% class1 - script used in first ECE 201 class

%% DJIA data
% begin by importing DJIA data from file djia.csv; use "Import Data ..." in
% "File" menu

% define length 50 running average filters to be used for smoothing
M = 50;
b = ones(1,M)/M;

M2 = 15;
b2 = ones(1,M2)/M2;

% extract "Close" data after import ...
djia  = flipud(data(:,4));
dates = datenum(flipud(textdata(2:end,1)));

% ... then plot
plot(dates,djia)
datetick('x','yyyy')
xlabel('Time');
ylabel('DJIA')
grid

pause

% filter data for smoother signals
smooth  = conv(b,djia);
smooth2 = conv(b2,djia);

hold on;
plot(dates(51:end,1), smooth(51:length(djia)), 'r');
plot(dates(51:end,1), smooth2(51:length(djia)),'g');
hold off;

% prepare for next example
disp('press return for next example');
pause
close(gcf)

%% Music
% load sampled signal from wav file
[y,fs,nbits] = wavread('music.wav');
% display sample rate and resolution of wav file ...
disp(sprintf('Fs: %5.0f\nNbits: %2d\n',fs,nbits))
% ... then play through speaker, and ...
soundsc(y,fs)

disp('press return for plot')
pause

% plot and play again after pause
t  = (1:length(y))/fs;  % time axis
plot(t,y)
xlabel('Time (seconds)')
ylabel('Signal Amplitude')

disp('press return for sound')
pause

soundsc(y,fs)

disp('press return for next example');
pause
close(gcf)

%% Heart beat signal
% read signal from wav file
[y,fs,nbits] = wavread('heart.wav');
% display sample rate and resolution
disp(sprintf('Fs: %5.0f\nNbits: %2d\n',fs,nbits))
% play through speaker
soundsc(y,fs)

disp('press return for plot')
pause

% plot and play again after pause
t = (1:length(y))/fs;    % time axis
plot(t,y)
xlabel('Time (seconds)')
ylabel('Signal Amplitude')
disp('press return for sound')

pause

soundsc(y,fs)

disp('press return to end');
pause
close(gcf)