bandpass-filter

问题 I am trying to get a third-octave frequency spectrum of a time signal. The time signal is the acoustic pressure of rotational rotor noise which is harmonic. Its fundamental frequency is ff = n * N_b and for that reason, all frequencies should be multiples of ff. Using fft I get the expected result: Multiples of the fundamental frequency are the relevant frequencies in the spectrum. To get the third-octave frequency spectrum I wanted to use python acoustics, but the result of the function

来源： https://stackoverflow.com/questions/50145529/band-pass-filter-valueerror-digital-filter-critical-frequencies-must-be-0-wn

问题 I am trying to extract the mu suppression values from my EEG dataset, which doesn't allow using EEGLab. I did most of the steps, but I need to add a bandpass filter and I am not sure how. The frequency band I would need is 8-13, my sampling rate is 1000 and I was told I would need an order of between 8 and 10. The MATLAB documentations lists this example: [A,B,C,D] = butter(10,[500 560]/750); d = designfilt('bandpassiir','FilterOrder',20, ... 'HalfPowerFrequency1',500,'HalfPowerFrequency2'

问题 I am trying to extract the mu suppression values from my EEG dataset, which doesn't allow using EEGLab. I did most of the steps, but I need to add a bandpass filter and I am not sure how. The frequency band I would need is 8-13, my sampling rate is 1000 and I was told I would need an order of between 8 and 10. The MATLAB documentations lists this example: [A,B,C,D] = butter(10,[500 560]/750); d = designfilt('bandpassiir','FilterOrder',20, ... 'HalfPowerFrequency1',500,'HalfPowerFrequency2'

问题 new attempt to understand this. I'm trying to get what bandpass matlab function does. So digging into the m-files, the filter object is constructed with: opts=signal.internal.filteringfcns.parseAndValidateInputs(x,'bandpass',var); opts = designFilter(opts); Then, the filtering is done with: y = signal.internal.filteringfcns.filterData(x,opts); Then going into the filterData function, the actual filtering is done with: y = filtfilt(opts.FilterObject,x); because it is an IIR filter. Now, if I

问题 I have implemented a bank of oriented bandpass filters described in this article. See the last paragraph of the section named " 2.1 Pre-processing ". We selected 12 not overlapping filters, to analyze 12 different directions, rotated with respect to 15° each other. I am having the following issue, The filter-bank was supposed to generate 12 filtered images. But, in reality, I am having only 03 outputs as seen in the following snapshot, Source Code: Here is the complete VS2013 solution as a

问题 I was trying to implement the following FFT filter kernel: This formula is missing with two squares under the sqrt. Source code public partial class Form1 : Form { public Form1() { InitializeComponent(); Bitmap image = DataConverter2d.ReadGray(StandardImage.LenaGray); Array2d<double> dImage = DataConverter2d.ToDouble(image); int newWidth = Tools.ToNextPowerOfTwo(dImage.Width) * 2; int newHeight = Tools.ToNextPowerOfTwo(dImage.Height) * 2; double n = 6; double f0 = 0.5; double theta = 60;