Frequency control circuit, and associated method, for a receiver operative to receive signals-transmitted thereto in intermittent bursts
First Claim
1. A frequency control circuit for a receiver operative to receive a signal transmitted thereto in intermittent bursts, said frequency control circuit for maintaining an oscillating signal defined by an oscillation frequency and generated by a receiver oscillator forming a portion of the receiver in a relative frequency relationship with the signal transmitted to the receiver, said frequency control circuit comprising:
- means for generating a first frequency control signal coupled to receive a first signal representative of the signal transmitted to the receiver and a first signal representative of the oscillating signal generated by the receiver oscillator, wherein the first frequency control signal generated by said means for generating the first frequency control signal is indicative of frequency differences between the first signal representative of the signal transmitted to the receiver and the first signal representative of the oscillating signal generated by the receiver oscillator;
means for generating a second frequency control signal coupled to receive a second signal representative of the signal transmitted to the receiver and a second signal representative of the oscillating signal generated by the receiver oscillator, wherein the second frequency control signal generated by said means for generating the second frequency control signal is indicative of frequency differences between the second signal representative of the signal transmitted to the receiver and the second signal representative of the oscillating signal generated by the receiver oscillator;
means for determining when the receiver is in time-synchronization with the signal transmitted to the receiver, said means for determining coupled to receive a third signal representative of the signal transmitted to the receiver and operative to generate a synchronization signal of a first signal level when the receiver is in time-synchronization with the signal transmitted thereto; and
means for altering the oscillation frequency of the oscillating signal of the receiver oscillator coupled to receive the first frequency control signal and the second frequency control signal generated by the means for generating the first frequency control signal and the second frequency control signal, respectively, said means for altering operative responsive to values of the second frequency control signal when the means for determining generates the synchronization signal of the first signal level and the frequency differences between the first signals representative of the oscillating signal generated by the receiver oscillator and the signal transmitted to the receiver, respectively, are within a selected range and, otherwise, responsive to the first frequency control signal.
1 Assignment
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Accused Products
Abstract
A frequency control circuit, and associated method, for a receiver operative to receive a TDMA signal transmitted by a transmitter in a TDMA communication system. A first frequency detector generates a first frequency control signal. A second frequency detector, comprised of a portion of a decision-directed demodulator, generates a second frequency control signal. The first frequency control signal is utilized to effectuate frequency control when a signal is continuously received by the receiver, such as times immediately subsequent to initial powering of the receiver as the receiver becomes synchronized with the TDMA signal transmitted thereto. Onces a receiver becomes synchronized to the transmitter, the receiver need only be powered during intermittent time periods when the TDMA signal is transmitted to the receiver. The second frequency control signal is utilized to effectuate frequency control only after the receiver is synchronized with the transmitter to permit intermittent operation of the receiver, and the frequency differences between the signal transmitted to the receiver and a receiver-oscillator, oscillation frequency is less than a maximum level.
55 Citations
16 Claims
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1. A frequency control circuit for a receiver operative to receive a signal transmitted thereto in intermittent bursts, said frequency control circuit for maintaining an oscillating signal defined by an oscillation frequency and generated by a receiver oscillator forming a portion of the receiver in a relative frequency relationship with the signal transmitted to the receiver, said frequency control circuit comprising:
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means for generating a first frequency control signal coupled to receive a first signal representative of the signal transmitted to the receiver and a first signal representative of the oscillating signal generated by the receiver oscillator, wherein the first frequency control signal generated by said means for generating the first frequency control signal is indicative of frequency differences between the first signal representative of the signal transmitted to the receiver and the first signal representative of the oscillating signal generated by the receiver oscillator; means for generating a second frequency control signal coupled to receive a second signal representative of the signal transmitted to the receiver and a second signal representative of the oscillating signal generated by the receiver oscillator, wherein the second frequency control signal generated by said means for generating the second frequency control signal is indicative of frequency differences between the second signal representative of the signal transmitted to the receiver and the second signal representative of the oscillating signal generated by the receiver oscillator; means for determining when the receiver is in time-synchronization with the signal transmitted to the receiver, said means for determining coupled to receive a third signal representative of the signal transmitted to the receiver and operative to generate a synchronization signal of a first signal level when the receiver is in time-synchronization with the signal transmitted thereto; and means for altering the oscillation frequency of the oscillating signal of the receiver oscillator coupled to receive the first frequency control signal and the second frequency control signal generated by the means for generating the first frequency control signal and the second frequency control signal, respectively, said means for altering operative responsive to values of the second frequency control signal when the means for determining generates the synchronization signal of the first signal level and the frequency differences between the first signals representative of the oscillating signal generated by the receiver oscillator and the signal transmitted to the receiver, respectively, are within a selected range and, otherwise, responsive to the first frequency control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for a receiver operative to receive a signal transmitted thereto in intermittent bursts, said method for maintaining an oscillating signal defined by an oscillation frequency and generated by a receiver oscillator forming a portion of the receiver in a relative frequency relationship with the signal transmitted thereto in the intermittent bursts, said method comprising the steps of:
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generating a first frequency control signal indicative of frequency differences between a first signal representative of the signal transmitted to the receiver and a first signal representative of the oscillating signal generated by the receiver oscillator; generating a second frequency control signal indicative of frequency differences between a second signal representative of the signal transmitted to the receiver and a second signal representative of the oscillating signal generated by the receiver oscillator; and altering the oscillation frequency of the oscillating signal of the receiver oscillator responsive to values of the second frequency control signal when the receiver is synchronized with the signal transmitted thereto and the frequency differences between the first signals representative of the oscillating signal generated by the receiver oscillator and the signal transmitted to the receiver, respectively, are within a selected range and, otherwise, responsive to the first frequency control signal. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. In a receiver having receiver circuitry operative to receive a signal transmitted thereto in intermittent bursts, a combination with the receiver circuitry of a frequency control circuit for maintaining an oscillating frequency of an oscillating signal generated by a receiver oscillator forming a portion of the receiver circuitry in a relative frequency relationship with the signal transmitted to the receiver, said frequency control circuit comprising:
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a first frequency detector having a first input and a second input, wherein said first input thereof is coupled to receive a first signal representative of the signal transmitted to the receiver and the second input thereof is coupled to receive a first signal representative of the oscillating signal generated by the oscillator, the first frequency detector comparing frequency magnitudes of the signals received at the first and second inputs, respectively, thereof and for generating a first frequency control signal representative of frequency magnitude differences therebetween; a decision-directed demodulator having a first input and a second input, wherein said first input thereof is coupled to receive a second signal representative of the signal transmitted to the receiver and the second input thereof is coupled to receive a second signal representative of the oscillating signal generated by the oscillator, the decision-directed demodulator comparing frequency magnitudes of the signals received at the first and second inputs, respectively, thereof and for generating a second frequency control signal representative of frequency magnitude differences therebetween; a digital signal decoder circuit having a first input coupled to receive a third signal representative of the signal transmitted to the receiver, said digital signal decoder circuit operative to generate a synchronization signal of a first signal level when the receiver is in time-synchronization with the signal transmitted thereto; and processing circuitry having inputs for receiving the first control signal the second control signal, and the synchronization signal and an output coupled to the oscillator, said processing circuitry for generating an oscillator-warp signal at the output thereof responsive to values of the second frequency control signal when the synchronization signal is of the first signal level and the frequency differences between the first signals representative of the oscillating signal generated by the receiver oscillator and the signal transmitted to the receiver, respectively, are within a selected range and, otherwise, responsive to the first frequency control signal.
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Specification