touchToneDecoder

%touchToneDecoder.m
%Peter Heitkemper
%5-3-21

clear all; 
format compact;
clc;

% Change sample location to isolate each digit
% 30,000 total samples/10 digits = 3,0000 samples per digit
% Creating an array and looping through would be next step
% Then writing a method to determine frequency peaks and calculate 
% digits automatically. 
sample = [27000,30000];

[signal,samplerate]=audioread('PeterHeitkemper.wav',sample);
t=0:1/samplerate:(length(signal)-1)/samplerate;


% signal = signal(1:2500,1)
% t = t(:,1:2500);

    % Calculate Fast Fourier Transform of a Signal
Y = fft(signal);
L = length(Y);

% Calculate the DC offset of the signal
A0 = Y(1)/L;
% Calculate Amplitude Spectra
Amp2 = abs(Y/L); % Divide the L and find the magnitude
Amp1 = 2*Amp2(2:L/2+1); % Parse the array and multiply by 2

% Calculate Frequency Array
freq = linspace(samplerate/L,samplerate/2,L/2);

%Amplitude Spectra
subplot(2,1,1)
hold on
stem(freq,Amp1) 
xlabel('frequency (Hz.)')
ylabel('Amplitude')
grid on
box on
% Plot the zero line
plot(t,(t.*0),'k')
hold off

subplot(2,1,2);
hold on

%Plot the superpositioned signal
plot(t,signal,'k')

xlabel('Samples ')
ylabel('Signal')
grid on
box on
% Plot the zero line
plot(t,(t.*0),'k')
hold off