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Questions tagged [aliasing]

In signal processing and related disciplines, aliasing refers to an effect that causes different signals to become indistinguishable (or aliases of one another) when sampled.

It also refers to the distortion or artifact that results when the signal reconstructed from samples is different from the original continuous signal. When a digital image is viewed, a reconstruction—also known as an interpolation—is performed by a display or printer device, and by the eyes and the brain. If the resolution is too low, the reconstructed image will differ from the original image, and an alias is seen.

Source: Wikipedia.

196 questions
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Can addition of two band limited signals create aliasing?

Can mixing/adding two band-limited signals create any frequencies above Nyquist?
user17127
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Problem Involving Aliasing and Critical Fusion Frequency Concepts

I have been trying to study a course from MIT on Biomedical Signal Processing and I thought that the best way to learn would be to solve some problems. Although they might be out of my depth, I am not looking for so much as quick answers as ways to…
The Contextual Path
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Avoid Aliasing when filming a moving car

I want to film a moving car with a rolling circumference: 190,5 cm and wheel circumference: 60 cm and 5 spokes. I record with 24Hz. What can be the maximal speed of the car to avoid aliasing?
xava
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Sine Wave "Lobes" (Basics, and probably a dumb question)

I am beginning my journey on trying to understand a little deeper on signal processing. I wonder if the effect I am seeing is worth any spit or is there a deeper level of understanding is apparent I do not grasp. I was initially using Jupyter…
post malone
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What does it mean for a signal to alias to another?

I know the definition of this is simple and I do understand the concept of aliasing (I think) in the way that multiple signals can be aliases of each other. For example, I get it when some one says: sampling of a 7-kHz sinewave at a sample rate of 6…
Jamy codes
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Visualizing aliasing in Matlab

I am trying to verify for myself that aliasing actually makes it impossible to distinguish the "real" and the aliased frequency. What I have done it set the sampling rate to 20 Hz and created two sine wave with 2 Hz and 18 Hz. As far as I understand…
uniquenamehere
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Difficulty Understanding a Triangular Graph: Aliasing of Signals

I have been reading a textbook on the "fundamentals" of signal processing but the author of the textbook has not given any explanation for the triangular graph located at the bottom of the figure. I understand the general concept of aliasing, but I…
Sebastian Szymczyk
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Frequency of a single sample in a digital signal and aliasing

I'm involved with digital audio synthesis. I know that if I create a raw non band-limited waveform it would contain frequencies above Nyquist thus violating the Nyquist Shannon theorem and the signal will contain aliased components. So I wonder if I…
user17127
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What happens if an harmonic in a band-limited signal at Nyquist frequency is added to a 90 degrees out-of-phase replica of it?

I'm interested about aliasing in digital audio and I wonder if aliasing can be produced by simple mixing of band-limited signals. As I know a band limited signal can contain frequencies up to sample rate/2 frequency, the so-called Nyquist frequency.…
user17127
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low frequency transform

I was wondering which type of signals have bounded-support Fourier transform. e.g. their transform is limited from zero to some non-infinite frequency. The main reason I'm into it is that in Shannon's sampling theorem, we know that for some…
arash
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What happens on signal during aliasing?

So I have signal with frequency of $15Hz$ and sample rate frequency is $20Hz$. What happens if we sample the signal at a frequency that is lower that the Nyquist rate? We will have aliasing. Sample rate frequency should be at least bigger than…
Alen
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How much can we downsample by? and how much can we upsample by?

e.g. let's say we have a signal with B = 100 Hz that is sampled at 400 Hz. The anti-aliasing filter will remove replicas, and there is nothing to alias, and we downsample. If we downsample by 2, we will get signal of 200 Hz. But what's stopping us?…
aliasing
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Aliasing of a Signal

I am really confused about this exam question regarding Aliasing. I have a signal of 2Hz, which I needed to draw a square wave of, over a period of 8 seconds. It Then asks, "Starting from the square wave you plotted above, plot the resulting wave…
malteser
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