US3568069A
Expired / Lapsed
US
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Digitally controlled frequency synthesizer
Assignee: Lockheed Martin Corp
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Filing: 1968-12-16
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Granted: 1971-03-02
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Expires: 1988-12-16
Abstract
Abstract A digitally controlled variable frequency synthesizer has a register which stores a number corresponding to the desired output frequency. This number is loaded into a counter which counts pulses from a stable, fixed-frequency oscillator. The counter then counts backward from that number to zero and then emits an output pulse. That causes the stored number to be loaded into the counter again. The frequency of these output pulses thus depends upon the number stored in the register. By properly selecting the number, this frequency can be varied widely and yet it has the stability of the fixed crystal oscillator.
Inventors
- 👤 William D Gabor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:31
CPC Classifications
H; H03; H03B; H03B21/00; H03B21/01; H03B21/02; H03B21/025
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
106 words
A variable frequency synthesizer comprising: A. a fixed frequency oscillator; B. a counter for counting pulses from said oscillator; C. means for controlling said counter so that said counter counts from a first count to a second second count; D. means for emitting an output pulse each time said counter reaches said second count, said pulse being applied to said controlling means to cause them to recycle said counter; E. means for controlling the difference between said first and second counts so as to vary the frequency of said output pulses; and F. a signal-purifying network for removing sidebands and harmonics from said emitting means output.
Claim 2
Dependent Claim
106 words
A variable frequency synthesizer comprising: A. a fixed frequency oscillator; B. a counter for counting pulses from said oscillator; C. means for controlling said counter so that said counter counts from a first count to a second second count; D. means for emitting an output pulse each time said counter reaches said second count, said pulse being applied to said controlling means to cause them to recycle said counter; E. means for controlling the difference between said first and second counts so as to vary the frequency of said output pulses; and F. a signal-purifying network for removing sidebands and harmonics from said emitting means output.
Claim 3
Dependent Claim
86 words
A variable frequency synthesizer as defined in claim 1 wherein said signal-purifying network comprises: A. a first filter section having a first passband characteristic; B. a second filter section having A second passband characteristic; C. means for switching said output pulses to said first filter section when the difference between the counts in said counter exceeds a predetermined amount; and D. means for switching said output pulses to said second filter section when the difference between the counts in said counter is below said predetermined amount.
Claim 4
Dependent Claim
26 words
means for producing a signal each time said second counter completes its count, said signal being applied to said pulse-emitting means to control said pulse widths.
Claim 5
Dependent Claim
26 words
means for producing a signal each time said second counter completes its count, said signal being applied to said pulse-emitting means to control said pulse widths.
Claim 6
Dependent Claim
25 words
whose output has a frequency which is half the frequency of said output pulses; and B. a filter for filtering the output of said flip-flop.
Claim 7
Dependent Claim
25 words
whose output has a frequency which is half the frequency of said output pulses; and B. a filter for filtering the output of said flip-flop.
Claim 8
Dependent Claim
81 words
arranged to emit an output signal when said multivibrator is in its unstable state; C. a second counter arranged to count pulses from said oscillator; D. means for controlling the length of the count of said second counter; and E. means for emitting an output each time said second counter completes its count, said output being applied to reset said flip-flop so that its output has a pulse width which is is dependent upon the number loaded into said second counter.
Claim 9
Dependent Claim
81 words
arranged to emit an output signal when said multivibrator is in its unstable state; C. a second counter arranged to count pulses from said oscillator; D. means for controlling the length of the count of said second counter; and E. means for emitting an output each time said second counter completes its count, said output being applied to reset said flip-flop so that its output has a pulse width which is is dependent upon the number loaded into said second counter.
Claim 10
Dependent Claim
15 words
remains in said unstable state for a selected number of pulses from said oscillator, and
Claim 11
Dependent Claim
15 words
remains in said unstable state for a selected number of pulses from said oscillator, and
Claim 12
Dependent Claim
36 words
emits a said output pulse each time time it returns to said stable state to insure that said counter has counted to said other number before it is reloaded with said number; B. a complementing flip-flop
Claim 13
Dependent Claim
36 words
emits a said output pulse each time time it returns to said stable state to insure that said counter has counted to said other number before it is reloaded with said number; B. a complementing flip-flop
Claim 14
Dependent Claim
70 words
A variable frequency synthesizer as defined in claim 2 wherein each said filter section comprises: A. a complementing flip-flop arranged to be toggled by said output pulses; B. a filter connected to filter the output of said flip-flop; C. an oscillator; and D. a mixer for mixing the outputs of said filter and said oscillator to develop an output signal whose frequency varies with the frequency of said output pulses.
Claim 15
Dependent Claim
120 words
A variable frequency synthesizer comprising: A. a register for storing numbers in binary form; B. a fixed frequency oscillator; C. a counter for counting pulses from said oscillator; D. means for loading a number from said register into said counter so that said counter commences counting from said number to another predetermined number; E. means for emitting an output pulse each time said counter reaches said other number, each said output pulse also being applied to said loading means to reload said number into said counter so that the synthesizer continues to emit output pulses whose frequency is determined by said number; and F. a signal-purifying circuit connected to filter harmonics and sidebands from the output of said pulse-emitting means.
