US3943459A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tuning system for a microwave local oscillator
Assignee: Cutler Hammer Inc
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Filing: 1975-04-02
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Granted: 1976-03-09
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Expires: 1995-04-02
Abstract
Abstract A variable frequency voltage controlled oscillator is tuned to a selected frequency by applying a varying voltage to the control port of the oscillator to sweep the oscillator signal through a frequency range which includes the frequency of a reference frequency source. The value of the varying voltage is stored at the instant the oscillator frequency coincides with the frequency of the reference source. A dc offset voltage is then added to the stored voltage to produce a sum voltage which is substituted for the varying voltage at the control port of the oscillator to tune the oscillator to the selected frequency. The offset voltage is equal to the difference in the control voltages at the selected and reference frequencies and may be determined from the oscillator control voltage characteristic. The oscillator can be set reliably to a selected frequency without using temperature compensation, provided that, at each frequency in a range of interest, the rate of change df/dv of the oscillator frequency with respect to the change in control voltage is constant despite changes in temperature.
Inventors
- 👤 Paul S. Tosto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:58
CPC Classifications
H; H03; H03L; H03L7/00; H03J; H03J7/00; H03J7/02; H03J7/04; H03J7/06
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
224 words
Apparatus for generating a signal at a selected frequency, comprising: a. a voltage controlled oscillator having, at each frequency in a range of interest, a rate of change df/dv of frequency with respect to a change in control voltage that is constant despite changes in environmental conditions, b. means for generating a primary reference frequency signal, c. means for generating a varying control voltage to sweep the tuning of said oscillator through a first frequency range which includes a secondary reference frequency that differs from said primary reference frequency by a specified difference frequency, d. means for applying said varying control voltage to the control port of the oscillator, e. means for comparing the primary reference signal with the oscillator signal to produce an output pulse when the two differ by said specified difference frequency and said oscillator is at said secondary reference frequency, f. means responsive to said output pulse to store the instantaneous value of said varying voltage, g. means for producing a dc offset voltage equal to the difference in the control voltage at said secondary reference frequency and at said selected frequency, h. a voltage summing network to add the stored voltage and the offset voltage to produce a sum voltage, and i. means for substituting said sum voltage for said varying voltage at the control port of the oscillator.
Claim 2
Dependent Claim
224 words
Apparatus for generating a signal at a selected frequency, comprising: a. a voltage controlled oscillator having, at each frequency in a range of interest, a rate of change df/dv of frequency with respect to a change in control voltage that is constant despite changes in environmental conditions, b. means for generating a primary reference frequency signal, c. means for generating a varying control voltage to sweep the tuning of said oscillator through a first frequency range which includes a secondary reference frequency that differs from said primary reference frequency by a specified difference frequency, d. means for applying said varying control voltage to the control port of the oscillator, e. means for comparing the primary reference signal with the oscillator signal to produce an output pulse when the two differ by said specified difference frequency and said oscillator is at said secondary reference frequency, f. means responsive to said output pulse to store the instantaneous value of said varying voltage, g. means for producing a dc offset voltage equal to the difference in the control voltage at said secondary reference frequency and at said selected frequency, h. a voltage summing network to add the stored voltage and the offset voltage to produce a sum voltage, and i. means for substituting said sum voltage for said varying voltage at the control port of the oscillator.
Claim 3
Dependent Claim
13 words
Apparatus as claimed in claim 1, wherein the specified difference frequency is zero.
Claim 4
Dependent Claim
39 words
Apparatus as claimed in claim 1, wherein said control voltage characteristic is nonlinear and is shifted by the same voltage at all frequencies in a range of interest when the oscillator is subject to a change in environmental conditions.
Claim 5
Dependent Claim
68 words
Apparatus as claimed in claim 1, wherein said frequency control voltage characteristic is essentially linear and said characteristic is subject to variation with changes in environmental conditions, but retains a constant slope df/dv throughout a frequency range of interest, and said offset voltage is equal to the product of the reciprocal of said constant slope df/dv and the difference between said selected frequency and said secondary reference frequency.
Claim 6
Dependent Claim
106 words
Apparatus as claimed in claim 1, wherein said means for comparing comprises: a. a superheterodyne circuit, b. means for applying the reference frequency signal to the RF input port of said superheterodyne circuit, and c. means for applying the oscillator signal to the local oscillator port of said superheterodyne circuit to sweep the RF tuning of said circuit through a second frequency range that includes the reference frequency signal, and to produce an output pulse from said circuit when the reference signal and oscillator signal have a frequency difference equal to the IF frequency of said circuit and the oscillator is at said secondary reference frequency.
