Signal Processing Stack Exchange
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Questions tagged [frequency-response]

Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system.

Frequency response is a measure of magnitude and phase of the output as a function of frequency, in comparison to the input. In simplest terms, if a sine wave is injected into a system at a given frequency, a linear system will respond at that same frequency with a certain magnitude and a certain phase angle relative to the input. Also for a linear system, doubling the amplitude of the input will double the amplitude of the output. In addition, if the system is time-invariant, then the frequency response also will not vary with time.

Source: Frequency response

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What is meant by a system's "impulse response" and "frequency response?"

Can anyone state the difference between frequency response and impulse response in simple English?
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How poles are related to frequency response

I have recently fallen into fallacy, considering pole s=1 as there is infinite response at frequency 1. Yet, response was only 1. Now, can you derive the frequency response, given the poles? Secondly, the theory says that a system is stable when…
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How to estimate a transfer function from a magnitude-only frequency response?

Given an arbitrary frequency response, what signal processing methods might exist that could guess, estimate or determine a transfer function (pole and zero constellation) which gives a "reasonably good" approximation (for some given estimation…
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How to Average Complex Responses (and Justification)?

I am developing software that calculates the response of a system by comparing the FFT of input and output signals. The input and output signals are divided into windows and, for each window, the signals are median-subtracted and multiplied by a…
andrew cooke
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Approximating the frequency response of a median filter

A median filter is a non-linear and lossy process, so it doesn't have a closed form frequency response as would a FIR filter (say a box filter of the same length) in an LTI system. But how closely can something similar to a frequency response of a…
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Ultrasonic speaker calibration and emitting calibrated signals

I'm trying to calibrate an ultrasonic speaker with the aim of emitting predictable signals, but alas I keep running into trouble, probably due to my lack of DSP-fu. A little background I want to be able to playback sounds as close as possible to a…
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For an LTI system, why does the Fourier transform of the impulse response give the frequency response?

I know that for a given system, the Fourier transform of its impulse response gives its frequency response. I want to find where this property comes from, but haven't been able to find if it's a definition or if there's a mathematical proof…
Florian Castellane
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Why are there comb-like hills in a periodogram?

I am playing with the periodogram of MATLAB. I created a simple script to observe how it behaves: rng(1); %# initialize the random number generator Fs = 1000; %# Sampling frequency duration = 0.1; %# seconds A = 1; %# Sinusoid amplitude f = 150;…
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Evaluating loudspeakers

If you don't have a lot of money to spend but you want to estimate the frequency response of different loudspeaker setups what is the best way to do it? I bought a very nice microphone and built a box with foam on the inside. My idea is to place the…
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Design of a digital A-weighting filter with arbitrary sample rate

I want to A-weight a time series with arbitrary sample rate. An analog A-weighting filter is defined exactly by IEC 61672-1. But there's no definition for a digital filter. One method is to use the bilinear transform (BLT) to convert the analog…
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Plotting the magnitude response of a biquad filter

I've put together a multi-band audio EQ using biquad filters. I'm getting the coefficients using the methods from the RBJ cookbook. Now I want to plot the curve showing the magnitude response. I'm using an equation from this source Here is my…
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Constant Magnitude Chirp across audio band (Parseval's Theorem?)

I want to excite a loudspeaker with a constant magnitude chirp that sweeps across all frequencies in the audio band. I downloaded a test file from this Audio Check - High Definition Audio Test Files to start with. I plot the log magnitude of the…
Kyle Weller
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Can two different impulse responses give the same frequency response?

I have two different impulse response each with different length, is it possible that they have the same frequency response?
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Relationship between the Real and Imaginary parts of a LTI causal system

Prelude I am writing an elaborate text on the relationship between the real and imaginary parts of a LTI causal system and how stability, causality and analyticity imposes various constraints on its magnitude response and the phase response. I am…
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Sine sweep vs impulse response

What kind of pros and cons does these method for identifying a system have? I seem to have a hard time finding literature discussion in this issue. I am operating on a linear system, or the linear area of the system. So non linearity isn't an issue…
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