US3681706A
Expired / Lapsed
US
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Variable-frequency generator with digital frequency selection
Assignee: Wandel and Golterman GmbH and Co
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Filing: 1970-12-01
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Granted: 1972-08-01
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Expires: 1990-12-01
Abstract
Abstract The operating frequency of an electronically adjustable oscillator is continuously determined by a digital counter establishing a variable measuring interval during which the number of oscillator cycles reaches a magnitude preset in a digital selector. A feedback circuit from the output of a comparator, receiving the values stored in the counter and in the selector, readjusts the oscillator to make the measuring interval equal to a predetermined base period (e.g., of 1 second), consistent with the selected frequency, starting concurrently with that base period. A timing circuit periodically emits a pair of reference pulses marking the beginning and the end of the base period, at least the second pulse being subject to shifting under the control of a synchronization monitor to compensate for any time lag between the beginning of the base period and the start of the first full oscillator cycle; a further shifting of the second reference pulse, under the control of an ancillary selector, enables the generation of frequencies whose chosen magnitudes lie between adjacent settings of the digital selector. A pair of such digital selectors, alternately connectable to one of the comparator inputs, may serve for the establishment of upper and lower limits of a sweep range for the oscillator frequency; a third selector, effective during the sweep, may generate a frequency marker whenever the value registered therein matches the momentary output frequency of the oscillator.
Inventors
- 👤 Peter Harzer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:58
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/18; H03B; H03B23/00; H03L7/181; H03B2200/00; H03B2200/006; H03B2200/0092
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
258 words
A variable-frequency generator comprising: an adjustable oscillator; a frequency counter with an input receiving the output of said oscillator; a presettable digital frequency selector; timer means for establishing a recurrent base period substantially of predetermined duration; a coincidence circuit connected to receive from said selector a numerical value representing a preset frequency and to receive from said counter a progressively varying signal representing the number of operating cycles of said oscillator counted during a measuring interval starting with the moment of inception of said base period, said coincidence circuit emitting an identity signal upon said progressively varying signal reaching said numerical value; test means connected to receive from said timer means a terminal pulse at the end of said base period and to receive said identity signal from said coincidence circuit, said test means generating an electrical control variable of a sign depending upon the relative order of occurrence of said terminal pulse and said identity signal; feedback means for applying said control variable to said oscillator to vary the operating frequency thereof in a sense tending to make said identity signal coincide with said terminal pulse; monitoring means connected to said timer means and to the input of said counter for detecting any time lag between said moment of inception and the beginning of the first full cycle of said oscillator occurring during said measuring interval; and delay means coupled to said timer means and controlled by said monitoring means for retarding the effecTiveness of said terminal pulse by a length of time equaling said time lag.
Claim 2
Dependent Claim
258 words
A variable-frequency generator comprising: an adjustable oscillator; a frequency counter with an input receiving the output of said oscillator; a presettable digital frequency selector; timer means for establishing a recurrent base period substantially of predetermined duration; a coincidence circuit connected to receive from said selector a numerical value representing a preset frequency and to receive from said counter a progressively varying signal representing the number of operating cycles of said oscillator counted during a measuring interval starting with the moment of inception of said base period, said coincidence circuit emitting an identity signal upon said progressively varying signal reaching said numerical value; test means connected to receive from said timer means a terminal pulse at the end of said base period and to receive said identity signal from said coincidence circuit, said test means generating an electrical control variable of a sign depending upon the relative order of occurrence of said terminal pulse and said identity signal; feedback means for applying said control variable to said oscillator to vary the operating frequency thereof in a sense tending to make said identity signal coincide with said terminal pulse; monitoring means connected to said timer means and to the input of said counter for detecting any time lag between said moment of inception and the beginning of the first full cycle of said oscillator occurring during said measuring interval; and delay means coupled to said timer means and controlled by said monitoring means for retarding the effecTiveness of said terminal pulse by a length of time equaling said time lag.
Claim 3
Dependent Claim
28 words
A frequency generator as defined in claim 1 wherein said monitoring means includes integrating means for generating a corrective voltage proportional to the duration of said time lag.
Claim 4
Dependent Claim
49 words
A frequency generator as defined in claim 2 wherein said timer means comprises a chain of binary frequency dividers, said delay means being inserted between successive dividers of said chain for retarding the transmission of a stepping pulse therebetween by a length of time proportional to said corrective voltage.
Claim 5
Dependent Claim
43 words
A frequency generator as defined in claim 2 wherein said delay means is interposed between said timer means and said test means for retarding the transmission of said terminal pulse to the latter by a length of time proportional to said corrective voltage.
Claim 6
Dependent Claim
25 words
A frequency generator as defined in claim 4 wherein said delay means includes a monostable element having a relaxation period variable by said corrective voltage.
