26-06-2013, 12:52 PM
Implementation of amplitude shift keying modulator and demodulator using matlab.
Learning Objectives
To be familiar with concept of amplitude shift keying with the use of MATLAB.
THEORY
ASK (amplitude shift keying) modulator:
Amplitude-shift keying (ASK) is a form of modulation that represents digital data as variations in the amplitude of a carrier wave.
The amplitude of an analog carrier signal varies in accordance with the bit stream (modulating signal), keeping frequency and phase constant. The level of amplitude can be used to represent binary logic 0s and 1s. We can think of a carrier signal as an ON or OFF switch. In the modulated signal, logic 0 is represented by the absence of a carrier, thus giving OFF/ON keying operation and hence the name given.
ASK is implemented by changing the amplitude of a carrier signal to reflect amplitude levels in the digital signal.
For example: a digital ―1 could not affect the signal, whereas a digital ―0 would, by making it zero.
The line encoding will determine the values of the analog waveform to reflect the digital data being carried.