MATLAB: How to generate a signal with duration and period

signal processing

I want to generate a signal using the function: (sin(2π/u)T +1), taken at t = 0, 1, 2, . . . 32sec with u = 32 sec and repeated every 128 seconds.

A noise with the variance of 0.01 also needs to be added to the signal.

The signal should look like this:

Best Answer

I guess you made a mistake will writing the equation of periodic function. (sin(2π/u)T +1) canot create such a signal. Try the following code

duration = 32;
period = 128;
u = 32;
T = 0:32;
one_cycle = [sin(pi/u*T) zeros(1, period-numel(T))]+1;
num_cycles = 5;
signal = repmat(one_cycle, 1, num_cycles);
noisy_signal = signal + randn(1, numel(signal))*0.1; % noise with variance 0.1
T = 0:numel(noisy_signal)-1;
subplot(2,1,1);
plot(T, signal);
subplot(2,1,2);
plot(T, noisy_signal);

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MATLAB: Sine wave oscilating around sine wave

Hi Artur,

I understand that you want to plot a sine wave and add another sine wave of smaller amplitude to it, so that it looks like noise.

The following code may be helpful:


t = 0:0.01:2;  % time

n_t = length(t);
fs = 1;  % frequency of signal

signal = sin(2.*pi.*fs.*t);
fn = 10; % frequency of noise

noise_Amplitude = 0.1;
sine_noise = noise_Amplitude.*sin(2.*pi.*fn.*t);
plot(t, signal+sine_noise)

If the requirement is to have the original signal and noisy signal in the same plot, the following code may be used:


t = 0:0.01:2;  % time
n_t = length(t);
fs = 1;  % frequency of signal
signal = sin(2.*pi.*fs.*t);
fn = 10; % frequency of noise
noise_Amplitude = 0.1;
sine_noise = noise_Amplitude.*sin(2.*pi.*fn.*t);
plot(t, signal, 'b')
hold on
plot(t, signal+sine_noise, 'r')
hold off

Regards,

Shubhankar.

MATLAB: How to create a single square wave of variable duty cycle and length.

From my assumption, you are trying to generate a square wave which looks like in the below image, when length_of_wave is 100, num_cycle is 10 and dutycycle is 0.75

In this case your code throws an error because the value of duty_cycle * length_of_wave/num_cycle is not an integer and you are trying to pass this non-integer value to "zeros" function. Hence the error.

You can make use of the following piece of code

function waveform = squareWave(length_of_wave, num_cycle, duty_cycle)
oneCycleLength =  length_of_wave/num_cycle;
t=1:oneCycleLength;
oneCycle(t)=0;
oneCycle(oneCycleLength*duty_cycle+1:end) =  1;
waveform = repmat(oneCycle, [1,num_cycle]);
plot(waveform)
end

In the above code, you have to handle the case when length_of_wave = num_cycle

Best Answer

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MATLAB: Sine wave oscilating around sine wave

MATLAB: How to create a single square wave of variable duty cycle and length.

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