SUPPRESSION OF A PHASE-SENSITIVE SPECTRAL COMPONENT FROM A SIGNAL

• US 3,633,117 A
• Filed: 07/29/1970
• Issued: 01/04/1972
• Est. Priority Date: 07/29/1970
• Status: Expired due to Term

• Current Assignee: ITT Corporation (ITT, Inc.)
• Original Assignee: Robert A. Reilly Jr
• Inventors: Reilly, Robert A. Jr.
• Primary Examiner(s): Krawczewicz, Stanley T.
• Application Number:
  US05/059,218
• Time in Patent Office: 524 Days
• Field of Search: 328/166,165,139,109 307/232,233 333/7A,7R 324/83Q,83FE 332/18 330/149
• US Class Current: 327/552
• CPC Class Codes: G01S 1/24 the synchronised signals being pulses or equivalent modulations on carrier waves and the transit times being compared by measuring the difference in arrival time of a significant part of the modulations , e.g. LORAN systems
• CPC Class Codes: H03H 19/00 Networks using time-varying elements, e.g. N-path filters

Abstract

A method and apparatus for suppressing a phase-sensitive spectral component from a given signal. A phase and amplitudesensitive blocking pulse is generated at the frequency of the spectral component. This blocking pulse is subtracted from the signal and the unsuppressed portion of the spectral component is used to adjust the phase and amplitude of the blocking pulse, so as to more completely eliminate the spectral component from the signal.

Claims

1. Apparatus for suppressing a phase-sensitive spectral component from a signal comprising:

means for filtering said phase-sensitive spectral component from said signal;

means for generating first and second reference pulses at the frequency of said spectral component, said second reference pulse being in phase quadrature with said first reference pulse;

means coupled to said first and second reference pulses and said filtered spectral component for converting said filtered spectral component into respective first and second phase quadrature error signals;

first and second means coupled to said first and second reference pulses, respectively, and to said respective first and second phase quadrature error signals for multiplying the respective first and second reference pulses by a factor varying between 0 and 1, the factor of each of said first and second multiplying means being determined by said respective first and second phase quadrature error signals;

means coupled to the multiplied first and second reference pulses for summing the multiplied first and second reference pulses to obtain said blocking pulse at the frequency of said spectral component;

means coupled to said blocking pulse and said input signal for subtracting said blocking pulse from said signal; and

means for coupling the remainder of said signal to said filtering means, so as to readjust the amplitude and phase of said blocking pulse in order to more completely eliminate said spectral component from said signal.

2. Apparatus according to claim 1, wherein said converting means further comprises:

first and second synchronous detectors coupled to the output of said filtering means, said first reference pulse activating said first synchronous detector, said second reference pulse activating said second synchronous detector, whereby the outputs of each of said detectors are DC error levels in phase quadrature with each other; and

first and second accumulator means coupled to the respective outputs of said first and second synchronous detectors for cumulatively producing said respective first and second phase quadrature error signals at the respective outputs of said first and second accumulator means.

3. Apparatus according to claim 2, wherein said first and second accumulator means are integrators.

4. A method of suppressing a phase-sensitive spectral sensitive component from a signal comprising the steps of:

filtering said phase-sensitive spectral component from said signal;

generating first and second reference pulses at the frequency of said spectral component, said second reference pulse being in phase quadrature with said first reference pulse;

converting said filtered spectral component into respective first and second phase quadrature error signals;

multiplying the respective first and second reference pulses by a factor varying between 0 and 1, the multiplying factor for each of said first and second reference pulses being determined by said respective first and second phase quadrature error signals;

summing the multiplied first and second reference pulses to obtain said blocking pulse at the frequency of said spectral component;

subtracting said blocking pulse from said signal; and

readjusting the phase and amplitude of said blocking pulse with the use of the unsuppressed portion of said spectral component so as to more completely eliminate said spectral component from said signal.