MATLAB Code for Quantization of discrete analog signals.

% Sampling and Quantization

b=4; % Number of bits.

N=120; % Number of samples in final signal.

n=0:(N-1);

x=sin(2*pi*n/N);

%x=sawtooth(2*pi*n/N);

%x=randn(1,N);%Random Signal

%x=x/max(abs(x));

% Signal is restricted to between -1 and +1.

x(x>=1)=(1-eps);

x(x<-1)=-1;

% Quantize a signal to “b” bits.

xq=floor((x+1)*2^(b-1));

xq=xq/(2^(b-1)); % Signal is from 0 to 2 (quantized)

xq=xq-(2^(b)-1)/2^(b); % Shift signal down (rounding)

xe=x-xq; % Quantization error

stem(x,’b’);

hold on;

stem(xq,’r’);

hold on;

stem(xe,’g’);

legend(‘Exact’,’Quantized’,’Error’,’Location’,’Southeast’)

title(sprintf(‘Signal, Quantized signal and Error for %g bits, %g quantization levels ‘,b,2^b));

hold off

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