Patent US5101210A successfully refreshed from Google Patents.
US5101210A
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Signal dynamic range compression apparatus and method including clutter estimation and reduction
Assignee: ITT Inc
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Filing: 1990-12-21
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Granted: 1992-03-31
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Expires: 2010-12-21
Abstract
Abstract The maximum amplitude of an input signal (IN) is compressed or reduced to a smaller value suitable for operation on the compressed signal (OUT) by a downstream signal processing stage (16) having insufficient dynamic range, ratio of maximum amplitude to root-mean-square (RMS) noise, to accommodate the original input signal (IN). The input signal (IN) is digitally sampled with coarse resolution to generate a correction signal (44) having a waveform which approximates only the large signal components (24) of the input signal (IN). Where the input signal (IN) consists of recurring received radar pulses, the large signals (24) represent clutter. The amplitude of the correction signal (44) is lower than and increases as a predetermined function of the amplitude of the input signal (IN), and is subtracted from the input signal (IN) so that the large signal components (24) are reduced whereas the small signal components (26), which represent desired target information, retain their original amplitude. Time and/or space estimates of the large signals may be stored and updated, and combined with the sampled input to generate the correction signal (44). A threshold is provided such that only input signals have a predetermined maximum amplitude are compressed.
Inventors
- 👤 John M. Milan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:18
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/28; G01S7/285; G01S7/34
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
86 words
A signal compression apparatus for selectively compressing large signal components of a composite input signal, comprising: correction signal generator means for coarsely sampling the input signal and generating a correction signal in response thereto having a waveform which approximates only the large signal components of the input signal and an amplitude which is lower than and increases as a predetermined function of the maximum amplitude of the input signal; and subtractor means for subtracting the correction signal from the input signal to produce an output signal.
Claim 2
Dependent Claim
86 words
A signal compression apparatus for selectively compressing large signal components of a composite input signal, comprising: correction signal generator means for coarsely sampling the input signal and generating a correction signal in response thereto having a waveform which approximates only the large signal components of the input signal and an amplitude which is lower than and increases as a predetermined function of the maximum amplitude of the input signal; and subtractor means for subtracting the correction signal from the input signal to produce an output signal.
Claim 3
Dependent Claim
40 words
An apparatus as in claim 1, in which the generator means is constructed to generate the correction signal in accordance with the predetermined function such that the maximum amplitude of the output signal is always lower than a predetermined value.
Claim 4
Dependent Claim
33 words
An apparatus as in claim 1, in which the generator means is constructed to coarsely sample the input signal such that small signal components having amplitudes lower than a predetermined value are ignored.
Claim 5
Dependent Claim
28 words
An apparatus as in claim 3, in which the generator means comprises means for digitally sampling the input signal with a minimum resolution corresponding to the predetermined value.
Claim 6
Dependent Claim
36 words
An apparatus as in claim 1, in which the generator means further comprises threshold means for inhibiting generation of the correction signal when the sampled amplitude of the input signal is below a predetermined threshold value.
Claim 7
Dependent Claim
54 words
An apparatus as in claim 1, in which: the input signal comprises recurring pulses; and the generator means further comprises: mapping means for storing averaged time estimates of the amplitudes of the pulses; and estimator means for generating the correction signal as a predetermined function of the sampled input signal and the time estimates.
Claim 8
Dependent Claim
33 words
An apparatus as in claim 6, in which the estimator means is further constructed to update the time estimates stored in the mapping means as a predetermined function of a current correction signal.
Claim 9
Dependent Claim
35 words
An apparatus as in claim 1, further comprising delay means disposed upstream of the subtractor means for delaying the input signal such that the delayed input signal is equal in phase with the correction signal.
Claim 10
Dependent Claim
33 words
An apparatus as in claim 1, further comprising delay means disposed upstream of the subtractor means for delaying the input signal such that the delayed input signal is time-aligned with the correction signal.
