US3775665A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for generating an electrical output signal of variable frequency
Assignee: Gemalto Terminals Ltd
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Filing: 1972-11-08
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Granted: 1973-11-27
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Expires: 1992-11-08
Abstract
Abstract The invention provides a frequency generator capable of producing an output frequency which is continuously variable but which is nevertheless phase-locked to a stable reference frequency. The output frequency is derived from a V.C.O., and is sampled at the reference frequency to produce a difference frequency equal to the difference between the output frequency and a harmonic of the reference frequency. This difference frequency is maintained equal to another reference frequency, lower than the first, by comparison with this other reference frequency in a phase-sensitive detector, whose output is applied to the V.C.O. to complete a phase-locked loop. The first reference frequency is produced by mixing the outputs of two variable-frequency crystal-controlled oscillators, one of which is manually adjustable and the other of which is controlled by a control circuit. It is arranged that while the output frequency of the V.C.O. is being coarsely manually adjusted, the phase-locked loop is disabled and the control circuit adjusts the frequency of its crystal-controlled oscillator to maintain the difference frequency substantially equal to the other reference frequency. After coarse adjustment, therefore when the phaselocked loop is re-enabled it is already almost in lock. The output frequency is then finely adjusted by manual adjustment of the frequency of the other crystal-controlled oscillator.
Inventors
- 👤 P Sample
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:48
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/22; Y; Y10; Y10S; Y10S331/00; Y10S331/02
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
238 words
Apparatus for generating an electrical output signal of variable frequency, the apparatus comprising: first oscillator means for generating a first frequency from which the output signal is derived; means for varying the first frequency to select approximately a desired value thereof; second oscillator means for generating a second frequency lower than the first frequency; circuit means connected to receive the first and second frequencies and arranged to produce a frequency equal to the difference between the first frequency and a harmonic of the second frequency; phase-sensitive detector means arranged to compare the frequency produced by the circuit means with a third frequency and to produce a control signal dependent upon the difference therebetween; means for applying the control signal to the first oscillator means to vary the first frequency, so as to maintain the frequency produced by the circuit means substantially equal to the third frequency, and thereby phaselock the first frequency to the second and third frequencies; and means for varying the second frequency to select said desired value of the first frequency, the means for varying the second frequency being arranged to render the first frequency continuously variable and including control means operative, in response to a predetermined difference between the frequency produced by the circuit means and the third frequency, to produce a further control signal which is applied to the second oscillator means to vary the second frequency so as to reduce said difference.
Claim 2
Dependent Claim
238 words
Apparatus for generating an electrical output signal of variable frequency, the apparatus comprising: first oscillator means for generating a first frequency from which the output signal is derived; means for varying the first frequency to select approximately a desired value thereof; second oscillator means for generating a second frequency lower than the first frequency; circuit means connected to receive the first and second frequencies and arranged to produce a frequency equal to the difference between the first frequency and a harmonic of the second frequency; phase-sensitive detector means arranged to compare the frequency produced by the circuit means with a third frequency and to produce a control signal dependent upon the difference therebetween; means for applying the control signal to the first oscillator means to vary the first frequency, so as to maintain the frequency produced by the circuit means substantially equal to the third frequency, and thereby phaselock the first frequency to the second and third frequencies; and means for varying the second frequency to select said desired value of the first frequency, the means for varying the second frequency being arranged to render the first frequency continuously variable and including control means operative, in response to a predetermined difference between the frequency produced by the circuit means and the third frequency, to produce a further control signal which is applied to the second oscillator means to vary the second frequency so as to reduce said difference.
Claim 3
Dependent Claim
27 words
Apparatus as claimed in claim 1, wherein the circuit means comprises sampling means arranged to sample the output of the first oscillator means at the second frequency.
Claim 4
Dependent Claim
84 words
Apparatus as claimed in claim 1, wherein the control means comprises a source of clock pulses, a counter arranged to receive and count the clock pulses, digital-to-analogue converter means arranged to produce an output signal which is dependent upon the count in the counter and which constitutes said further control signal, and means for preventing the supply of clock pulses to the counter when the difference between the frequency produced by the circuit means and the third frequency is less than said predetermined difference.
Claim 5
Dependent Claim
78 words
Apparatus as claimed in claim 3, wherein the means for preventing the supply of clock pulses comprises a band-pass filter whose pass-band includes the third frequency and which is connected to the output of the circuit means, and a detector which is connected to the output of the filter and which is arranged to prevent the supply of clock pulses to the counter when the frequency produced by the circuit means lies within the pass-band of the filter.
