US3641460A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency shift transmitter
Assignee: Infinet Inc
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Filing: 1970-11-09
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Granted: 1972-02-08
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Expires: 1990-11-09
Abstract
Abstract A frequency shift keying oscillator comprising filter circuits and a positive feedback circuit. First resistors and reactance elements in each filter determine the natural frequency of the oscillator. Keying signals selectively switch second resistors in parallel with the first resistors to change the natural frequency. The percentage resistance variations produced by the keying signals are substantially equal. This equalizes the steady-state gains of the oscillator in its two modes so that no amplitude discontinuities occur in the output signal as the oscillator switches from one mode to the other. As the reactor in each filter is a constant value element, no phase discontinuities occur. Hence, the output signal is a continuous, fundamental sinusoidal signal which has two mutually exclusive frequencies.
Inventors
- 👤 Jerry L Holsinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:31
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/10; H04L27/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
165 words
An oscillator for mutually exclusively generating two frequency output signals in response to control signals, said oscillator comprising: A. a first operational amplifier, B. an active low-pass filter comprising a first resistance means and first capacitor in parallel connected between the output and inverting input of said amplifier, said first resistance means having first and second values, C. a high-pass filter comprising a second capacitor and a second resistance means in series with the inverting input of said first amplifier, D. a feedback circuit including a second operational amplifier for inverting signals from the output of said first amplifier and applying the feedback signals to said high-pass filter, said feedback circuit additionally including means for limiting the feedback signal to a value within the linear operating regions of said operational amplifiers, and E. means for switching said first and second resistance means between the first and second values simultaneously in response to control signals to thereby vary the oscillator output frequency without producing significant transients.
Claim 2
Dependent Claim
165 words
An oscillator for mutually exclusively generating two frequency output signals in response to control signals, said oscillator comprising: A. a first operational amplifier, B. an active low-pass filter comprising a first resistance means and first capacitor in parallel connected between the output and inverting input of said amplifier, said first resistance means having first and second values, C. a high-pass filter comprising a second capacitor and a second resistance means in series with the inverting input of said first amplifier, D. a feedback circuit including a second operational amplifier for inverting signals from the output of said first amplifier and applying the feedback signals to said high-pass filter, said feedback circuit additionally including means for limiting the feedback signal to a value within the linear operating regions of said operational amplifiers, and E. means for switching said first and second resistance means between the first and second values simultaneously in response to control signals to thereby vary the oscillator output frequency without producing significant transients.
Claim 3
Dependent Claim
54 words
An oscillator circuit as recited in claim 1 wherein said first and second resistance means each comprise a first resistor and, in parallel therewith, switching means and a second resistor in series, said first and second resistor being paralleled in response to first control signals to thereby increase the natural frequency of said oscillator.
Claim 4
Dependent Claim
176 words
An oscillator for mutually exclusively generating first and second frequency signals in response to keying signals, said oscillator comprising: A. a first operational amplifier, B. a low-pass filter including a first inductor and a first resistance means in series with said first operational amplifier, said first resistance means having first and second values, C. a high-pass filter including a second inductor and a second resistance means in parallel and connected betwEen the output and inverting input of said first amplifiers, said second resistance means having first and second values, D. a feedback circuit including a second operational amplifier for inverting signals from the output of said first amplifier and applying the feedback signals to said low-pass filter, said feedback circuit additionally including means for limiting the feedback signal to a value within the linear operating regions of said operational amplifiers, and E. means responsive to the control signals for simultaneously switching said first and second resistance means between their first and second values simultaneously in response to control signals to thereby vary the oscillator output frequency.
Claim 5
Dependent Claim
176 words
An oscillator for mutually exclusively generating first and second frequency signals in response to keying signals, said oscillator comprising: A. a first operational amplifier, B. a low-pass filter including a first inductor and a first resistance means in series with said first operational amplifier, said first resistance means having first and second values, C. a high-pass filter including a second inductor and a second resistance means in parallel and connected betwEen the output and inverting input of said first amplifiers, said second resistance means having first and second values, D. a feedback circuit including a second operational amplifier for inverting signals from the output of said first amplifier and applying the feedback signals to said low-pass filter, said feedback circuit additionally including means for limiting the feedback signal to a value within the linear operating regions of said operational amplifiers, and E. means responsive to the control signals for simultaneously switching said first and second resistance means between their first and second values simultaneously in response to control signals to thereby vary the oscillator output frequency.
Claim 6
Dependent Claim
54 words
An oscillator as recited in claim 3 wherein each of said first and second resistance means comprises a first resistor and, in parallel therewith, switching means and a second resistor in series, said first and second resistors being paralleled in response to first control signals to thereby increase the natural frequency of said oscillator.
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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) | 1975-02-07 | 1975-08-09 | 1976-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-07 | 1979-08-09 | 1980-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-07 | 1983-08-09 | 1984-02-08 | $7700.00 | Window Closed / Lapsed |