clear all;
close all;
clc;

v = 1;%signal amplitude (max "voltage")
f = 1.6e4;%sampling frequency (arbitrary)
nbit = [4 6 8];%signal bit depth(s)

nsamples = 1e4;
pe = logspace(-9,-1,500);%Probabilities of Error (of binary symmetrical channel)
sig = 2*v*(rand(1, nsamples)) -v ;%signal (randomly generated)
figure(1);
grid on;
hold on;
histogram(sig,20,'normalization','pdf');%ProbabilityDensityFunction histograms
xlabel("Amplitude")
ylabel("PDF")

psd = abs(fft(sig)).^2;%Square PowerSpectralDensity vector
figure(2);
df = f/nsamples;
xtest = (-f/2:df:f/2-df);%frequency values for the signal
plot(xtest, fftshift(psd));
xlabel("Frequency")
ylabel("Weight")

grid on;
for counter=1:length(nbit)
    M = 2^nbit(counter);
    SNR = M^2./(1+4*(M^2-1)*pe);
    figure(3)
    semilogx(pe,10*log10(SNR))
    grid on;
    hold on
    dv = 2*v/M;
    partition = -v+dv:dv:v-dv;
    codebook = -v+dv/2:dv:v-dv/2;
    [index,quanz] = quantiz(sig,partition,codebook);
    words = de2bi(index,nbit(counter));
    for c2=1:length(pe)
        out = bsc(words,pe(c2));
    end
end