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0
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1answer
172 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 ...
0
votes
2answers
51 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 ...
0
votes
1answer
37 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. ...
0
votes
1answer
24 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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0answers
19 views

Optimal Channel Bit Allocation For Branches

The Question Hi. I was asked to solve this problem. I solved the part a but could not be able to solve the b part. Also found that $(\frac{2(1+p)^2}{(1+p)(1-p)})^2 = \frac{{{\sigma_\theta}_1}^2}{{...
0
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0answers
60 views

I/Q imbalance correction with multi-tone system

I'm trying to compensate I/Q imbalance from a system that uses multiple tones. I've tried to use Analog Devices' approach, https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms1-ebz/...
0
votes
1answer
70 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 ...
0
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0answers
32 views

temporal smoothing and signal distortion

I compare two signals (blue and red). Each signal is an average of many observations (shades are standard error of mean). I need to show that the the blue signal is significantly above red one at the ...
0
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0answers
17 views

Linear distortions in transmission systems [duplicate]

I am quite new in Signal Processing and I do not know even the basics. In my lecture slide notes, I came across with the following sentence: Phase distortions happen if the phase function b(f) of ...
1
vote
0answers
108 views

How to calculate THD+N from signal

Currently writing a program to measure the distortion of audio receiving signals(FM signal). I am studying audio's signal distortion analysis. I have survey THD+N's knowledge on the Internet. But they ...
3
votes
1answer
194 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 ...
1
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0answers
42 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 ...
2
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0answers
54 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 ...
2
votes
1answer
114 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 ...
3
votes
2answers
232 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: ...
4
votes
1answer
101 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 ...
3
votes
0answers
273 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 ...
3
votes
1answer
122 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[...
1
vote
1answer
40 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 ...
1
vote
1answer
124 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 ...
0
votes
1answer
873 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 ...
0
votes
0answers
128 views

How to calculate THD+$N$ of a wav audio file?

I have sine tone of $F_s= 192\textrm{ kHz}$ which contains frequency from $20$ to $20\textrm{ kHz}$. I have converted that to $44\textrm{ kHz}$ sampling rate. I am supposed to calculate THD+N value ...
0
votes
1answer
132 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 ...
0
votes
1answer
107 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 ...
0
votes
1answer
108 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 ...
0
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0answers
711 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 ...
1
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0answers
223 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 ...
0
votes
0answers
308 views

STFT on audio signal

I am trying to implement a STFT on audio signal as an exercise, and in order to do real-time filtering if I can get the "sound->STFT->inverseSTFT->reconstructed sound" chain to work. What I do for ...
1
vote
0answers
109 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 ...
7
votes
1answer
181 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 ...
0
votes
1answer
238 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!
2
votes
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 ...
3
votes
2answers
1k 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 ...
0
votes
1answer
153 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 ...
1
vote
0answers
258 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. ...
0
votes
2answers
112 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^{-...
1
vote
1answer
322 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. ...
-1
votes
1answer
354 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 ...
1
vote
0answers
226 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 ...
3
votes
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 ...
2
votes
4answers
435 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 ...
2
votes
0answers
423 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 ...
9
votes
3answers
9k 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|}...
0
votes
3answers
575 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 ...
1
vote
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 + ...
11
votes
2answers
9k 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 ...
43
votes
10answers
27k views

Algorithm(s) to mix audio signals without clipping

I'd like to mix two or more PCM audio channels (eg recorded samples) digitally in an acoustically-faithful manner, preferably in near-real-time (meaning little or no peek-ahead). The physically "...
12
votes
4answers
2k views

Is there such a thing as band-limited non-linear distortion?

So if you generate a square wave by just switching a signal between two values, at sample boundaries, it produces an infinite series of harmonics, which alias and produce tones below your fundamental, ...