Patent US5360398A successfully refreshed from Google Patents.
US3644847A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency-following voltage-controlled filter providing substantially constant output amplitude
Assignee: Motors Liquidation Co
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Filing: 1970-11-30
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Granted: 1972-02-22
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Expires: 1990-11-30
Abstract
Abstract A filter arrangement for extracting the fundamental frequency from an input periodic electrical signal controlled to follow changes in frequency by the input electrical signal to provide an output sinusoidal signal whose frequency continuously follows the frequency of the input signal. This filter arrangement includes a voltage-controlled filter in combination with a feedback loop comprising an amplitude sensing circuit, a voltage comparator and an amplifier to provide an error signal related to the difference between the instantaneous output voltage of the voltagecontrolled filter and a reference voltage. This error signal is applied to the voltage-controlled filter to modify its characteristic response and, accordingly, to enable the voltagecontrolled filter to extract a fundamental frequency sinusoid which follows frequency changes by the input signal. Additionally, the instant filter arrangement inherently adjusts for variations in the amplitude of the input signal to effect automatic gain control providing a substantially constant amplitude output voltage.
Inventors
- 👤 John G Neuman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:34
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H02; H02P; H02P23/00; H02P23/28
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
206 words
An electrical system for providing a sinusoidal output voltage from a periodic input voltage comprising: a voltagecontrolled filter having input, output and control terminals, said input terminals being adapted for connection with an input electrical signal, said voltage-controlled filter having a frequency-dependent gain defined by a family of transfer curves relating the voltage at said output terminals to the voltage at said input terminals, said voltage-controlled filter operating on a predetermined transfer curve when a predetermined voltage is applied to said control terminals, each of said transfer curves defining a cutoff frequency for Said filter whereby, the cutoff frequency of said filter is determined by the voltage applied to said control terminals, means for sensing the voltage amplitude at said output terminals, means providing a reference direct voltage, means responsive to said sensed voltage and said reference direct voltage for providing an error signal representative of the voltage amplitude difference between said sensed voltage and said reference direct voltage, and means for applying said error signal to said control terminals whereby, the cutoff frequency of said filter is regulated by said error signal and is maintained at predetermined instantaneous values which pass the instantaneous fundamental frequency of the voltage applied to the input of said filter.
Claim 2
Dependent Claim
206 words
An electrical system for providing a sinusoidal output voltage from a periodic input voltage comprising: a voltagecontrolled filter having input, output and control terminals, said input terminals being adapted for connection with an input electrical signal, said voltage-controlled filter having a frequency-dependent gain defined by a family of transfer curves relating the voltage at said output terminals to the voltage at said input terminals, said voltage-controlled filter operating on a predetermined transfer curve when a predetermined voltage is applied to said control terminals, each of said transfer curves defining a cutoff frequency for Said filter whereby, the cutoff frequency of said filter is determined by the voltage applied to said control terminals, means for sensing the voltage amplitude at said output terminals, means providing a reference direct voltage, means responsive to said sensed voltage and said reference direct voltage for providing an error signal representative of the voltage amplitude difference between said sensed voltage and said reference direct voltage, and means for applying said error signal to said control terminals whereby, the cutoff frequency of said filter is regulated by said error signal and is maintained at predetermined instantaneous values which pass the instantaneous fundamental frequency of the voltage applied to the input of said filter.
Claim 3
Dependent Claim
257 words
A controlled filter system comprising: a voltage-controlled filter having input, output and control terminals, said input terminals being adapted for connection with an input electrical signal, said voltage-controlled filter having a frequency dependent gain defined by a family of transfer curves relating the voltage at said output terminals to the voltage at said input terminals, said voltage-controlled filter operating on a predetermined transfer curve when a predetermined voltage is applied to said control terminals, each of said transfer curves defining a cutoff frequency for said filter whereby, the cutoff frequency of said filter is determined by the voltage applied to said control terminals, means for sensing the voltage amplitude at said output terminals, means providing a reference direct voltage having an amplitude substantially equal to a preselected voltage amplitude at said output terminals, means for providing an error signal representative of the voltage amplitude difference between said sensed voltage amplitude and said reference direct voltage, and means connecting said error signal with said control terminals whereby, the cutoff frequency is lowered if the voltage amplitude at the output terminals increases and the cutoff frequency is raised if the voltage amplitude at the output terminals decreases such that the output voltage at said output terminals is maintained substantially constant at said preselected voltage amplitude level, said cutoff frequency being controlled in response to variations in the amplitude of the output voltage to provide a constant amplitude output signal having the frequency of the fundamental harmonic of the input electrical signal connected with the input terminals to the filter.
