Question

Modes of communication systems classified into ?

Answer 1

Communication is the whole process of transmission and reception of information and elements of the communication system comprises transmitter, communication channel and receiver, etc even all small elements contributing to the process of communication in other words the system which basically describes the information exchange between two points. And this process of transmission and reception of information is called communication.

Complete answer:
Modes of communication: In the Point-to-Point Mode of Communication, the communication takes place over a provided link between a transmitter signal and the receiver. Example- Telephone

Broadcast Mode of Communication: In this mode there are a large number of receiver’s signals corresponding to a transmitter signal. Radio and television are examples of broadcast modes of communication.

Analog Mode of Transmission: In an analogue mode of transmission the message is a physical quantity that varies with time usually in a smooth and continuous fashion.
Digital Mode of Transmission: In this mode of transmission the digital message is an ordered sequence of symbols selected from a finite set of discrete

Additional information:
Bandwidth of Signals and Transmission: Medium The speech signal has a bandwidth of $2800Hz$ $(3100 Hz – 300 Hz)$ for commercial telephonic communication and for the frequencies being produced by the musical instruments, the audible range of the frequencies extends from $20Hz$ to $20kHz$ while video signals for transmission require about $4.2MHz$ of bandwidth. A TV signal that contains both the voice and the picture is usually allocated bandwidth of $6MHz$ for transmission. The commonly used medium for transmission are wire, free space and fibre optic cable.

Propagation of Electromagnetic: Waves For the propagation or the transmission of electromagnetic waves over long distances, signals are radiated into space by using the devices called antennas. This radiated signal propagates as electromagnetic waves and the mode of propagation is generally influenced due to the earth and its atmosphere. Near the surface of the earth, electromagnetic waves propagate as surface waves.

Surface wave propagation is generally useful up to a few MHz frequencies and the long-distance communication between the two points on the earth is achieved through reflection of electromagnetic waves by the ionosphere. Such waves are generally called sky waves. The propagation of the sky waves takes place up to frequency of about 30 MHz and above this value, the electromagnetic waves essentially propagate as space waves.

Note: Electromagnetic waves are shown by a sinusoidal graph. It consists of time-varying electric and magnetic fields which are perpendicular to each other and are also perpendicular to the direction of propagation of waves. Electromagnetic waves are transverse in nature. The highest point of the wave is known as crest while the lowest point is known as a trough. In vacuum, the waves travel at a constant velocity of $3 \times {10^{8{\text{ }}}}m/s$.