Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [magnitude]

84 questions
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Why are magnitudes normalised during synthesis (IDFT), not analysis (DFT)?

In most examples and FFT code that I've seen, the output (frequency magnitudes) of the forward DFT operation is scaled by N -- i.e. instead of giving you the magnitude of each frequency bin, it gives you N times the magnitude. Operationally, this is…
bryhoyt
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Power spectral density vs. FFT bin magnitude

What's the difference between these? Both are measurements of some form of signal power, but surely there's some difference between the power they are measuring?
mavavilj
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Understanding FFTs for simple Sin / Cos

this is my first question in this forum, and although I read several threads on this side and googled a lot I could not find the answer to my question (maybe it is too basic)? For anyone reading this thread with a similar question: The code is now…
Jonas Jo
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How does zero-padding affect the magnitude of the DFT?

Let's simulate sinusoids of two frequencies using the following Matlab code: fs = 1000; t = 0 : 1/fs : 1 - 1/fs; f1 = 3; f2 = 3.5; x1 = cos(2*pi*f1*t); x2 = cos(2*pi*f2*t); L1 = length(x1); L2 = length(x2); If I take the FFT of the first signal…
Vivek Subramanian
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Identifying the magnitude and impulse response from pole zero plot quickly

I have an exam next week and it's verty certain that a task of this kind will be there. Are there some good tips how to match the right pole zero plot to the right responses? No proof is needed in the task. At the moment I try to find two of the…
JavaForStarters
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Calculating phase response of maximum phase filter using Hilbert Transform

Given only a magnitude response $A(\omega)$ of a minimum phase filter, one can calculate the phase response using the Hilbert Transform: $$θ(ω) = -\mathcal{H}\{\ln(A(\omega)\}$$ This paper suggests that there is another Hilbert Transform…
Moonpepper
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Energy calculation in frequency domain

I was just wondering... The formula I learned to calculate the energy of the signal is expressed in the time domain: $$E_x^{\text{time}} = \sum_{n=-\infty}^{\infty} |x[n]|^2$$ Then, what does the amount of energy gotten from the magnitude spectrum…
JMFS
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recover image by only magnitude of image fourier transform

I have a image and I want calculate fft2 of it, after it I want recover image only by magnitude of it. how can I achieve this work? I=imread('1.bmp'); I = rgb2gray(I); imafft = fft2(double(I)); % Gets magnitude and phase. mag = abs(imafft); %…
Yuseferi
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Calculate the magnitude and phase of a signal at a particular frequency in python

I have a signal for which I need to calculate the magnitude and phase at 200 Hz frequency only. I would like to use Fourier transform for it. I am very new to signal processing. And this is my first time using a Fourier transform. I found that I can…
thileepan
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Given a plot of both the magnitude $|H(\omega)|$ and its angle, How can you find the $H(\omega)$?

I'm specifically trying to use an inverse Fourier Transform to find $h(t)$, but I'm finding it difficult to get $H(\omega)$ in the first place. I'm under the impression from my textbook that $H(\omega) = |H(\omega)|e^{j\arg\{H(\omega)\}}$, and that…
tim
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How to compute magnitude and phase response from transfer function in Z-domain?

I have a transfer function $$H(z)=\frac{1+1.2z^{-1}+0.8z^{z^-2}}{1-0.9z^{-1}}$$ from which I'm supposed to sketch the magnitude and phase response. I know that you can transform $z=e^{j\omega}$ to get the frequency response, but I don't really…
markus
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Adequate representation of frequency domain amplitude/magnitude of FFT of a signal

I'm quite new to the subject and am having fun playing around with the FFT. What I am currently doing is trying to sample an audio signal and display its frequency spectrum at the same time. This works alright with what I am doing so far, but there…
YeahShibby
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retrieving original data from phase and magnitude of Fourier transform

I use this snippet of python code to transform data to Fourier phase and magnitude and then retrieving original data. from random import randint as RI import numpy.fft as FFT import math w = 4 h = 4 random_range = 255 vals = [[] for i in…
Hesam Qodsi
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Non-zero DFT components where zero is expected?

I am implementing DFT in Octave. Here's my code: function [real_comp, imag_comp] = mydft (samples) N = columns(samples); for m = 1:N real_accum = 0; imag_accum = 0; for n = 1:N real_factor = cos((2 * pi *…
Devashish Jaiswal
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Matlab IIR cheby2 bandpass, problems with Magnitude

I am trying to implement an IIR bandpass in Matlab. There are two things I don't understand. But first of all, let me post the code. fs = 50000; %Hz f1filter = 1000; %Hz f2filter = 2000; %Hz filterOrdnung = 6; %erzeugt (2 * filterOrdnung)…
user44791
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