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Questions tagged [anti-aliasing-filter]

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Benefit of Anti-Aliasing for Wideband Finite Time Duration Signals prior to Sampling

Most literature about sampling explains the need for anti-alias filters in terms of periodic signals, preventing a periodic signal with frequency greater than half the sampling frequency from ...
abnowack's user avatar
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1 answer
152 views

FIR filter design for resampling

I am working on an audio resampler that is realized as a polyphase FIR filter. While testing, I found that it does not suppress aliasing as well as I would have expected. For testing, a sine sweep is ...
wolframw's user avatar
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1 answer
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How does aliasing affect bits in an ADC?

I want to measure a signal whose frequency spectrum is infinite, but I am particularly interested in the frequency range $ 0 - 500 \ \text{Hz}$. I have a 12-bit ADC. The ADC has dynamic range $ 6 \ \...
Carl's user avatar
  • 364
2 votes
1 answer
160 views

Low-pass filtering a clipped signal

In order to downsample a signal sampled at 48KHz, I implemented an anti-aliasing filter. An Elliptic LPF with a cutoff at 16KHz and order of 10. Everything looks OK until the input to this filter is a ...
Yaz's user avatar
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0 answers
70 views

What order to apply noise shaping and anti-aliasing to an idealized synth

I am trying to write a small synth code that goes something like this, I have an abstract symbolic sound representation, sine/square/saw waves. To generate final sound and make it sound good I thought ...
Ilk's user avatar
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5 votes
2 answers
887 views

How to measure aliasing?

Aliasing is bad, and we want good filters when downsampling. While what qualifies as aliasing is well-defined mathematically, and we can manually design filters with various tradeoffs, how do we ...
OverLordGoldDragon's user avatar
2 votes
3 answers
727 views

How to align timeseries by decimating while preventing aliasing?

I have two pandas DataFrames, dfb and dfv, where dfb has a higher sampling rate than ...
Jokerp's user avatar
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1 vote
1 answer
38 views

Taking every third value or the mean of three

Referring to Sampling, filters, windowing, FFT. From theory to help on this coding list with the figure, I now have some more questions. How will taking every third of the 48 kHz vs. taking the mean ...
Øyvind Teig's user avatar
3 votes
1 answer
486 views

How does SDRs implement anti-aliasing filters, when the sampling rate can be fairly arbitrary?

I was looking at the schematic for the small USRP B205-mini SDR from Ettus. I can't seem to find any switchable analog anti-aliasing filter on the input of the chip, or anything resembling a filter ...
Linkyyy's user avatar
  • 133
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1 answer
202 views

Sampling, filters, windowing, FFT. From theory to help on this coding list

My plan is to analyse the spectrum of samples from a microphone. I wonder how correct this suggestion is. The below description may then fail on several points. I am in need of somebody with a red ...
Øyvind Teig's user avatar
1 vote
1 answer
287 views

How is sampling affecting this sine wave?

I am trying to create a sine wave in python, but when I graph it, it looks like this: here is the code I used to make the signal: ...
user57935's user avatar
1 vote
1 answer
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what is the correct order of applying a nonlinear operation and downsampling (with anti-aliasing)

In UltraSound imaging, after beam-forming and obtaining the envelope, Log-compression which is a non-linear operation and scan conversion which is a 2D interpolation (with inherent down-sampling) is ...
Mohammad M's user avatar
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2 answers
4k views

How to apply an anti-aliasing filter before downsampling

I have an eeg signal with two channels (f3m2 and f4m1) which is divided into epochs. I want to augment the data by taking every 5th sample. I can re-use the discarded samples to create 5 versions of ...
Amanda Punch's user avatar
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1 answer
255 views

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 ...
DSPinfinity's user avatar
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1 answer
608 views

Oversampling, decimation and Nyquist

I know this is a bit of a fundamental DSP question but I want to finally understand this and I think I need some help to finally put it all together. Let's say I have an RF complex sampling ADC with a ...
Josh W's user avatar
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1 vote
1 answer
212 views

DDS generated chirp and antialiasing filter : what is the best suited filter for a chirp?

I am defining the required antialiasing (analog) filter for a chirp generated by a DDS. The chirp is produced in a FPGA (NCO generation) and forwarded to the DAC for the samples generation (with ...
AtoM_84's user avatar
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1 vote
0 answers
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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, ...
Khan's user avatar
  • 141
2 votes
2 answers
885 views

Does resampling cause phase shifts?

