Communication Engineering - Modulation, Study notes of Communications Engineering

Download Communication Engineering - Modulation and more Study notes Communications Engineering in PDF only on Docsity! Modulation • Systematic alteration of a parameter of carrier wave (amplitude, phase and frequency) in accordance with instantaneous magnitude of the message signal. • Generally, Frequency domain analysis provides more information about modulation operation. Modulation Continuous wave Pulse PAM PPM PWM PCM Digital Analog ASK FSK PSK, etc Linear Exponential AM DSB-SC SSB VSB FM PM Based on the type of carrier wave Based on the type of modulating signal Based on the relationship between modulating and modulated signal Tone modulation and phasor analysis • Let x(t)= µAmcosωmt, xc(t)= Accosωct and µAm= 2/3. Draw the line spectra and phasor diagram for AM (i) undistorted transmission (ii) lower sideband is completely removed by the channels. Modulators and transmitters • Product modulator • Square law modulator • Balanced modulator • Ring modulator (sampling) • Switching modulator Square law modulator • A nonlinear device is used • vout = a1vin(t) + a2vin2(t) • vin = x(t)+cosωct