Whitham, Curtis & Whitham
Logical comb filter and chroma signal separation circuit
 A logical comb filter comprises a first delay circuit receiving an input composite video signal called a succeeding signal for delaying the received succeeding signal by one scan line period so as to output a main signal composed of the delayed succeeding signal, and a second delay circuit receiving the main signal for delaying the received main signal by one scan line period so as to output a preceding signal composed of the delayed main signal. An addition circuit is connected at its first input to receive the main signal. A selection and control circuit receives the succeeding signal, the main signal and the preceding signal for supplying the succeeding signal to a second input of the addition circuit when the relation of the main signal>(is greater than) the succeeding signal>the the preceding signal or the relation of the preceding signal>the succeeding signal>the main signal is satisfied. When the relation of the main signal>the preceding signal>the succeeding signal or the relation of the succeeding signal>the the preceding signal>the main signal is satisfied, the selection and control circuit supplies the preceding signal to the second input of the addition circuit. When the relation of the preceding signal>the main signal>the succeeding signal or the relation of the succeeding signal>the main signal>the preceding signal is satisfied, the selection and control circuit supplies the main signal to the second input of the addition circuit. 
NEC Corporation
H
H04N
inventional
Akira
Sawada