10k views

Delete frequency components with FFT and IFFT [duplicate]

I have a signal in Matlab defined by signal and t. As it is a noisy signal, I want to delete every component below a certain ...
1k views

About designing digital filters [duplicate]

I'm currently using MATLAB's fdatool for filter design. Using that tool, I can easily design different kind of filters. For example, let's take a band-pass FIR filter with 10-40 Hz passband, and 5-10 ...
880 views

Is ideal band pass filter (brick wall filter) linear phase? [duplicate]

I'm very new in digital signal processing. I have multiple sensors and the way I filters the signals in post processing is: take FFT of the signals. put zero on out range of interesting frequency (...
477 views

Remove Noise from Physiological Signals [duplicate]

I have collected a set of physiological signals through emg sensors. I will link at the end of the post an example (10 sec.) of a signal collected on zygomatic muscle. When I analyzed these data, I ...
218 views

Why do we not use square filters without windows? [duplicate]

This question may sound like "why do we use window functions", but it's not. So here it's: What we currently do: If we have a function $g(t)$ and its Fourier transform $G(f)$, and a window $W(f)$ and ...
278 views

Beginner's question on LPF, Need for Sinc and windowing [duplicate]

As a student who has never constructed any real world DSP application, I am inclined to ask the following. Convolution in time domain is multiplication in frequency domain. For low pass filtering, ...
164 views

Advantage of using nonideal filter in purely digital application [duplicate]

Say I'd like to bandpass filter a signal with corner frequencies 1 kHz and 2 kHz (i.e., passes signals between 1 kHz and 2 kHz and suppresses other frequencies) using software like MATLAB. Intuition ...
153 views

Attenuate frequency bin in FFT array resulting in artifacts [duplicate]

Am trying to remove noise for certain frequency bands by attenuating freqeuncy bins in the FFT array. However this results in artifacts to be formed, where there are clicking sounds in between each ...
75 views

What happens if I zero out the initial terms of the fft output and take inverse fft? [duplicate]

I am new to signal processing domain. When I run fft on data of length 1000, I get 1000 complex numbers. Now, if I want to extract the low frequency information or signal approximation, I take the ...
42 views

Bringing the signal into the same level [duplicate]

I have a signal, shown in the attachment (blue one). As you can see that the latter part of my signal has a higher dc offset. I want to bring the signal into the same level. I have tried eliminate the ...
30 views

Use Cases of FFT in Signal Processing [duplicate]

I am trying to learn about signal processing and fft's applications within it. My understanding is that a classical use case for fft is to remove "noise" (ex. high frequencies that are not supposed to ...
29 views

Is it possible to recover the time-domain signal after manipulating it in the frequency-domain? [duplicate]

I've worked a fair amount with EEG signals, though I've never had formal training in signal processing, so please excuse my ignorance. The problem is this: my signal has noise at many, many ...
24k views

Why do we use window in time domain rather than do FFT modify the spectrum and than inverse FFT

I thought that DSP would be done by using FFT of portions of a signal, modify the samples that result from FFT (since they represent the spectrum of our signal + noise) and remove any unwanted signals ...