US4020425A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital settable frequency generator with phase-locking loop
Assignee: Wandel and Golterman GmbH and Co
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Filing: 1976-03-26
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Granted: 1977-04-26
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Expires: 1996-03-26
Abstract
Abstract A digitally settable frequency generator comprises a master oscillator whose operating frequency f Q is variable between a normal value f Q " and a slightly lower value f Q ' = (1-p)f Q " with the aid of a normally disconnected tuning capacitor. The master oscillator works into a frequency divider of fixed step-down ratio m:1 (or 2m:1) to produce a reference frequency f B . A slave oscillator, generating an output frequency f A = gf B , is controlled by a phase-locking loop including a phase comparator to which the reference frequency f B is fed along with a like frequency obtained from output frequency f A with the aid of another divider having a digitally variable integral step-down ratio g:1. A fractional value i, which may range from 0 to 100%, is set with the aid of a numerical interpolation selector to determine the number n<m of cycles of operating frequency f Q within a cycle (or half-cycle) of reference frequency f B during which that operating frequency is changed to its lower value f Q '. With a division factor of 2m, alternate half-cycles of reference frequency f B can be used for stabilizing the frequency f Q with the aid of another phase-locking loop driven by a standard oscillator. Such a division factor also allows the operating frequency of the master oscillator to be held at its normal value f Q " throughout the first half of every odd-numbered reference-frequency cycle (n=O) and at its reduced value f Q ' throughout the first half of every even-numbered cycle (n=m), independently of the setting of the interpolation selector which controls that operating frequency only during the remaining half-cycles (n=im); with a switchover from g to g + 1 during each even-numbered cycle, the parameter p can be adapted to changes in the division factor g by periodically adjusting the tuning capacitor in response to an error signal derived from any variation, between consecutive cycles, in the relative phasing of the two oscillations of reference frequency f B fed to the phase comparator which controls the slave oscillator.
Inventors
- 👤 Gunther Hoffmann
- 👤 Peter Harzer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:15
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/18; H03L7/183; H03L7/22; H03L7/23
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
188 words
A frequency generator comprising: a source of variable reference frequency f B including an adjustable master oscillator of operating frequency f Q = smf B , said master oscillator being provided with tuning means, and a fixed first frequency divider with an integral step-down ratio m:1 driven by said master oscillator, s being an integer not greater than 2; a continuously adjustable slave oscillator provided with a phase-locking loop including a phase comparator; a digitally settable second frequency divider with an integral step-down ratio g:1 driven by said slave oscillator, said phase comparator having inputs respectively connected to said first and second frequency dividers for receiving therefrom respective oscillations of said reference frequency f B ; integral selector means connected to said second frequency divider for changing the division factor g thereof to vary the output frequency f A = gf B of said slave oscillator; and interpolating selector means connected to said tuning means for varying said output frequency f A in fractional increments by changing said operating frequency f Q between a plurality of different values within every cycle of said reference frequency f B .
Claim 2
Dependent Claim
188 words
A frequency generator comprising: a source of variable reference frequency f B including an adjustable master oscillator of operating frequency f Q = smf B , said master oscillator being provided with tuning means, and a fixed first frequency divider with an integral step-down ratio m:1 driven by said master oscillator, s being an integer not greater than 2; a continuously adjustable slave oscillator provided with a phase-locking loop including a phase comparator; a digitally settable second frequency divider with an integral step-down ratio g:1 driven by said slave oscillator, said phase comparator having inputs respectively connected to said first and second frequency dividers for receiving therefrom respective oscillations of said reference frequency f B ; integral selector means connected to said second frequency divider for changing the division factor g thereof to vary the output frequency f A = gf B of said slave oscillator; and interpolating selector means connected to said tuning means for varying said output frequency f A in fractional increments by changing said operating frequency f Q between a plurality of different values within every cycle of said reference frequency f B .
Claim 3
Dependent Claim
124 words
A frequency generator as defined in claim 1 wherein said tuning means has a first position establishing a value f Q ' and a second position establishing a value f Q " for said operating frequency f Q , said values bearing the relationship 1 - f Q '/f Q " = p<<1, further comprising switchover means responsive to said interpolating selector means and connected to said tuning means for maintaining one of said positions during n cycles and the other of said positions during the remaining m-n cycles of said operating frequency f Q occurring during at least one half-cycle of said reference frequency f B , n being a whole number less than the division factor m of said first frequency divider.
Claim 4
Dependent Claim
26 words
A frequency generator as defined in claim 2 wherein said tuning means comprises at least one capacitor connectable to said master oscillator by said switchover means.