Claim 4
Dependent Claim
257 words
A controlled filter system comprising: a voltage-controlled filter having input, output and control terminals, said input terminals being adapted for connection with an input electrical signal, said voltage-controlled filter having a frequency dependent gain defined by a family of transfer curves relating the voltage at said output terminals to the voltage at said input terminals, said voltage-controlled filter operating on a predetermined transfer curve when a predetermined voltage is applied to said control terminals, each of said transfer curves defining a cutoff frequency for said filter whereby, the cutoff frequency of said filter is determined by the voltage applied to said control terminals, means for sensing the voltage amplitude at said output terminals, means providing a reference direct voltage having an amplitude substantially equal to a preselected voltage amplitude at said output terminals, means for providing an error signal representative of the voltage amplitude difference between said sensed voltage amplitude and said reference direct voltage, and means connecting said error signal with said control terminals whereby, the cutoff frequency is lowered if the voltage amplitude at the output terminals increases and the cutoff frequency is raised if the voltage amplitude at the output terminals decreases such that the output voltage at said output terminals is maintained substantially constant at said preselected voltage amplitude level, said cutoff frequency being controlled in response to variations in the amplitude of the output voltage to provide a constant amplitude output signal having the frequency of the fundamental harmonic of the input electrical signal connected with the input terminals to the filter.
Claim 5
Dependent Claim
186 words
A frequency following filter system comprising: means providing a periodic input signal, a voltage-controlled filter having input, output and control terminals, means connecting said input signal with said input terminals, said voltage-controlled filter having a frequency dependent gain defined by a family of transfer curves relating the voltage at said output terminals with the voltage at said input terminals, said voltage-controlled filter operating on a predetermined transfer curve when a predetermined voltage is applied to said control terminals, each of said transfer curves defining a cutoff frequency for said filter whereby, the cutoff frequency of said filter is determined by the voltage applied to said control terminals, means for sensing the peak voltage amplitude at said output terminals, means providing a reference direct voltage having an amplitude substantially equal to a preselected peak voltage amplitude at said output terminals, means for providing an error signal representative of the voltage amplitude difference between said sensed voltage and said reference direct voltage, and means connecting said error signal with said control terminals whereby, the cutoff frequency of said voltage-controlled filter follows the frequency of said periodic input signal.
Claim 6
Dependent Claim
186 words
A frequency following filter system comprising: means providing a periodic input signal, a voltage-controlled filter having input, output and control terminals, means connecting said input signal with said input terminals, said voltage-controlled filter having a frequency dependent gain defined by a family of transfer curves relating the voltage at said output terminals with the voltage at said input terminals, said voltage-controlled filter operating on a predetermined transfer curve when a predetermined voltage is applied to said control terminals, each of said transfer curves defining a cutoff frequency for said filter whereby, the cutoff frequency of said filter is determined by the voltage applied to said control terminals, means for sensing the peak voltage amplitude at said output terminals, means providing a reference direct voltage having an amplitude substantially equal to a preselected peak voltage amplitude at said output terminals, means for providing an error signal representative of the voltage amplitude difference between said sensed voltage and said reference direct voltage, and means connecting said error signal with said control terminals whereby, the cutoff frequency of said voltage-controlled filter follows the frequency of said periodic input signal.
Claim 7
Independent Claim
159 words
A method for extracting a constant amplitude first harmonic output signal from a periodic input signal comprising: providing a voltage-controlled filter having input, output and control terminals whose frequency dependent Gain is defined by a family of transfer curves relating the voltage at said output terminals with the voltage at said input terminals, applying said periodic input signal to said input terminals, sensing the voltage at said output terminals, providing a reference direct voltage, generating an error signal representative of the voltage amplitude difference between said sensed voltage and said reference voltage, applying said error signal to said control terminals, and operating said voltage-controlled filter over a predetermined range near cutoff of a predetermined transfer curve when a predetermined voltage is applied to said control terminals such that the cutoff frequency of said voltage-controlled filter varies in conformity with both the amplitude and the frequency of said periodic input signal to provide said constant amplitude first harmonic output signal.
Claim 8
Independent Claim
159 words
A method for extracting a constant amplitude first harmonic output signal from a periodic input signal comprising: providing a voltage-controlled filter having input, output and control terminals whose frequency dependent Gain is defined by a family of transfer curves relating the voltage at said output terminals with the voltage at said input terminals, applying said periodic input signal to said input terminals, sensing the voltage at said output terminals, providing a reference direct voltage, generating an error signal representative of the voltage amplitude difference between said sensed voltage and said reference voltage, applying said error signal to said control terminals, and operating said voltage-controlled filter over a predetermined range near cutoff of a predetermined transfer curve when a predetermined voltage is applied to said control terminals such that the cutoff frequency of said voltage-controlled filter varies in conformity with both the amplitude and the frequency of said periodic input signal to provide said constant amplitude first harmonic output signal.
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) | 1975-02-21 | 1975-08-23 | 1976-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-21 | 1979-08-23 | 1980-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-21 | 1983-08-23 | 1984-02-22 | $7700.00 | Window Closed / Lapsed |