Signal Processing

Questions tagged [distortion]

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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
42 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
49 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
34 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
287 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
40 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
53 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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14 views

Rate distortion function for a Gaussian process with a squared exponential kernel

This is probably a question whose answer should be available in some paper or textbook, but my searching for it hasn't helped me find a result that I could use. The question is basically just what ...
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33 views

How can I quantify the distortion in a speech signal?

I am working with certain speech enhancement algorithms, for instance to remove stationary noise or impulse noise from a speech signal. Filters such as those can enhance the speech signal, but they ...
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1answer
39 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
215 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
66 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
101 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
33 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
117 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
337 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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62 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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74 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
233 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
315 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
125 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
387 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
164 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
64 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
153 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
1k 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
136 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
182 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
118 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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977 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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283 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
120 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
191 views

Quantitative comparison of scaled-, delayed- and warped-signals

The following question is detailed in 1D, with time as the ordinal variable. Similar questions could apply in other dimensions. In several signal processing techniques, such as blind source ...
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1answer
270 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!
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1answer
90 views

Distances In a Single Image With Some Real References

Consider following image: We have some real references here: Stonehenge measurements (stone dimensions and distances), some strait lines at the back of carts, cart wheels that are almost of the same ...
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2answers
2k views

How to estimate radial distortion from lens characteristics?

Is there a way to estimate the radial distortion coefficients without calibration, given the lens characteristics, such as its diameter and its focal length? Typically for camera calibration a ...
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1answer
194 views

Slight crackle with overlap-add frequency-domain convolution

I'm trying to make an FFT audio filter using overlap-add but there's some slight rhythmic distortion/crackle in the output. I have an irSize (impulse response size) of 512 samples and a blockSize of ...
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296 views

Can sample aliasing of strictly white noise lead to random walk (drift) in the sampled signal?

Aliasing of tones higher than the Nyquist frequency, and where the tone may have some degree of nonlinear distortion can appear as low frequency 'drift' or even near static bias in the sampled signal. ...
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2answers
170 views

What is done to minimize distortion due to the hold operation?

A hold operation can be modeled using a step function over one sampling period i.e. $R(t) = 1/T * (h(t) - h(t-T))$, $h(t)$ the step function In frequency domain this is equivalent to $R(jw) = e^{-...
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1answer
384 views

Total Harmonic Distortion calculation and its origins

I ve been researching about harmonic distortion and THD. From what i ve seen on the internet, HD is caused by non-linear signal processing. I want to calculate it using an digital signal processor. ...
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1answer
422 views

FFT window corrupts signal

this is a newbie question. My goal is to create audio filter that cleans human speech from noise. I started with learning all about fft filters. At first I've created simple fft filter with ...
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288 views

Why does my overlap-add integrator in frequency domain result in distorted signals?

With help from the dsp guide and DSP-Related, I tried to implement a leaky integrator in octave/matlab. It seems to work in general, but there are a few problems. So that's what I do: Calculate the ...
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1answer
3k views

How to model Tape Saturation (Audio DSP)?

I'm looking for info that would help me to build a Tape Saturation process. I'm working with the WebAudio API. The API provides a number of DSP nodes that perform basic processes, such as a Convolver ...
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4answers
498 views

Camera Calibration using Single Input Image

Given a camera, permanently located at the same position, angle and distance from what is being captured, and a single calibration image ( a row of vertical lines [ | | | | ] ), how would one go about ...
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446 views

Motion and Distortion Estimation using multiple still images?

TL/DR: I'd like to take the median of lots of images to make a single "better" image. The problem is, the camera is slowly moving, and there is significant lens distortion. On the plus side the ...
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3answers
11k views

Digital Distortion effect algorithm

I read the DAFX book by Udo Zölzer about the distortion effect at pages 124-125 and it says that suitable simulation of the distortion is given by the function: $$f(x)=\frac{x}{|x|}\left(1-e^{x^2/|x|}...
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3answers
639 views

importance of symmetric windows for STFT for practical applications

I am wondering why is the linear phase property of filters with symmetric coefficients important for some practical applications of short time fourier transform, such as image processing? I have read ...
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1answer
1k views

How to calculate Noise and distortion of an image?

I need to make an application in iphone which needs to calculate noise, geometric deformation other distortions in an image. How to do this? I have done some image processing stuff with opencv + ...
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2answers
10k views

Add odd/even harmonics to signal?

How do I add odd or even harmonics to a floating point signal? Do I have to use tanh or sin? What I'm trying to do is achieve some very simple distortion effects, but I'm having a hard time finding ...

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