Questions tagged [distortion]

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25 views

Deconvolution of signal with harmonic distortion

I came across these measurements done using a stepped sine sweep covering only some frequencies (~800 frequency points). I would like to get an impulse response from these measurements to convolve ...
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41 views

Guitar Amp/Fuzz Box with Asymmetrie Control

I'm trying to implement a guitar amp/fuzz box with a variable symmetry control of the transfer curve, but the asymmetry should influence the clipping ceiling as well as the knee (for example, the ...
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38 views

Emulating tape distortion of low-level audio signals

I'm working on a tape echo emulation in Reaktor, and I've based the frequency response, tape speed warble, high-amplitude saturation and tape hiss on a paper I found about the Roland Space Echo. ...
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1answer
46 views

Error correcting code? - using RGB space with a lookup table

This problem could be thought about as how to transmit a signal with 3x8bit RGB in a way that is robust to the distortion of antialiasing blends colors. The context: I need to rewrite a short utility ...
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1answer
56 views

High FIR order in time critical classification task

I have a question regarding filtering (bandpass in my case) as a preprocessing step before a classification task. The frequency band I am interested in lies between 0.5 - 22 Hz which results in a ...
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2answers
134 views

Can harmonics be created or simulated a la carte

I am trying to learn about adding harmonics (audio) with a goal to make a plugin that can allow adjustment of the amplitude of each harmonic being added. I would not have the ability to write this but ...
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1answer
48 views

Fixing integer overflow in wave file

I have this recording from my DAW that showed a strange form of distortion: the signal clipped at many places, but instead of simply being clipped (loss of information), somehow the integer value of ...
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1answer
87 views

Finding the Transfer Function of a Multiplicative Distortion in MATLAB

I have the frequency response of two signals shown above. One is uncontaminated, and the other is the same signal contaminated by a multiplicative distortion with two poles and two zeros. I need to ...
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0answers
316 views

How does image rotation affect the intrinsic camera parameters?

I am considering the problem of how to (manually) change camera model parameter to make it "valid" on a rotated image. This question tackles resizing, but does not consider lens distortion. ...
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1answer
79 views

Exponential Swept Sine Distortion

I was able to get passable results on fundamental measurements using and exponential swept sine. Now I am trying to get distortion information from the same measurement but am puzzled by the results. ...
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1answer
31 views

Signal distortion under non-linear channel

The channel is given to have these characteristics, and its required to study the affect on Frequency Modulated signal and its demodulation. Since there are no sharp corners (like during clipping) ...
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1answer
296 views

What function to apply a Metamorphopsia (grid warp) translation?

How would I go about finding or creating a function to warp images dependent on grid lines surrounding an origin (I don't wish for a grid on my actual images): It should work in practically the same ...
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1answer
75 views

Understanding legacy code: Algorithm to remove radial lens distortion

The method below to remove lens distortion from a camera was written more than ten years ago and I am trying to understand how the approximation works. ...
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1answer
103 views

Total Harmonic Distortion THD for the rectifier

I have a circuit with rectifier and this cause the non-linearity and consequently harmonic. I show it on the oscilloscope and then collect the signal from the oscilloscope to the computer by using the ...
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1answer
249 views

Group Delay for Hilbert Transformer and Resulting Dispersion

An ideal Hilbert Transformer shifts the phase for all positive frequencies by $-\pi/2$ and all negative frequencies by $+\pi/2$ while maintaining constant magnitude everywhere. Group Delay is the ...
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1answer
83 views

How to quantify phase distortion of a filter specific to a signal?

For example, a EKG input signal is filtered with a known transfer function that does not have linear phase. How do you quantify the phase distortion of the output signal given you have the input? I ...
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1answer
592 views

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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873 views

How to measure SINAD of an audio signal?

