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Questions tagged [nyquist-plot]

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How does a time delay affect the Gain and Phase Margin?

How does a time delay affect the gain and phase margin. Answers using nyquist plots would be helpful I know that a time delay of t corresponds to gain multiplying by 1 and phase subtracting omega*T . ...
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1answer
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According to the Nyquist criterion this system is stable but when I apply an impulse I get an unstable response, why?

I have this open loop transfer function and I have to study the stability of the closed loop transfer function using the Nyquist criterion. What I got is that the characteristic equation 1+GH(s)=0 has ...
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Nyquist Stability Criteria

Find the stability where: Find the stability: \$ G(s)= \frac{(s+3)(s+5)}{(s-2)(s-4)}; \$ \$ H(s)= 1; \$ I run this code in matlab: ...
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2answers
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Why isn't Nyquist taught like this?

When I learnt how to do a Nyquist plot I was taught a really long-winded method that I don't understand to this day. I realised by myself that if you are given a system like below where \$s=j\omega\$ $...
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Cole-cole plot curve collapses when trying to alter the valule of horisontal axis

I am a beginner and trying to simulate a cole-cole plot of a simple parallel circuit having two R, one coil and a capacitor. Image attaced, LTspice version is XVII, pc is windows7. I've read this Q-A;...
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906 views

Sampling rate understanding for ADC requirement

So I have this voltage plot. These are voltages corresponding to a current changes on a wire. I am trying to understand the rate of transmission for choosing a ADC to read these analog values. The ...
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158 views

How to plot a Nyquist Diagram in Simulink?

I can get the impedance in powergui,and I want to plot a Nyquist with this impedance
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4answers
350 views

Is the Nyquist plot useful in actual electrical engineering?

I am currently doing a course on linear control theory, and we are covering Nyquist Plot to study phase and gain margin. I find myself unable to appreciate this concept. One, the proof of the Nyquist ...
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2answers
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What are the connection between bandwidth, Nyquist criteria and quantization?

I am trying to solve the below problem and I was not able to find the relation between bandwidth, Nyquist criteria and quantization. Can you please provide some hint? Imagine that the possible ...
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2answers
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Why is this system stable?

I was given the system defined by the open-loop transfer function: \$L(s)=\frac{5(s^2+1.4s+1)}{(s-1)^2}\$ I was told to use the Nyquist criterion to determine stability. Examining the Nyquist plot ...
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1answer
154 views

Nyquist plot Phase Question

The above graph is pulled from the book "Automatic Control Systems" by Kuo. The subject loop transfer function is $$L(s)=\frac{K}{s(1+T_1s)}$$ or $$L(j\omega)=\frac{-jK(1-jT_1\omega)}{\omega(1+T_1^2\...
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Pure transport delay? (Nyquist plot)

How does pure transport delay affect the Nyquist plot, and how is it possible to find the maximum value of the delay, such that the system stays stable even after delay is introduced?
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335 views

sampling frequency for less duty cycle message signal?

I have a question regarding the sampling frequency ? Normally we will take 50% duty cycle square/ sine wave to explain about sampling frequecny/ nyquist theorem.. My doubt is what is he sampling ...
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1answer
316 views

How to find the nyquist rate

I have the following signals and their Fourier transforms: \$x(t)\$ and \$r(t)\$. The signals are limited such that \$X(e^{j\omega}) = 0\$ for \$|\omega| > \Omega\$ and \$R(e^{j\omega}) = 0\$ for \$...
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2answers
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Doubt regarding Nyquist theorem for sampling analog signals [duplicate]

If for an arbitrary signal H(f) = 1 for 300-f-3700 Hz; 0 otherwise, what should be the minimum sampling rate? 7400 Hz or 6800 Hz and why?
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1answer
913 views

How to plot Nyquist Plots?

By using the open loop transfer function for a control system, how would you then sketch the Nyquist plot by hand? I'm aware you'd substitute any \$s\$ term for \$j\omega\$ and then rationalise the ...
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When is it required or permitted to sample below Nyquist rate

I have searched past questions and answers on this platform but none answers this question. A prof said it is possible to sample below Nyquist rate under certain conditions. I will like to know, first,...
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Problem about Nyquest signalling theorem?

A sinusoidal signal with amplitude 20 V and bandwidth 35 kHz is sampled at 2.5 times its Nyquist rate and then quantized using a 128-level quantizer. Determine: i) The resulting data bit rate? The ...
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Is the Nyquist plot a plot of Re(G(s)) v.s. Im(G(s) or Re(G(jω)) v.s. Im(G(jω))

It seems that people in control theory are divided over whether the Nyquist Plot/Diagram (that is the plot, not the contour!) is a plot of $$\text{Re}(G(s)) \text { v.s. } \text{Im}(G(s))$$ or $$\text{...