Abstract: In a television receiver using synchronous detection of the I.F. signal a picture carrier regenerator is used which is active for a small deviation of the picture intermediate frequency relative to the regenerator frequency and is passive for a large deviation so that the drawbacks of both a passive and of an active regenerator are obviated.

Abstract: A television camera which scans an image provides a camera video signal having an amplitude representative of light received from an element of the image being scanned. Prior to a scan a sync pulse is generated which increments a raster counter. Accordingly, the roster counter provides a signal representation of a cumulative number of scans of the image. During the scanning, clock pulses increment a horizontal deflection counter which provides a signal representation of a horizontal deflection number corresponding to the horizontal coordinate of the line of sight. When the cumulative number of scans equals the horizontal deflection number, a comparator provides a gating signal which causes a sample and hold circuit to store a sampled video signal having an amplitude equal to the amplitude of the camera video signal. The sampled video signal is provided to the input of an analog to digital converter for conversion to digital signals which may be stored in a digital computer.