Method and circuit for processing and filtering signals

• US 5,428,834 A
• Filed: 10/12/1993
• Issued: 06/27/1995
• Est. Priority Date: 12/11/1991
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation), Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Original Assignee: Xetron Corp. (Honeywell International Inc.)
• Inventors: Dickerson, Roger W.
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): WISLER, MARK
• Application Number:
  US08/134,807
• Time in Patent Office: 623 Days
• Field of Search: 375/102, 375/104, 375/99, 375/100, 375/11-15, 328/162, 328/165, 328/164, 360/38.1, 358/314, 329/320, 455/295, 455/296, 455/65, 455/304, 307/556, 307/542, 364/724.19, 364/724.2, 333/18, 333/28 R
• US Class Current: 455/304
• CPC Class Codes: H03H 17/0251 Comb filters

Abstract

A method for processing electrical signals includes the steps of: storing a plurality of first data signals, each representative of an instantaneous amplitude of a first input signal in a memory; selecting one of the first data signals in response to a second input signal; combining the selected one of the first data signals with a second data signal representative of a subsequent instantaneous amplitude of the first input signal, to produce a difference signal; producing a first output signal in response to the difference signal; and combining the difference signal and the selected first data signal to produce a modified data signal and for replacing the selected one of the first data signals with the modified data signal in the memory. The method can be performed by an equalizer in a circuit for compensating for amplitude variations in a radio frequency signal or by a comb notch filter. The invention also encompasses circuits and combinations of such circuits which perform the above signal processing method.

Claims

1. A circuit for processing electrical signals comprising:

a memory having a plurality of addresses for storing a plurality of first data signals, each representative of an instantaneous amplitude of a first input signal;

means for selecting one of said first data signals in response to a second input signal;

means for combining the selected one of said first data signals with a second data signal representative of an additional instantaneous amplitude of said first input signal, to produce a difference signal;

means for producing a first output signal in response to said difference signal; and

means for combining said difference signal and the selected one of the first data signals to produce a modified data signal and for replacing the selected one of the first data signals with said modified data signal in said memory.

2. A circuit for processing electrical signals according to claim 1, wherein:

the first input signal includes a signal of interest and an interfering signal; and

said interfering signal being correlated with said second input signal.

3. A circuit for processing electrical signals according to claim 1, further comprising:

means for producing a second output signal in response to the selected one of said first data signals.

4. A circuit for processing electrical signals according to claim 1, wherein said means for combining said difference signal and the selected one of said first data signals to produce a modified data signal and for replacing the selected one of said first data signals with said modified data signal in said memory, comprises:

a scaling circuit for attenuating said difference signal by a preselected amount to produce a correction signal; and

an adder adding said correction signal to the selected first data signal to produce said modified data signal.

5. A circuit for processing electrical signals according to claim 1, wherein said means for selecting one of said first data signals in response to a second input signal comprises:

a counter for producing said second input signal in response to a clock signal.

6. A method for processing electrical signals comprising the steps of:

providing a memory having a plurality of addresses for storing a plurality of first data signals, each representative of an instantaneous amplitude of a first input signal;

selecting one of said first data signals in response to a second input signal;

combining the selected one of said first data signals with a second data signal representative of an additional instantaneous amplitude of said first input signal, to produce a difference signal;

producing a first output signal in response to said difference signal; and

combining said difference signal and the selected one of said first data signals to produce a modified data signal and replacing the selected one of said first data signals with said modified data signal in said memory.

7. A method for processing electrical signals according to claim 6, wherein:

the first input signal includes a signal of interest and an interfering signal; and

said interfering signal is correlated with said second input signal.

8. A method for processing electrical signals according to claim 6, further comprising the step of:

producing a second output signal in response to the selected one of said first data signals.

9. A method for processing electrical signals according to claim 6, wherein said step of combining said difference signal and the selected one of said first data signals to produce a modified data signal and for replacing the selected one of said first data signals with said modified data signal in said memory, comprises the steps of:

attenuating said difference signal by a preselected amount to produce a correction signal; and

adding said correction signal to the selected one of said first data signals to produce said modified data signal.

10. A circuit for compensating for amplitude variation in an angle modulated composite signal comprising:

a memory having a plurality of addresses for storing a plurality of first data signals, each representative of an instantaneous amplitude of the composite signal, wherein the composite signal includes a signal of interest and an interfering signal;

means for selecting one of said first data signals in response to a second input signal, said interfering signal being correlated with said second input signal;

means for combining the selected one of said first data signals with a second data signal representative of an additional instantaneous amplitude of said composite signal, to produce a difference signal;

means for producing a first analog output signal in response to said difference signal; and

means for combining said difference signal and the selected one of said first data signals to produce a modified data signal and for replacing the selected one of said first data signals with said modified data signal in said memory.

11. A circuit for compensating for amplitude variation in an angle modulated composite signal according to claim 10, further comprising:

means for producing a second output signal in response to the selected one of said data signals.

