Video signal processor

摘要

A video signal processor reduces the deterioration of image quality due to the superposition of noise on a sync signal included in a luminance signal. A frequency discriminator (15) outputs a first error signal if a ratio of the frequency of a frequency-modulated signal during a sync-signal interval to the frequency of a reference frequency signal is smaller than a predetermined ratio. Alternatively, the discriminator (15) outputs a second error signal if the ratio is greater than the predetermined ratio. If the first error signal has been input to a frequency controller (100) a preset number of times or more during an interval before the second error signal is input thereto, the controller (100) instructs a frequency modulator (14) to increase the frequency of the frequency-modulated signal. On the other hand, if the second error signal has been input to the controller (100) a preset number of times or more during an interval before the first error signal is input thereto, the controller (100) instructs the modulator (14) to decrease the frequency of the frequency-modulated signal. <IMAGE>