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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.

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0answers
698 views

real refractive index from Kramers Kronig relation

I have a measurement of the complex part of the refractive index $k$ (where the refractive index is $m = n + i\,k$) measured at a nonlinear grid of wavelengths or frequencies that span several orders ...
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1answer
417 views

Backward finite difference differentiation filter frequency response

As title says what would be frequency response of backward finite difference differential filter, or what would be error of this differential filter, analyzed upon frequency of a signal?
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2answers
615 views

What does it mean for a function to have frequencies?

In a lecture, my professor mentioned that $\cos$ has two frequencies. I see that using the inverse Euler's formula we can express $\cos$ as a some linear combination of complex exponentials, each with ...
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1answer
235 views

Impulse response from Frequency response: why using $e^{j\omega}$ as an input?

Every resource that I can find uses this identity when deriving impulse response: $h[n] = IDTFT \Big\{H(e^{j\omega}) \Big\}$ Suggesting that the input signal was $e^{j\omega}$. But by definition ...
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1answer
207 views

Phase wrap when computing impulse response from frequency response [closed]

Short: I have the frequency response of a system as a set of complex numbers. I want the impulse response for that system. Problem: The phase of my frequency response wraps around 2pi multiple times....
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1answer
38 views

How do I generate sine waves with MATLAB’s max operator and the plot the resulting values in dB versus log frequency? [closed]

I just start learning about matlab. Im very confuse with this. Can anyone gives me such an example solution or any kind of help? HINT: Put the desired input frequencies in an array and use a for-loop ...
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1answer
44 views

How to make semilogx to get a plot gain against log frequency with several values? [beginner] [closed]

Gain: 20 log (Vout/Vin) with Vin = 1.0. I've been searching for gain values: a. -156.48 dB b. -80 dB c. -53.98 dB d. -13.98 dB e. 3.52 dB f. 10.32 dB g. 13 dB h. 13.93 dB i. 13.96 dB j. 13.98 dB I am ...
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3answers
401 views

How to calibrate a signal with respect to frequency

I have recordings from accelerometers (non-flat response with respect to frequency) and I'd like to convert my voltage time series into acceleration values. Is there a standard method for doing this? ...
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2answers
139 views

Reconciling Continuous and Discrete Complex Domains

Having taken some courses in Systems and Stability dealing mostly with continuous time signals, I am accustomed to thinking about the Laplace and Fourier transforms dealing with complex and pure ...
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1answer
174 views

The desired frequency-response specifications

The complex function $ D (e^{-jw})$ is defined on the domain of approximation $\Omega$ .In most cases the domain $\Omega$ is the union of several disjoint frequency bands which are separated by ...
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2answers
273 views

How to compute the impulse response from incomplete frequency response data?

I need to compute the impulse response of a system, but I only have access to the frequency response data. This data contains the output magnitude of the system (for a fixed input amplitude) at ...
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1answer
742 views

Shelving filter (2nd order)

I'm trying to find the equation of a shelving filter of the second order. I easily found the equation for a first order filter on wikipedia with a transition region which have a 6db per octave slope. ...
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88 views

Given a log-plot of frequency-magnitude-phase how to apply it as an EQ curve to a signal?

I have several hundred data points that represents an EQ correction curve, where each point contains frequency, magnitude, and phase (-1..+1). The frequencies are distributed exponentially, not ...
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1answer
377 views

How to evaluate CCDE at a given frequency?

Consider the following Constant Coefficient Difference Equation (CCDE) given below $$y[n] - \frac{1}{2}y[n-1] = 2x[n] - 5x[n-1] - x[n-2]$$ Let $H(e^{j\omega})$ denote the transfer function of this ...
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1answer
172 views

How do I plot the square of the amplitude response?

I have calculated the transfer function of an FIR filter $$ y[n] = x[n] + α · x[n − R] $$ This is what I have $$ H(z) = 1 + αz^{-R} $$ Now I should plot the square of the amplitude response. So I ...
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93 views

Making longer a time domain signal by adding values on its frequency domain. What am I doing wrong?