Claim 16
Dependent Claim
120 words
A variable frequency synthesizer comprising: A. a register for storing numbers in binary form; B. a fixed frequency oscillator; C. a counter for counting pulses from said oscillator; D. means for loading a number from said register into said counter so that said counter commences counting from said number to another predetermined number; E. means for emitting an output pulse each time said counter reaches said other number, each said output pulse also being applied to said loading means to reload said number into said counter so that the synthesizer continues to emit output pulses whose frequency is determined by said number; and F. a signal-purifying circuit connected to filter harmonics and sidebands from the output of said pulse-emitting means.
Claim 17
Dependent Claim
86 words
A variable frequency synthesizer as defined in claim 4 wherein said purifying circuit includes a first filter section which comprises: A. a complementing flip-flop arranged to be toggled by said output pulses; B. a second oscillator; C. means; mixer for mixing the outputs of said second oscillator and said flip-flop to develop an output signal whose frequency varies with the frequency of the pulses from said pulse-emitting means; and D. one or more filters for filtering the sidebands and harmonics from the output of said flip-flop.
Claim 18
Dependent Claim
79 words
A variable frequency synthesizer as defined in claim 5 and further including: A. a second filter section similar to the first, included in said purifying circuit; B. means for gating the pulses from said pulse-emitting means to said first filter section when the number in said register exceeds a predetermined value; and C. means for gating the pulses from said pulse-emitting means to said second filter section when the number in said register does not exceed said predetermined value.
Claim 19
Dependent Claim
42 words
A variable frequency synthesizer as defined in claim 4 and further including means responsive to said number and to the output pulses from said pulse emitting means for controlling the pulse width of said output pulses as a function of said number.
Claim 20
Dependent Claim
20 words
A variable frequency synthesizer as defined in claim 4 wherein: A. said pulse emitting means comprises a monostable multivibrator which:
Claim 21
Dependent Claim
71 words
A variable frequency synthesizer as defined in claim 8 wherein said controlling means causes said second counter to: A. count through one count when said number in said register exceeds a predetermined value; and B. count through a different count when said number in said register does not exceed said value so that the pulse width of the output of said flip-flop depends upon the frequency of said synthesizer output pulses.
Claim 22
Dependent Claim
94 words
A variable frequency synthesizer as defined in claim 4 and further including: A. first and second filter sections having first and second passband characteristics, respectively, included in said purifying circuit; B. means for switching said output pulses to said first filter section when the number in said register exceeds a predetermined magnitude; and C. means for switching said output pulses to said second filter section when said number does not exceed said predetermined magnitude so that the output of said synthesizer has a relatively low harmonic content over a relatively wide range of frequencies.
Claim 23
Dependent Claim
19 words
A variable frequency synthesizer as defined in claim 10 wherein each said filter section includes: A. a complementing flip-flop
Claim 24
Dependent Claim
34 words
A variable frequency synthesizer as defined in claim 10 and further including: A. a second synthesizer section similar to the first said synthesizer; and B. means for mixing the outputs of said synthesizer sections.
Claim 25
Dependent Claim
66 words
A variable frequency synthesizer as defined in claim 12 wherein: A. one of said synthesizer sections is arranged to emit signals in relatively large frequency increments over a relatively large frequency range; and B. the other section is arranged to emit signals in smaller increments over a smaller range so that said two sections may be used together as a coarse and fine tunable frequency source.
Claim 26
Dependent Claim
135 words
A variable frequency synthesizer comprising: A. a register for storing numbers in binary form; B. a fixed frequency oscillator; C. a counter for counting pulses from said oscillator; D. means for loading a number from said register into said counter so that said counter commences counting from said number to another predetermined number; E. means for emitting an output pulse each time said counter reaches said other number, each said output pulse also being applied to said loading means to reload said number into said counter so that the synthesizer continues to emit output pulses whose frequency is determined by said number; and F. means responsive to said number and to said output pulses of the pulse-emitting means for controlling the widths of said output pulses as a function of the value of said number.
Claim 27
Dependent Claim
135 words
A variable frequency synthesizer comprising: A. a register for storing numbers in binary form; B. a fixed frequency oscillator; C. a counter for counting pulses from said oscillator; D. means for loading a number from said register into said counter so that said counter commences counting from said number to another predetermined number; E. means for emitting an output pulse each time said counter reaches said other number, each said output pulse also being applied to said loading means to reload said number into said counter so that the synthesizer continues to emit output pulses whose frequency is determined by said number; and F. means responsive to said number and to said output pulses of the pulse-emitting means for controlling the widths of said output pulses as a function of the value of said number.
Claim 28
Dependent Claim
11 words
The invention according to claim 14 wherein said controlling means includes:
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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) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |