delay and sum beamforming

Hi, i am running a program for dealy and sum beamforming. When i run the program i get this error

"Error using line

Vectors must be the same length.

Error in examplesSteeredResponse (line 64)

line(ax, [thetaScanAngles(indx) thetaScanAngles(indx)], ax.YLim,'LineWidth', 1, 'Color', 'r', 'LineStyle', '--');"

Here's some part of the code i am running:

%% Examples on delay-and-sum response for different arrays and input signals


%% 1D-array case

% Create vectors of x- and y-coordinates of microphone positions 
xPos = -0.8:0.2:0.8; % 1xP vector of x-positions [m]
yPos = zeros(1, numel(xPos)); % 1xP vector of y-positions [m]
zPos = zeros(1, numel(xPos));
elementWeights = ones(1, numel(xPos))/numel(xPos); % 1xP vector of weightings

% Define arriving angles and frequency of input signals
thetaArrivalAngles = [-30 10]; % degrees
phiArrivalAngles = [0 0]; % degrees
f = 800; % [Hz]
c = 340; % [m/s]
fs = 44.1e3; % [Hz]

% Define array scanning angles (1D, so phi = 0)
thetaScanAngles = -90:0.1:90; % degrees
phiScanAngles = 0; % degrees


% Create input signal
inputSignal = createSignal(xPos, yPos, zPos, f, c, fs, thetaArrivalAngles, phiArrivalAngles);

% Create steering vector/matrix
e = steeringVector(xPos, yPos, zPos, f, c, thetaScanAngles, phiScanAngles);

% Create cross spectral matrix
R = crossSpectralMatrix(inputSignal);

% Calculate delay-and-sum steered response
S = steeredResponseDelayAndSum(R, e, elementWeights);

%Normalise spectrum
spectrumNormalized = abs(S)/max(abs(S));

%Convert to decibel
spectrumLog = 10*log10(spectrumNormalized);


%Plot array
fig1 = figure;
fig1.Color = 'w';
ax = axes('Parent', fig1);
scatter(ax, xPos, yPos, 20, 'filled')
axis(ax, 'square')
ax.XLim = [-1 1];
ax.YLim = [-1 1];
grid(ax, 'on')
title(ax, 'Microphone positions')

%Plot steered response with indicator lines
fig2 = figure;
fig2.Color = 'w';
ax = axes('Parent', fig2);
plot(ax, thetaScanAngles, spectrumLog)
grid(ax, 'on')
ax.XLim = [thetaScanAngles(1) thetaScanAngles(end)];

for j=1:numel(thetaArrivalAngles)
    indx = find(thetaScanAngles >= thetaArrivalAngles(j), 1);
    line(ax, [thetaScanAngles(indx) thetaScanAngles(indx)], ax.YLim,'LineWidth', 1, 'Color', 'r', 'LineStyle', '--');
end
xlabel(ax, '\theta')
ylabel(ax, 'dB')

[Naman Bhaia]

Hello Dhananjay,

I think this question was posted twice by mistake. There are people from the community answering on the other question so please redirect there to follow that thread.

Answer 1

[prabhat kumar sharma]

Hello Dhananjay,

The error you're encountering is due to a mismatch in the lengths of the vectors used in the line function within your plotting code. Specifically, the line function expects the X and Y data to be of the same length, but you're providing a single X value (thetaScanAngles(indx)) and a range for Y (ax.YLim), which causes the error.

To fix this, you should specify both X and Y as pairs of points that define the start and end of the line. Here's I'm providing a reference code snippet for modifying the line plotting section. You can adjust this code according to your specific needs.

% Plot steered response with indicator lines
fig2 = figure;
fig2.Color = 'w';
ax = axes('Parent', fig2);
plot(ax, thetaScanAngles, spectrumLog)
grid(ax, 'on')
ax.XLim = [thetaScanAngles(1) thetaScanAngles(end)];

% Add indicator lines for each arrival angle
for j = 1:numel(thetaArrivalAngles)
    indx = find(thetaScanAngles >= thetaArrivalAngles(j), 1);
    % Ensure indx is valid
    if ~isempty(indx)
        % Draw vertical line at arrival angle
        line(ax, [thetaScanAngles(indx) thetaScanAngles(indx)], [min(spectrumLog), max(spectrumLog)], ...
            'LineWidth', 1, 'Color', 'r', 'LineStyle', '--');
    end
end

xlabel(ax, '\theta')
ylabel(ax, 'dB')

I hope it helps!