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US 4,193,084 AGranted
Video recorder having means for maintaining constant the amplitude of the frequency-modulated signal
AssigneeSony Corporation
InventorsKazuo Yamagiwa, Kaneo Saito, Toshihiko Numakura
Life of this patent
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Abstract
In apparatus for recording, or otherwise transmitting, video or other information signals, and in which at least a portion of the signal to be recorded, for example, the luminance component of a color video signal, is frequency modulated and then passed through a filter for limiting the frequency band of the resulting frequency modulated component or signal which is recorded; a signal processor, such as, an automatic gain control or limiter, acts on the frequency modulated output of the filter to eliminate or compensate for amplitude variations that may occur therein by reason of the filter, for example, at portions of the signal where substantial pre-emphasis was applied.
Claims25
Apparatus for processing a video signal to be recorded, comprising
- pre-emphasis means for pre-emphasizing a frequency signal in said video signal to produce a pre-emphasized video signal;
- modulating means for frequency modulating a carrier with the pre-emphasized video signal to be recorded;
- high pass filter means for limiting the frequency band of the frequency modulated signal from said modulating means, in which said high pass filter is an active filter adapted to have its cut-off frequency varied;
- and
- means for maintaining a constant amplitude of said frequency modulated signal as derived from said filter means for recording on a record medium, wherein said maintaining means is operative to decrease said cut-off frequency in correspondence with the pre-emphasis of the video signal.
2 more elements
Apparatus for processing a video signal to be recorded, comprising
- pre-emphasis means for pre-emphasizing a frequency signal in said video signal to produce a pre-emphasized video signal;
- modulating means for frequency modulating a carrier with the pre-emphasized video signal to be recorded;
- high pass filter means for limiting the frequency band of the frequency modulated signal from said modulating means;
- and
- means for maintaining a nearly constant amplitude of said frequency modulated signal as derived from said filter means for recording on a record medium, including soft limiter means acting on the output of said filter means.
2 more elements
Apparatus for processing a video signal to be recorded, comprising
- pre-emphasis means for pre-emphasizing a frequency signal in said video signal to produce a pre-emphasized video signal;
- modulating means for frequency modulating a carrier with the pre-emphasized video signal to be recorded;
- high pass filter means for limiting the frequency band of the frequency modulated signal from said modulating means;
- and
- means for maintaining a constant amplitude of said frequency modulated signal as derived from said filter means for recording on a record medium, including automatic gain control means coupled to the output of said filter means for directly regulating the amplitude of the signal at said output, and detector means for controlling the gain of said gain control means in the sense to maintain said constant amplitude.
2 more elements
Apparatus for processing a video signal to be recorded, comprising
- modulating means for frequency modulating a carrier with the video signal to be recorded;
- high pass filter means for limiting the frequency band of the frequency modulated signal from said modulating means;
- and
- means for maintaining a constant amplitude of said frequency modulated signal as derived from said filter means for recording on a record medium, including automatic gain control means acting on the output of said filter means, and detector means for controlling the gain of said gain control means in the sense to maintain said constant amplitude, in which said detector means is responsive to a pre-emphasized video signal in advance of said modulating means.
1 more element
Apparatus for recording and reproducing video signals in successive parallel tracks on a record medium, comprising:
- transducer means for scanning said successive parallel tracks on the record medium;
- a recording section including modulating means for frequency modulating at least a portion of said video signals on a carrier, record signal processing means including pre-emphasizing means operative on at least said portion of the video signals in advance of the frequency modulation of said carrier therewith, high pass filter means for limiting the frequency band of the frequency modulated signal applied from said modulating means to said transducer means for recording by the latter in said tracks scanned thereby, in which said high pass filter means is an active filter adapted to have its cut-off frequency varied, and means for maintaining a constant amplitude of said frequency modulated signal as derived from said filter means, wherein said maintaining means is operative to vary said cut-off frequency in correspondence with the pre-emphasis of said portion of the video signals and
- a reproducing section including demodulating means for frequency demodulating the frequency modulated signals reproduced by said transducer means from the successive parallel trakcs on the record medium, and reproduced signal processing means operative on the demodulated signals from said demodulating means and including de-emphasizing means for providing an amount of de-emphasis to said demodulated signals which is substantially complementary to the amount of emphasis provided by said pre-emphasizing means.
Apparatus for recording and reproducing video signals in successive parallel tracks on a record medium, comprising:
- transducer means for scanning said successive parallel tracks on the record medium;
- a recording section including modulating means for frequency modulating at least a portion of said video signals on a carrier, record signal processing means including pre-emphasizing means operative on at least said portion of the video signals in advance of the frequency modulation of said carrier therewith, high pass filter means for limiting the frequency band of the frequency modulated signal applied from said modulating means to said transducer means for recording by the latter in said tracks scanned thereby, and means for maintaining a nearly constant amplitude of said frequency modulated signal as derived from said filter means, in which said means for maintaining said nearly constant amplitude is constituted by soft limiter means acting on the output of said filter means and
- a reproducing section including demodulating means for frequency demodulating the frequency modulated signals reproduced by said transducer means from the successive parallel tracks on the record medium, and reproduced signal processing means operative on the demodulated signals from said demodulating means and including de-emphasizing means for providing an amount of de-emphasis to said demodulated signals which is substantially complementary to the amount of emphasis provided by said pre-emphasizing means.
Apparatus for recording and reproducing video signals in successive parallel tracks on a record medium, comprising:
- transducer means for scanning said successive parallel tracks on the record medium;
- a recording section including modulating means for frequency modulating at least a portion of said video signals on a carrier, record signal processing means including pre-emphasizing means operative on at least said portion of the video signals in advance of the frequency modulation of said carrier therewith, filter means for limiting the frequency band of the frequency modulated signal applied from said modulating means to said transducer means for recording by the latter in said tracks scanned thereby, and means for maintaining a constant amplitude of said frequency modulated signal as derived from said filter means, including automatic gain control means acting on the output of said filter means, and, detector means for controlling the gain of said automatic gain control means in the sense to maintain said constant amplitude and
- a reproducing section including demodulating means for frequency demodulating the frequency modulated signals reproduced by said transducer means from the successive parallel tracks on the record medium, and reproduced signal processing means operative on the demodulated signals from said demodulating means and including de-emphasizing means for providing an amount of de-emphasis to said demodulated signals which is substantially complementary to the amount of emphasis provided by said pre-emphasizing means.
Dependencies are inferred from the claim text.