error signal δ

(j), for adaptively adjusting coefficients of said filtering means using a least-means-square (LMS) algorithm, an output of said coefficients adjusting means being the coefficients of said filtering means;

a level adjusting means, having as an input the delayed signal D(j), for adjusting a level of the delayed signal D(j), an output of said level adjusting means being a signal D'"'"'(j);

an adding means, having as inputs the signals Y(j) and D(j), for adding the signal D'"'"'(j) to the signal Y(j), an output of said adding means being the output signal Z(j).