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US 3,940,554 AGranted
Automatic frequency control device for television receiver
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorMitsuya Masuda
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Abstract
An automatic frequency control device is disclosed wherein the S-shaped waveform character voltage derived by the FM detection of the video intermediate frequency signal is applied to a local oscillator so as to correct its oscillation frequency. The S-shaped waveform character voltage is corrected in response to the output voltage derived by the detection of the sound carrier of the adjacent receiving channel so that the pull-in range may be increased.
Claims6
An automatic frequency control device for a television receiver comprising
- a. a mixer for mixing a received TV signal with the output of a local oscillator,
- b. said local oscillator coupling its output of a predetermined oscillation frequency to said mixer,
- c. a video intermediate frequency amplifier for amplifying the output of said mixer,
- d. an FM detector for detecting the output of said video intermediate frequency amplifier, the S-shaped output voltage of said FM detector being coupled to said local oscillator so as to automatically correct the oscillation frequency thereof,
- e. means connected to said video intermediate amplifier and bypassing said FM detector for detecting the signal with a frequency equal to the video intermediate frequency minus the difference between said video intermediate frequency and the sound intermediate frequency of the adjacent receiving channel, and
- f. means for correcting said S-shaped output voltage in response to the output of said detecting means so as to prevent the pull-in of the sound carrier of the adjacent receiving channel.
3 more elements
An automatic frequency control device for a television receiver comprising
- a. a mixer for mixing the received TV signal with the output of a local oscillator,
- b. said local oscillator coupling its output of a predetermined oscillation frequency to said mixer,
- c. a video intermediate frequency amplifier for amplifying the output of said mixer,
- d. an FM detector for detecting the output of said video intermediate frequency amplifier, the S-shaped voltage output of said FM detector being coupled to said local oscillator so as to control automatically the oscillation frequency of said local oscillator,
- e. a clamping circuit, consisting of a capacitor, a clamping diode and a resistor serially connected, for clamping the sync signals by horizontal flyback pulses,
- f. a peak detector for detecting the peak voltage of the output of said clamping circuit, and
- g. means for correcting, in response to the output of said sync signal detecting means, said S-shaped voltage output so as to increase the pull-in range.
4 more elements
Dependencies are inferred from the claim text.