Abstract: A circuit for detecting a level of an input direct voltage comprises a comparator for comparing the input direct voltage with a reference signal, which by means of an integrator is derived from pulses whose charge quantity is variable in dependence on a comparator direct voltage. The reference voltage has a d.c. component and an a.c. component. The comparator supplies comparator pulses of a given pulse duration when the d.c. component of the reference voltage is substantially equal to the input direct voltage. The level of the input direct voltage is determined from the charge quantity of the pulses and from the pulse duration of the comparator pulses.

Abstract: System for processing teletext information which makes it possible practically without any delay to reproduce the information pages transmitted by television transmitters on the screen of a television set, the updated state of the reproduced pages being ensured. The system includes a buffer (46) for the data signals corresponding in each case to an information page. Furthermore, it includes a microprocessor (32) which receives the buffered data signals and within the period required for the transmission of an information page stores them in a main memory (24) for all information pages. In dependence upon a page request signal entered by a user a control unit (26) generates a control command for the microprocessor (32) which causes the latter to fetch from the main memory (24) the page requested by the page request signal and supply it to an image processor (42) which generates from the data signals the signals necessary for the reproduction on the screen.