Background Here's the thing: using software for Finite Element Acoustic Simulation I got the dataset of frequency response from a room; software works by solving the wave equation in the interval $`[...
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2answers
248 views

Frequency response of marginally stable LTI systems

The frequency response of a system is defined as: $$\int_0^\infty{h(t)e^{-j\omega t}dt}$$ where $h(t)$ is the impulse response. But in marginally stable systems, $h(t)$ does not decay so the integral ...
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2answers
149 views

Equalize Speaker using impulse response

So I have this school project where my aim is to improve a loudspeaker in general, my idea is to mesure the impulse response of the room using a mic, then use this mesure to conceive a loudspeaker ...
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1answer
84 views

Homework Help: What does $h[0] = 1$ represent? What is $\ln \big| H(e^{j \omega})\big|$?

I have been staring at this problem for a week now... Suppose $H(e^{j \omega})$ is the frequency response of a stable and causal minimum-phase discrete-time system with $h[0]=1$ ($h[n]$ is the ...
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33 views

Effect of sampling frequency to the center of a bandbass filter

Is it true that if you have some sort of filter, e.g. a digital bandpass filter around the frequency 1000 Hz that is given in the form of a transfer function $H(z)$ and you then change the sampling ...
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1answer
3k views

Get the frequency response curve from FIR filter coefficients + sampling rate

What's the fastest way (if possible in the browser thanks to an online tool, or if not possible easily, with Python), to get the frequency response curve (x-axis: Hz, y-axis: dB), when giving just: ...
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1answer
483 views

Pole zero plot, normalizing frequency response plot?

I'm asked to plot the frequency response (amplitude) given a specific pole-zero diagram. $$ H(z) = H_0 \frac{\prod\limits_{m=1}^{M} (z - q_m)}{\prod\limits_{m=1}^{M} (z - p_m)}$$ $$ H(e^{i\omega}) =...
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1answer
54 views

Evauating response to $x(n) = \sin{2\pi\frac{1}{4}n}$ given the system function

Let the input signal $x(n) = \sin{2\pi\frac{1}{4}n}$ go in to the system described by: $$y(n) - y(n-1)+\frac{3}{16}y(n-2) =x(n).$$ What is the output signal? I've calculated the system function $H(...
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3answers
390 views

How to calculate the frequency response of LTI system based on measured impedance

I have an analog circuit containing unknown resistance, capacitance, and inductance. I have measured its complex impedance across the frequency range of interest. Is there an equation that will allow ...
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2answers
260 views

Phase function of filter

I have a filter with the transfer function $$H(z) = 1 - 2z^{-2} + z^{-4}.$$ The task is to find the phase function $\theta (\omega).$ My attempt is to start by expressing the frequency response \...
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1answer
206 views

RC circuit frequency response

I am developing a project where I must analyze an incoming signal that was acquired from a microcontroller. The objective is to obtain the main frequency of the incoming signal. At first, I’m ...
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3answers
442 views

Why are numerator coefficients named $b$ and denominator coefficients named $a$?

This is not a technical question, it is rather a question about the implicit notation used in MATLAB and some digital signal processing books to refer to the numerator and denominator coefficients of ...
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0answers
123 views

Difference between $H(\omega)$ and $H(j\omega)$ [duplicate]

What is the difference between $H(\omega)$ and $H(j\omega)$, in terms of impulse response. And if so, when do I have to use one or another.
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2answers
1k views

How to obtain impulse response from a plot of magnitude of frequency response?

I have a plot of a magnitude response of a frequency response, how can I get the impulse response using only this plot and nothing else?
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1answer
492 views

Design Lowpass Filter With -7.5 dB/Octave Rolloff

I am working on a project that needs a lowpass filter with a -7.5 dB/Octave rolloff. This is somewhere between the rolloff of a one-pole and two-pole filter, so I wanted to ask what some standard ...
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2answers
752 views

Why do we need to find the frequency response of FIR filter? [closed]

Sorry about my unscientific and informal question but i have an exam $3$ days later and i need to learn this. Can anyone explain clearly, shortly and without formula Why do we need to find the ...
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3k views

Why do we choose cutoff frequency to be taken for “1/sqrt(2) magnitude reduce”?

Why don’t we instead choose (calculate) our bandwidth to be between two purple “dot’s”? Why don’t those purple dot’s represent points for “cutoff frequency”? Looking at this picture “frequency ...
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2answers
175 views

How can I know the type of filter from its cutoff frequency?

