In signal processing noise can be considered random unwanted data without meaning.
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voice with a random noise redction - MATLAB
I have this assignment that I can't figure how to solve.
I have a sound.wav human-voice file, and a matlab add-random-noise (monotonic)
Goal: remove the noise from the sound (and the sound from the ...
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2answers
109 views
Removing noise from audio using Fourier transform in Matlab
I'm trying to remove noise from an audio file. This audio file contains speech as well as constant pink noise. I know that I have to use the Fourier transform to convert to the frequency domain then ...
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1answer
50 views
What are some suitable methods for removing low-frequency line noise from measured data prior to system identification/deconvolution?
I am performing a system identification by striking an experimental model with an instrumented impact hammer and measuring the strain response.
The timebase for the recorded signals is 5 microseconds ...
3
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2answers
139 views
variance of white gaussian noise
it could seem an easy question and without any doubts it is but I'm trying to calculate the variance of white gaussian noise without any result.
PSD of AWGN is $\frac{N_0}{2}$ while autocorrelation ...
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1answer
131 views
Remove spurious peaks of Hilbert transform
I want to eliminate spurious peaks of Hilbert transform for finding Glottal closure in LP residual. I have the following 4 steps:
1-down-sample.
2-Hilbert Transform.
3-Identify Peaks in Hilbert ...
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2answers
93 views
Power spectral density and SNR for AWGN
I have a GMSK modulator in MATLAB and wish to generate AWGN with a specific SNR, and I'm having some issues figuring out just how.
I have found this step-by-step process to generate zero-mean ...
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2answers
85 views
Where can we find noises like Gaussian, Rayleigh, Gamma, exponential noises in real world images?
I know that while taking pictures from a camera, noise may appear in the image.
It is often described as Gaussian, but what about the other noises, when do they occur in real world?
Please help!
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1answer
136 views
What is the phase and magnitude response of white noise?
I would like to create white noise in the frequency domain, and then transform it to the time domain using python. To understand the problem, I simply generated white noise in the time domain, and ...
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1answer
92 views
Why is Frequency Shift Keying more immune to noise than ASK?
Is it because noise manifests itself in the transmitted signal's amplitude?
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1answer
46 views
How to know if the noise was removed in an image?
I am looking for a technique for measure the quality of my denoise filter, is the SNR formula useful for that purpose?
My problem is, I have an image with noise, I apply the "adaptive median filter", ...
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1answer
69 views
Finding circle in binary image (R, not matlab)
How would I go about extracting the circular area of a binary image which looks like:
The two rods emerging from the side of the circle are noise.
I know of the hough transform in Matlab. However, ...
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1answer
67 views
Remove noise on edge (compression deffects)
I have the images of cartoons, that were compressed. The example:
They have such noise, that is not easy to delete.
Even though the pixels are on the gray background, the noise pixels can be of ...
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2answers
139 views
Fitting piecewise splines to noisy data
I have a system that gives me a noisy data set similar to the one generated by this matlab/octave code. The y-axis represents the signal intensity and the x-axis represents spatial distance.
...
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1answer
210 views
ADC performance simluation: How to calculate SINAD from FFT?
While working on this problem, I started to have doubts that my initial definition of
$$SINAD = 10 \log_{10} \left( \frac{p_f} {\sum_i{(p_i)} - p_0 - p_f} \right)dB$$
is correct. In this equation, ...
5
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1answer
118 views
Received Morse Code signal-to-noise ratio?
I have some digital recordings of some received over-the-air CW broadcasts of known plain-text (W1AW code practice) at known WPM code speeds, but in moderate to heavy RF noise and fading.
Can I ...
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0answers
79 views
How to choose FFT depth for ADC performance analysis (SINAD, ENOB)
I am trying to simulate a model of an ADC and determine its performance.
One of the interesting properties is the ENOB (Effective Number Of Bits), which can be calculated from SINAD (SIgnal-to-Noise ...
