US4032852A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter which tracks changing frequency of input signal
Assignee: RCA Corp
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Filing: 1976-01-02
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Granted: 1977-06-28
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Expires: 1996-01-02
Abstract
Abstract A signal-frequency tracking band-pass filter useful for passing an input signal which changes rapidly in frequency. The tracking filter includes a voltage-controlled band pass filter, and a frequency-to-voltage converter for translating the output frequency of the filter to a voltage for controlling the pass band center frequency of the filter. The Q of the filter is controlled by a feedback circuit which makes the Q vary inversely with output signal amplitude. The Q is high for weak signals that are hard to lock on to, and the Q is low for strong signals to facilitate tracking of signals which change rapidly in frequency. The filter is especially useful for inclusion in internal combustion engine diagnostic equipment.
Inventors
- 👤 Leonard Robin Hulls
- 👤 Stephen Clow Hadden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:37
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
99 words
A band-pass filter having a frequency pass band which tracks the changing frequency of an input signal, comprising a voltage-controlled filter including a signal input terminal, a signal output terminal and a frequency control terminal, a frequency-to-voltage converter coupled from said signal output terminal to said frequency control terminal to cause the pass band frequency of the filter to track the frequency of the input signal, and means coupled from said signal output terminal to said signal input terminal to cause the Q of the filter to vary in an inverse relation with the amplitude of the input signal.
Claim 2
Dependent Claim
99 words
A band-pass filter having a frequency pass band which tracks the changing frequency of an input signal, comprising a voltage-controlled filter including a signal input terminal, a signal output terminal and a frequency control terminal, a frequency-to-voltage converter coupled from said signal output terminal to said frequency control terminal to cause the pass band frequency of the filter to track the frequency of the input signal, and means coupled from said signal output terminal to said signal input terminal to cause the Q of the filter to vary in an inverse relation with the amplitude of the input signal.
Claim 3
Dependent Claim
52 words
A filter as defined in claim 1 wherein said voltage-controlled filter includes a first voltage-controlled integrator coupled from said signal input terminal to said signal output terminal, and a second voltage-controlled integrator and a variable Q circuit coupled in parallel feedback paths from said signal output terminal to said signal input terminal.
Claim 4
Dependent Claim
68 words
A filter as defined in claim 1 wherein said means to cause the Q of the filter to vary includes a peak detector having an input coupled to said signal output terminal, and a multiplier having one input coupled to said signal output terminal, and having a second input coupled to the output of said peak detector and having an output terminal coupled to said signal input terminal.
Claim 5
Dependent Claim
31 words
A filter as defined in claim 3 and in addition an inverting amplifier located in the coupling to the second input of said multiplier from the output of said peak detector.
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) | 1980-06-27 | 1980-12-27 | 1981-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-27 | 1984-12-27 | 1985-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-27 | 1988-12-27 | 1989-06-28 | $7700.00 | Window Closed / Lapsed |