Code covered by the BSD License

# What's New for Object-Oriented Programming in MATLAB Webinar - Code Examples

### Stuart McGarrity (view profile)

10 Apr 2008 (Updated )

Code examples used in "What's New for Object-Oriented Programming in MATLABĀ®" Webinar

```% Sensor Array Data Set Class
properties
Data         % Sampled sensor data
SampleRate   % Sample rate (Hz)
Spacing      % Spacing of array (m)
Name         % Sensor array test run name
end
properties (Access=private)
Wavelength   % Wavelength of sources (m)
end
properties (Constant)
c=3e8;       % Speed of wave in medium (m/s)
end
properties (Dependent)
NumSensors   % Number of sensors
NumSamples   % Number of samples
end
methods
% SADS Create sensor array data set
% Example:

obj.Data=Data;
obj.SampleRate=SampleRate;
obj.Spacing = Spacing;
obj.Name=Name;
obj.Wavelength=Wavelength;
end
% MAGFFT Calculate the magnitude square of the FFT of the
% Example:
%  result=magfft(s,128);

mag=zeros(obj.NumSamples,zeroPadTo); % Preallocate store of magnitudes
fflip=fliplr(f); % Flip frequencies

% Take the sum over each sensor array sample
for k=1:obj.NumSamples
avbig(1:obj.NumSensors)=obj.Data(1,:);
response=fft(avbig)/zeroPadTo;       % FFT of normalized signal
mag(k,:)=abs(fftshift(response)).^2; % Mag squared of FFT
end
mags=sum(mag);
end
function NumSensors=get.NumSensors(obj)
% Get NumSensors property
NumSensors=size(obj.Data,2);
end
function NumSamples=get.NumSamples(obj)
% Get NumSamples property
NumSamples=size(obj.Data,1);
end
function plot(obj)
% PLOT Plot the sensor array sample data set
% Example:
%  plot(ds);

surf(real(obj.Data)',...
'EdgeLighting','flat','FaceLighting','none',...
'FaceColor',[1 1 1],...
'EdgeColor',[0 0 1]);
view([-55.5 74]);
title(obj.Name);
xlabel('Samples')
ylabel('Sensors')
zlabel('Amplitude')
xlim([1 obj.NumSamples]);
ylim([1 obj.NumSensors]);
set(gca,'xtick',(1:obj.NumSamples/8:obj.NumSamples));
end
% MAGFFTPLOT Plot the magnitude square of the FFT of the sensor
% array data
% Example:
%  magfftplot(s,128);

grid
title(['Averaged Magnitude Squared FFT of: ' obj.Name]);
xlabel('Degrees');
ylabel('Amplitude');
end
function angles=doa(obj)
% DOA  Estimate the direction of arrival of the sources in the
% sensor array data set using simplistic peak finding method
% Example:
%  angels=doa(ds)

maxtab=peakdet(mags,.1);             % Use peakdet function
angles=sort(fflip(maxtab(:,1))*180); % Angles
end
function obj=steer(obj,theta)
% STEER Steer array electronically by angle theta (in degrees), returning a new sensor array data set
% Example:
%   s=steer(s,10);
delta=obj.Spacing; thetaR=theta*(pi/180);
Wc=2*pi*(obj.c/obj.Wavelength); % Source frequency in radians per sec
phaseShift=exp(-j*Wc*delta*(0:obj.NumSensors-1)*sin(thetaR)/obj.c);
obj.Data=bsxfun(@times,obj.Data,phaseShift); % Multiply by phaseshift
end
end
methods (Static)
function showarray(Targets,NumSensors,Spacing)
% SHOWARRAY  Illustrate a sensor array with ideal sources
% Example:
%  showarray(Targets,NumSensors,Spacing)

numTargets=size(Targets,1);
orgX=(NumSensors+1)/2;         % Center of array on x-axis

% Plot sensors
plot((1:NumSensors)',zeros(NumSensors,1),'o');
axis tight
set(gca,'xtick',1:NumSensors); % Ensure tick marks at each sensor
set(gca,'ytick',[]);           % Remove y tick marks
ylim([0 NumSensors/1.5]);      % Set Y axis limit
hold on

% Plot normal to array (Array direction)
plot(ones(NumSensors,1).*orgX,(0:NumSensors-1)','--k');

% Plot Incident rays
for tar=1:numTargets
bearing=.5*pi-Targets(tar,1);
length_line=orgX;
rayX=length_line*cos(bearing)+orgX;
rayY=length_line*sin(bearing);
plot([rayX orgX]', [rayY 0]','r');
end
hold off

% Annotations
legend('Sensors','Direction of Array','Direction of Sources');
xlabel(['Sensor spacing is ',num2str(Spacing), ' m']);
title([int2str(NumSensors),' sensor array with ' int2str(numTargets) ' sources']);
end
end
end
function [maxtab, mintab]=peakdet(v, delta)
%PEAKDET Detect peaks in a vector
%        [MAXTAB, MINTAB] = PEAKDET(V, DELTA) finds the local
%        maxima and minima ("peaks") in the vector V.
%        A point is considered a maximum peak if it has the maximal
%        value, and was preceded (to the left) by a value lower by
%        DELTA. MAXTAB and MINTAB consists of two columns. Column 1
%        contains indices in V, and column 2 the found values.
% Eli Billauer, 3.4.05 (Explicitly not copyrighted).
% http://www.billauer.co.il/peakdet.html
% This function is released to the public domain; Any use is allowed.

maxtab = [];
mintab = [];

v = v(:); % Just in case this wasn't a proper vector

if (length(delta(:)))>1
error('Input argument DELTA must be a scalar');
end

if delta <= 0
error('Input argument DELTA must be positive');
end

mn = Inf; mx = -Inf;
mnpos = NaN; mxpos = NaN;

lookformax = 1;

for i=1:length(v)
this = v(i);
if this > mx, mx = this; mxpos = i; end
if this < mn, mn = this; mnpos = i; end

if lookformax
if this < mx-delta
maxtab = [maxtab ; mxpos mx];
mn = this; mnpos = i;
lookformax = 0;
end
else
if this > mn+delta
mintab = [mintab ; mnpos mn];
mx = this; mxpos = i;
lookformax = 1;
end
end
end
end```