I tried to measure the SINAD and SNR of a recorded audio signal using MATLAB. The following is the process I did to measure the 2 parameters: Firstly, I generated an FM modulated signal(1 kHz audio ...
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1answer
167 views

Distort voice to hide talker identity as much as possible

I need to develop an app which makes speech recognition. Because I need to be able to constantly improve the recognition capability, I would like to train the engine with real recordings and match the ...
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1answer
143 views

Recommendations for SINAD equipment

I am interested in buying a device that measures the SINAD of the audio signal(FM signal) that I receive from PC. Here is the setup: Signal generator (generating 1kHz FM signal ) $\rightarrow$ ...
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21 views

Any recommendations for buying SINAD measuring equipment? [duplicate]

I am interested in buying a device that measures the SINAD of the audio signal(FM signal) that I receive from PC. Here is the setup : Signal generator -> attenuator ->HackRF connected to PC with SDR# ...
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1answer
302 views

Linear vs Non linear distortion

I'm learning about distortion and I got stuck at "What is the difference between linear and non-linear distortion?" (Also in frequency spectrum i.e. Amplitude and phase spectrum)
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3answers
872 views

Precise 5th and 7th harmonics of a sampled sine wave

Does anyone know in decibels (to 1/100th of a dB) what the theoretical 3rd, 5th and 7th harmonic of a 0dB fs 24-bit (i.e. full-level; 0dB = -8,388,607 to 8,388,607) sampled sine wave without dither ...
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1answer
394 views

Can I use SINAD for THD+N measurements? Are they inverse of each other?

I'm looking for a clarification, which I haven't really been able to find. It's probably obvious but I'd like to be absolutely sure of what I'm calculating. I noticed that the formula that calculates ...
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2answers
54 views

Audio sounds oddly distorted [closed]

https://clips.twitch.tv/TangentialObliqueLobsterSaltBae https://clips.twitch.tv/CharmingBashfulAlfalfaRickroll https://clips.twitch.tv/NaiveKindGorillaGivePLZ (Disclaimer: These were not recorded on ...
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1answer
167 views

Finding the memory polynomial model coefficients

I want to build a memory polynomial model given that I know the corresponding output signals for known input signals. What is the easiest way to find the coefficients of it? And how do we take the ...
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1answer
355 views

Dithering adds harmonic distortion after filtering and upsampling

I have an issue which I wasn't able to solve for a few days. I have implemented a polyphase FIR interpolation filter within an FPGA which does interpolate by a factor of 8 or 16 times. I do accept an ...
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2answers
109 views

Why is distorted / quantized white noise still white noise?

White noise can be created by setting every sample in the time domain to a random number with a gaussian distribution. Every sample is random, so the frequency response is obviously random. Easy ...
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1answer
420 views

Identify the Type of Image Distortion (On Lena Image)

I want to understand the distortions in each of the lena images shown in the image below. I see that the first one is a blur. How can undo the blur. The second one is colored salt and pepper noise. ...
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1answer
66 views

THD requirement for generated sine

I need to generate a sine signal using a DAC with a certain THD specification, say 0.1% @ 1KHz. As a first approach I’m considering it to be an ideal DAC along with an ideal LPF for aliasing removal ...
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1answer
378 views

Redistributing Color in a RGB Image According to a Gaussian Distribution

I haven't done this stuff in a while. If I have an image $I$ I can equalize the histogram of the image using some opencv procedure, it's already defined. Equalizing an histogram means essentially to ...
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1answer
735 views

Can someone explain waveshaping to me?

Can someone explain waveshaping to me? I only know it shapes waveshapes by passing through some functions, but I don't yet understand e.g. what the plots (such as the following in Melda Production ...
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107 views

Calculating Transfer Functions From Harmonic Distortion Percentage

Hi I am working on emulating a piece of analog audio equipment and would like to be able to create a transfer function based on the measured percentages of harmonic distortion. I know that harmonic ...
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0answers
121 views

Wave Shaper Function From A Waveshaped Singal

Is there a way to work out an unknown waveshaper function, that was used to distort and map the values of an input signal to new output signal, form the output if we only have input signal and the ...
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1answer
456 views

