# Questions tagged [nyquist]

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### Bandwidth with complex sampling

On the transmit side, I have a 20 MHz carrier frequency carrying a signal with bandwidth of 40 MHz (so 0 Hz to 40 MHz, center at 20 MHz). On the receive side, I have a dual channel ADC with each ...
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### Determine stability of feedback system from open loop transfer function and Nyquist stability criterion gives different results

I'm confused due to the fact that the Nyquist stability criterion and looking at the transfer function doesn't give the same results whether a feedback system is stable or not. When I have the system ...
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### I need help in understanding “Nyquist Criterion” definition

I am researching the split-step parabolic equation and its split step solution as in: Ozgun, Ozlem & Apaydin, Gokhan & Kuzuoglu, Mustafa & Sevgi, Levent. (2011). PETOOL: MATLAB-based one-...
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### Why the Nyquist frequency is 0.5 of Fs, why not 0.55 or 0.65?, brief explanation [duplicate]

This my elaboration of the aliasing issue: a continuous signal can be represented by factors of : $e^{(i2{\pi}ft)}$ if we sample this signal then I will get: $e^{(i2{\pi}fk/N)}$ where $k=0,1,2.., N-1$ ...
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### aliasing in image processing

I know that aliasing occurs when a signal is subsampled. If the sampling rate is lower than twice the max frequency in a signal, aliasing occurs. How is it in pictures? as far as I know, a sinc-filter ...
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### Sub nyquist sampling, required number of samples for time sparse grouped signals

Question: Does it make sense to perform compressed sampling if the non zero samples are grouped in time? If so, what is the minimal length of the vector x that should be acquired to allow full signal ...
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### creating this famous basic nyquist theory photo

Hello i ha built this code which create a only one replica of the data, how can i create the whole photo shown bellow of many cycles as shown bellow? i read in the internet that zero padding could ...
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### Perform frequency analysis on grouped pulses

I have a system which consists of individual pulses grouped in trains. The trains have a frequency of 10 Hz, with a timing precision of sub ns. The pulses have a frequency of 2.2 MHz with a timing ...
534 views

### Stability of open-loop transfer function from its Nyquist plot

I am facing a confusion on understanding system open-loop transfer function stability from its Nyquist plot. According to the formula, for open loop transfer function stability: $$Z=N+P=0$$ where $N$ ...
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### Sampling and Reconstruction of digital signal in Matlab

I'm trying to write a program in Matlab that samples (using Nyquist theorem) and recovers signal. However, I cannot write sampling part for sum of 2 signal. ...
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### Nyquist Theorem adding two same frequency near to Nyquist Frequency with phase shift

This is my first question on this platform. Sorry if I made mistakes. What happens if we add two or more same frequency signals near to Nyquist Frequency with phase shift and sample them? For ...
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### Link between DFS, DFT, DTFT

My understanding of DFT is as follows For a signal $x[n]$ of finite-length, the DFT is DFS of the periodic extension, $\tilde{x}[n]$, of that signal $x[n]$ and also another way to view DFT is that it’...
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### How to select the sampling frequency when the input signal frequency is not known

I am trying to observe the noise produced by UPS present in our lab, under no load (a normal running condition when its power is on). As I don't know its frequency range, I have randomly chosen 4 ...
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### Whats the difference between spatial and temporal resolution?

Iam trying to understand how super-resolution works. But i think i have not understood correctly the difference between the optical resolution (spatial resolution?) and the resolution i know from a ...
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### Upsampling with time offsets

Suppose I have done 4x oversampling for a continuous time signal, but the successive sampling times have a linearly increasing offset. Specifically, the samples with indices {4k; k=0, 1, 2,...} are ...
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### Nyquist frequency and DC

Im studying the DSP book by Steven W. Smith. On page 41 he covers the Nyquist frequency. He makes up an example by writing the following. ... consider an analog signal composed of frequencies ...
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### Nyquist-Shannon sampling theorem: implications on matching data records?

I have two data records $R_1$ and $R_2$ with sampling periods $T_1$ and $T_2$, where $T_1$ < $T_2$. These records arise from sampling and filtering two signals to remove any noise (including ...
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### does aliasing occur always if i sample a vibration in real world applications?

I was reading about the aliasing effect and nyquist. I understand that aliasing effect occurs if the sampling rate is lower than twice the maximum frequency in the signal I want to sample. So I was ...
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### Nyquist theorem vs sampling theorem vs shannon sampling theorem?

Is there any difference between these three?or these are just three names of same theorem?
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### How to estimate the frequency of a feature in an image?

