Intro-to-Communication-System.pdf

 Modulation & Demodulation Modulation - is a process of impressing a low frequency signal(audio signal) onto a high frequency signal(carrier signal) for effective transmission. Demodulation – is a process of extracting a low frequency signal(audio signal) from a high frequen...

 Modulation & Demodulation Modulation - is a process of impressing a low frequency signal(audio signal) onto a high frequency signal(carrier signal) for effective transmission. Demodulation – is a process of extracting a low frequency signal(audio signal) from a high frequency signal(carrier signal). Why is there a need for Modulation-Demodulation process? a. Length of Antenna b. Narrow Banding of Signal c. Frequency Multiplexing d. Effective Radiated Power Equation of the Carrier Signal eC = Em Sin (ωt + θ ) where Em - amplitude ωt - angular frequency θ - phase angle  If the amplitude of the carrier signal is varied, Amplitude Modulation ( AM ) audio signal carrier signal AM signal Source: https://www.physics-and-radio-electronics.com/blog/amplitude-modulation/  If the frequency of the carrier signal is varied, Frequency Modulation ( FM ) audio signal carrier signal FM signal Source: https://www.physics-and-radio-electronics.com/blog/frequency-modulation/  If the phase angle of the carrier signal is varied, Phase Modulation ( PM ) audio signal carrier signal PM signal Source: https://www.physics-and-radio-electronics.com/blog/amplitude-modulation/ Block Diagram of Basic Communication System Noise ELEMENTS OF BASIC COMMUNICATION SYSTEM 1.Input transducer. 2.Transmitter. 3.Communication channel. 4.Receiver. 5.Output transducer.  1. INPUT TRANSDUCER The information in the form of sounds, picture signal can not be transmitted as it is first it has to be connected into a suitable electrical signal the input transducer done this job.  2. Transmitter The function of transmitter block is to convert the electrical signals to the information of a suitable form. The transmitter consists of the electronic circuit such as amplifier oscillator & power amplifier.  3. Communication Channel The communication channel is the medium used for transmission of signal from one place to another. The communication medium can be conducting optical fiber depending two types of communication medium which exist they are. (i)wire communication (II)wireless communication  Noise Noise is an unwanted electrical signal which gets added to the transmitted signal when it is travelling towards the receiver the noise can be natural or man made. The source of natural noise one lighting or radiation from the sum and stars etc. the man made noise includes the noise produce by electrical ignition system of the automobile machine etc.  4. RECEIVER The reception is exactly the opposite process of transmission demodulation and connected into a suitable form the receiver consists of electronic circuit line oscillator amplifier etc.  5. OUTPUT TRANSDUCER It connects the electrical signal at the output of the receiver back to the original form that is sound, picture, video etc.