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Questions tagged [bode]

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truncating a system and plotting it on bode

Let system G(s) be: $$ G(s)=\sum_{i=0}^{10}\frac{(-1)^i}{(2i+1)^2}\frac{\omega_i}{s^2+2\zeta_i \omega_i s+\omega_i ^2}$$ $$\omega_i=\frac{(2i+1)\pi}{T}\, T=1\, \zeta_i=0.2$$ Its impulse response is an ...
Rice's user avatar
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33 views

Does calculating the phase margin when the phase is positive has any meaning?

I want to calculate the phase margin and the gain margin of my transfer function to have an idea about the system's stability. The transfer function is quite complicated since it contains an ...
Bilal abu kamal's user avatar
1 vote
1 answer
60 views

Extracting Transfer function from Bode's gain plot

Let the figure of the Bode's Gain plot of a certain transfer function, estimate what could this transfer function be: Here is what I tried to do: since at $\omega = 0 , |G(j \omega)|_{db} = 20\log(K) ...
Knowledge Seeker's user avatar
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49 views

Bode plot phase shift equation when poles and zeros are not at the origin

Let $$H(s)=\frac{s^{n}}{s^{m}}$$ For $n \ne m$ the phase shift between output and input will be $\frac{\pi}{2}(n-m)$. For situations where the poles and zeros are not at the origin, I could find the ...
Cerise's user avatar
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1 vote
1 answer
240 views

Why does the discrete bode plot look like the following and if possible explain the black vertical line at the end for an averaging filter

Why in the attached image for a simple 3 point moving average that has been converted into a TF (z domain) is there a wired dip? It seems that when I change the sampling time, the dip shifts to the ...
George kirby's user avatar
0 votes
2 answers
68 views

Can you plot an irrational transfer function on matlab?

For example if I have the following transfer function: $$H(s) = \frac{1}{\cosh(\sqrt{s/10})}$$ Can I do the bode plot it in matlab or do I need to rationalize it beforehand?
FISqrt's user avatar
  • 25
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1 answer
166 views

Bode Plot - Why we add dB value in some situations?

Question: Specify the straight -line approximation of the Bode magnitude plot: $$H(j\omega) = 0.04 \cdot \frac{jw+50}{jw+0.2}$$ I don't understand that in the plotting part we add 6dB for two ...
XcellentEEE's user avatar
0 votes
2 answers
211 views

Why do I need to multiply the frequencies with a number, to get correct "shift" in the bode plot?

Assume that we got a sine wave function $$u(t) = A\sin(2\pi \omega(t)t)$$ Where the frequency $\omega(t)$ changes over time $t$ and $A$ is the amplitude. Assume that we apply that $u(t)$ signal onto a ...
euraad's user avatar
  • 405
2 votes
1 answer
86 views

How does the phase/gain margin method work?

We have the closed loop transfer function: $$T(s)=\frac{L(s)}{1+L(s)}$$ So as far as I understand we check along the $j\omega$-axis on the Bode plot whether $L(s)=-1$, cause that's when $T(s)$ has ...
Kakukk777's user avatar
1 vote
0 answers
84 views

How can to obtain the hughcut, lowcut and bode constant of a bandpass digital filter?

I need to create a bandpass filter amplifier in python; and determine the transfer function, graph the bode diagram, and print the highcut frequency, lowcut frequency, the bode constant and the ...
Marcia Cocozza's user avatar
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0 answers
28 views

How can to obtain the transfer function of a bandpass digital filter? [duplicate]

I've been asked to: create a bandpass filter amplifier in python, determine the transfer function, graph the bode diagram, and print the highcut frequency, lowcut frequency, the bode constant and the ...
Marcia Cocozza's user avatar
1 vote
1 answer
94 views

Differences between MATLAB and WolframAlpha and AstromMurray (minimun phase)

I have the following problem when I graph the phase of my transfer function in matlab I get that it starts at 360 while with wolfram it gives me 0 and if I do the calculation that is in astromurray it ...
MaxPower1995's user avatar
1 vote
2 answers
226 views

Bode plot of the transfer function with unstable pole

Let's say I have a LTI system described by following transfer function $$G(s) = \frac{(s+1)}{s(\frac{s}{10} - 1)}.$$ As soon as I run following Matlab code ...
Steve's user avatar
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0 answers
70 views

Bode plot of transfer function with vs without feedback

I am looking at some old exams. Particularly, one question where there is a Bode plot of a transfer function $G(s)$, and some questions about the Bode plot. So far so good. However, part b) of the ...
J. Doe's user avatar
  • 101
2 votes
0 answers
82 views

Mismatch between the frequency response of a transfer function and bode plot

I generate a state space model as follows (The details are not important. This part is used to get matrix A_xi and B_xi and the state space model is xi(k+1) = A_xi*xi(k)+B1_xi*u0(k); y(k) = x(k)): <...
SoftSail's user avatar
0 votes
1 answer
625 views

Z domain Transfer function to magnitude

How would one go about calculating the Magnitude of... $\mathcal{Z}$-transform = $$\frac{1}{1-z^{-2}}$$ I understand that z can be replaced with $${exp}^{j\omega}$$ and I am aware of the identities $${...
New2Dsp's user avatar
0 votes
1 answer
454 views

Finding transfer function from bode plot

Given a bode diagram From the figure, I see that when $\omega = 100 \text{ rad/s}$ the magnitude response starting to go down and when $\omega = 1000 \text{ rad/s}$ the slope become higher. Then $$H(...
love you's user avatar
  • 113
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1 answer
1k views

Stabilizing an unstable system and removing oscillations from step response

I have a system with the transfer function given in this MATLAB code ...
Carl's user avatar
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1 vote
2 answers
868 views

How to deal with "weird" phase plots in bode diagram when designing a controller

I am trying to design a balance controller for a robot. With MATLAB simulink I arrived at the transfer function between the input and the pitch angle for the robot. I have plotted the bode and Nyquist ...
Carl's user avatar
  • 364
2 votes
1 answer
2k views

Creating Bode Plot from Experimental Data

I have a blackbox system in which I can input a function and obtain the output signal (in MATLAB). I'm attempting to reconstruct a Bode diagram and have had success with the Magnitude plot, however, I'...
migeve3630's user avatar
5 votes
2 answers
2k views

Which step response matches the system transfer function

A system has the following open loop bode plot: - Which one of the plots below describe the closed loop step response for the entire system? My attempt My initial thought was to look at the static ...
Carl's user avatar
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0 answers
403 views

System identification from Bode plot

Please can anyone address me to routines (possibly for MATLAB/Octave) to identify system poles and zeros from its Bode plot (magnitude+phase)? I am aware there are functions for system identification ...
stefanoc's user avatar
0 votes
1 answer
1k views

What is the frequency of the Gaussian white noise model in control systems?

The design of control systems, particularly for SISO systems, is made convenient by tools such as Bode plots and the corresponding Nyquist stability criterion. These concepts allow engineers to design ...
kbakshi314's user avatar
0 votes
1 answer
2k views

Bode plot from from step response data

For quality control, I want to measure the frequency response of hardware I built. What I can easily generate on the hardware is a step response. Thus, I want to derive the magnitude and phase from ...
JLo's user avatar
  • 121
0 votes
1 answer
52 views

Why is my MATLAB's bode plot wildly off?

I will give out all the details in case it is relevant. I have a MIMO state space system. I find its bode plot using MATLAB and separately using Mathematica. The plot from MATLAB is wildly off ...
ModCon's user avatar
  • 103
0 votes
1 answer
429 views

Analyze stability of a closed loop system with Bode

How can one know, with just looking at the Bode plots, if the closed-loop system is going to be stable or not? This closed-loop system is unstable, why? @DSP Novice @Jake It was my fault that the ...
Ed_Wu's user avatar
  • 1
1 vote
1 answer
99 views

Why if I place the zero of the lead compensator at lower frequencies, do I obtain a resonance peak?

I am studying control systems, and I am studying the lead and lag compensator. I have seen than if I use a lead compensator for the closed loop transfer function, $T(s)=\frac{s+2}{(s+1)(s+8)},$ with ...
J.D.'s user avatar
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1 vote
2 answers
591 views

bode plot, zero at 0Hz

I'm learning to draw magnitude bode plots from transfer functions: $$ H(s) = \frac{sRC}{sRC+1} $$ So I can see that I have a zero at s = 0, which corresponds to 0 Hz. I know this will add a +20dB/...
Sittin Hawk's user avatar
0 votes
1 answer
282 views

Find the error in phase angle and dB gain Function Transfer

This is a question paper that I've tried to solved but seems I am missing something. My attempt: $$ |G|_{w=0} = K$$ So, $\require{cancel}|G|_{w=0.5a} = \dfrac{K}{\left|1+\dfrac{j0.5\cdot \cancel{a}...
miguel747's user avatar
1 vote
2 answers
222 views

