Unwanted signal suppression device

• US 5,304,940 A
• Filed: 06/19/1992
• Issued: 04/19/1994
• Est. Priority Date: 06/28/1991
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Harasawa, Yasuhiro, Kirimoto, Tetsuo, Oh-Hashi, Yoshimasa
• Primary Examiner(s): Callahan, Timothy P.
• Application Number:
  US07/901,566
• Time in Patent Office: 669 Days
• Field of Search: 328/165, 328/167, 307/520, 307/521, 364/724
• US Class Current: 327/552
• CPC Class Codes: G01S 13/5246 post processors for coherent MTI discriminators, e.g. residue cancellers, CFAR after Doppler filters
• CPC Class Codes: G01S 7/2921 based on data belonging to one radar period

Abstract

An unwanted signal suppression device is disclosed for suppressing unwanted signals in input signals containing desired and unwanted signals. The input signals are divided into segments in the time domain. The device includes a unit for detecting the segment having maximum power, a unit for computing reflection coefficients on the basis of the segments except the detected power segment, and a lattice filter for suppressing the unwanted signals by using the computed reflection coefficients. A second device includes a reflection coefficient computing unit, a median filter and a lattice filter. A third device includes a unit for estimating unwanted signals frequency, a filter for computing filter weights on the basis of the estimated frequency and filter coefficients and for applying the computed weights to the input signals so as to suppress the unwanted signals.

Claims

1. An unwanted signal suppression device for suppressing unwanted signals from input signals which include desired signals and the unwanted signals, comprising:

a power detection means for sampling the input signals at specified time intervals, each sample being a signal segment, said power detection means having means for detecting the signal segment which exhibits at least the maximum power and having means for providing a maximum power segment signal which indicates the signal segment which exhibits the maximum power,

a reflection coefficient computing means for computing reflection coefficients, said reflection coefficient computing means receiving the maximum power segment signal, said reflection coefficient computing means computing the reflection coefficients based on the signal segments except for the signal segment corresponding to the maximum power segment signal, and

a lattice filter for suppressing said unwanted signals and for generating said desired signals, said lattice filter receiving said reflection coefficients and said input signals.

2. An unwanted signal suppression device for suppressing unwanted signals from input signals which include desired signals and the unwanted signals, comprising:

a reflection coefficient computing means for sampling the input signals at specified time intervals, each sample being a signal segment, the reflection coefficient computing means having means for computing reflection coefficients for each signal segment,

a median filter means for receiving the reflection coefficients and for determining a median reflection coefficient, the median reflection coefficient being a median value of the reflection coefficients, said median filter means having means for outputting the median reflection coefficient, and

a lattice filter, receiving the median reflection coefficient and said input signals, said lattice filter suppressing said unwanted signals and outputting the desired signals.

3. An unwanted signal suppression device for suppressing unwanted signals from input signals which include desired signals and the unwanted signals, comprising:

an unwanted signal frequency estimation means for estimating a frequency of said unwanted signals, said unwanted signal frequency estimation means receiving said input signals and having means for outputting an estimate signal which is indicative of the frequency estimate for the unwanted signals, said estimate signal determined on the basis of said input signals, and

a filter means for computing a filter weight, said filter means receiving said estimate signal, said filter means computing a filter weight based upon the estimate signal and filter coefficients exhibiting a desired amplitude characteristic, said filter means having means for applying said filter weight to a notch filter which receives said input signals, said notch filter suppressing said unwanted signals and outputting said desired signals.

4. The unwanted signal suppression device of claim 3, wherein said unwanted signal frequency estimation means comprises a reflection coefficient computing means for computing the reflection coefficients on the basis of said input signals, said reflection coefficient computing means providing reflection coefficients and wherein said unwanted signal frequency estimation means further comprises an unwanted signal frequency determination means for determining the frequency of said unwanted signals, said unwanted signal frequency determination means receiving said reflection coefficient and having means for determining the frequency of said unwanted signals based on said reflection coefficients.

5. The unwanted signal suppression device of claim 3, wherein said filter means comprises a filter weight computing means for computing the filter weight on the basis of said estimate signal and the filter coefficient exhibiting a desired amplitude characteristic.

