| 摘要 |
PURPOSE:To simplify the constitution of a circuit device and, at the same time, to reduce the manufacturing cost of the title device by making a frequency area in which no folding distortion is produced by internal interpolation in corresponding to a subsampling frequency and another frequency area in which the movement of pictures is detected by using inter-one-frame difference signals coincident with each other and detecting the movement of the pictures by using inter-two-frame signals. CONSTITUTION:The cut-off frequencies of a high-pass filter(HPF) 7 which fetches high-band picture signal components only from the demodulated output of an MUSE decoder 6 and a low-pass filter (LPF) 8 which fetches low-band signal components only from the input picture signals are made coincident with each other and the filter outputs of the filters 7 and 8 are synthesized by means of an adder 9. When the above- mentioned low band replacement is performed on low-band picture signal components of 0-4MHz in frequency, all of various frequency areas become coincident with each other and changes following the movement of pictures are not contained in the low- band picture signal components of 1-4MHz. Therefore, a one-frame difference detection circuit 10 to be used for detecting the movement of picture on the above-mentioned low-bend picture signal components becomes unnecessary and the constitution of this picture signal demodulator can be simplified. |
