Abstract: A digital servo control with improved control accuracy, in which the arithmetical mean of a sequential series of n data words is used as a basis for the nominal value for a NOMINAL/ACTUAL value comparison to derive a setting signal. Depending on the value of the arithmetical mean, also intermediate values of adjacent quantization stages may thus be included and taken into consideration for control purposes.

Abstract: Sequentially scanned digital input signals are applied to the controller to derive output signals which are formed of the sum of scanned values of the signals weighted with selected coefficients. The weighting with the coefficients is carried out by use of coefficients stored in a table, for example a read-only memory (3, 16); the sum of the respectively weighted signals is then formed in a sequential adder (4, 5; 23, 26, 24, 25). Multiplex operation of respective signals, associated with selected coefficient addresses, can be obtained.

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.

Abstract: To control a reversible element (E), such as a motor and especially a motor operating a tape recorder tape transport, actual operating level input signals in form of timed pulses, depending on speed, and operating sign input signals are applied to a controller (8) through a frequency measuring circuit (5). The controller (8) compares the command level input signal and the actual input signal and provides corresponding error or control output signals. In accordance with the invention, a switch or gate (6) is interposed between the actual operating level input and a frequency measuring circuit (5) which, in turn, controls the controller, the gate or switch being conductive if and only if the sign of the actual operating signal and the sign of the command signal agree, as determined by an antivalence or AND-function gate (7). Upon disagreement of the sign signals, the gate is opened.