Method and apparatus for equalizing FM video signals using variable equalizer
AssigneeKabushiki Kaisha Toshiba
InventorShigeo Kizu
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Abstract
An equalization apparatus in which a variable equalizer is used to equalize the frequency response of an FM video signal obtained by frequency-modulating a carrier signal with a video signal in which a reference signal of a constant frequency is inserted during a predetermined interval. The equalization apparatus includes a comparator section for making a comparison in amplitude between first upper and lower sidebands in the FM video signal and a control section for controlling the variable equalizer in accordance with an output of the comparator section.
Claims15
An equalization apparatus for equalizing a modulated video signal obtained by frequency-modulating a carrier signal with a video signal in which a reference signal of a constant frequency is inserted during a predetermined period, comprising:
- variable equalizer means having a controllable response, for equalizing a frequency response of the modulated video signal;
- means for comparing, during the predetermined period, each amplitude of at least a pair of upper and lower sidebands in the modulated video signal which each are symmetrical with respect to the frequency of the carrier signal;
- and
- control means for controlling the response of said variable equalizer means according to an output of said comparing means.
An equalization apparatus for an FM video signal obtained by frequency-modulating a carrier signal with a video signal in which a reference signal of a constant frequency is inserted during a predetermined interval, comprising:
- variable equalizer means for equalizing the frequency response of the FM video signal;
- detector means for detecting, during the predetermined interval, a ratio in amplitude between a pair of upper and lower sidebands in an FM video output signal of said variable equalizer means which are symmetrical about the frequency of the carrier signal;
- and
- control means for controlling said variable equalizer means such that the detected ratio takes a predetermined constant value.
An equalization apparatus for an FM video signal obtained by frequency-modulating a carrier signal with a video signal in which a reference signal of a constant frequency is inserted during a predetermined interval, comprising:
- variable equalizer means for equalizing the frequency response of the FM video signal;
- comparator means for making, during said predetermined interval, a comparison in amplitude between a pair of upper and lower sidebands in an FM video input signal of said variable equalizer means which are symmetrical about the frequency of the carrier signal;
- and
- means for converting the amplitude and DC level of an output signal of said comparator means to produce a control signal for controlling said variable equalizer means.
A video recording and reproducing apparatus comprising:
- means for generating an FM video signal by frequency-modulating a carrier signal with a video signal in which a burst signal of a predetermined frequency is inserted during a predetermined blanking interval;
- recording means for recording the FM video signal;
- reproducing means for reproducing the recorded FM video signal;
- variable equalizer means for equalizing the frequency response of the reproduced FM video signal;
- comparing means for making, during said predetermined blanking interval, a comparison in amplitude between a pair of upper and lower sidebands in the reproduced FM video signal which are symmetrical about the frequency of the carrier signal;
- and
- control means for controlling said variable equalizer means according to the output of said comparing means.
A video recording and reproducing apparatus using a magnetic recording medium comprising:
- means for generating an FM video signal by frequency-modulating a carrier signal with a video signal in which a reference signal of a predetermined frequency is inserted during a predetermined interval;
- recording means having a plurality of recording heads for recording the FM video signal on the recording medium;
- reproducing means having a plurality of reproducing heads for reproducing the recorded FM video signal;
- multiplexing means for multiplexing FM video signals reproduced by said reproducing heads for transmission over one channel;
- variable equalizer means connected to said multiplexing means for equalizing the frequency response of the multiplexed FM video signals;
- comparing means for making, during said predetermined interval, a comparison in amplitude between a pair of upper and lower sidebands in the multiplexed FM video signal which are symmetrical about the frequency of the carrier signal;
- and
- control means for controlling said variable equalizer means according to the output of said comparing means.
Dependencies are inferred from the claim text.