So I have the following equation $$ y[n]=0.9y[n-1]+0.1x[n] $$ We can find easily find the transfer function, which is $$ H(z)=\frac{0.1}{1-0.9z^{-1}} $$ and from that, the frequency response, ...
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3answers
189 views

LTI system phase response given $z$-transform

I have been given this question \begin{equation} H\left(z\right)\:=\:\frac{1}{6}\left(1+z^{-2}\right)^6 \end{equation} (a) Compute and plot the phase response of the system. (b) Determine ...
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156 views

why exponential term neglected in equation?

where does that exponential term gone, is this because it is a constant term or it has to do something with stablity?
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43 views

why this frequency response is added to the power of e?

From where did this ${\angle}H{(\Omega)}$ came into power of $e$ ?
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1answer
4k views

Impulse response from difference equation without partial fractions

I have a system with input $x[n]$ and output $y[n]$, described by the difference equation $$y[n] - 0.3y[n-1] + 0.1 y[n-2] = 3x[n] - x[n -1]$$ and I am trying to find the frequency and impulse ...
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1answer
840 views

Why zeroes near the unit circle cause a dip in frequency response, while poles cause a peak?

I have an exam tomorrow and I really can't figure out the question in the title.
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1answer
2k views

Differences between FFT from acceleration, velocity and displacement data of a dynamic system

I am new to vibration mechanics and signal processing. Recently, I’ve performed an experimental test with an accelerometer mounted on a plate (shaker). The plate vibrates with exact frequencies 10 and ...
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2answers
828 views

Design a linear-phase FIR filter approximating the magnitude of a given IIR filter

I have a biquad IIR filter from which I want to get a linear-phase FIR. I saw that related question but the OP does not care much about phase. I have troubles getting the exact same magnitude curve ...
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1answer
655 views

What is the time unit of the converted Channel Impulse Response?

I don't have a lot of background on wireless communication but as far as I understand, applying IFFT on Channel Frequency Response (CFR) would transform the data into time domain Channel Impulse ...
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2answers
2k views

Could someone please explain how to get frequency response of a given Bode Plot?

Having trouble with bode plots. I understand that the is to be converted to $dB$ but after that I'm stuck. Could someone please show me how this graph gives a frequency response of $10/1+jw10$
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1answer
225 views

Filter signal for beamforming and phase response

I was wondering this for quite some time but couldnt find a satisfied answer. Seems like not a lot worry about phase response in general. But maybe I'm thinking about it in a wrong way... I want to ...
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1answer
562 views

Determining power spectral density from a sample

To start, I have absolutely no background in electrical engineering, I am a computer scientist by trade. I'm currently working on a project where I am attempting to code a function that uses the ...
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1answer
547 views

MATLAB: $\tt freqz$ vs $\tt bode$

I started studying DSP recently. In my MATLAB assignments, I am often asked to plot the frequency response of a digital filter using freqz. I know there's another ...
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1answer
66 views

Frequency of Signal of a point tracked in a video?

I have used MATLAB to track a feature point (corner point) using Lucas-Kanade tracker and plotted its movement through each frame now I need to find its frequency content, how should I find it? (I ...
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2answers
598 views

Deriving Frequency Response for 2-pole Zero-Delay Feedback State Variable Filter

I have an existing zero-delay feedback (ZDF) 2-pole state variable filter implementation (along the lines of the theory presented in VA Filter Design by V. Zavalishin), and I wish to determine the ...
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1answer
999 views

Estimate transfer function from Bode curve

I have measured the magnitude response Y_mag(f) and phase response Y_phase(f) of an unknown physical system. Is it possible to ...
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1answer
623 views

how to understand frequncy response and lowpass filter?

I am troubled with understanding freqency response. In lecture, my teacher talked about $H(f)$, which i know means that the response depend on frequency, $f$. But when I read text book, it uses a ...
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1answer
483 views

FIR Filter - Transfer Function

I am dealing with the transfer function of an FIR filter: $$H(z) = (1-0.5z^{-1})(1-2z^{-1})$$ I am having trouble determining which type of Linear-phase FIR filter it is, Type 1-4. I believe it ...

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