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.
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Is spectral density conserved after aliasing?
Will the integral of the PSD of a down-sampled signal still equal the variance in all cases
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Aliasing below $f_s/2$
phi = exp(linspace(0, log(511), 1024)) - 1
x = cos(2 * pi * phi)
Above will alias, despite peak instantaneous frequency evaluating to ...
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Condition for aliasing
Which one of the following is the condition of aliasing?
(a) Tails of the replicas enter into the Nyquist
interval
(b) The tails of the replicas enter into the Nyquist
interval and add to the ...
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Question about aliasing
As far as I understand, you can have two different continuous-time signals with the same discrete-time frequency spectrum after they are sampled and it may be possible these shifted replicas in the ...
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Prefiltering to Avoid Aliasing
In processing analog signals using discrete-time systems, it is generally desirable to
minimize the sampling rate. This is because the amount of arithmetic processing required
to implement the system ...
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Multiple choice on sampling and aliasing
I found some multiple choices in a well known book . The problem is that I don't get the answers in some and I want to do so.
Question 1:
The signal x(t) with Fourier transform $X(j\omega) = u(\omega)-...
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Sampling pure tone sine waves [closed]
What would happen if I am using the maximum frequency as the sample rate for sampling a pure tone sine wave?
For example, a $10\ \rm kHz$ sampling frequency for a $10\ \rm kHz$ monotone sine wave. ...
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Difference in information between IQ Sampling vs. Real Sampling at $2F_s$
As per my current understanding we use IQ sampling as way to increase the useful bandwidth to Fs rather than $F_s/2$ when viewing the FFT because the IQ sampling removes the negative frequencies and ...
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What can be meant by "bandlimited"?
This question was a source of disagreement on whether "amplitude aliasing" can occur for a signal bandlimited to below half the sampling frequency. The question was closed before the ...
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Aliasing at $f_0 + kf_s$
In this question, it has been proved that $x(t) = \sin(2\pi f_0 t)$ and $x_k(t) = \sin(2\pi (f_0 + k f_s) t)$ have the same sample points. So sinusoids with frequencies $f_0$ and $f_0 + kf_s$ will ...
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Generating digitized white noise: uniform vs normal sampling
Consider the following two ways of generating noise in the time domain for audio applications:
Generate samples from a uniform distribution [-amplitude, +amplitude]...
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Sampling a low-frequency sound doesn't work at some sampling rates
When sampling a low-frequency sound (like a 55Hz sine wave) I hear an additional high frequency sound at certain sampling rates, but not at others. This happens in Audacity and in my own program. For ...
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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 ...
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Why should wavelet re-synthesis produce an output when the main component is suppressed and what does this mean for denoising?
I understand that aliasing occurs in DWPT if the wavelet used is of low order since the "filters" are not perfect and the combination of down sampling and overlapping between bands causes ...
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PolyBLEP: solving two part residual
The Polynomial Bandlimited Step (PolyBLEP) methodology involves approximating the sinc() function with a polynomial. The most basic polynomial to choose is a uni-polar triangular pulse as it is the ...
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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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Decimation Question about using a low pass filter before downsampling
I have a bunch of audio files that have a sample rate of 380kHz, however I would like to reduce this sampling rate to 44.1kHz. From doing some research online, it seems like I will have to use a low ...
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synchronize adcs with neuronal network
if i have two adcs(analog to digital converters) sampling a signal. Is it possible to synchronize the two adcs with deep learning?
as far as i know, with super-resolution on image processing it is the ...
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Direct Digital Frequency Synthesis, NCO and negative frequencies
I need to translate a frequency band generated by a DDFS designed in a FPGA (using Xilinx DDS Compiler). My output to the NCO is in I/Q format.
I chose to use a NCO to perform the frequency shift but ...
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Partially aliasing in Signals
I have read a paper about super resolution where signals are used that are partially aliased. here the paper
If the sampling rate is smaller than the 2*max frequency but greater the max frequency, ...
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What is an example of using aliasing to your advantage when recovering an input signal?
Suppose you have an arbitrary analog input signal $x_a(t)$ guaranteed to have frequencies within a bandwidth $[f_1,f_2]$ Hz.
Suppose your sampling frequency $F_s$Hz, and sample $x_a(t)$ to produce $...
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Multichannel sampling with aliasing
if i have 2 sensors, sensor1 and sensor2, that sample a signal on complementary points so that sensor2 samples always between sensor1s sampling points. can I achieve the doubled sampling rate with the ...
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Loosing information in decimation - without aliasing
We sample each other sample (01010101). Now say we have a signal - that is inside the original sample which has the pattern of (010-1).
Decimation gives us 000 for this sub-signal.
How to prove this ...
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How do you sub-sample an FFT?
I'm currently trying to understand this paper on a Sparse Fourier Transform.
On page four, there is a section on a sub-sampled FFT. The purpose of this section is to show that you can compute a sub-...
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Measuring Phase Difference at DC bin aliased frequency using FFT
I have a code in which two complex signals (I/Q) are created having same frequency but with phase difference. FFT of both signals is taken and atan2 is used to compute phase after which the difference ...
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aliasing folding phenomena in frequency domain matlab
Hello i am trying to create the folding phenomena of undersampling in matlab,
When i undersample the sampling frequency is 135 less than the Nyquist frequency for 70 Hz signal
ou will see that it is ...