6. The unwanted signal suppression device of claim 3, wherein

said unwanted signal frequency estimation means comprises a power detection means for sampling the input signals at specified time intervals, each sample being a signal segment, said power detection means having means for detecting the signal segment which exhibits at least the maximum power, a reflection coefficient computing means for computing the reflection coefficients on the basis of the remaining signal segments excluding said detected signal segment exhibiting the maximum power, and an unwanted signal frequency determination means for determining the frequency of said unwanted signals on the basis of said computed reflection coefficients.

7. The unwanted signal suppression device of claim 3, wherein said unwanted signal frequency estimation means comprises a reflection coefficient computing means for sampling the input signals at specified time intervals, each sample being a signal segment, the reflection coefficient computing means having means for computing reflection coefficients for each signal segment, a median filter for outputting a median reflection coefficient out of said reflection coefficients, and an unwanted signal frequency determination means for determining the frequency of said unwanted signals on the basis of the median reflection coefficient output from said median filter.

8. The unwanted signal suppression device of claim 3, wherein

said unwanted signal frequency estimation means comprises a first reflection coefficient computing means sampling the input signals at specified time intervals, each sample being a signal segment, the reflection coefficient computing means having means for computing reflection coefficients for each signal segment, a lattice filter for processing said input signals so as to reduce the unwanted signals on the basis of said computed first reflection coefficients, a second reflection coefficient computing means for computing second reflection coefficients for each of the signal segments produced by sampling the signals from said lattice filter by said specified time intervals, and an unwanted frequency determination means for determining the frequency of said unwanted signals on the basis of said computed first and second reflection coefficients.

9. An unwanted signal suppression device for suppressing unwanted signals from input signals which include desired signals and the unwanted signals, comprising:

a maximum power detector, which samples the input signals at specified time intervals, each sample being a signal segment, and which detects the signal segment which exhibits at least the maximum power and which provides as an output a maximum power segment signal, which indicates the signal segment that exhibits the maximum power,

a reflection coefficient computer, which receives the maximum power segment signal, and which computes the reflection coefficients based upon the received signal segments except for the signal segment corresponding to the maximum power segment signal, and

a lattice filter, which receives the reflection coefficients and the input signals and which suppresses said unwanted signals.

10. An unwanted signal suppression device for suppressing unwanted signals from input signals which include desired signals and the unwanted signals, comprising:

a reflection coefficient computer, which samples the input signals at specified time intervals, each sample being a signal segment, and which computes reflection coefficients for each signal segment,

a median filter, which receives the reflection coefficients and which outputs a median reflection coefficient that is a median value of the reflection coefficients, and

a lattice filter, which receives the median reflection coefficient and the input signals and which suppresses the unwanted signals and outputs the desired signals.

11. An unwanted signal suppression device for suppressing unwanted signals from input signals which include desired signals and the unwanted signals, comprising:

an unwanted signal frequency estimator, which receives the input signals and which determines a frequency estimate of the unwanted signal based upon the input signals and which provides an estimate signal that is indicative of the frequency estimate, and

a filter, which receives the estimate signal and which has a filter weight computer that determines a filter weight based upon the estimate signal and filter coefficients, which exhibit a desired amplitude characteristic, wherein the filter uses the filter weight to suppress the unwanted signals and output the desired signals.

12. In a system receiving input signals that include desired signals and unwanted signals, a method of suppressing the unwanted signals, comprising the steps of:

dividing the input signals into signal segments, corresponding to specified time intervals,

detecting the signal segment which exhibits at least the maximum power, and

computing reflection coefficients based upon all signal segments except for the signal segment exhibiting at least the maximum power and applying the reflection coefficients to a filter to suppress the unwanted signals.

13. In a system receiving input signals that include desired signals and unwanted signals, a method of suppressing the unwanted signals, comprising the steps of:

dividing the input signals into signal segments, corresponding to specified time intervals,

computing reflection coefficients based upon the input signals, and

determining a median value reflection coefficient from the computed reflection coefficients and applying the median value reflection coefficient to a filter to suppress the unwanted signals.

14. In a system receiving input signals that include desired signals and unwanted signals, a method of suppressing the unwanted signals, comprising the steps of:

dividing the input signals into signal segments, corresponding to specified time intervals,

computing reflection coefficients based upon all signal segments except for the signal segment that exhibits at least the maximum power.