Signal converting apparatus

Claim 1

A signal converting apparatus comprising: an analog-to-digital converter converting a MUSE television signal into a corresponding digital signal and outputting said digital signal; a deemphasis circuit subjecting the output signal from the analog-to-digital converter to a deemphasis process; a frame memory delaying an output signal from the deemphasis circuit by a time corresponding to one frame; an intra-field interpolation circuit subjecting the output signal from the deemphasis circuit to an intra-field interpolation process; an inter-frame interpolation circuit subjecting the output signal from the deemphasis circuit to an inter-frame interpolation process; a vertical low pass filter removing components from an output signal of the inter-frame interpolation circuit, said components having vertical frequencies equal to and close to N/2 cpH, where N is the number of horizontal scanning lines per frame of the MUSE television signal; a motion detector deriving a difference signal from the output signal of the deemphasis circuit and an output signal from the frame memory, said difference signal representing a difference between frames, the motion detector including a low pass filter acting on the difference signal, and means for deriving an absolute value of an output signal of said low pass filter to detect a motion; a mixer mixing an output signal from the intra-field interpolation circuit and an output signal from the vertical low pass filter, the mixing rate of the output signal from the intra-field interpolation circuit and the output signal from the vertical low pass filter being varied in response to the difference signal from the motion detector; and a scan converter converting an output signal from the mixer into a signal of a predetermined scan format.