Linked Questions

1
vote
2answers
1k views

Difference between bandpass filter and using fast fourier transform to extract power of frequency bands

In signal processing, I have heard of two terms: Using band-pass filter to extract some frequency bands. Using Discrete/Fast Fourier Transform (DFT/FFT) to extract some frequency bands. Are these ...
0
votes
1answer
1k views

How do I apply a binary mask and STFT to produce an audio file?

So here's the idea: you can generate a spectrogram from an audio file using shorttime Fourier transform (stft). Then some people have generated something called a "binary mask" to generate different ...
1
vote
1answer
902 views

Complex output after inverse FFT of a real signal

I have a real one dimensional signal s (light absorbance in a flow cell), which has significant noise and some periodic noise after performing a deconvolution of $S$ from $S_o$. Basically fft($S$) was ...
0
votes
2answers
733 views

FFT and IFFT : filtering frequencies

I am sampling at $30 Hz$. I have a sample of $N=150$. Here is an example of how my sample looks like, which starts at 54 and ends on 203 on the X Axis I am interested in observing frequencies ...
0
votes
2answers
1k views

Filter to add 3dB per octave?

If I want to add 3dB per octave to signal (e.g. to flatten out the power spectrum of an exponential sine sweep), is it really just as simple as... Take the Fourier transform of the time-domain signal,...
1
vote
2answers
760 views

Jack buffer size and FFT frequency resolution

In my actual Jack Audio setup (almost default values), Fs = 48kHz the buffer size is 1024 samples. I'm planning to do some filtering (lowpass, highpas, ...) and ...
0
votes
1answer
857 views

FFT frequency bands and filtering

I don't really understand FFTs, and filtering neither. I hope I can explain my confusion in a way that is not too confusing for you to understand. consider the following example: I have an EEG signal,...
0
votes
2answers
508 views

How do Anti-Aliasing Filters filter the signal?

I have programmed a anti-aliasing filter that uses the fourier-transformation and makes a perfect cutoff on my desired cutoff frequency for downsampling without aliasing. I have read about other ...
0
votes
1answer
1k views

Filtering on time or frequency domain?

I'm applying an ideal filter on the frequency domain. My code below: ...
1
vote
1answer
746 views

Easy Filter with FFT and Convolution

I'am pretty new to this topic so i dont have much experience with DSP. I want to filter(highpass) a WAVE file, i have already programmed the FFT, and now want to filter the FFT vector via convolution (...
1
vote
1answer
645 views

Removing frequency using FFT

So if I were to have an $n$ length sample of a given sample rate and were to run it through an FFT, resulting in $n$ complex elements. How would I obtain the frequency bins, such that if I know the ...
0
votes
2answers
460 views

Amplifying part of a signal

If I want to amplify a certain frequency in a digital signal, can I just take the FFT, increase the real part of the value for the frequency I want (leaving the imaginary part alone), and then take ...
1
vote
2answers
730 views

Curved noise floor and ugly unexplained peaks after FFT

It has been so long since I studied this at University, so I'll better ask here if I'm doing something really wrong here. I'm using a USRP frontend for L1 band surveillance. I want a 20MHz bandwidth, ...
0
votes
0answers
666 views

How to implement a time-varying filter?

I'm working on a 10-second sound, sampled at 44.1 khz. I want to do filtering, and have a desired EQ (equalization) curve that varies over time, as suggested here (here $f0=250\ Hz$) How to ...
0
votes
2answers
2k views

MATLAB : How to filter a data signal

I have a data signal (column vector) with N values taken over at specific sample rate (dx) at a fixed frequency. After taking the Fourrier transform of this signal and representing it in the Fourier ...

15 30 50 per page