Claim 7
Dependent Claim
46 words
A frequency generator as defined in claim 5 wherein said delay means further includes an OR gate with a first input connected to the output of said monostable element and with a second input connected to said timer means via a path shunting said monostable element.
Claim 8
Dependent Claim
38 words
A frequency generator as defined in claim 1 wherein said counter is provided with an ancillary binary input stage reversible by a first counting pulse from said oscillator and connected to trigger said monitoring means upon such reversal.
Claim 9
Dependent Claim
38 words
A frequency generator as defined in claim 1, further comprising ancillary selector means and frequency-modifying means coupled thereto and to said timer means for additionally changing said operating frequency by varying the effective length of said base period.
Claim 10
Dependent Claim
74 words
A frequency generator as defined in claim 8 wherein said frequency-modifying means comprises a retarding network for said terminal pulse interposed between said timer means and said test means, said ancillary selector means including a source of control voltage for said network and weighting means responsive to the setting of said digital frequency selector for making the delay time of said network a function of said control voltage varying inversely with said operating frequency.
Claim 11
Dependent Claim
25 words
A frequency generator as defined in claim 9 wherein said retarding network comprises a monostable element having a relaxation period variable by said control voltage.
Claim 12
Dependent Claim
60 words
A frequency generator as defined in claim 9 wherein the delay time of said network is variable within a predetermined range, said frequency-modifying means further including presetting means coupled with said counter for registering therein a negative preliminary count which corresponds to a frequency rise substantially compensating the frequency drop introduced by said network at the midpoint of said range.
Claim 13
Dependent Claim
37 words
A frequency generator as defined in claim 11 wherein said network comprises a time-constant circuit, said presetting means being coupled to an impedance of said circuit for modifying said delay time in conformity with said negative count.
Claim 14
Dependent Claim
20 words
A frequency generator as defined in claim 11 wherein said source of control voltage comprises a generator of sawtooth voltages.
Claim 15
Dependent Claim
43 words
A frequency generator as defined in claim 9 wherein the delay time of said network is variable between zero and a maximum time corresponding to a frequency drop substantially equaling the minimum frequency increment obtainable by a unit step of said digital selector.
Claim 16
Dependent Claim
28 words
A frequency generator as defined in claim 14 wherein said source of control voltage is calibrated in discrete steps corresponding to decimal fractions of said minimum frequency increment.
Claim 17
Dependent Claim
180 words
A variable-frequency generator comprising: an adjustable oscillator; a frequency-determining circuit for said oscillator including storage means for an electrical control variable, the operating frequency of the oscillator being a function of the magnitude of said control variable; A first and a second source of charging current for said storage means determining a lower limit and an upper limit, respectively, for said operating frequency; switch means for alternately connecting said first and second sources to said frequency-determining circuit during successive switchover periods sufficient to allow modification of said control variable in said storage means to establish said lower and upper limits, respectively, for said operating frequency; selector means settable to a desired frequency between said upper and lower limits and including a third source of charging current; register means chargeable by said third source for storing an electrical variable corresponding to said desired frequency; comparison means connected to said storage and register means for ascertaining a match between the electrical variables stored therein; and indicator means connected to said comparison means for emitting an identity signal upon ascertainment of such match.
Claim 18
Dependent Claim
180 words
A variable-frequency generator comprising: an adjustable oscillator; a frequency-determining circuit for said oscillator including storage means for an electrical control variable, the operating frequency of the oscillator being a function of the magnitude of said control variable; A first and a second source of charging current for said storage means determining a lower limit and an upper limit, respectively, for said operating frequency; switch means for alternately connecting said first and second sources to said frequency-determining circuit during successive switchover periods sufficient to allow modification of said control variable in said storage means to establish said lower and upper limits, respectively, for said operating frequency; selector means settable to a desired frequency between said upper and lower limits and including a third source of charging current; register means chargeable by said third source for storing an electrical variable corresponding to said desired frequency; comparison means connected to said storage and register means for ascertaining a match between the electrical variables stored therein; and indicator means connected to said comparison means for emitting an identity signal upon ascertainment of such match.
Claim 19
Dependent Claim
92 words
A frequency generator as defined in claim 16, further comprising timer means for controlling said switch means to disconnect said frequency-determining circuit from said first and second sources for a limited readjustment interval at the end of each switchover period, each of said sources including an individual frequency selector and test means effective during said readjustment interval for feeding to said frequency-determining circuit a corrective voltage to modify the stored control variable in a sense compensating for any disparity between said operating frequency and the setting of the respective individual frequency selector.
Claim 20
Dependent Claim
50 words
A frequency generator as defined in claim 17 wherein said test means includes a threshold device for comparing the magnitude of said disparity with a predetermined level, said timer means being responsive to said threshold device for extending the duration of said readjustment interval upon said disparity surpassing said level.
