Patent JPS5933874A successfully refreshed from Google Patents.
US4060773A
Expired / Lapsed
US
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Frequency modulation system
Assignee: Toshiba Corp
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Filing: 1977-01-24
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Granted: 1977-11-29
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Expires: 1997-01-24
Abstract
Abstract An output frequency of a first variable frequency oscillator is frequency-divided and the frequency divided signal is compared in phase with the output frequency of a reference frequency oscillator. The result of the phase comparing is fed back to the first variable frequency oscillator for controlling the output frequency of the first variable frequency oscillator. The output frequency of a second variable frequency oscillator is mixed with the output frequency of a fixed frequency oscillator to produce a difference frequency between both output frequencies. The difference frequency is compared in phase with the output frequency of the first variable frequency oscillator. The result of the phase comparing is used for controlling the output frequency of the second variable frequency oscillator. The output frequency of the fixed frequency oscillator is frequency-modulated by the frequency of a modulating signal.
Inventors
- 👤 Masaaki Hata
- 👤 Sotaro Wada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:34
CPC Classifications
H; H03; H03C; H03C3/00; H03C3/02; H03C3/09; H03C3/0908; H03C3/0983; H03C3/06; H03C3/0975; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/22; H03L7/23
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
222 words
A frequency modulation system comprising: first means including a first variable frequency oscillator, a frequency divider for frequency dividing the output frequency of said first variable frequency oscillator, a reference frequency oscillator, and a first feedback circuit in which the output frequency of said reference frequency oscillator is compared in phase with that of said frequency divider and the result of the phase comparing is fed back to said first variable frequency oscillator through a first filter for controlling the output frequency of said first variable frequency oscillator; second means including a second variable frequency oscillator, a fixed frequency oscillator, means in which the output frequencies of said second variable frequency oscillator and of said fixed frequency oscillator are mixed in a mixer thereby to obtain a difference frequency between said both frequencies, and a second feedback circuit in which said difference frequency is compared in phase with the output frequency of said first variable frequency oscillator and the result of the phase comparing is fed back to said second variable frequency oscillator through a second filter for controlling the output frequency of said second variable frequency oscillator; and third means in which the output frequency of said fixed frequency oscillator is frequency-modulated by the frequency of a modulating signal thereby to obtain a frequency-modulated wave from said second variable frequency oscillator.
Claim 2
Dependent Claim
222 words
A frequency modulation system comprising: first means including a first variable frequency oscillator, a frequency divider for frequency dividing the output frequency of said first variable frequency oscillator, a reference frequency oscillator, and a first feedback circuit in which the output frequency of said reference frequency oscillator is compared in phase with that of said frequency divider and the result of the phase comparing is fed back to said first variable frequency oscillator through a first filter for controlling the output frequency of said first variable frequency oscillator; second means including a second variable frequency oscillator, a fixed frequency oscillator, means in which the output frequencies of said second variable frequency oscillator and of said fixed frequency oscillator are mixed in a mixer thereby to obtain a difference frequency between said both frequencies, and a second feedback circuit in which said difference frequency is compared in phase with the output frequency of said first variable frequency oscillator and the result of the phase comparing is fed back to said second variable frequency oscillator through a second filter for controlling the output frequency of said second variable frequency oscillator; and third means in which the output frequency of said fixed frequency oscillator is frequency-modulated by the frequency of a modulating signal thereby to obtain a frequency-modulated wave from said second variable frequency oscillator.
Claim 3
Dependent Claim
21 words
A frequency modulation system according to claim 1, in which said frequency divider includes means for changing the frequency division ratio.
Claim 4
Dependent Claim
30 words
A frequency modulation system according to claim 1, in which the output frequency of said first variable frequency oscillator is higher than the maximum output frequency of said modulating signal.
Claim 5
Dependent Claim
19 words
A frequency modulation system according to claim 1, in which said fixed frequency oscillator is a quartz crystal oscillator.
Claim 6
Dependent Claim
27 words
A frequency modulation system according to claim 1, in which output frequency of said mixer is applied to said second phase comparator through a band pass filter.
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) | 1980-11-28 | 1981-05-30 | 1981-11-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-11-28 | 1985-05-30 | 1985-11-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-11-28 | 1989-05-30 | 1989-11-29 | $7700.00 | Window Closed / Lapsed |