CS252563B1 - Digital and analogue TV signal converters - Google Patents

Abstract

The device relates to applied computer technology and is intended for synchronization of analog and digital television signals, which may not be precisely given by the television standard, and for use in computer didactic systems, information systems, and for further processing of these television signals in television control equipment.

Description

BACKGROUND OF THE INVENTION The present invention relates to an apparatus for concurring digital and analogue television signals, enabling both to be displayed simultaneously on a single screen, wherein the digital alphanumeric, graphic or color graphics television signal is obtained from the logic unit of the computing device and analogue television signal from any television source.

The digital signal synchronization pulses generated by the logic units of the computing systems and the synchronization pulses of some of the primary analog TV signal sources do not exactly match the television standard in terms of duration, time sequence and phase of the individual sync pulse pulses or some auxiliary pulses are omitted. For these reasons, it is not possible to perform concurrency of such television signals by means of synchronization pulses, and therefore the comparison of auxiliary pulses of the duration of one TV line, ie 64 / is irrespective of the duration and phase of the synchronization pulses, is used.

At present, a method of comparing the frequency and phase difference of the synchronization pulses or by using a buffer after previous digitization of the entire television picture is used for the concurrence of two analog TV signals.

The method of concurrence by comparing the phase and frequency differences of the synchronization pulses assumes a synchronization mixture of the two television signals coincident in time. Buffer-overlapping requires demanding special equipment.

SUMMARY OF THE INVENTION The synchronization mixture obtained from an external analogue television signal source is applied to the input of the analogue signal line suppression pulse and the digital television synchronization mixture to the input of the digital signal line synchronization pulse suppression circuit. The output signals of both of these blocks, which are auxiliary pulses of a duration of one television line of 64 microns, are applied to the individual inputs of the circuit for frequency and phase comparison of the auxiliary pulses. The output control signal of this block controls the basic oscillator of the logic unit generating the digital television signal.

The advantage of the device according to the invention is that it is possible to synchronize digital and analog television signals, which need not be precisely determined by the television standard and display both of these signals on one screen, or used for further processing in television overhead devices. The block diagram of the device is in the drawing.

The analog TV signal synchronization mixture is applied to the input of the first analogue signal line suppression circuit 11 and the digital TV signal synchronization mixture to the input of the second digital signal line counter synchronization pulse input 2. The output of the first circuit 1 is connected to the first input of the circuit 2 for phase and frequency comparison of the TV lines and the output of the second circuit 2 is connected to its second input and its output is connected to the control signal input 4 of the logic unit 6 to generate a digital television signal. the output of the TV digital signal sync mixture is connected to the input of the line 2 pulse suppression circuit.

The device for the concurrence of a digital television signal and an analogue television signal is specifically used in a didactic terminal which is part of a computerized didactic system. The logic unit of the terminal is connected to a computing system via a serial or parallel communication channel and connected to a concurrency unit which ensures the synchronization of the digital television signal and the analogue television input signal so that both signals can be simultaneously displayed on the terminal screen, operation of individual signals. The output TV signal is connected to the television subsystem of the computer didactic system.

Analog and digital TV signal concurrency device can be used for color graphic terminals with the possibility of input and output of TV signals for connection to

Also television circuits, which are terminal devices of computer didactic systems, information systems or for further processing - in television directing devices.

Claims (1)

SUBJECT OF THE INVENTION An apparatus for concurrence of a digital and an analogue television signal, characterized in that the output of the first circuit (1) for suppressing the line synchronization pulses of the analogue television signal is connected to the first input of the phase and frequency comparison circuit of the television lines. the output of the second circuit (2) for suppressing the line sync pulses of the digital television signal is connected and the output of the circuit (3) is connected to the control signal input (4) of the digital television signal generation unit (6). connected to the input of the second circuit (2) for suppressing the line sync pulses of the digital television signal.