Question

Modern communication system use
A) Analogy circuit.
B) Digital circuit.
C) Combination of analogy and digital circuit.
D) Radio circuit

Answer 1

Modern communication system include satellite, fibre optic, mobile cellular phone, microwave system and internet communication as well as cable TV, AM and FM radio, local government and computer networking system.

Complete Solution:-
Working of a communication system is as follows:-

1. Source:- Daya the origin of a message or input signal. Examples of source include email messages, electromagnetic radiation, human voice audio files at 17.
2. Input transducer/ sensor:- Samsung live microphones and camera capture non electric sources, like sound and light and convert them into Electrical signals. These types of sensors are called input transducers in modern analogue and digital communication systems. Translations include microphone, camera, accelerometer etc.
3. transmitter:- once the source signal has been converted into an electric signal, the transmitter will modify the signal for efficient transmission. Signal is allowed to pass through 1) noise filter 2) analogue to digital converter 3) encoder 4) modulator 5) signal amplifier.
   After passing through all above components, the signal is amplified and ready for transmission. At an antenna the signal is released as electromagnetic waves.
4. communication channel:- communication channel is a medium by which a signal travels. There are two types of channel guided and unguided. Guided refers to a medium that can be directed from transmitter to receiver by means of connecting cable. unguided media refers to any communication channel that creates space between transmitter and receiver. Air is the only thing between transmitter and receiver. Channel include almost everything from the vacuum of space to the solid piece of metal
   Receiver :-
   Once the signal has passed through the communication channel, it must be effectively captured by a receiver. The purpose of the receiver is to capture and reconstruct the signal before it passes through the transmitter. Received signal is passed through
5. Noise filter 2) digital to analog converter. 3) Decoder 4) De modulator. 5) Signal amplifier.
6. Output transducer:- output transducer converts the signal into its original form. Example:- speakers, monitors, motors, lighting etc.
   Above process describe the procedure how communication system works

Modern communication systems use digital circuits for communication. So option B the correct answer.

Additional information:-
Fibre optic communication systems transmit information from one place to another by sending light through an optical fibre. The light forms a carrier signal that is modulated to carry information. A radio communication system comprises a transmitting conductor in which electrical oscillations to be propagated through the free space medium from one point to another remote they form and a receiving conductor at such distant point adapted to be excited by the oscillation or current propagated from the transmitter.
a power line communication system operates by impressing a modulated carrier signal on power lines. Different types of power LINE communication use different frequency bands, standing on the signal transmission.
Characteristic of the power wiring used. The propagation problem is a limiting factor for each type of power LINE communication.

Note:-
Vacuum or air constitutes a good transmission medium for electromagnetic waves such as light or radio waves. Fibres are used instead of metal wires because signal travels along them with less loss in addition fibres are immune to electromagnetic interference. Problem from which metal wire suffers extensively. it is the only propagation method possible at microwave frequency and above