Phase determining circuit to generate a phase control signal, and method

Abstract

The phase of an actual pulse signal (2') with respect to a phase reference pulse signal (1') can be accurately determined and a control output signal in form of a digital number be obtained rapidly depending on the relative temporal position of the phase pulse signals by counting at a high rate with respect to the pulse repetition rate of the phase reference pulse signal and providing count numbers as well as count rates in dependence of the time of occurrence of the actual pulse signal in relation to the reference pulse within a window period; if the actual pulse falls within the window period, the counting rate for the counter is increased, for example by decreasing the division ration of a divider (6), and the starting time for counting after the reference pulse is likewise extended, for example by addressing a starting time counter (4) from a PROM (5) the address of which is changed in dependence on the relationship of the actual pulse and the reference pulse. The steepness of the control curve will thus change and rotate about a center point (C), thereby, within a counter (7) of a given capacity, providing highly accurate control by high resolution due to rapid counting when the actual pulse and the digital pulse are close to or in phase, while permitting ready latching-in or locking-in of the system by counting at a much slower rate if the deviation between the phase of the actual pulse and the desired phase position in relation to the reference pulse is greater.