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.

Abstract: A frequency region split type noise reducing apparatus, comprising a compressor and an expander; the compressor (or the expander) including a plurality of frequency region splitting filters for splitting the frequency range of the signal into a plurality of frequency regions, a plurality of level sensors for detecting the levels of the signals in the respective frequency regions split by the plurality of filters, a plurality of voltage controlled amlifiers responsive to the level detected outputs of the corresponding level sensors for linearly compressing (or expanding) in terms of a logarithmic scale the dynamic range of the signal, and an adder for adding the outputs as compressed by the voltage controlled amplifiers for providing a composite signal, and the expander (or the compressor) including an amplifier and a switch circuit for connecting the compressor (or expander) to the amplifier to form a negative feedback circuit, whereby the expander (or the compressor) is implemented by a negative feedback amp