Norm MPEG-1 Layer III (Mp3) Filter banks distortion

So, I'm working with the filter banks used in Mp3, in Matlab. I am obtaining quite a huge distortion in the output and I don't really know whether I'm making something wrong. I've reviewed the ...
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2answers
629 views

Digital modelling of circuits with diode (i.e. guitar distortion)

For the last few days I was struggling to come up with an idea how to model a guitar overdrive effect which works in realtime. One of the simplest circuit diagrams that produce it looks as follows: ...
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1answer
193 views

Spectral baseline distortion simulation - Bruker smile

I work with Magnetic Resonance Spectroscopy data. Data (complex signals) obtained from Bruker scanners (one of the biggest manufacturers of MRS scanners) start with an important group delay - around ...
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0answers
507 views

Demodulation distortion in single-sideband and double-sideband

I am trying to compare the demodulation for single sideband (SSB) and dual sideband modulation formats (DSB) when the reconstructed carrier is not perfect (i.e. shifted in both frequency and phase). I ...
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1answer
334 views

Regarding the advantages of generalized linear phase filters

I know that for a linear-phase filter with frequency response given by $$H(e^{j\omega}) = |H(e^{j\omega})|e^{j\phi(\omega)} $$ if the input of the system is $$x[n] = s[n]\cos[\omega_0 n] $$ where $s[...
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1answer
92 views

Can IR emitter signal be distorted by curved glass housing around receiver?

I have built a garage door opening circuit that includes an IR sensor and an IR emitter (a remote control). When the IR sensor is in the open air it works fine. If I put the sensor inside a glass ...
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1answer
234 views

Create distortion from basic linear (and non-linear if neccessary) DSP elements

I'm studying mechatronics and I'm intrested in DSP basics. My lecturer said that there are four basic linear DSP elements: Adder (and other mathematical operations) Amplification (shown on diagrams ...
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1answer
2k views

If a filter has a non-linear phase lag will the output signal be distorted?

EDIT: From here (https://www.mathworks.com/help/signal/ref/butter.html) it appears that an Butterworth filter has a non-linear phase lag at the normalized frequency of 0.5 onwards. Does that mean that ...
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1answer
141 views

Determine modulation function from spectrum?

I have a two periodic signals $x(t)$ and $y(t)$ which are related to each other by a periodic modulation function $\alpha(t)$: $$y(t) = \alpha(t) x(t)$$ If $x(t)$ is a sinusoid, is it possible to ...
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1answer
322 views

How to analyze image quality?

I have a few sequences of images, taken at fixed camera position, that address a moving object, which means the object moves towards the camera. But all the sequences of images are the cropped images ...
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1answer
131 views

What is this kind of distortion called?

Today while watching a movie I noticed the following distortion: Note. The red ring is me painting over to show the area of interest. There are certain areas in which I can see non-smooth shades of ...
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0answers
2k views

How to estimate THD?

I have a signal source that I can digitise and read. It produces mainly a 50Hz sine wave, but there is distortion as well. I'd like to estimate the total harmonic distortion for this signal. I've ...
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339 views

how to get an input test signal for convolution/ distortion method

i am trying to do some experiments with Total Harmonic Distortion. According to ...
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0answers
140 views

FFT Convolution: missing sample somewhere

For a piece of software I've been working on lately I need to implement FFT convolution for performance reasons. Doing so has been mildly succesfull but there is still a error somewhere causing lots ...
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1answer
288 views

Looking for pratical quantitative comparison metrics for scaled, delayed and warped Signals

[Nota: I have validated the only answer so far, yet more explicit versions are still welcome] The following question is detailed in 1D, with time as the ordinal variable. Similar questions could apply ...
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1answer
370 views

Vinyl Crackling Effect

I want to know how can I achieve this effect: https://www.youtube.com/watch?v=DQg9M_47c3A Do I need to use a filter? And what can I use for the crackling, poping effect? Thanks in advance!