четверг, 21 мая 2020 г.

21.05.2020

http://jerome.boulinguez.free.fr/english/file/hotpotatoes/havegotpresent.htm







How do remote controls work? – Ethan, 10, Sydney.

Thanks, Ethan. I was younger, I wondered the same. I was completely mesmerised with how a lump of plastic could possibly change channels on a TV without any physical connection.
Very early TV remote controls worked with wires. Then we created battery-powered remotes and we didn’t need the wires any more.

Now remotes are everywhere. In fact, the planet-watching Voyager spacecraft are controlled remotely and they are presently 20 billion kilometres away. It takes 20 hours for instructions to travel from Earth to the spacecraft but we can do it – using a remote.

A remote control has three things, what engineers would call a “communications channel”, a “procotol”, and an “interface”. I will explain what those words mean.

The communications channel

The communications channel is what connects the remote to the device you want to control (like a TV).
It could be light (such as infra-red light), sound or radio waves (sometimes called electromagnetic waves). The human eye cannot see infra-red light or radio waves. 

Protocol

You can think of the protocol as the “language” the remote uses to communicate with the TV, XBox or whatever the device may be.

User interface

“User interface” is just a fancy way of saying how the remote looks and is used.
TV remotes just have a rather boring array of buttons. Some remotes have a screen and look like a mobile phone.








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