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I have been writing a very simple code to remove noise from a signal.

The signal is just a sinusoidal wave, the noise is a random matrix, and the noisy signal is the addition of both. Figure 2; which is the figure for comparing both the filtered signal and the original signal; always appear like the image below.

I believe that the Wn variable is not right, but I don't know how to calculate the correct normalized frequency.

Following this example form Matlab's documentation , if you want the cutoff frequency to be at fc Hz at a sampling frequency of fs Hz, you should use:. However you should note that this will produce a Butterworth filter with an attenuation of 3dB at the cutoff frequency.

If you want less signal attenuation, you should increase the filter cutoff frequency.

## Description

Of course doing so will also let a bit more noise through, so the exact amount is a trade-off between on how much signal attenuation your application can tolerate and how much noise you need to get rid of. For example, adding a margin of 1Hz and increasing the filter order which gives you less attenuation for the same margin with.

Learn more. Asked 3 years, 1 month ago.

Active 3 years, 1 month ago. Viewed 14k times. Tes3awy Tes3awy 1, 3 3 gold badges 18 18 silver badges 37 37 bronze badges. SleuthEye SleuthEye Is it right that the filtered signal has an offset?

## Your Answer

The noise you add with rand has a uniform distribution in the range 0,1 , which offsets the input on average by 0. Gaussian distribution. Sign up or log in Sign up using Google. Sign up using Facebook.

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