I.F. Response control system for a television receiver

In a television receiver, including a source of intermediate frequency television signals containing a picture carrier and a chrominance subcarrier;

• means, responsive to said intermediate frequency signals, for processing said intermediate frequency signals;
• and a video detector responsive to said processed intermediate frequency signals for producing baseband video signals including a VIR signal having a chrominance reference bar and a luminance reference level;
• apparatus for controlling the intermediate frequency passband response of said television receiver in response to said VIR signal, comprising:
• means, operable during a first portion of said VIR signal, for detecting the amplitude of said chrominance reference bar of said VIR signal;
• means, operable during a second portion of said VIR signal, for detecting the amplitude of said luminance reference level of said VIR signal;
• means, responsive to said detected amplitudes of said chrominance reference bar and said luminance reference level, for producing a control signal indicative of the ratio of said detected signal amplitudes;
• and
• a passband shaping circuit, included within said intermediate frequency signal processing means, and exhibiting an amplitude versus frequency response characteristic occupying a band of frequencies including the frequencies of said picture carrier and said chrominance subcarrier, said response characteristic being variable in response to variations of said control signal so as to affect the attenuation produced at said picture carrier and said chrominance subcarrier frequencies in a complementary manner.

In a television receiver, including a source of intermediate frequency television signals containing a picture carrier and a chrominance subcarrier, means, responsive to said intermediate frequency signals, for processing said intermediate frequency signals;

• and a video detector responsive to said processed intermediate frequency signals for producing baseband video signals including a VIR signal havng a chrominance reference bar and a luminance reference level;
• apparatus for controlling the intermediate frequency passband response of said television receiver in response to said VIR signal, including:
• means, operable during a first portion of said VIR signal, for detecting the amplitude of said chrominance reference bar of said VIR signal;
• means, operable during a second portion of said VIR signal, for detecting the amplitude of said luminance reference level of said VIR signal;
• means, responsive to said detected amplitudes of said chrominance reference bar and said luminance reference level, for producing a control signal indicative of the ratio of said detected signal amplitudes;
• and
• a passband shaping circuit, included within said intermediate frequency signal processing means, and exhibiting an amplitude versus frequency response characteristic defining a passband and occupying a band of frequencies including the frequencies of said picture carrier and said chrominance subcarrier, said passband shaping circuit being responsive to changes of said control signal for selectively moving said passband in one of an upward or downward direction in frequency.