Dual frequency narrow-band frequency modulated keyable control circuit and keying circuit therefor
First Claim
1. A keyable control circuit and keying circuit therefor comprising:
- a. an rf oscillator operating at a first mean frequency;
b. means for cyclically varying the frequency of said rf oscillator about its mean frequency;
c. means for producing a first signal each time said oscillator is swept past some frequency within said cyclic frequency variation about said first mean frequency;
d. means for detecting said first signal;
e. means, operative in response to detection of said first signal, for shifting the mean frequency of said rf oscillator to a second mean frequency, the magnitude of said mean frequency shift being greater than twice the peak-to-peak amplitude of said cyclic variation imposed on said first and second mean frequencies;
f. means for producing a second signal each time said oscillator is swept past some frequency within said cyclic frequency variation about said second mean frequency;
g. means for detecting said second signal; and
h. means operative in response to detection of said second signal to generate a control signal.
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Accused Products
Abstract
A keyable control circuit generates a narrow-band FM signal. A keying circuit, containing two tuned circuits, placed next to the tank coil of the keyable control circuit, absorbs rf energy each time the FM signal sweeps past the resonant frequency of one of the tuned circuits. Detector circuits within the keyable control circuit, upon sensing the amplitude modulation imposed by the cyclic absorption by one of the tuned circuits, cause the rf frequency of the FM signal to jump to a second frequency region. If the second tuned circuit in the keying circuit matches the new frequency, detector circuits again detect the amplitude modulation imposed by the cyclic absorption. After detecting the second signal, the keyable control circuit generates an electrical control signal output for use by external circuits.
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Citations
9 Claims
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1. A keyable control circuit and keying circuit therefor comprising:
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a. an rf oscillator operating at a first mean frequency; b. means for cyclically varying the frequency of said rf oscillator about its mean frequency; c. means for producing a first signal each time said oscillator is swept past some frequency within said cyclic frequency variation about said first mean frequency; d. means for detecting said first signal; e. means, operative in response to detection of said first signal, for shifting the mean frequency of said rf oscillator to a second mean frequency, the magnitude of said mean frequency shift being greater than twice the peak-to-peak amplitude of said cyclic variation imposed on said first and second mean frequencies; f. means for producing a second signal each time said oscillator is swept past some frequency within said cyclic frequency variation about said second mean frequency; g. means for detecting said second signal; and h. means operative in response to detection of said second signal to generate a control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A keyable control circuit and keying circuit therefor comprising:
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a. at least one oscillator operating at a first mean frequency; b. means for producing cyclical frequency variation in the frequency of said oscillator about said first mean frequency; c. means for producing a first detection signal each time said oscillator is swept past some frequency within said cyclic frequency variation about said first mean frequency; d. at least one means, operative in response to at least one previously produced detection signal, for shifting the mean frequency of said oscillator to at least a second mean frequency, said at least a second mean frequency being at least twice the magnitude of the peak-to-peak frequency variation away from each previously stated mean frequency; e. means for producing at least a second detection signal each time said oscillator is swept past some frequency within said cyclic frequency variation about said at least a second mean frequency; and f. means, operative in response to a predetermined one of said at least a second detection signal, for generating a control signal.
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Specification