Since the advent of TVs, they have been the standard single channel. That is, only one TV program was broadcast, and even the switch was not provided. After a while, in 1952. appeared three-channel televisions of the "North" brand with a corresponding switch. Three years later, Avangard-55 with five channels began to be produced. First time in 1957 on the new Rubin-101 model, manufacturers have installed switching devices on as many as twelve TV channels. But what is most interesting, as before, only one TV program was broadcast.
In 1965, a second TV program became available, but only Muscovites could enjoy watching it. When it appeared in settlements more remote from the center, people decided that twelve channels would soon be able to watch. But as it turned out, they rejoiced early, since they were clearly not made for this purpose.
Why was a multichannel switch needed?
Initially, at the dawn of television, a single copy of TV towers were installed in large cities. They were able to transmit a signal to an area of 30-70 kilometers and were not a hindrance to anyone.
But for a big city with a suburban area, such a TV tower is not enough. To cover the entire territory, additional similar structures were needed. In this regard, problems arose. Noise is generated when broadcasting a TV program from all existing towers on the same channel. To avoid this phenomenon, programs from neighboring structures are broadcast not on one, but on different channels.
A total of twelve channels were made, which were enough to broadcast two TV programs. To expand broadcasting, it became necessary to use frequencies in the decimeter range (UHF).
For what reasons, the choice fell on the number of channels in the amount of twelve is not known for certain. But it can be assumed that the engineers were based on the twelve-hour system familiar to everyone.
The TV channel system was developed by the IBU (International Broadcasting Union). In 1950 g. it developed into an organization called the EBU. The Soviet Union, along with 25 other states, left it in 1946, after which they created their own organization - OIRT.
The PTK (TV channel switch) of Soviet-made tube TVs looks like a plate with a side wheel. It is the spring that is responsible for one step of turning the drum.
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A push-button SVP was installed on semiconductor models, which served as a switch. There were only six buttons. When these televisions began to be made, four television programs were broadcast. Two buttons were for the future. The fact that it would be possible to watch 150 or more channels was not even dreamed of at that time.
Continuing the topic read, what kind of pictures with girls Soviet guitars were decorated with, and why they were popular.
Source: https://novate.ru/blogs/041120/56631/
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