# Questions tagged [nyquist]

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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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### 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 ...
26 views

### 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) ...
98 views

### 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 ...
125 views

### Spherical equivalent of Nyquist frequency

Let $\phi$ be a scalar function defined on the surface of a sphere. I have samples of $\phi$ at various locations on the sphere. I want to apply a spherical harmonic transform. I know that $\phi$ is '...
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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 ...
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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 ...
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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 ...
138 views

### 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 ...
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### Conclusions of sampling around Nyquist Rate

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 ...
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### Minimum sample frequency of IMU accelerometer and gyroscope

I was wondering how I would justify a sampling rate of 125 Hz for accelerometer and gyroscope data from wearable sensors. This is a rate used in a lot of biomechanics literature, but I can't seem to ...
1k views

### reconstruction filter - How does it actually work?

I'm trying to form my own understanding on the religious war around using 192kHz as a sampling rate for playback (the Internet seems to have a wealth of material on both sides). I'm struggling to ...
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### One sided frequency spectrum (Matlab vs. Origin)

There are a lot of queries on fft frequency all over the web. I guess the following point not discussed anywhere explicitly. Hope someone can provide an insight here. If we have and even number of ...
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### Number of discrete samples required for the longest wavelength

I am trying to understand the effect of the critical Nyquist frequency when applying the Goertzel algorithm for estimating the power spectrum of a discrete signal. (Goertzel doesn't really matter, ...
29 views

### Frequency spectra of a sampled process

I have a process $X$ with frequency spectra I sample this process with sampling frequency $f_s = 2$. What will the frequency spectra $R_z(f)$ of the sampled process $Z$ look like? I realize that ...
418 views

### Higher order harmonics during sampling

I am studying about the sampling theorem in conjunction for ADC. I got little confused while reading about aliased frequencies. I see that as per the Nyquist theorem, the sampling frequency (fs) ...