In-wire selective active cancellation system

• US 5,126,681 A
• Filed: 10/16/1989
• Issued: 06/30/1992
• Est. Priority Date: 10/16/1989
• Status: Expired due to Term

• Current Assignee: Noise Cancellation Technologies, Inc. (NCT Group, Inc.)
• Original Assignee: Noise Cancellation Technologies, Inc. (NCT Group, Inc.)
• Inventors: Gardner, John W., Ziegler, Eldon W. Jr.
• Primary Examiner(s): Callahan, Timothy P.
• Application Number:
  US07/421,759
• Time in Patent Office: 988 Days
• Field of Search: 307/529, 307/520, 307/521, 328/165, 328/167, 381/71, 381/94
• US Class Current: 327/552
• CPC Class Codes: H03H 21/0001 Analogue adaptive filters
• CPC Class Codes: H04B 3/00 Line transmission systems combined with near-field transmission systems H04B5/00

Abstract

An in wire active cancelling system cancels undesirable repetitive signal components from a primary electronics signal controlling desired intelligent signal components and undesirable repetitive signal components. The primary electronic signal is fed as an input to an electronic mixer. A second input to the electronic mixer is a repetitive cancelling signal which is applied by the mixer to cancel the undesirable repetitive signal component from the primary signal without interfering with passage of the primary signal intelligent signal components. The repetitive cancellation signal is developed from a residual signal developed by the mixer and a timing signal obtained from a timing signal generator.

Claims

1. Active cancellation system for cancelling undesirable repetitive signal components from a primary electronic signal containing desired intelligent signal components and undesirable repetitive signal components, comprising:

an electronic mixer producing a mixer output signal and a residual signal representation of the residual error in the mixer output signal,

primary signal input means conducting the primary electronic signal as an input signal to the electronic mixer, a timing generator generating a timing signal related to the frequencies of the undesired repetitive signal components,

selective active cancellation controller means receiving said timing signal from said timing signal generator and developing a repetitive cancellation signal for supply as a second input signal to the electronic mixer, and

operator interface control means operatively connected to said selective active cancellation controller means for accommodating control of a range of frequencies within which the harmonics of desired fundamental frequency are to be cancelled,

wherein said electronic mixer includes means for combining the primary electronic signal and the cancelling signal to produce the mixer output signal, the cancelling signal cancelling the undesirable repetitive signal components from the primary electronic signal while permitting passage of the desired intelligent signal components as the mixer output signal.

2. Active cancellation system for cancelling undesirable repetitive signal components from a primary electronic signal containing desired intelligent signal components and undesirable repetitive signal components, comprising:

an electronic mixer producing a mixer output signal and a residual signal representation of the residual error in the mixer output signal,

primary signal input means conducting the primary electronic signal as an input signal to the electronic mixer, and a timing generator generating a timing signal related to the frequencies of the undesired repetitive signal components,

selective active cancellation controller means receiving said timing signal from said timing signal generator and developing a repetitive cancellation signal for supplying a repetitive cancelling signal as a second input signal to the electronic mixer, and

a primary signal input level shifter, operatively connected between said primary signal input means and said mixer, for shifting the level of said primary electronic signal so that the level of the undesirable repetitive signal components thereof match the level of the repetitive cancelling signal supplied to the electronic mixer,

wherein said electronic mixer includes means for combining the primary electronic signal and the cancelling signal to produce the mixer output signal, the cancelling signal cancelling the undesirable repetitive signal components from the primary electronic signal while permitting passage of the desired intelligent signal components as the mixer output signal.

3. Active cancellation system for cancelling undesirable repetitive signal components from a primary electronic signal containing desired intelligent signal components and undesirable signal components, comprising:

an electronic mixer producing a mixer output signal and a residual signal representation of the residual error in the mixer output signal,

primary signal input means conducting the primary electronic signal as an input signal to the electronic mixer, and a timing generator generating a timing signal related to the frequencies of the undesired repetitive signal components,

selective active cancellation controller means receiving said timing signal from said timing signal generator and developing a repetitive cancellation signal for supplying a repetitive cancelling signal as a second input signal to the electronic mixer, and

a primary signal output level shifter, operatively connected to said electronic mixer and receiving said mixer output signal, for shifting the level of the primary output

wherein said electronic mixer includes means for combining the primary electronic signal and the cancelling signal to produce the mixer output signal, the cancelling signal cancelling the undesirable repetitive signal components from the primary electronic signal while permitting passage of the desired intelligent signal components as the mixer output signal.

4. Active cancellation system for cancelling undesirable repetitive signal components from a primary electronic signal containing desired intelligent signal components and undesirable repetitive signal components, comprising:

an electronic mixer producing a mixer output signal and a residual signal representation of the residual error in the mixer output signal,

primary signal input means conducting the primary electronic signal as an input signal to the electronic mixer, a timing generator generating a timing signal related to the frequencies of the undesired repetitive signal components,

selective active cancellation controller means receiving said timing signal from said timing signal generator and developing a repetitive cancellation signal for supply as a second input signal to the electronic mixer,

and a residual error signal level shifter operatively connected between said mixer and said selective active cancellation controller for shifting the residual signal level to a required level for its input to the selective active cancellation controller,

wherein said electronic mixer includes means for combining the primary electronic signal and the cancelling signal to produce the mixer output signal, the cancelling signal cancelling the undesirable repetitive signal components from the primary electronic signal while permitting passage of the desired intelligent signal components as the mixer output signal.