I have a signal sampled at 40MHz, I would like to resample it to 37MHz. The signal is not periodic, I did resampling with Matalb resample function and it doesn't cause phase shift (as far as I ...
Farnaz's user avatar
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2 answers
2k views

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 ...
Khan's user avatar
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3 answers
257 views

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 ...
Khan's user avatar
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1 vote
2 answers
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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 ...
Natalie Johnson's user avatar
2 votes
1 answer
370 views

Variance of a signal

How to calculate the variance of noise samples modeled as follows: $n_a(t)$ is a Gaussian zero-mean white noise process with (two-sided) power spectral density $\frac{N_0}{2}$. $n_a(t)$ is passed ...
Raksha's user avatar
  • 23
0 votes
2 answers
1k views

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, ...
Stephen Collings's user avatar
1 vote
0 answers
284 views

What is the minimum and maximum cutoff frequencies for the antialiasing filter for this ADC?

https://www.analog.com/en/products/ad9675.html https://www.analog.com/media/en/technical-documentation/data-sheets/AD9675.pdf It says in the data sheet that the Anti-Aliasing Filter has : "...
Alex Nguyen's user avatar
1 vote
1 answer
637 views

How do Anti-Aliasing-Filters in audio signal processing work?

I am a little confused about the use of anti-aliasing filters. As on how I am confused, please consider the following task: Consider a simple sampling rate conversion system with a conversion rate ...
user503842's user avatar
3 votes
1 answer
2k views

polyBLAMP anti-aliasing in C++

How should 4 point polyBLAMP work. It does not really seem to dampen aliasing. I have an floating point digital audio oscillator that makes a +1.0f jump at the end of every period. My question is, ...
Invariant's user avatar
  • 159
0 votes
1 answer
1k views

Understanding anti aliasing filter

I'm working on a project for the university about the anti aliasing filter. I have a small audio file, which has a sampling rate of 22KHz. Now when I downsample it 8 times, the file sounds weird. So ...
Van Gan's user avatar
2 votes
1 answer
878 views

How can I implement a triangular filter in MatLab, given it's Z-transform representation?

I have to implement an anti-aliasing filter for a certain processing step in MatLab. While searching in literature for inspiration, I came accross a paper in which the authors wrote the following: We ...
Floris's user avatar
  • 123
4 votes
3 answers
6k views

What is the filter with the less phase shift?

I have to analyze a dynamic signal but there is too much noise so I applied low pass filter but then there is too much phase shift.So what is the most reactive filter I can apply to my signal ? Best ...
alexgrover's user avatar
1 vote
2 answers
789 views

Confused on application of Anti-Aliasing Filter

I have a question about the use of anti-aliasing filters prior to sampling a finite time signal and if they actually help anything. The point of the anti-aliasing filter is to remove high-frequency ...
FourierFlux's user avatar
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1 answer
677 views

Aliasing in digital communication system

In a digital communication system, is it possible to counteract the aliasing problem by properly tuning the constellation order $M$ and/or the carrier frequency? Here is my train of thought, please ...
Tilen Kavčič's user avatar
3 votes
2 answers
5k views

Why analog anti aliasing filter is used before analog to digital converter when there is already a digital filter after ADC?

Normal data acquisition consist of: Analog anti aliasing filter( Sampling frequency : $5\textrm{ kHz}$) ADC - Digital Filter - (Sampling : 200K samples /sec) Digital low pass filters Filters DAC ...
user2121195's user avatar
0 votes
1 answer
704 views

Anti-Aliasing when oversampled

From a comment in another question I read a statement "In addition, the initial rate of 48kHz is already performing 6 times oversampling and therefore the subsequent decimation by 6 will not ...
Johu's user avatar
  • 103
4 votes
3 answers
801 views

How do optical anti-aliasing filters work from a frequency domain perspective?

To prevent aliasing caused by the finite number of pixels on a sensor, a blurring filter is commonly used. How does that work from a frequency domain perspective? What is the transfer function of such ...
user110971's user avatar
5 votes
2 answers
9k views

Why is a square wave aliased?

I understand an ideal analog square wave contains sine-wave-components above Nyquist frequency (and towards infinity) and is thus subject to aliasing. So obviously we need an anti-aliasing-filter. Or ...
Andrew G's user avatar
  • 234
0 votes
2 answers
3k views

Interpolation based on sinc function

I implemented an interpolation method in C++ based on this equation ...
eryk's user avatar
  • 5
0 votes
2 answers
126 views

Does MSAA make sense in audio / 1d data streams?

In graphics, MSAA is a technique where you take multiple samples of something per pixel and then average the values to get the final pixel value. The image quality improves as a result, and its ...
Alan Wolfe's user avatar
0 votes
2 answers
1k views

Confused about anti-aliasing in analog filters

I'm a newbeginner when it comes to signal processing. I'm reading up about anti-aliasing, Nyquist and band-pass filters. There's something I don't get: Anti-aliasing in analog filters. Lemme try to ...
spginner's user avatar
1 vote
0 answers
290 views

Anti-aliasing requirements for a Muxed Sigma-Delta Converter

It seems to be reasonably well accepted that Sigma-Delta ADCs have much looser requirements for the anti-aliasing filter due to both the noise shaping and high modulation frequency. However, it seems ...
Damien's user avatar
  • 606