The tuner includes a bandpass filter ( 22 ) for removing signals other than the selected pilot signal from the output of the tuner. A tuner ( 30 ) receives the signals and provides an output signal to a loop compensation circuit ( 26 ). Gain control of the analog signal system and the digital signal system, before and after the A-D converter, is effected by a single amplitude detecting unit.read more read lessĪbstract: An apparatus ( 7 ) for switching from a first pilot signal and a second pilot signal on a system transporting a plurality of signals. At this time, the analog variable gain amplifier is controlled so that the level of the control signal for controlling the digital variable gain amplifier is equal to a specified reference value, thereby maintaining the signal of the A-D converter at a fixed level. The amplitude level of the output of the digital variable gain amplifier is detected by an amplitude detecting unit and is controlled so as to be equal to a specified reference value. In this apparatus, an input signal is passed through an analog variable gain amplifier, the signal is converted into digital form, and the output of an A-D converter is passed through a digital variable gain amplifier. The amplitude of the feedback voltage is thus equal to the absolute value of the peak differential amplitude of the input signal.read more read lessĪbstract: A digital automatic gain control apparatus is provided which controls gain such that when an analog video signal is converted into digital signals for processing, the input of the A-D converter is maintained at a fixed level, and after the analog signal has been converted into digital form, the output of the digital system circuit is also maintained at a fixed level. A current source applies current to the capacitor responsive to receiving either the first or second signal. A second differential comparator generates a second signal whenever the negative of the differential voltage from the differential amplifier is greater than the voltage of the output signal.
A first differential comparator generates a first signal whenever the differential voltage from the differential amplifier is greater than the voltage of the output signal. The voltage detector also includes a capacitor on which an output signal is generated. The peak voltage detector includes a differential amplifier receiving the differential input signal and generating a corresponding pair of differential output signals. Abstract: A peak voltage detector is used to detect the absolute value of the peak differential amplitude of a differential input signal.
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