Plotting multiple plots on the same graph

So I am trying to plot this noisy data, and the output from each individula filter on the same graph. The filters are in cascade so the output to one is the input to the other. The first figure works, but the second one I can't seem to fix. I added hold on/off which didnt help and don't know what to try next. Thank you for your time!

fs = 20e3; 
numFilts = 32;
filter_number = 16;
t = linspace(0,2*pi,200);
input = sin(t) + 0.25*rand(size(t));
% 
figure
hold on
for ii = 1:filter_number
    output = gammatone(input, CenterFreqs(ii), fs);
    plot(output)
    LEGs{ii} = ['Filter # ' num2str(ii)]; %assign legend name to each
    legend(LEGs{:})
    legend('Show')
end

figure %This one!!
plot(t, input, 'k-', 'LineWidth', 2, 'DisplayName', 'Data')
plot(t,output(ii,:), 'LineWidth', 1.25)
title('Signal after Filters up to Filter', num2str(filter_number));
xlabel('t')
ylabel('x(t) & x_{filtered} (t)')

Answer 1

[Hassaan]

@S Try this and let me know:

fs = 20e3;
numFilts = 32;
filter_number = 16;
t = linspace(0, 2*pi, 200);
input = sin(t) + 0.25*rand(size(t));

% Define the center frequencies for the filters (example: linearly spaced)
lowFreq = 200; % lowest center frequency
highFreq = fs/2; % highest center frequency (Nyquist frequency)
CenterFreqs = linspace(lowFreq, highFreq, numFilts);

% Initialize the cumulative output variable
cumulative_output = input;

figure
hold on

% Apply the filters in cascade and plot the outputs
for ii = 1:filter_number
    output = gammatone(cumulative_output, CenterFreqs(ii), fs);
    cumulative_output = output; % Update the cumulative output
    plot(t, output, 'LineWidth', 1.25)
    LEGs{ii} = ['Filter # ' num2str(ii)]; % Assign legend name to each
end

% Add the original data to the plot
plot(t, input, 'k-', 'LineWidth', 2, 'DisplayName', 'Original Data')

legend(LEGs{:}, 'Original Data') % Add the original data to the legend
hold off

title(['Signal after Filters up to Filter ' num2str(filter_number)]);
xlabel('t')
ylabel('x(t) & x_{filtered} (t)')

The gammatone function you're using should be correctly defined or available in your MATLAB path for the script to work.

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It's important to note that the advice and code are based on limited information and meant for educational purposes. Users should verify and adapt the code to their specific needs, ensuring compatibility and adherence to ethical standards.

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• Technical Services and Consulting
• Embedded Systems | Firmware Developement | Simulations
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Feel free to contact me.

[S]

I dont want all of the fliter outputs to be cumulative, I want to be able to see the indivisual filter results. The input of filter 2 is the output of filter 1 for example so series/cascade but not cumulative

[Hassaan]

@S Try this:

fs = 20e3;
numFilts = 32;
filter_number = 16;
t = linspace(0, 2*pi, 200);
input = sin(t) + 0.25*rand(size(t));

% Define the center frequencies for the filters (example: linearly spaced)
lowFreq = 200; % lowest center frequency
highFreq = fs/2; % highest center frequency (Nyquist frequency)
CenterFreqs = linspace(lowFreq, highFreq, numFilts);

% Initialize a variable to store the output of each filter
outputs = zeros(filter_number, length(t));

% Apply the filters in cascade
for ii = 1:filter_number
    if ii == 1
        output = gammatone(input, CenterFreqs(ii), fs);
    else
        output = gammatone(outputs(ii-1, :), CenterFreqs(ii), fs);
    end
    outputs(ii, :) = output; % Store the output of each filter
end

% Now plot the original data and the output of each filter
figure;
hold on;

% Plot the original data
plot(t, input, 'k-', 'LineWidth', 2, 'DisplayName', 'Original Data');

% Plot the output of each filter
for ii = 1:filter_number
    plot(t, outputs(ii, :), 'LineWidth', 1.25, 'DisplayName', ['Filter # ' num2str(ii)]);
end

% Add legend and labels
legend('show');
title(['Signal after Filter ' num2str(filter_number)]);
xlabel('t');
ylabel('x(t) & x_{filtered} (t)');

hold off;

• An outputs matrix that stores the output of each filter.
• A loop that applies each filter in series, where each filter's input is the output of the previous filter.
• After all filters have been applied, we plot the original data and the outputs from each filter on the same graph.

-----------------------------------------------------------------------------------------------------------------------------------------------------

If you find the solution helpful and it resolves your issue, it would be greatly appreciated if you could accept the answer. Also, leaving an upvote and a comment are also wonderful ways to provide feedback.

It's important to note that the advice and code are based on limited information and meant for educational purposes. Users should verify and adapt the code to their specific needs, ensuring compatibility and adherence to ethical standards.

Professional Interests

• Technical Services and Consulting
• Embedded Systems | Firmware Developement | Simulations
• Electrical and Electronics Engineering

Feel free to contact me.

[S]

This has the correct number of filters in legend! But it is only graphing the input and then everything else is a flat line

[Hassaan]

@S A potential problem with the gammatone function's application or its response to the input signals.

1. Test the gammatone Function Individually: Before applying it in a loop, test the gammatone function with a single frequency to verify it produces a meaningful output. This will help determine if the issue lies with the function itself or its usage in the loop.
2. Visualize Filter Response: Visualize the frequency response of the gammatone filter for a few center frequencies to ensure they are behaving as expected (i.e., filtering around the intended center frequency).
3. Check for Overlapping Filters: If the filters' frequency responses do not overlap with the input signal's frequency content, subsequent filtering stages might further attenuate the signal, leading to flat outputs. This is particularly relevant if your input signal's frequency content does not match the filters' designed center frequencies.
4. Adjust Filter Parameters: If the filters are designed correctly but their parameters (center frequencies, bandwidths, etc.) are not suitable for the input signal, consider adjusting these parameters. Ensuring that at least some of the filters are centered around frequencies present in your input signal can help.

Without the specific implementation of the gammatone function, these suggestions are generalized troubleshooting steps.

-----------------------------------------------------------------------------------------------------------------------------------------------------

If you find the solution helpful and it resolves your issue, it would be greatly appreciated if you could accept the answer. Also, leaving an upvote and a comment are also wonderful ways to provide feedback.

It's important to note that the advice and code are based on limited information and meant for educational purposes. Users should verify and adapt the code to their specific needs, ensuring compatibility and adherence to ethical standards.

Professional Interests

• Technical Services and Consulting
• Embedded Systems | Firmware Developement | Simulations
• Electrical and Electronics Engineering

Feel free to contact me.

[S]

The plot of the filters themselves looks correct! So could the issue be the way I am trying to plot it or the way I wrote the loop?

[S]

I even tried to do just:

figure

plot(t,output(ii,:), 'LineWidth', 1.25)

But that gives:

Index in position 1 exceeds array bounds. Index must not exceed 1.

Error in t131 (line 39)

plot(t,output(ii,:), 'LineWidth', 1.25)

which I dont understand as my filter_number is set to 16 not 1