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公开(公告)号：US3628058A
公开(公告)日：1971-12-14
申请号：US3628058D
申请日：1970-02-24
Applicant: MOTOROLA INC
Inventor： ESPE ROY H
CPC classification number: H03G3/34
Abstract: An integrated circuit dual time constant squelch circuit for eliminating squelch tail includes a short time constant ripple filter which produces a filtered noise voltage which is applied to the inputs three differential switch circuits actuated at three different threshold levels. The differential switch with the lowest threshold level establishes the minimum detected noise voltage to which the circuit responds and, upon actuation, charges a long time constant storage capacitor to a value exceeding a second threshold of a second of the differential switch circuits used as an output switch and having the capacitor connected to a second input thereof. The third differential switch circuit is actuated when a third, higher, threshold level is exceeded by the detected noise voltage and operates to disable the output of the second differential switch at strong signal levels, thereby switching control of the circuit solely to the short time constant ripple filter.
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公开(公告)号：DE68922006D1
公开(公告)日：1995-05-11
申请号：DE68922006
申请日：1989-01-26
Applicant: MOTOROLA INC
Inventor： ESPE ROY H , ECKLUND LAWRENCE M
Abstract: There is disclosed a circuit (60) responsive to control signals applied thereto for alternatively sourcing and sinking current at an output which includes a first controlled current source (48) responsive to selective ones of the control signals for sourcing a current of a predetermined magnitude to the output of the circuit; a second controlled current source (50) responsive to other selective ones of the control signals for sinking a current of a predetermined magnitude from the output of the circuit; and a disabling circuit (42, 44) for respectively disabling said first and second controlled current sources whenever the voltage potential at the output of the circuit becomes greater or less than a predetermined value respectively.
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公开(公告)号：DE68922006T2
公开(公告)日：1995-10-26
申请号：DE68922006
申请日：1989-01-26
Applicant: MOTOROLA INC
Inventor： ESPE ROY H , ECKLUND LAWRENCE M
Abstract: There is disclosed a circuit (60) responsive to control signals applied thereto for alternatively sourcing and sinking current at an output which includes a first controlled current source (48) responsive to selective ones of the control signals for sourcing a current of a predetermined magnitude to the output of the circuit; a second controlled current source (50) responsive to other selective ones of the control signals for sinking a current of a predetermined magnitude from the output of the circuit; and a disabling circuit (42, 44) for respectively disabling said first and second controlled current sources whenever the voltage potential at the output of the circuit becomes greater or less than a predetermined value respectively.
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公开(公告)号：CA1196387A
公开(公告)日：1985-11-05
申请号：CA429897
申请日：1983-06-07
Applicant: MOTOROLA INC
Inventor： ECKLUND LAWRENCE M , ESPE ROY H
Abstract: In the field of AM stereo detection, co-channel or adjacent channel interference may cause some distortion and side-to-side movement of a stereo signal source as well as false "stereo detect" signals in AM stereo receivers having phase locked loop (PLL) systems. The invention provides a filter receiving the incoming signal and passing only the frequencies resulting from said interference; a sensor measures the output of the filters and if this signal is above a given level, the monophonic mode is enabled, i.e., the pilot detector, the stereo presence indicator and the stereo mode switch are disenabled for a timed interval. A higher given level of interference is required for stereo disenablement when stereo transmission with pilot tone is already being received.
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