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Method and apparatus for tuning a tuneable filter for the purpose of improving the signal/noise ratio during use of base band signals in an FM television system
Method and apparatus for tuning a tuneable filter for the purpose of improving the signal/noise ratio during use of base band signals in an FM television system
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机译:用于在FM电视系统中使用基带信号期间调谐可调谐滤波器以提高信噪比的方法和装置
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摘要
In an FM television signal angle modulated with luminance and chrominance information, there exists a high degree of correlation between picture elements occurring one line period apart. In an effort to steer the pass band of a tunable bandpass filter to the instantaneous frequency of the incoming television signal, a steering signal is developed which utilizes this high degree of correlation. For NTSC systems, luminance information is delayed by one-line period (63.5 us in the U.S.A.) and combined with suitable delayed chrominance information to form the filter's steering signal. For MAC systems, one-line delayed luminance and two-line delayed chrominance information are alternately applied to the filter as its steering signal. By steering the pass band of the filter to the incoming signal, maximum signal will be captured with minimum noise, enhancing the signal-to-noise ratio of a color television system.
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