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1answer
85 views
Approximating the frequency response of a median filter
A median filter is a non-linear and lossy process, so it doesn't have a closed form frequency response as would a FIR filter (say a box filter of the same length) in an LTI system.
But how closely ...
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1answer
68 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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0answers
29 views
Smoothing data from a 3D camera
The camera uses two cameras and reflective infrared markers to compute 3D positions. For recognized marker configurations, the camera computes a translation and an orientation (quaternion). For stray ...
6
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2answers
126 views
Determining the “whiteness” of noise
How does one quantify how "white" some noise is? Are there any statistical measures, or any other measures (FFTs for example) that can quantify how close to white noise a particular sample is?
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1answer
38 views
Obtaining the variance of the image noise
I am implementing a digital image correlation algorithm, and I found that for some calculations the variance of the image noise would be very interesting.
How can I determine that parameter? The ...
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0answers
27 views
Local signal-to-noise ratio for an image
I want to do one of these common experiments to see the effect of increased noise on the performance of a feature detector.
To do this add zero mean gaussian noise with fixed sigma to the image and ...
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1answer
92 views
A very fundamental question about average normalized power of noise
If I have a average normalized power spectrum of noise is like this
$W(f)=N_0$ while frequency is $-B$ to $B$.
Why the average normalized power is $1/4 N_0 (2B)$ insteat of $N_0 (2B)$?
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3answers
240 views
Recover filter coefficients from filtered noise
I have a digital signal which may be represented as a pulse noise source filtered with an FIR (finite impulse response) filter. Suppose that the noise consists of discrete pulses (nonzero samples ...
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0answers
65 views
Edge detection in Fast Noise Estimation method (link to document inside)
A Fast Method For Image Noise Estimation Using Laplacian Operator and Adaptive Edge Detection
I have some troubles trying to decide edge-map threshold. As i understood this document in link above, ...
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3answers
140 views
best window for close frequency components
I'm currently designing a receiver which has to determine whether a signal contains specific frequencies or not. The frequencies are at constant 215Hz difference:
...
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1answer
32 views
Strange noise deviation formula
I'm having troubles trying to use one relatively simple noise estimation method, here it is:A Fast Method For Image Noise Estimation Using
Laplacian Operator and Adaptive Edge Detection
My problem ...
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4answers
124 views
Vertical lines noise in spectrogram
I have started looking into DSP and made an implementation of short-time fourier transform, using kissFFT to perform the FFT. I then render a spectrogram.
An example image that I have generated can ...
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1answer
110 views
Degraded image: Wiener Filter vs Wiener deconvolution
I am studying methods for recovering images (that has been blurred and noised).
Can someone explain the difference between:
http://en.wikipedia.org/wiki/Wiener_deconvolution
...
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2answers
139 views
What do colored noises look like in the time domain?
I understand that the time domain representation of white noise looks like impulses. How do colored noises like brown, pink etc. look like when we perform an inverse Fourier Transform on them ? What ...
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1answer
190 views
Producing Colored Noise from a given PSD Data
I need to estimate (extract/produce) the colored noise of a given PSD Data. I have the following procedure to get the desired results.
First of all I calculate the filter coefficiencts using firls ...
5
votes
1answer
131 views
Filter message from noisy voice signal
I am trying to decipher a message hidden within a very noisy audio file(.wav)(I think it is white noise with an additional low drone). The message is a six digit number. I have not have any further ...
2
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1answer
150 views
Audio signal noise filter problem
I'm currently working with audio signals and have a problem:
C = A*B + N, where
C = recorded signal from microphone consisting of:
A = known music file data played on speakers next to microphone ...
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1answer
147 views
SQNR when multiplying 2 16 bit signed integers and truncating result?
I'm trying to figure out what the Signal to Quantized Noise Ratio (SQNR) is if I multiply 2 16-bit signed integer values and store the result as a 16-bit signed integer, dropping the least significant ...
