Color television system determination circuit

A color system determination circuit for use with an input video signal having a frequency component, said circuit comprising:

• a color trap filter for attenuating the frequency component in the input video signal, said color trap filter providing a color burst output signal;
• a comparator for comparing the color burst output signal of said color trap filter and said frequency component of the input video signal;
• a first absolute value circuit which receives the color burst output signal of said color trap filter, and applies a first absolute value processing to said color burst output signal;
• a second absolute value circuit which receives said input video signal and applies a second absolute value processing to said input video signal;
• a first maximum value detector which receives an output signal of said first absolute value circuit and said color burst sampling signal, and detects a maximum value of the output signal of said first absolute value circuit during a period corresponding to the color burst sampling signal;
• and
• a second maximum value detector which receives an output signal of said second absolute value circuit and said color burst sampling signal, and detects the maximum value of the output of said second absolute value circuit during the period corresponding to the color burst sampling signal;
• wherein said comparator receives output signals of said first maximum value detector and said second maximum value detector, compares both signals, and outputs a comparison result.

A color system determination circuit for use with an input video signal having a frequency component, said circuit comprising:

• a color trap filter for attenuating the frequency component in the input video signal, said color trap filter providing a color burst output signal;
• a comparator for comparing the color burst output signal of said color trap filter and said frequency component of the input video signal;
• a first absolute value circuit which receives the said input video signal which has passed through said color trap filter, and applies a first absolute value processing to said filtered video signal;
• a second absolute value circuit which receives said input video signal and applies a second absolute value processing to said input video signal;
• a first LPF which receives an output signal of said first absolute value circuit and removes a high-frequency component from said output signal of said first absolute value circuit;
• a second LPF which receives an output signal of said second absolute value circuit, and removes a high-frequency component from said output signal of said second absolute value circuit;
• a first maximum value detector which receives an output signal of said first LPF and a color burst sampling signal, and detects a maximum value of the output signal of said first LPF during a period corresponding to the color burst sampling signal;
• and
• a second maximum value detector which receives an output signal of said second LPF and said color burst sampling signal, and detects a maximum value of the output signal of said second LPF during the period corresponding to said color burst sampling signal;
• wherein said comparator receives output signals of said first maximum value detector and second maximum value detector, compares both signals, and outputs a comparison result.

A color system determination circuit for use with an input video signal having a frequency component, said circuit comprising:

• a color trap filter for attenuating the frequency component in the input video signal, said color trap filter providing a color burst output signal;
• a comparator for comparing the color burst output signal of said color trap filter and said frequency component of the input video signal;
• a first absolute value circuit which receives said input video signal which has passed through said color trap filter, and applies a first absolute value processing to said filtered input video signal;
• a second absolute value circuit which receives said video signal and applies a second absolute value processing to said input video signal;
• a first integrator which receives an output signal of said first absolute value circuit and a color burst sampling signal, and integrates the output signal of said first absolute value circuit during a period corresponding to said color burst sampling signal;
• and
• a second integrator for integrating an output signal of said second absolute value circuit during the period corresponding to said color burst sampling signal;
• and
• wherein said comparator receives output signals of said first integrator and said second integrator, compares both signals, and outputs a comparison result.

A color system determination circuit for use with an input video signal having a frequency component, said circuit comprising:

• a color trap filter for attenuating the frequency component of the input video signal, and amplifying said input video signal around said frequency;
• a first absolute value circuit which receives said input video signal which has passed through said color trap filter, and applies a first absolute value processing to said filtered input video signal;
• a second absolute value circuit which receives said video signal and applies a second absolute value processing to said input video signal;
• a first integrator which receives an output signal of said first absolute value circuit and a color burst sampling signal, and integrates the output signal of said first absolute value circuit during a period corresponding to said color burst sampling signal;
• a second integrator for integrating an output signal of said second absolute value circuit during the period corresponding to said color burst sampling signal;
• a subtractor which receives an output signal of said first integrator and a subtraction value, and subtracts the subtraction value from the output signal of said first integrator;
• and
• a comparator which receives output signals of said subtractor and said second integrator, compares both signals, and outputs a comparison result.