I have a background in the 1-D signal analysis but I am totally new to image analysis. I would appreciate any help. Given the following original image and the downsampled image, as you could see, ...
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### Reconstructing/interpolating small regions of a bandlimited signal by taking the fewest possible samples

I have a signal which is bandlimited and can be sampled at arbitrary continuous positions. The value at any position is given by an expensive computation. I need to do some further computation on ...
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### A question about sampling rate of cosine signal

Given $$c(t) = \cos(2\pi\cdot 30 \cdot t)$$ If we sample this signal at the Nyquist rate 60 Hz and at a higher rate of 80 Hz, we get the following: There is no aliasing as $f$ = 30 Hz is less than ...
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### No of samples 4mega samples per second,using 8 bit ADC,V p_p is6V. calculate frequency and peak power

This place has been great in helping me to understand my online image and signals class! I've moved on to another question and wanted to see if I'm correctly grasping the subject. The next question ...
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### anti-alias filter of square pulses

I'm trying to determine whether or not an anti-alias filter is needed for sampling square waves. The goal is to sample square wave pulses from a video detector with an ADC, do some time-domain digital ...
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### Understanding the Conditions for Recovering a Discrete Time Signal Through Sampling

So, we had a very brief introduction to the Nyquist-Shannon sampling theorem (the discrete time version). While discussing this, we have seen that multiplying a discrete time signal $x[n]$ by an ...
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### Downsampling and Gaussian Filtering in the Context of Scale Space Pyramids

In the context of scale space image pyramids using Gaussian filters I noticed that it's common to downsample the image after blurring with $\sigma = 2*\sigma_{init}$ . My question is: What is the ...
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### Bandwidth computation for NRZ baseband transmission scheme

In Andrew Tanenbaum's book on Computer Networks, while explaining about bandwidth of a NRZ (Non Return to Zero) baseband transmission scheme, he says the following: With NRZ, the signal may cycle ...
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### How do I apply the Nyquist criterion on the following spectrum to see if it satisfies the criterion or not?

I am trying to find out if the pulse in the figure satisfies the Nyquist criterion for a modulation interval T. I'm used to the Nyqusit frequency, but I cannot grasp what the Nyquist criterion is ...
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### What is the right way to downsample using Fourier method?

I want to know what is the right way to downsample a sampled signal using Fourier transform as the implementation in scipy.signal.resample confuses me. Reading ...
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### How to determine sampling frequency for an x(t) signal avoiding aliasing?

The antitransform of the function is given: $\hat{x}(f) = \frac{123 + i246\pi f}{246 - 24600 \pi^2 f^2 + i4920\pi f}$ I'm asked to determine which frequency can I sample using the function x(t) ...
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### Do you really have to always satisfy Nyquist with all signals if your purpose is to reconstruct a signal?

If not, when can you not comply with it?
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### Nyquist sampling theorem / Nyquist - Shannon theorem evaluation over M-PSK

I am trying to simulate an M-PSK Tx-Rx System on Simulink and analyse what the effect of sampling rate reduction would have on it. More, particular I am trying to prove what Nyquist sampling theorem ...
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### Nyquist zero ISI criterion for rectanguar pulses in the frequency domain

Nyquist criterion for zero ISI states that in the frequency domain, the replicas of the frequency characteristic of combined: TX pulse shaping filter - channel - RX pulse shaping filter must add ...
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### Sampling a signal with varying frequency

Question I'm trying to figure out the sampling rate for my ADC to sample essentially signal essentially of the form: $$y(t) = \sin(\max(t, \omega_{max})\times t) + n$$ where $n$ is noise. Context This ...
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### Passing a sampled signal through a filter

I was wondering why is it wrong to use a band-pass filter on a sampled signal? If the signal we want to sample has frequencies up to fmax, we sample it with frequency fs = 2fmax (so that Nyquist ...
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### Derivation of Nyquist Frequency and Sampling Theorem [closed]

I have been looking through different sites and questions over the internet about Sampling theory, but couldn’t find the clear definition of how nyquist frequency condition is derived? It would be ...
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### Compensation for Irregular Time Step for DFT (FFT)

I want to run a clustering algorithm (svm, knn) on the ferquency spectrum data of a temperature sensor that published at irregular times. Here is the temperature data to take the FFT: I got the ...
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### Where can I find an authoritative (peer-reviewed or textbook) reference to sampling-induced beating?

I presume we are all here well aware about foldback aliasing when sampling signals above the Nyquist frequency; i.e. half the sampling rate. By contrast, the phenomenon of beating occurs when ...
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### Nyquist noiseless channel capacity; how can bit-rate be two times the bandwidth?

I'm confused by the Nyquist channel capacity formula. How can channel maximum capacity approach double the bandwidth. $C = 2\times BW \times log_{2}(L)$ bits/sec The way it was explained to me ...
I'm trying to understand some results of playing around with sampling around a signal's Nyquist sampling rate. For my example, I'm sampling a $B=5\mathrm{Hz}$ wave over a 1 second period. In the ...