Claim 6
Dependent Claim
31 words
Apparatus as claimed in claim 1, wherein there is provided disabling means for disabling the phase-locked loop which includes the first oscillator means, the circuit means and the phase-sensitive detector means.
Claim 7
Dependent Claim
42 words
Apparatus as claimed in claim 5, wherein the disabling means comprises a switching device operatively connected to the means for varying the first frequency and arranged to disable said phase-locked loop while said means for varying the first frequency is in operation.
Claim 8
Dependent Claim
17 words
Apparatus as claimed in claim 1, wherein the second oscillator means includes at least one crystal-controlled oscillator.
Claim 9
Dependent Claim
71 words
Apparatus as claimed in claim 7, wherein the second oscillator means comprises first and second crystal-controlled oscillators for generating fourth and fifth frequencies respectively, at least one of said fourth and fifth frequencies being variable, and mixing means connected to receive said fourth and fifth frequencies and arranged to produce an output frequency which is equal to the difference between the fourth and fifth frequencies and which constitutes said second frequency.
Claim 10
Dependent Claim
41 words
Apparatus as claimed in claim 8, wherein both of said fourth and fifth frequencies are variable, and wherein the control means is operatively connected to one of the crystal-controlled oscillators and the frequency of the other crystal-controlled oscillator is manually variable.
Claim 11
Dependent Claim
16 words
Apparatus as claimed in claim 1, wherein the third frequency is lower than the second frequency.
Claim 12
Dependent Claim
20 words
Apparatus as claimed in claim 10, wherein the third frequency is substantially equal to one quarter of the second frequency.
Claim 13
Dependent Claim
19 words
Apparatus as claimed in claim 1, wherein the first oscillator means comprises at least one voltage- or current-controlled oscillator.
Claim 14
Dependent Claim
19 words
Apparatus as claimed in claim 12, wherein the first oscillator means comprises at least one varactor-controlled transmission line oscillator.
Claim 15
Dependent Claim
46 words
Apparatus as claimed in claim 1, wherein the first oscillator means comprises a plurality of oscillators having different operating frequency ranges, and means for selecting one of said oscillators to produce the first frequency, the frequency of the output signal being constituted by the first frequency.
Claim 16
Dependent Claim
39 words
Apparatus as claimed in claim 1, wherein there is provided adjustable first frequency-dividing meaNs connected to receive and divide the first frequency, the frequency of the output signal being constituted by the frequency produced by the first frequency-dividing means.
Claim 17
Dependent Claim
48 words
Apparatus as claimed in claim 1, wherein there is provided means for measuring the frequency of the output signal, which means includes a counter connected to receive pulses at the first frequency and timing means for causing the counter to count the pulses for a predetermined time interval.
Claim 18
Dependent Claim
31 words
Apparatus as claimed in claim 16, wherein the timing means comprises means for generating a fixed reference frequency, and second frequency-dividing means connected to receive and divide the fixed reference frequency.
Claim 19
Dependent Claim
20 words
Apparatus as claimed in claim 17, wherein the means for generating the fixed reference frequency comprises a third crystal-controlled oscillator.
Claim 20
Dependent Claim
72 words
Apparatus as claimed in claim 17, wherein there is provided adjustable first frequency-dividing means connected to receive and divide the first frequency, the frequency of the output signal being constituted by the frequency produced by the first frequency-dividing means, and wherein the second frequency-dividing means is also adjustable, in synchronism with the first frequency-deviding means, whereby said predetermined time interval is inversely proportional to the division ratio of the first frequency-dividing means.
Claim 21
Dependent Claim
26 words
Apparatus as claimed in claim 17, wherein the third frequency is produced by frequency-dividing means which is connected to receive and divide said fixed reference frequency.
Claim 22
Dependent Claim
16 words
Apparatus as claimed in claim 1, wherein the third frequency is produced by a voltage-controlled oscillator.
Claim 23
Dependent Claim
22 words
Apparatus as claimed in claim 21, wherein there is provided means for frequency-modulating the third frequency, whereby to frequency-modulate the output signal.
Claim 24
Dependent Claim
16 words
Apparatus as claimed in claim 1, wherein there is provided means for amplitude-modulating the output signal.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |