# Questions tagged [bode]

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### 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 ...
105 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 ...
62 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?
134 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 ...
179 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 ...
65 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 ...
1 vote
63 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 ...
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 ...
1 vote
92 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 ...
1 vote
172 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 ...
61 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 ...
72 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)): <...
525 views

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### Stabilizing an unstable system and removing oscillations from step response

I have a system with the transfer function given in this MATLAB code ...
1 vote
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### 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 ...
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'...
1k 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 ...
378 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 ...
984 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 ...
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 ...
49 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 ...
330 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 ...
1 vote
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### 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 ...
1 vote
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/...