US3833855A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Coherent filter
Assignee: Collins Radio Co
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Filing: 1973-09-28
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Granted: 1974-09-03
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Expires: 1993-09-28
Abstract
Abstract A high Q bandpass filter employing coherent techniques to synthesize the fundamental component of an input signal under control of a driving signal with frequency like that of the input signal. Enacting maintenance of amplitude and phase characteristics is realized by a feedback loop wherein the output is subtracted from the input signal.
Inventors
- 👤 M Lundgreen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:16
CPC Classifications
G; G01; G01S; G01S1/00; G01S1/02
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
188 words
The method of filtering and input signal in a narrow bandwidth, high Q circuit to obtain an output signal which maintains high accuracy phase and amplitude information carried by said input signal, comprising the steps of: subtracting said output signal from said input signal to provide a different signal; low-pass filtering said difference signal in a first filtering means; quadraturizing a reference signal source with frequency substantially equal that of said input signal into first and second driving signals; separately phase detecting said low-pass filtered different signal against each of said first and second driving signals in respective first and second phase detecting means; separately integrating the outputs from each of said phase detecting means in respective first and second integrating means; separately chopping the respective outputs of said first and second integrating means with respect to said second and said first ones of said driving signals in respective first and second signal chopping means; summing the respective outputs from said first and second signal chopping means; and low-pass filtering the above-defined signal sum in a further low-pass filtering means the output of which comprises said output signal.
Claim 2
Independent Claim
188 words
The method of filtering and input signal in a narrow bandwidth, high Q circuit to obtain an output signal which maintains high accuracy phase and amplitude information carried by said input signal, comprising the steps of: subtracting said output signal from said input signal to provide a different signal; low-pass filtering said difference signal in a first filtering means; quadraturizing a reference signal source with frequency substantially equal that of said input signal into first and second driving signals; separately phase detecting said low-pass filtered different signal against each of said first and second driving signals in respective first and second phase detecting means; separately integrating the outputs from each of said phase detecting means in respective first and second integrating means; separately chopping the respective outputs of said first and second integrating means with respect to said second and said first ones of said driving signals in respective first and second signal chopping means; summing the respective outputs from said first and second signal chopping means; and low-pass filtering the above-defined signal sum in a further low-pass filtering means the output of which comprises said output signal.
Claim 3
Dependent Claim
31 words
The method of claim 1 wherein each of said first and second low-pass filtering means comprises a 3-pole filter introducing substantially 315* signal lag at the frequency of said input signal.
Claim 4
Dependent Claim
20 words
The filtering method as defined in claim 2 wherein said first and second driving signals comprise respective square wave signals.
Claim 5
Dependent Claim
169 words
Signal filtering means whereby an output signal is caused to maintain both phase and amplitude characteristics carried by an input signal comprising; means for subtracting said output signal from said input signal; first low-pass filtering means receiving the output of said means for subtracting; means for developing first and second mutually quadraturized driving signals with frequency substantially equal that of said input signal; first and second phase detecting means receiving the output of said first low-pass filtering means as respective first inputs thereto and respective ones of said first and second driving signals as second inputs thereto; means integrating the outputs from each of said phase detecting means; means for chopping the respective outputs of each said means for integrating under control of respective ones of said first and second driving signals; means for summing the outputs from respective ones of said means for chopping; and second low-pass means receiving the output from said means for summing, the output from said second low-pass filtering means comprising said output signal.
Claim 6
Dependent Claim
169 words
Signal filtering means whereby an output signal is caused to maintain both phase and amplitude characteristics carried by an input signal comprising; means for subtracting said output signal from said input signal; first low-pass filtering means receiving the output of said means for subtracting; means for developing first and second mutually quadraturized driving signals with frequency substantially equal that of said input signal; first and second phase detecting means receiving the output of said first low-pass filtering means as respective first inputs thereto and respective ones of said first and second driving signals as second inputs thereto; means integrating the outputs from each of said phase detecting means; means for chopping the respective outputs of each said means for integrating under control of respective ones of said first and second driving signals; means for summing the outputs from respective ones of said means for chopping; and second low-pass means receiving the output from said means for summing, the output from said second low-pass filtering means comprising said output signal.
Claim 7
Dependent Claim
35 words
Signal filtering means as defined in claim 4 wherein each of said first and second low pass filtering means comprises a 3-pole filter introducing substantially 315* phase lag at the frequency of said input signal.
Claim 8
Dependent Claim
81 words
Signal filtering means as defined in claim 5 wherein said first and second low-pass filtering means each include means for signal amplification with respective transfer functions of K1 and K5, said phase detecting means exhibiting transfer functions of K2, said signal integrating means exhibiting transfer function of K3/s, where s is the LaPlacian operator, said signal chopping means exhibiting transfer functions of K4, said signal filtering means thereby functioning as a bandpass filter the transfer function of which is defined as
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-02 | 1978-03-04 | 1978-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-02 | 1982-03-04 | 1982-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-02 | 1986-03-04 | 1986-09-03 | $7700.00 | Window Closed / Lapsed |