Apparatus for demodulating sub-nyquist sampled video signal and

Abstract

An apparatus (MD) for reproducing, by a low-frequency replacement method, a noise-free high definition video (MUSE) signal obtained by band-compressing the high definition video signal in a time-compressed integration Sub-Nyquist encoding system so as to include no aliasing noise in a low-frequency component below 4 MHz. This reproducing apparatus includes a converter (3) for converting a reproduced or received MUSE signal into digital data and a memory (7) for outputting feedback data in which preceding by two fields and data preceding by four fields with respect to the current field are alternately arranged, a circuit (6; 33) for replacing/non-replacing the data preceding by four fields by first data corresponding to the current field data from the current field data and the feedback data and deriving a data train in which the first data and the data preceding by two fields are alternately arranged. Output from the data train deriving circuit is employed to be converted to composite data by a mixture 11, and a circuit (LC) for replacing the low-frequency component of the current field data or the first data with the low-frequency component of the composite data. The reproducing apparatus further includes a circuit (15, 18, 19, 19, 54; 15, 35; 34, 15', 54') for inhibiting this low-frequency replacement as well as replacement of the data preceding by four fields and the first data upon generation of noise such as dropout in the reproduced MUSE signal.