The DC Quadricorrelator: A Two-Mode Synchronization System

The dc quadricorrelator is a new form of automaticphase-control circuit which, when applied to color synchronization, gives better performance and appears easier to manufacture than circuits previously used. It is intended to provide automatic color synchronization without need for a manually-operated frequency or phase control. The circuit combines good noise immunity with rapid pull-in, exceeding the capabilities of widely used earlier arrangements. Its performance and relative simplicity indicate a possible net reduction in over-all receiver cost. The DC Quadricorrelator also provides reliable, noise-immune, automatic switching of receiver circuits for monochrome or color operation. The dc quadricorrelator is a two-mode synchronization system in which the pull-in and hold-in modes of operation are made essentially independent of each other by means of a simple automatic switch. The basic principle, which is presented here in the environment of color synchronization, is also applicable to line and field synchronization for television.