MATLAB: Sum of signals and filter the sum and recuperate the inicial frequencies

filterfilteringsum of signals

Hello, I am new to matlab,

I would like to generate two diffrent sinus signal with diffrent frequencies f1 and f2. One generated I want to do the sum of them (let's call it totalSignal) . Next, I want t filter the total signal and recuperate f1 and f2.

Any body can help me?

Best Answer

Making the simulated signal is quite simple. First, make a vector t which covers the time domain you are interested in. Then, generate your two sine vectors from this x, and add them together:

t=0.001:0.001:1;  %this gives you t that starts from 0.001, in steps of 0.001, up to 1. 
f1=10;
f2=100;
totalSignal=sin(2*pi*f1*t)+sin(2*pi*f2*t); %two signals with frequency 10 and 100 Hz, lets imagine. 
plot(t,totalSignal);

Now that you have your signal, you can look into different options for recovering your original input frequencies. Fourier analysis is a great way of achievting this - check out the fft documentation for more info.

Related Solutions

MATLAB: How to execute fft and ifft

Hi thereb, the sine wave is right there, but the problem is that after FFTing the your y data, YfreqD contains half the samples than the original. When calculating the iFFT, that length is kept and plot(t1,B) plots half the original data.

You can try plot like this to see the points you are plotting in each case:

figure(1)
plot(t,y,t,y,'r*')
figure(3)
plot(t1,B,t1,B,'r*')

You can add a higher sampling rate at the beginning of your code and your figure(3) will appear like a less "straight" sine wave.

fo = 4; %frequency of the sinewave
Fs = 200; %sampling rate 
Ts = 1/Fs; %sampling time interval
t = 0:Ts:1-Ts; 
n = length(t); %number of samples 
y = sin(2*pi*fo*t);
figure(1)
plot(t,y,t,y,'r*')
grid on
[YfreqD,freqRng] = positiveFFT(y,Fs);
figure(2)
stem(freqRng,abs(YfreqD));
B = ifft(YfreqD)*length(y);
t1 = (0:(1-Ts)/(length(B)-1):1-Ts);
figure(3)
plot(t1,B,t1,B,'r*')
grid on

MATLAB: How to plot frequency spectrum of a signal in matlab

Hi there!

I don't know why your instructor didn't like it! Maybe it's missing a division and he is picky on that!

fftNoisySignal = fft(NoisySignal)./numel(NoisySignal);

Maybe that is the case, basically the magnitude of the fft has an issue, I guess! You need to apply this division on every fft command you use.

Hope this helps.

Good luck!

Best Answer

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MATLAB: How to execute fft and ifft

MATLAB: How to plot frequency spectrum of a signal in matlab

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