Matlab - Bode plot of Lag Filter + Integrator

I am rather new to Matlab and I just cant make sense of what I see in the bode plot of the continuous and discrete version of the same function. The bode plot of the continuous function looks as ...
Martin's user avatar
  • 11
-1 votes
1 answer
292 views

How to draw the magnitude plot of a variable slope low/high pass shelving filter? (eg. as a function of cascaded shelving filters)

I am interested in making a magnitude graph of a variable slope low/high pass filter. I would like to set slope in dB/oct and a cutoff pitch. The y-axis should be amplitude from 0 to 1, and the x-axis ...
mike's user avatar
  • 533
2 votes
1 answer
2k views

How do bode plots work with unstable systems work?

If I had a system with right-half s-plane poles, how would a frequency response work? Since a purely imaginary value for s, would cause the Laplace transform to diverge for such a system, what meaning ...
Colin Hicks's user avatar
0 votes
1 answer
2k views

Is there a way to obtain the transfer function from a bode plot on Python? (I know that it is possible on Matlab)

Quite simply, I have a bode plot obtained from a source signal. Now I wish to obtain the transfer function. I know it is possible with Matlab: http://www.mathworks.com/help/ident/examples/frequency-...
tbarros's user avatar
  • 31
0 votes
2 answers
381 views

How to make bode plot when output signal changes amplitude?

When I do frequency analysis on my feedback controlled system and the controller is really tightly tuned, I get a frequency response that looks like this: Blue is excitation signal and green is ...
Martin's user avatar
  • 296
0 votes
0 answers
562 views

rank-1 array error using bode function

Some time a go i got a matlab script for speaker design. But since i don't use matlab i try to edit to python. Now i have a problem with the script. Since it is in the bode i was doubting which place ...
Jan-Bert's user avatar
  • 335
1 vote
2 answers
3k 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 $10/1+jw10$
towns's user avatar
  • 13
1 vote
0 answers
118 views

How can I find the transfer function from this Bode diagram?

I've been given this bode diagram : I've been asked to find the transfer function only by using the bode diagram. It's the first time I'm doing this so here's what I thought. The starting value is ...
John Katsantas's user avatar
0 votes
1 answer
438 views

What is the frequency response function for the Bode Plot pictured here?

I've forgotten how to get the frequency response function out of a Bode Plot. The phase component of $H(j\omega) = e^{j\pi/2}$, right? But I am having trouble finding $|H(j\omega)|$. How would I get ...
JobHunter69's user avatar
0 votes
1 answer
425 views

Derive Bode Diagram from difference equation

I have designed a 2nd order low pass butterworth filter for the following: Sampling Frequency: 10kHz. Cut-off Frequency: 1kHz After doing a bit of maths I worked out the difference equation: ...
embedded.95's user avatar
0 votes
1 answer
2k views

Matlab freqz and custom implementation differences

I am making some homemade tools on Matlab. I made function that plot the frequency response of a discrete transfer function (just like freqz does). When I compare ...
Pier-Yves Lessard's user avatar
1 vote
1 answer
2k views

Slow and fast filter

According to my knowledge a filter with low cut off frequency is called slow and with hgih cut off frequency is called fast filter. I am trying to understand more about these two. I know what happens ...
Aashu10's user avatar
  • 85
1 vote
1 answer
3k views

Bode plot of discrete-time transfer function $H(z)$

$H(z)$ is the transfer function of a biquad filter as described here. I would like to plot the Bode plot of the magnitude response of $H(z)$. Scipy has a bode method (...
kiigass's user avatar
  • 113
1 vote
0 answers
68 views

amplitude at exact frequency in wide band signal

Could anyone suggest the most computationaly efficient method for finding amplitude of exact frequency having a noisy wide band signal. To be more specific about a task. I have some physical ...
aliko's user avatar
  • 111
1 vote
1 answer
2k views

Phase wrapping in Bode plot

I'm trying to model the transfer function of a linear system (a MOEMS mirror) based on a datasheet plot of its response. I'm developing the model in the python-control model and I think that I've got ...
kjgregory's user avatar
  • 113
1 vote
4 answers
18k views

Analyze stability of a closed-loop system with Bode

I have an open-loop system function $L(s)$ and its Bode plot is As MATLAB says, it is stable if we close the loop with unitary feedback. I thought that, seeing the Bode plots one could tell if the ...
Tendero's user avatar
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