12. A circuit for compensating for amplitude variation in an angle modulated composite signal according to claim 10, wherein said means for combining said difference signal and the selected one of said first data signals to produce a modified data signal and for replacing the selected one of said first data signals with said modified data signal in said memory, comprises:

a scaling circuit for attenuating said difference signal by a preselected amount to produce a correction signal; and

an adder adding said correction signal to the selected one of said first data signals to produce said modified data signal.

13. A circuit for compensating for amplitude variation in an angle modulated composite signal comprising:

a memory having a plurality of addresses for storing a plurality of first data signals, each representative of an instantaneous amplitude of the composite signal, wherein the composite signal includes a signal of interest and an interfering signal;

a first analog to digital converter producing an address signal for selecting one of said first data signals in response to a second input signal, said second input signal being correlated with said interfering signal;

a first adder for combining the selected one of said first data signals with a second data signal representative of an additional instantaneous amplitude of said composite signal, to produce a difference signal;

means for producing a first analog output signal in response to said difference signal; and

a second adder for combining said difference signal and the selected one of said first data signals to produce a modified data signal and for replacing the selected one of said first data signals with said modified data signal in said memory.

14. A circuit for compensating for amplitude variation in an angle modulated composite signal according to claim 13, further comprising:

means for producing a second output signal in response to the selected one of said data signals.

15. A method for compensating for amplitude variation in an angle modulated composite signal, said method comprising the steps of:

providing a memory having a plurality of addresses for storing a plurality of first data signals, each representative of an instantaneous amplitude of the composite signal, wherein the composite signal includes a signal of interest and an interfering signal;

selecting one of said first data signals in response to a second input signal, said second input signal being correlated with said interfering signal;

combining the selected one of said first data signals with a second data signal representative of an additional instantaneous amplitude of said composite signal, to produce a difference signal;

producing a first analog output signal in response to said difference signal;

combining said difference signal and the selected one of said first data signals to produce a modified data signal; and

replacing the selected one of said first data signals with said modified data signal in said memory.

16. A method for compensating for amplitude variation in an angle modulated composite signal according to claim 15, further comprising the step of:

producing a second output signal in response to the selected one of said data signals.

17. A method for compensating for amplitude variation in an angle modulated composite signal according to claim 15, wherein said step of combining said difference signal and the selected one of said first data signals to produce a modified data signal, comprises the steps of:

attenuating said difference signal by a preselected amount to produce a correction signal; and

adding said correction signal to the selected one of said first data signals to produce said modified data signal.

18. A circuit for processing electrical signals comprising:

a first equalizer including a first memory having a plurality of addresses for storing a plurality of first data signals, each representative of an instantaneous amplitude of a first input signal;

means for selecting one of said first data signals in response to a second input signal;

means for combining the selected one of said first data signals with a second data signal representative of an additional instantaneous amplitude of said first input signal, to produce a first difference signal;

means for producing a first output signal in response to said first difference signal; and

means for combining said first difference signal and the selected one of the first data signals to produce a first modified data signal and for replacing the selected one of the first data signals with said first modified data signal in said first memory;

a second equalizer including a second memory having a plurality of addresses for storing a plurality of third data signals, each representative of an instantaneous amplitude of said first output signal;

means for selecting one of said third data signals in response to a third input signal;

means for combining the selected one of said third data signals with a fourth data signal representative of an additional instantaneous amplitude of said first output signal, to produce a second difference signal;

means for producing a second output signal in response to said second difference signal; and

means for combining said second difference signal and the selected one of the third data signals to produce a second modified data signal and for replacing the selected one of the third data signals with said second modified data signal in said second memory.

19. A circuit for processing electrical signals according to claim 18, wherein said third input signal is representative of a derivative of said second input signal.

20. A circuit for processing electrical signals according to claim 19, wherein said derivative is taken with respect to either time or frequency.

21. A method for processing electrical signals comprising the steps of:

providing a first memory having a plurality of addresses for storing a plurality of first data signals, each representative of an instantaneous amplitude of a first input signal;

selecting one of said first data signals in response to a second input signal;

combining the selected one of said first data signals with a second data signal representative of an additional instantaneous amplitude of said first input signal, to produce a first difference signal;

producing a first output signal in response to said first difference signal;

combining said first difference signal and the selected one of said first data signals to produce a first modified data signal and replacing the selected one of said first data signals with said first modified data signal in said first memory;

providing a second memory having a plurality of addresses for storing a plurality of third data signals, each representative of an instantaneous amplitude of said first output signal;

selecting one of said third data signals in response to a third input signal;

combining the selected one of said third data signals with a fourth data signal representative of an additional instantaneous amplitude of said first output signal, to produce a second difference signal;

producing a second output signal in response to said second difference signal;

combining said second difference signal and the selected one of said third data signals to produce a second modified data signal and replacing the selected one of said third data signals with said second modified data signal in said second memory.

22. A method for processing electrical signals according to claim 21, wherein said third input signal is representative of a derivative of said second input signal.

23. A circuit for processing electrical signals according to claim 22, wherein said derivative is taken with respect to either time or frequency.