Claim 11
Dependent Claim
51 words
An apparatus as in claim 1, in which: the input signal comprises recurring pulses; and the apparatus further comprises delay means disposed between the generator means and the subtractor means for delaying a correction signal corresponding to a previous pulse so as to be equal in phase with a current pulse.
Claim 12
Dependent Claim
64 words
An apparatus as in claim 1, in which the generator means is constructed to generate the correction signal in accordance with the predetermined function so as to reduce the large signal components of an input signal which has a first predetermined maximum amplitude such that the corresponding output signal has a second predetermined maximum amplitude which is lower than the first predetermined maximum amplitude.
Claim 13
Independent Claim
115 words
A method of compressing a composite input signal having large and small signal components, comprising the steps of: (a) coarsely sampling the input signal to isolate the large signal components; and (b) compressing only the large signal components of the input signal to produce an output signal; step (b) comprising the substeps of: (c) generating a correction signal in response to the sampled input signal having a waveform which approximates only the large signal components of the input signal and an amplitude which is lower than and increases as a predetermined function of the maximum amplitude of the input signal; and (d) subtracting the correction signal from the input signal to produce an output signal.
Claim 14
Independent Claim
115 words
A method of compressing a composite input signal having large and small signal components, comprising the steps of: (a) coarsely sampling the input signal to isolate the large signal components; and (b) compressing only the large signal components of the input signal to produce an output signal; step (b) comprising the substeps of: (c) generating a correction signal in response to the sampled input signal having a waveform which approximates only the large signal components of the input signal and an amplitude which is lower than and increases as a predetermined function of the maximum amplitude of the input signal; and (d) subtracting the correction signal from the input signal to produce an output signal.
Claim 15
Dependent Claim
37 words
A method as in claim 12, in which step (c) comprises generating the correction signal in accordance with the predetermined function such that the maximum amplitude of the output signal is always lower than a predetermined value.
Claim 16
Dependent Claim
32 words
A method as in claim 12, in which step (c) further comprises inhibiting generation of the correction signal when the sampled amplitude of the input signal is below a predetermined threshold value.
Claim 17
Dependent Claim
51 words
A method as in claim 12, in which: the input signal comprises recurring pulses; and step (c) comprises the substeps of: (e) storing averaged time estimates of the amplitudes of the pulses; and (f) generating the correction signal as a predetermined function of the sampled input signal and the time estimates.
Claim 18
Dependent Claim
34 words
A method as in claim 15, in which step (c) further comprises the substep of: (g) updating the time estimates stored in the mapping means as a predetermined function of a current correction signal.
Claim 19
Dependent Claim
35 words
A method as in claim 12, further comprising the step of: (e) delaying the input signal prior to performing step (d) such that the delayed input signal is equal in phase with the correction signal.
Claim 20
Dependent Claim
49 words
A method as in claim 12, in which: the input signal comprises recurring pulses; and the method further comprises the step, performed between steps (c) and (d), of: (e) delaying a correction signal corresponding to a previous pulse so as to be equal in phase with a current pulse.
Claim 21
Dependent Claim
62 words
A method as in claim 12, in which step (c) further comprises: generating the correction signal in accordance with the predetermined function so as to reduce the large signal components of an input signal which has a first predetermined maximum amplitude such that the corresponding output signal has a second predetermined maximum amplitude which is lower than the first predetermined maximum amplitude.
Claim 22
Dependent Claim
29 words
A method as in claim 12, in which step (a) comprises sampling the input signal such that small signal components having amplitudes lower than a predetermined value are ignored.
Claim 23
Dependent Claim
25 words
A method as in claim 20, in which step (a) comprises digitally sampling the input signal with a minimum resolution corresponding to the predetermined value.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-03-31 | 1995-09-30 | 1996-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-31 | 1999-09-30 | 2000-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-31 | 2003-09-30 | 2004-03-31 | $7700.00 | Window Closed / Lapsed |