Questions tagged [nyquist-plot]

For questions about Nyquist plots, often used to assess the stability of an electrical circuit which includes feedback. Consider also using the "frequency-response" tag, and "stability" tag if your question is about the stability of an electrical circuit.

A type of plot of the frequency response of an electrical circuit, often used to assess the stability of an electrical circuit which includes feedback.

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Is the book wrong about the Nyquist Sampling Criterion?

Is the following statement from a book wrong? I thought sampling with twice the signal's highest frequency component would be adequate to completely recover the signal. But above it says sampling twice creates a saw-tooth like wave. Is the book…
user1245
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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, if it is possible to do this, if so, when?
Mikky Mikky
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What would a polar plot or a Nyquist plot of an undamped second order system look like?

I'm relatively new to control systems. I got to know how critically damped system looks like in Nyquist plot (same gain and phase cross over frequencies. PS. correct me if I'm wrong) and Bode plot thanks to the Octave online simulator, but I'm…
yogesh
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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\$ $$\frac{s+1}{s+10}$$ you can just replace \$s\$…
CoderEH
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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 peak to peak time is 3-4us. I need to sample them in…
Newbee
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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 criterion is very non-intuitive to me, something…
Coco Jambo
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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 denominator by moving the \$j\$ terms to the…
jackthompson
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Drawing Polar/Nyquist Plots without Calculator

For Polar Plots, when transfer function is given, it is possible to find the starting and ending angles and magnitudes. I had a misconception that curve joining the starting and ending point is straightforward to estimate (based on the real or/and…
Lajai Bagan
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Recording aliased tones on purpose

For research purposes, I am trying to transmit a tone and record it using sub-Nyquist sampling. Via the PC microphone, for instance, I would expect to see the aliasing effect somewhere in the spectrum plot, but no matter what I try it is absent. I…
Dannynis
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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 shows one CCW encirclement of the (-1,0) point. The…
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Why is the following system stable in closed loop despite having two poles open loop at origin?

I have the following open loop transfer function: H = ( 222915 s + 2.144e06)/(s^3 + 1.257e04 s^2) Here is the bode and nyquist plot: The gain margin is negative as is expected from double pole at origin. However the closed loop TF for unity gain:…
needbrainscratched
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What is the working justification of this circuit?

Made with microcap v12 . This is a circuit on which a question was asked by a user who later deleted the question. This circuit works at ~ 15 MHz. I would know how I could justify its operation. How could I do this justification?
Antonio51
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Sampling frequency of ADC and maximum frequency of input signal

As pair the datasheet of LTC2207, maximum input frequency can be 700MHz. whereas the sampling frequency is 105MSPS. Two times 700MHz is way less than 105MSPS. So how is this not contradicting with Nyquist theorem? ,
Fateme
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How to draw a Nyquist plot by hand using standard plotting strategies?

I want to draw by hand the Nyquist plot of an RC filter's transfer function. I do not want to use the "tricks" that help with building it faster (evaluating just some limits points) - I want to draw it using the usual plotting strategies.…
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Nyquist theory - Control system - Stability

I am trying to understand the Nyquist theory for knowing if a system is stable. Here is what I know : A system is unstable when the open loop transfer function + 1 of the system has one or more right half plane zeroes in the s-plane. The Nyquist…
Jess
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