DIGITAL MODULATOR USED TO APPLY SUB-NYQUIST SAMPLING TO SAMPLE OBTAINED BY RASTER-SCANNING INTENSITY OF VIDEO SIGNAL

摘要

PURPOSE: To match a sampling speed with a Nyquist interval of a prescribed maximum frequency by applying sub-Nyquist sampling to a digital video signal to display sample signals obtained by applying raster-scanning to the intensity of a video signal so as to obtain overlapped video signals with a reduced frequency band. ;CONSTITUTION: A digital subtractor 92 is used to subtract a response of a horizontal low-pass filter 91 consisting of a weighting and sum circuit from a luminance signal properly delayed and obtained from a tapped digital delay line 90 and a bisection circle digital multiplier 93 multiplies a factor less than the unity with a response from the horizontal high-pass filter before the response is overlapped with a base band signal. The multiplication factor to compress the response from the horizontal high-pass filter is decided as follows; that is, an absolute value circuit 90 is used to rectify the response from the horizontal high-pass filter with respect to the luminance signal and the response from the horizontal high-pass filter is fed to the tapped digital delay line 95 and the output therefrom is fed to a horizontal low-pass filter 96 consisting of a weighting and sum circuit. Thus, the response from the horizontal high-pass filter is compressed and reduced.;COPYRIGHT: (C)1994,JPO