Claim 21
Dependent Claim
47 words
A frequency generator as defined in claim 16 wherein said indicator means is connected to said switch means for temporarily disconnecting said frequency-determining circuit from said first and second sources in response to said identity signal, thereby holding said operating frequency constant for a limited evaluation period.
Claim 22
Dependent Claim
55 words
A frequency generator as defined in claim 19, further comprising additional switch means controlled by said indicator means for connecting said third source to said register means only during said evaluation period to reduce any divergence between the setting of said selector means and the magnitude of the electrical variable stored in said register means.
Claim 23
Dependent Claim
70 words
A frequency generator as defined in claim 20, further comprising detector means connected to said indicator means and other switch means controlled by said detector means in the absence of said identity signal during any switchover period for briefly establishing an equalizing circuit between said register means and said storage means at the end of such switchover period for letting said register means acquire the charge of said storage means.
Claim 24
Dependent Claim
202 words
A variable-frequency generator comprising: an adjustable oscillator; a frequency-determining circuit for said oscillator including storage means for a control variable, the operating frequency of the oscillator being a function of the magnitude of said control variable; first and second frequency selectors settable to a desired lower and upper limit, respectively, of a sweep range for said operating frequency; first and second register means for charges adapted to modify the magnitude of said control variable; first and second charging means for said first and second register means, respectively; switch means for alternately connecting said first and second register means to said frequency-determining circuit during successive switchover periods sufficient to allow modification of said control variable by the charges thereof; timer means for coNtrolling said switch means to disconnect said frequency-determining circuit from both said register means for a limited readjustment interval at the end of each switchover period and for alternately connecting said first and second register means to the associated charging means during successive readjustment intervals; and control means effective during each readjustment interval for comparing the operating frequency of said oscillator with the setting of the corresponding frequency selector and for enabling the associated charging means to reduce any disparity therebetween.
Claim 25
Dependent Claim
202 words
A variable-frequency generator comprising: an adjustable oscillator; a frequency-determining circuit for said oscillator including storage means for a control variable, the operating frequency of the oscillator being a function of the magnitude of said control variable; first and second frequency selectors settable to a desired lower and upper limit, respectively, of a sweep range for said operating frequency; first and second register means for charges adapted to modify the magnitude of said control variable; first and second charging means for said first and second register means, respectively; switch means for alternately connecting said first and second register means to said frequency-determining circuit during successive switchover periods sufficient to allow modification of said control variable by the charges thereof; timer means for coNtrolling said switch means to disconnect said frequency-determining circuit from both said register means for a limited readjustment interval at the end of each switchover period and for alternately connecting said first and second register means to the associated charging means during successive readjustment intervals; and control means effective during each readjustment interval for comparing the operating frequency of said oscillator with the setting of the corresponding frequency selector and for enabling the associated charging means to reduce any disparity therebetween.
Claim 26
Dependent Claim
38 words
A frequency generator as defined in claim 22, further comprising additional charging means coupled directly to said storage means and enabled concurrently with said first and second charging means by said test means to modify said control variable.
Claim 27
Dependent Claim
39 words
A frequency generator as defined in claim 22 wherein said control means includes a threshold device for comparing the magnitude of said disparity with a predetermined level and for generating an alarm signal upon said disparity surpassing said level.
Claim 28
Dependent Claim
34 words
A frequency generator as defined in claim 24 wherein said timer means is connected to respond to said threshold device for extending the duration of said readjustment interval in response to said alarm signal.
Claim 29
Dependent Claim
68 words
A frequency generator as defined in claim 25 wherein said timer means includes a generator of periodic reference pulses establishing a succession of recurrent periods for said control means, said timer means further comprising a sweep circuit establishing said switchover periods, said sweep circuit being jointly controlled by said reference pulses and said alarm signal for invariably terminating said readjustment intervals at the end of respective recurrence periods.
Claim 30
Dependent Claim
61 words
A frequency generator as defined in claim 22, further comprising a third frequency selector settable to a value between said lower and upper limits, said switch means operatively connecting said third frequency selector to said control means during said switchover periods for generating a marker pulse upon the operating frequency of said oscillator matching the setting of said third frequency selector.
Claim 31
Dependent Claim
126 words
A frequency generator as defined in claim 27 wherein said timer means comprises an emitter of periodic reference pulses defining recurrent base periods and wherein said control means includes a counter for the number of oscillator cycles periodically restarted by said reference pulses, coincidence means for generating an identity signal upon the count of said cycles matching the setting of said third frequency selector, test means responsive to said reference pulses and said identity signal for producing a discriminating signal during any switchover period with a polarity determined by the relative order of occurrence of said identity signal and of a reference pulse terminating a base period, and sensing means responsive to a change in the polarity of said discriminating signal for generating said marker pulse.
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) | 1975-08-01 | 1976-01-31 | 1976-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-01 | 1980-01-31 | 1980-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-01 | 1984-01-31 | 1984-08-01 | $7700.00 | Window Closed / Lapsed |