Claim 5
Dependent Claim
42 words
A frequency generator as defined in claim 3 wherein said master oscillator is provided with a frequency-determining crystal, said capacitor being connectable by said switchover means across said crystal to lower said operating frequency from f Q " to f Q '.
Claim 6
Dependent Claim
240 words
A frequency generator as defined in claim 2 wherein said tuning means includes adjustable reactance means for establishing a variable off-normal value for said operating frequency f Q which, over a period equaling m cycles of said operating frequency, changes the length of said period by a cycle of said output frequency f A in comparison with a like period at a normal value of said operating frequency; further comprising switch means controlled by said first frequency divider for compensatorily incrementing a selected division factor g of said second frequency ±1 during certain periodically recurring cycles of said reference frequency f B while controlling said reactance means independently of said interpolating selector means to maintain said off-normal value throughout a series of m cycles of said operating frequency and for keeping said division factor g unincremented during other periodically recurring cycles of said reference frequency f B while controlling said reactance means independently of said interpolating selector means to maintain said normal value throughout a series of m cycles of said operating frequency, and comparison means for deriving from said phase-locking loop an error signal proportional to any difference in the relative phasing of said oscillations of frequency f B between said certain cycles and said other cycles, said reactance means being connected to said comparison means for adjustment in a sense tending to minimize said error signal with resulting adaptation of said off-normal value to said division factor g.
Claim 7
Dependent Claim
117 words
A frequency generator as defined in claim 5 wherein said switch means is operative to increment said selected division factor g during every other cycle of said reference frequency f B ; said comparison means comprising: a storage condenser with a charging circuit connected to said phase-locking loop, an amplifier with an input circuit connected across said storage condenser, an output circuit including integrating means and a feedback circuit connected between said output and input circuits; a coupling condenser between said storage condenser and said input circuit; and a pair of interrupters alternately operated by said switch means for opering said output circuit and said feedback circuit during alternate cycles of said reference frequency f B .
Claim 8
Dependent Claim
72 words
A frequency generator as defined in claim 5 wherein s = 2, said second frequency divider including a final binary stage controlling said switch means for operating and deactivating said switchover means only during single half-cycles of said certain and other cycles of said reference frequency f B while subjecting said switchover means to the exclusive control of said interpolating selector means during the remaining half-cycles of said certain and other cycles.
Claim 9
Dependent Claim
35 words
A frequency generator as defined in claim 2 wherein said tuning means comprises two capacitors of different magnitudes independently connectable to said master oscillator under the control of respective sections of said interpolating selector means.
Claim 10
Dependent Claim
46 words
A frequency generator as defined in claim 2 wherein said master oscillator is adjustable, said source further comprising a standard oscillator and calibrating means controlled by said first frequency divider for intermittently connecting said master oscillator in a second phase-locking loop driven by said standard oscillator.
Claim 11
Dependent Claim
51 words
A frequency generator as defined in claim 9 wherein s = 2, said first frequency divider including a final binary stage controlling said calibrating means for connecting said master oscillator in said second phase-locking loop during alternate half-cycles of said reference frequency f B with simultaneous deactivation of said switchover means.
Claim 12
Dependent Claim
86 words
A frequency generator as defined in claim 2 wherein said switchover means comprises a coincidence circuit connected to receive said whole number n from said interpolating selector means and a count of cycles of said operating frequency f A from said first frequency divider, and a flip-flop connected to said first frequency divider and to said coincidence circuit for setting at the beginning of at least every other half-cycle of said reference frequency f B and for resetting upon said count reaching the value of n.
Claim 13
Dependent Claim
32 words
A frequency generator as defined in claim 11 wherein said interpolating selector means includes a calculator for computing the value of n from a fractional reading i ranging between zero and unity.
Claim 14
Dependent Claim
116 words
A frequency generator as defined in claim 2 wherein said switchover means comprises a third frequency divider driven by said slave oscillator to establish an ancillary frequency f C intermediate said operating and reference frequencies f Q and f B , a coincidence circuit connected to receive a fractional reading i from said interpolating selector means and a count of cycles of said output frequency f A from said third frequency divider, and a flip-flop connected to said third frequency divider and to said coincidence circuit for setting at the beginning of every cycle of said ancillary frequency f C and for resetting upon said count reaching a proportional value equal to said fractional reading i.
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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) | 1980-04-25 | 1980-10-25 | 1981-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-25 | 1984-10-25 | 1985-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-25 | 1988-10-25 | 1989-04-26 | $7700.00 | Window Closed / Lapsed |