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How do Anti-Aliasing Filters filter the signal?
I have programmed a anti-aliasing filter that uses the fourier-transformation and makes a perfect cutoff on my desired cutoff frequency for downsampling without aliasing.
I have read about other ...
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Super resolution with aliased signal
SKIP to Questions below if you want :
In super resolution I can create a high resolution signal from a low resolution signal.
But it is also possible that the low resolution signal contains aliasing. ...
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How to find correlation between two signals regarding peaks?
In a super-resolution task, I try to predict the higher frequencies of a signal.
X low-resolution (lr) is my input and Y high-resolution (hr) is the target. Where X contains only frequencies till 2 ...
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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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IQ Sampling and Oversampling Differences? *Confused*
Two different thought process that produce two different alias band calculations .... What concepts are these?
If I have two 1 GHz ADC's and they sample with 90 degree offset (A comment said this is ...
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Why is the digital frequency highest at $\pi$ and what does it mean in terms of analog frequency? [duplicate]
I can't seem to comprehend why the digital frequency is highest at $\pi$. I know the relationship between the digital and analog frequency is given by:
$$\omega = 2\pi\frac{F}{F_s}=2\pi f$$
Where $F$ ...
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Can the (point-wise) multiplication of two discrete band-limited functions be inherently aliased?
I'm not fully used to the language of DSP, so forgive me if I confuse some of the notation, or if the below is trivial.
I'm interested in the case where we want to do the point-wise multiplication ...
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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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Digital to analog aliasing or mirror query... DAC can output negative frequency?
Using a clock Fs = 1 MHz.
The Digital to Analog (DAC) can make frequencies upto 500 KHz.
500 kHz to 1 MHz is an alias? Or is it called a mirror?? Is aliasing a concept only on the ADC and sampling ...
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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 ...
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Where should I set my anti-aliasing filter corner frequency for this signal?
I have a Fourier transform of an arbitrary digital signal. The transform has For 1024 frequency bins. The magnitude plot of the first 100 is below, with no surprises in the unplotted 924 bins.
Now, ...
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Values of angular frequency of discrete-time sinusoidal signal
Why are the values of angular frequency of discrete-time sinusoidal signals in between -pi and pi?
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How to prevent distortion after down-sampling?
I am new to audio signal processing, but in one of my machine learning projects that I am working on, I need to down-sample my audio somewhere in the middle of my neural network. Therefore, I need a ...
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Why does my sinusoid look "AM" in shape?
My code is :
Fs=200e6;
Ts=1/Fs;
NFFT=2^14;
Runtime=(NFFT-1)*Ts;
t=0:Ts:Runtime;
f_in=90*1e6;
y_in=sin(2*pi *f_in *t);
plot(t,y_in)
ylim([-1.5 1.5])
Then why does ...
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Aliasing correspondance with respect to DFT
Given a sampling frequency Fs lets say we plot the magnitude of the fft of a temporal signal $x$, for different frequencies above the Nyquist frequency, to show the effect of aliasing:
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Better understanding of downsampling (decimation) and upsampling (interpolation)
Although some questions were asked about this topic, I have not seen any that answers all the basic questions, that is why I took the liberty to ask more about this.
I suggest to limit, (or at lest ...
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Is spectral leakage normal for FFT?
I record a sample of 2000 data points, with a sampling rate of 40khz, so freq. resolution is 20hz. I multiplied the chunk of data with a Hanning window prior to doing the FFT.
I recorded a 1khz test ...
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Aliased Signal's Frequency
So I have an incoming signal of 137.9 MHz and a sampling frequency of 1.4 MHz. Once sampled how do I calculate the aliased ...
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Sampling Audio Signal [closed]
I generate a 19kHz audio signal with sampling frequency of 44100 using Matlab. Due to the sampling, some other frequencies are generated in addition to the 19 kHz signal. When I play this audio, I ...
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Calculate aliasing of $x_a(t) = \cos{(2\pi300t)} + \cos(2\pi600t)$ when sampled with $F_s = 1000$
I'm asked to sample the signal
$$x_a(t) = \cos{(2\pi300t)} + \cos(2\pi600t)$$
with sampling frequency $F_s = 1000$ and plot the magnitude spectrum for the resulting sampled signal.
My thinking is ...
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Aliasing from downsampling and Nyquist
In a book Conceptual Wavelets in Digital Signal Processing by Lee Fugal 2009 on page 246 the author talks about aliasing present in DWT subbands due to downsampling by 2 and states:
Recall from DSP ...
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Understading sampling theorem and aliasing
A real-valued analog signal with a flat spectrum between f = 0 Hz, and fmax is sampled at a sampling frequency fs = 24 kHz. The sampled signal is then processed with an ideal lowpass filter with ...
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Amplitude Response at greater than half the sampling frequency
I am hoping to clear up some confusion I have. In a lab I am taking, we analyzed the amplitude response of a simple system. We found that as we increased the input signal frequency to greater than ...
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Minimum sample frequency that allows reconstruction of information signal but VIOLATES Nyquist?
Say in the frequency spectrum, you have an information signal between (-100, 100) Hz, and a noise signal between (-700, -500) and between (500, 700) Hz. What is the minimum possible sample frequency ...
