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公开(公告)号：CA1187945A
公开(公告)日：1985-05-28
申请号：CA387688
申请日：1981-10-09
Applicant: MOTOROLA INC
Inventor： BENNETT ROBERT M JR , CHAPMAN RONALD H
Abstract: An improved encoder/decoder circuit which utilizes a phase locked loop frequency synthesizer configuration to permit both encoder and decoder operation. In addition, a sampling filter detector is employed to permit monolithic integration of the circuit and minimize sensitivity to vibration. The sampling filter detector has digitally controlled bandwidth which permits rapid response to reverse burst turn-off. In addition, the circuit includes a pulse adder to implement an energy limited reverse burst turn-off mode.
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公开(公告)号：CA1094174A
公开(公告)日：1981-01-20
申请号：CA297221
申请日：1978-02-17
Applicant: MOTOROLA INC
Inventor： BENNETT ROBERT M JR
Abstract: IMPROVED SAMPLING FILTER-DETECTOR A sampling filter-detector receives input signals of different frequencies and provides an output, or detect signal, only when the input frequency has a predetermined value essentially equal to the drive frequency of the sampling circuit. The input signal is coupled through a series of solid state switches, or multipliers, to storage, or sampling, capacitors, the average voltages of which are coupled through-voltage peak and valley followers to a comparator which supplies an output or detect signal only when the difference between the positive and negative voltage inputs to the comparator is greater than a certain value. This occurs when the input frequency is within the detector bandwidth. A threshold voltage of a desired value may be placed in the circuit coupling the peak follower and the positive input of the comparator. The solid state switches are turned on and off by pulses from digital logic means such that the switches are on 120.degree. apart in time for the drive frequency which is equal to the frequency to be detected by the filter detector. The response to the third harmonic of the input signal fundamental is eliminated as are multiples of the third harmonic.
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公开(公告)号：CA1164960A
公开(公告)日：1984-04-03
申请号：CA387680
申请日：1981-10-09
Applicant: MOTOROLA INC
Inventor： BENNETT ROBERT M JR
Abstract: An improved sampling filter for processing a signal applied to an input terminal to detect at least one desired tone of a plurality of tones, in which a resistor is coupled to the input terminal and a plurality of switches are coupled to the resistor, each switch including an output and a control input, at least one capacitor is coupled to the output of each switch and each capacitor is coupled to a reference voltage, such as ground, a control is coupled to the switch control inputs, for activating each switch for a switching time period equal to approximately one-half the period of the desired tone, with each switch successively opened and closed at a frequency substantially higher than the frequency of the desired tone during its switching period, and so that no more than one switch is closed at any time, a peak voltage follower and a valley voltage follower each having inputs and an output, have an input coupled to each of the capacitors, a comparator is coupled to the output of the voltage peak follower and the output of the voltage valley follower for providing a detector output when one of the outputs of the peak and valley followers exceeds the other.
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