NOISE REJECTION CIRCUIT FOR PICTURE TRANSMITTER

PURPOSE:To attain optimizing processing for eliminating noise in a way of unsharpening a picture data by measuring a noise period of the picture data and applying variable control to a filter characteristic of a digital filter in response to the fluctuation of the noise period. CONSTITUTION:The filter characteristic of the digital filter 11 is made variable. A picture data is led to a noise detection circuit 27, where the period of noise caused in a desired are of the picture is measured and its output is fed to a filter control circuit 28 and a desired filter characteristic is selected by supplying the filter control circuit to the control input of an arithmetic circuit 26 of the digital filter 11. Thus, if noise is less, the filter characteristic is weakened to prevent sharpness of the picture data from being lost and noise rejection and prevention in the picture quality are made compatible to obtain a transmission signal.