Communication channel (QC), Types of information, Information...

Communication channel (CC)

Types of information

As a rule, the source and receiver of information is a person. A person perceives the world around him by means of five sense organs, which provide information about him.

If you take into account the share of information given to people by the senses, then in the first place is vision (more than 85%), on the second - hearing (10%), and the remaining 5% is attributed to touch, smell and taste.

The first two kinds of sense organs supply the person with more than 95% of all information about the world around him, therefore, we will pay special attention to the consideration of the peculiarities of communication channels intended for the transmission of precisely audiovisual information.

The audio information , perceived by one ear, can be generally described using a function that depends on two parameters (Figure 4.4) - the amplitudes and the phase of the audio signal:

(4.2)

The video information Z ( t ), perceived by one eye, can be described using a function that depends on two parameters (Figure 4.5) - brightness and the phase of the video signal:

(4.3)

In the simplest case, it is sufficient for a person to provide only the part of the information contained in the amplitude (brightness) of an audiovisual signal, which significantly reduces the requirements for the characteristics of information transfer channels.

Example of changing the

Fig. 4.4. Example of changing the amplitude in the function used to describe audio information

The

Fig. 4.5. Image brightness in the function used to describe the video signal

Information transfer channels

Development of communication channels occurred by increasing the speed and distance of information transfer. To warn about the threatening danger at night, bonfires were used, and in the afternoon - smoke. In Africa, drums are still being used to transmit messages between villages, and the lower the sound of the drum, the further this sound spreads.

For the transmission of oral and written messages, messengers (foot and horse) were used. In this regard, we can recall the historical race of the Athenian Fidippid, who overcame the marathon distance of 42 km 195 m. Regular mail service was established.

The invention of radio by Professor Alexander Stepanovic Popov allowed to increase the speed of message transmission to the speed of light (300 000 km/s). At present, telecommunication channels are used everywhere for transmitting messages to both near and long distances.

To transmit information on the telecommunication channels in the form of an image or sound, it is necessary to convert them into electrical signals, and then transmit them through the communication channel for a specified distance to the right place where again to reverse the conversion of electrical signals into the original information.

Below are the requirements for information transfer channels, presented by various types of information.

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