US3708746A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for spectrum analysis including digital filter with variable sampling rate
Assignee: Iowa State University Research Foundation Inc
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Filing: 1971-11-08
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Granted: 1973-01-02
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Expires: 1991-11-08
Abstract
Abstract A system for analyzing the frequency spectrum of an input signal includes a digital filter, the center frequency of which is varied by changing the sampling rate. The output signal of the digital filter is squared in a detector circuit; and the output signal of the detector circuit is fed to an integrator circuit. The integration time is varied inversely proportional to the center frequency of the digital filter to obtain a signal representative of the power spectrum of the input signal.
Inventors
- 👤 R Willett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 01:33
CPC Classifications
G; G01; G01R; G01R23/00
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
131 words
A system for analyzing the spectrum of an input time-varying electrical signal comprising: digital filter means receiving said input signal and generating an output signal representative of the amplitude of said input signal within a predetermined bandwidth, said filter means being characterized in that the center frequency of said filter varies with the sampling rate, said filter further being adapted to have a variable sampling rate; squaring circuit means receiving the output signal of said digital filter means for generating a signal representative of the square of said output signal and thereby representative of the power spectrum of said input signal; means for varying the sample rate of said digital filter means; and counter circuit means for decreasing the integration time of said integration circuit means as said sampling rate increases.
Claim 2
Independent Claim
131 words
A system for analyzing the spectrum of an input time-varying electrical signal comprising: digital filter means receiving said input signal and generating an output signal representative of the amplitude of said input signal within a predetermined bandwidth, said filter means being characterized in that the center frequency of said filter varies with the sampling rate, said filter further being adapted to have a variable sampling rate; squaring circuit means receiving the output signal of said digital filter means for generating a signal representative of the square of said output signal and thereby representative of the power spectrum of said input signal; means for varying the sample rate of said digital filter means; and counter circuit means for decreasing the integration time of said integration circuit means as said sampling rate increases.
Claim 3
Dependent Claim
37 words
The system of claim 1 wherein said counter circuit means includes a digital counter circuit counting the sampling rate pulses for resetting said integration circuit means when a predetermined number of sample rate pulses have been counted.
Claim 4
Dependent Claim
18 words
The system of claim 1 wherein said digital filter means is characterized in having a relatively narrow bandpass.
Claim 5
Independent Claim
162 words
A system for determining the frequency components of an input electrical signal comprising: narrow band digital filter means receiving said input signal for generating an output signal representative of the frequency components of said input wave form within the narrow band of said digital filter means; squaring circuit means receiving output signals of said digital filter means for generating a signal representative of the square thereof; integrator circuit means receiving the output signal of said squaring circuit means for integrating the same over a predetermined time; means for varying the sampling rate of said digital filter means to thereby change the center frequency of the bandwidth of said digital filter means; and counter circuit means responsive to the sampling rate of said digital filter means for resetting said integrating circuit means after a predetermined number of sample rate pulses whereby as the center frequency of the bandwidth of said digital filter means increases, the integration time of said integrating circuit means decreases.
Claim 6
Independent Claim
162 words
A system for determining the frequency components of an input electrical signal comprising: narrow band digital filter means receiving said input signal for generating an output signal representative of the frequency components of said input wave form within the narrow band of said digital filter means; squaring circuit means receiving output signals of said digital filter means for generating a signal representative of the square thereof; integrator circuit means receiving the output signal of said squaring circuit means for integrating the same over a predetermined time; means for varying the sampling rate of said digital filter means to thereby change the center frequency of the bandwidth of said digital filter means; and counter circuit means responsive to the sampling rate of said digital filter means for resetting said integrating circuit means after a predetermined number of sample rate pulses whereby as the center frequency of the bandwidth of said digital filter means increases, the integration time of said integrating circuit means decreases.
Claim 7
Dependent Claim
77 words
In a method of determining the frequency spectrum of an input signal, the steps comprising processing said signal in a narrow band digital filter, squaring the output signal of said digital filter, then integrating said squared signal, and incrementally increasing the sampling rate of digital filter while correspondingly decreasing the integration time of said squared signal to generate a set of signals representative of the energy coNtent of said input signal at predetermined bandwidths over a spectrum.
Claim 8
Dependent Claim
77 words
In a method of determining the frequency spectrum of an input signal, the steps comprising processing said signal in a narrow band digital filter, squaring the output signal of said digital filter, then integrating said squared signal, and incrementally increasing the sampling rate of digital filter while correspondingly decreasing the integration time of said squared signal to generate a set of signals representative of the energy coNtent of said input signal at predetermined bandwidths over a spectrum.
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) | 1976-01-02 | 1976-07-03 | 1977-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-02 | 1980-07-03 | 1981-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-02 | 1984-07-03 | 1985-01-02 | $7700.00 | Window Closed / Lapsed |