Category: History

Television is a set of methods and means of transmitting and receiving images (visual information) at a distance in real time, using wired electrical communication or wireless radio communication.

History

Types of television broadcasting systems

Brown Todd

Television (at the stage of its emergence, early television) is a set of methods and means of transmitting and receiving images (visual information) at a distance in real time, using wired electrical communication or wireless radio communication. Methods (theory) are general, conceptual and theoretical principles of a certain type of television, and means (“hardware”) are practically executed devices for the implementation of this type of television (hereinafter referred to as TV).

The means of transmission are designed to decompose the image into elements and convert them into an electrical signal with subsequent transmission. At the present stage of TV development, it is a TV center, TV studio, etc., equipped with stationary and mobile transmitting TV cameras. Receiving means are designed to reproduce the image from the received electrical signal. These are television receivers (TV sets) for watching television programs. The processes of image conversion and reproduction must be synchronized, that is, synchronism (equality in frequency) and in-phase (equality in phase) of these processes must be ensured. The means of transmission and means of reception constitute the TV system. Transmission of sound, at the stage of the emergence of TV, was not considered a priority.

The term “television” in 1900 was proposed by physicist K. Persky. Before that and even after that, there were synonymous terms in use: telescopy, electroscopy, farsightedness, etc. The criterion (the main feature, the rule) of the emergence of a certain type of TB is a public demonstration of its practically implemented means. Only this criterion of truth makes it possible to “dot the i’s and cross the t’s” in the emergence of a particular means of TB without additional, rather long and complex, professional, at the level of scientific research, analysis of the purpose, composition of types of TB and their means, which also existed in ancient times.

Depending on the type of components (parts) of the means of TB systems, the following types of TB can be distinguished:

electromechanical (mechanical) TV, the means of transmission and reception of which consisted of electrical, electromechanical (moving) and partly electronic components. There was wired and wireless transmission of moving images with low quality;
semi-electronic TV (the initial stage of development of electronic TV), in which electromechanical components were used along with electronic ones, mainly in the transmitting means. The transmitting means used a contact and later a non-contact method of scanning the image while converting it into an electrical signal, and in the receiving means, a cathode ray tube, later CRT, was used to display the image. The connection of receiving and transmitting means was wired. The transmission of still images was carried out;
electronic TV, which used only electronic components, including CRT in the transmitting and receiving means. Electronic TV, as a result of the use of practically inertial (within the framework of this task) electronic components, made it possible to transmit moving (dynamic) images and improve their quality, mainly by increasing the number of image elements. Wireless transmission of moving images with high quality (in comparison with other types of TV) was carried out.

Some articles do not distinguish between semi-electronic and electronic TV, and some call it electronic TV, the means of which consist of arbitrary components (including electromechanical) but with receiving and transmitting CRT. This confusion is probably caused by attempts to change the date (to an earlier one) of the emergence of a particular “electronic” TB, which is actually semi-electronic. Or these are theoretical studies, the stage of circuit development, patenting, etc. of a really electronic TB, but not confirmed by its practical implementation and demonstration.

In general, visual information was transmitted remotely in ancient times. These were beacons that informed about important events, signaling with semaphores, signal flags and searchlights in the fleet, heliograph, where information was transmitted in Morse code using solar “bunnies”, etc. At the same time, observers received information within the direct vision. Natural phenomena: night, fog, snow, rain nullified these types of communication. However, for example, the army heliograph in sunny weather provided a transmission range of up to 75 km, and the record was 295 km between two mountains in America.