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98 views
What causes High Intensity Noise after Acoustic Echo Cancellation for a VoIP?
I am trying to implement a Acoustic Echo cancellation algorithm in Java for a VoIP system. This AEC will help to cancel the echo (coming from Speaker) in microphone input at the same PC. The sound ...
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2answers
328 views
Adding noise to an ECG signal
I am doing a project on ECG arrythmia analysis using matlab.
I have designed notch filter for removing 50 Hz noise but don't know how to add a 50 Hz powerline interference noise to a clean ECG ...
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2answers
204 views
Recover myself from Dilate and Erode for noise reduction
i have obtained some skin detection map (i post below two example of detection map). but, i'm using a normal webcam and the map is noisy. Not a lot, just a bit.
I think i can remove noise only with ...
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0answers
45 views
Relative beat detection for two audio recordings
I'm trying to synchronize (overlap) two audio recordings of the same song: a complete HQ version, and an incomplete, noisy version (phone recording for example). The noisy recording may have had its ...
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3answers
439 views
Zero Crossing of a Noisy Sine Wave
I'm trying to find the zero crossings of a sine wave to transform the sine wave into a square wave. The only problem is that the sine wave is noisy, so I'm getting lots of jitter and false zero ...
6
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1answer
191 views
Gradient of total variation of magnitude of complex function for denoising
Say I have a complex function $f^*$ (e.g. a MRI image) that has a near piece-wise constant magnitude, but a non constant phase.
If I have an optimization problem to find $f^*$ and set up an objective ...
3
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1answer
157 views
FFT, How to decide if there is a signal among noise?
I have sets of data of different deep sky objects. My job is to check for any periodicity.
I use IDL to run an FFT and wavelet methods to check for a signal. To test my code I ran the IDL built in ...
6
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3answers
181 views
Solving optimization problem used for high quality denoising
The highest voted answer to this question suggests that to denoise a signal while preserving sharp transitions one should
minimize the objective function:
$$ |x-y|^2 + b|f(y)| $$
where ...
4
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1answer
811 views
PSK vs FSK for noise immunity?
Which method provides better noise immunity?
I know you can transmit more data via psk, but what about which method is less susceptible to noise?
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1answer
182 views
How to remove/reduce noise by using the Morlet wavelet?
Im trying to use morlet wavelet to reduce noise in my signal.
I found formula for morlet wavelet
$$\Psi(x) = \frac{1}{\sqrt{\pi\cdot bandwidth}} \cdot exp(i \cdot 2\pi \cdot centerFreq \cdot ...
4
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1answer
2k views
Adding Salt n Pepper noise into an Image manually
When i looked in to the algorithm of Salt n Pepper noise in a Matlab i've found this,
...
6
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1answer
185 views
laser speckle noise reduction
I'm trying to process an 1D signal containing a waveform of 100000 pixel.
As it was acquired with a laser scanning system, and therefore it is corrupted by some annoying speckle noise.
I tried to ...
2
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5answers
407 views
How can I measure noise and sharpness of an image?
I'm working on a project which ranked some images based on quality.
For this project, I want to figure out the noise and the sharpness from a image.
To calculate the noise (from a CCD-Sensor) I ...
2
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0answers
135 views
Equivalent number of looks (ENL) calculation
As stated in gagnon1997speckle in paragraph 2.2, under the unit-mean noise assumption one can say that:
\begin{equation}
ENL = \left(\frac{\bar{y}}{\sigma_{y}} \right)^2 = \frac{1}{\sigma_{n}^2}
...
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1answer
141 views
determining FEC or parity bits from percent error
I am very new to signal processing and my background is in physics. I would like to know if it is possible to determine the number of parity bits needs to theoretically get 100% transmission from a ...
5
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3answers
260 views
How to de-noise raw sound data
What techniques/algorithms can I use to remove noise from a raw recording of sound (voice)?
The purpose is to get a smoother graph (removing the "jaggedness"). What I have tried was to average-out ...
