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专利名称：Automatic frequency control发明人：Marz, Daniel J.,Schilling, John D.申请号：EP104874.6申请日：190318公开号：EP0343336A3公开日：19901227
专利附图：
摘要：An automatic frequency control tracks a television signal before and after aperiod of interruption. The automatic frequency control comprises a voltage controlledfeedback loop including a voltage controlled local oscillator (18) and a mixer (20) formixing the output of the oscillator (18) with the TV signal. The output of the mixer (20) isfiltered to remove unwanted components of the mixed signal and to equalize sidebandsof the television signal. The output of the filter (24) is supplied to a detector (30) which istuned to a component of the television signal, and produces a voltage corresponding tothe frequency of the component. The output of the detector (30) is supplied to thevoltage control input of the local oscillator (18) to track the television signal component.
Circuitry (71, 72) automatically senses the absence of the TV signal component from themixer (20), and automatically applies a reference voltage (V) to the voltage control inputof the oscillator (18) when the TV signal component is absent. The detector (30) isoperative to detect the television signal component following the application ofreference voltage (V to the oscillator so that when the television signal returns, thedetector (30) is capable of tracking it.
申请人：GENERAL INSTRUMENT CORPORATION OF DELAWARE
地址：181 West Madison Street Chicago, Illinois 60602 US
国籍：US
代理机构：Hoeger, Stellrecht & Partner
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