Claim 7
Dependent Claim
17 words
Apparatus as claimed in claim 5, wherein the voltage controlled oscillator is a varactor tuned Gunn oscillator.
Claim 8
Dependent Claim
47 words
Apparatus as claimed in claim 6, wherein said means for producing said varying voltage comprises a clock pulse generator, a digital counter for counting the pulses from said clock generator, and a digital to analog converter for converting the output of said counter to an analog voltage.
Claim 9
Dependent Claim
57 words
Apparatus as claimed in claim 7, wherein said means to store the control voltage includes means responsive to said output pulse to cut off the clock pulse input to the counter, whereby the outputs of said counter and said digital to analog converter remain at the values produced by the clock pulse immediately preceding said output pulse.
Claim 10
Dependent Claim
28 words
Apparatus as claimed in claim 8, wherein said means for producing a reference frequency signal includes a comb generator which produces a plurality of discrete comb frequency signals.
Claim 11
Dependent Claim
66 words
Apparatus as claimed in claim 9, wherein a plurality of secondary reference frequencies are separated from each other by a constant frequency difference, said plurality of discrete comb frequencies are separated by said constant frequency difference and each is displaced from a secondary reference frequency by one-half said constant frequency difference, and the IF frequency of said comparator is equal to one-half said constant frequency difference.
Claim 12
Dependent Claim
102 words
Apparatus as claimed in claim 9, further comprising: a. means for limiting the range of variation of said varying voltage to limit said second frequency range to less than the frequency difference between the closest discrete comb frequencies, b. means for producing a dc reference frequency selection voltage, c. means for applying said reference frequency selection voltage to said voltage summing network to produce a combined control voltage comprising the varying voltage and the reference frequency selection voltage, and d. means for adjusting said reference selection voltage to sweep said superheterodyne circuit through a selected one only of said discrete comb frequencies.
Claim 13
Independent Claim
209 words
A method for tuning a voltage controlled oscillator to a selected frequency, said oscillator having at each frequency in a frequency range of interest a rate of change df/dv of frequency with respect to the change in voltage that is constant despite changes in environmental conditions, comprising the steps of: a. generating a primary reference frequency signal, b. generating a varying control voltage to sweep the tuning of said oscillator through a frequency range which includes a secondary reference frequency that differs from said primary reference frequency by a specified difference frequency, c. applying the varying voltage to the control port of the oscillator, d. comparing the frequency of the reference signal with that of the oscillator to produce an output pulse when the two differ by said specified difference frequency and said oscillator is at said secondary reference frequency, e. storing the instantaneous value of said varying voltage in response to said output pulse, f. producing a dc offset voltage equal to the difference in the control voltage at said secondary reference frequency and at said selected frequency, g. adding the stored and the offset voltages to produce a sum voltage, and h. substituting said sum voltage for said varying voltage at the control port of the oscillator.
Claim 14
Independent Claim
209 words
A method for tuning a voltage controlled oscillator to a selected frequency, said oscillator having at each frequency in a frequency range of interest a rate of change df/dv of frequency with respect to the change in voltage that is constant despite changes in environmental conditions, comprising the steps of: a. generating a primary reference frequency signal, b. generating a varying control voltage to sweep the tuning of said oscillator through a frequency range which includes a secondary reference frequency that differs from said primary reference frequency by a specified difference frequency, c. applying the varying voltage to the control port of the oscillator, d. comparing the frequency of the reference signal with that of the oscillator to produce an output pulse when the two differ by said specified difference frequency and said oscillator is at said secondary reference frequency, e. storing the instantaneous value of said varying voltage in response to said output pulse, f. producing a dc offset voltage equal to the difference in the control voltage at said secondary reference frequency and at said selected frequency, g. adding the stored and the offset voltages to produce a sum voltage, and h. substituting said sum voltage for said varying voltage at the control port of the oscillator.
Claim 15
Dependent Claim
99 words
A method as claimed in claim 12, further comprising the steps of: a. periodically removing the sum voltage from the oscillator control port and reapplying said varying voltage to said port, b. recomparing the frequency of the oscillator to the primary reference frequency to correct the stored voltage for changes in the frequency control voltage characteristic of the oscillator caused by changes in environmental conditions, c. adding the offset voltage and the corrected stored voltage to produce a corrected sum voltage, and d. substituting the corrected sum voltage for the varying voltage at the control port of the oscillator.
References Cited (Backward Citations)
US3793594A
Cited
US3764933A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-09 | 1979-09-08 | 1980-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-09 | 1983-09-08 | 1984-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-09 | 1987-09-08 | 1988-03-09 | $7700.00 | Window Closed / Lapsed |