Circuit for detecting a video mode
AssigneeSony Corporation
InventorHajime Enoki
Life of this patent
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Abstract
The detection of whether an input FM signal, such as a reproduced signal, which includes particular frequency components representing predetermined information, was recorded in a first or second mode, with the modes having different frequency bands. A first output signal is produced when a particular frequency component in one of the frequency bands is detected and a second output signal is produced when a different frequency component, approximately equal to the difference between twice a predetermined frequency included in the other of the frequency bands and the particular frequency in the one frequency band, is detected. A mode identifying signal indicative of the frequency band occupied by the FM signal is produced in response to the first and second output signals.
Claims29
Apparatus for detecting whether a reproduced FM signal was recorded in a first mode or a second mode, the first and second modes having different frequency bands with respectively different carrier frequencies, and the FM signal containing particular frequency components in the respective frequency bands to represent predetermined information, said apparatus comprising:
- first detecting means for producing a first output signal when the particular frequency component in one of said frequency bands is detected;
- second detecting means for producing a second output signal when a different frequency component approximately equal to the difference between twice a predetermined frequency included in the other of said frequency bands and the particular frequency in said one frequency band is detected;
- input means for supplying the reproduced FM signal to said first and second detecting means;
- and
- signal sensing means coupled to said first and second detecting means and responsive to said first and second output signals for producing a mode identifying signal indicative of the mode in which the reproduced FM signal was recorded.
Video signal reproducing apparatus for recovering a luminance signal that is frequency modulated in either a first mode or a second mode, the first and second modes having different frequency bands with respectively different carrier frequencies, comprising:
- playback means for playing back a composite video signal including chrominance and FM luminance signals from a record medium;
- separating means coupled to said playback means for separating the composite video signal into a chrominance signal and an FM luminance signal;
- chrominance processing means for receiving and processing the separated chrominance signal;
- adjustable FM demodulating means for receiving and demodulating the separated FM luminance signal;
- de-emphasis means coupled to said FM demodulation means for de-emphasizing the demodulated luminance signal;
- and
- mode detecting means for detecting whether the FM luminance signal was recorded in the first or second mode, said mode detecting means comprising:
- first detecting means for producing a first output signal when a particular frequency component normally provided in one of said frequency bands is detected in the FM luminance signal;
- second detecting means for producing a second output signal when a different frequency component approximately equal to the difference between twice a predetermined frequency normally included in the other of said frequency bands and the particular frequency in said one frequency band is detected in the FM luminance signal;
- means for supplying the FM luminance signal to said first and second detecting means;
- signal sensing means coupled to said first and second detecting means and responsive to said first and second output signals for producing a mode identifying signal indicative of the mode in which the luminance signal was frequency modulated;
- and
- means for applying said mode identifying signal to said FM demodulating means to adjust the operation thereof in accordance with the frequency band occupied by the FM luminance signal.
A method of detecting whether an input FM signal, which includes predetermined information, occupies a first frequency band or a second frequency band, said predetermined information being represented by respective particular frequency components in the first and second frequency bands, comprising the steps of:
- detecting in said FM signal the particular frequency component in said first frequency band to produce a first output signal;
- detecting in said FM signal a different frequency component approximately equal to the difference between twice a predetermined frequency included in the second frequency band and the particular frequency component in said first frequency band to produce a second output signal;
- and
- producing a frequency band indicating signal in response to the combination of said first and second output signals.
Dependencies are inferred from the claim text.