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1500 questions
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What is the scaling function and wavelet function at wavelet analysis?

I'm trying to looking the meaning and functionality about scaling function and wavelet function at wavelet analysis. I have googling already. But I can't find and understand the meaning. What does those affect to analysis? Does anyone help me to…
gmotree
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How to fit an ellipse to 2D data

I'd like to find the "best" fit of an ellipse to contiguous, possibly concave shapes such as: What have I tried? I thought that one could assign the direction of the major and minor axes $\vec a, \vec b$ of the ellipse by mapping the pixel values…
Hooked
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Simulating BPSK Costas Loop in Matlab

I am trying to implement BPSK demodulator in FPGA. First, I am modeling the system in MATLAB. Now, I am trying to design Costas Loop for carrier synchronization. This is the block diagram I'm trying to achieve: I'm using RRC as a low pass filter.…
Siraj Muhammad
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How can noise be good?

It seems like (controlled) noise can sometimes be good: dithering in an image, or a softer sound in audio, or white noise alone. Here's a paper on noise improving detectability. My intuition also says that noise in a financial trading algorithm…
Toph
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Advantages/disadvantage of zero padding

I would like to know what are the advantages/disadvantage of zero padding with respect to frequency measurement and amplitude measurement
Shittu Olalekan
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How is the lowpass to bandpass transformation derived?

I'm using a lowpass to bandpass filter transformation: $$ s \leftarrow Q \left( \frac{s}{\omega_0} + \frac{\omega_0}{s} \right) $$ Based on the wiki article: http://en.wikipedia.org/wiki/Prototype_filter which basically is a change of variable. But…
keith
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Efficient calculation of correlation function every $N^{\rm th}$ point

I would like to calculate a long correlation function of length say, 1e6 points. I have a prior knowledge that the correlation peak will be in point k*1000. Is there an efficient way to apply this prior knowledge and perform a shorter calculation. I…
Vlad Sokolik
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Skel to infinity morphological operations on 3D volume

I have a 3D volume image that consists of 2D tomographic images. In MatLab, for 2D images, we can use bwmorph and call for 'skel' operation to infinity to get a pixel thick overall outline of the image. bwmorph cannot deal with 3D images, however,…
Karl
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How can I automatically identify and remove a fundamental frequency and all of its harmonics?

I have some microscopy data that is contaminated by a heartbeat artifact that I'd like to remove. The data consists of a large time series of images captured at ~60Hz. Here's a small example clip in GIF form: I have taken the average pixel…
ali_m
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What is the relationship between poles and system stability?

I see two notions that describe the relationship between poles and system stability. But they are not the same from my understanding The system is BIBO stable if and only if all the poles are in the left half of the complex plane A LTI system with…
Joe
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Low MIPS Video Encoder

I am looking for a low MIPS, low compression video encoder. This is for a 10fps, VGA type quality compression. What are my options? I need to be able to do this compression using a 150MHz ARM M4 CPU with Floating point support. (STM32F4).. My idea…
Ktuncer
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Do Causal Discrete-time systems have proper transfer functions?

In the case of continuous-time systems, if the system is causal, its Laplace transfer function is strictly proper (the degree of the numerator is less than the degree of the denominator). Is this true also in case of discrete-time systems? That is,…
Simone Giorgi
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Analytical Expression for Convolution of Two 2D DFTs

I am trying to do an image analysis problem on some images, and I want to calculate some things in the frequency domain which are giving me problems. Say I have an (discrete) image $I(x,y)$ of size $N_x\times N_y$ (in practice this size is about…
A. Kennard
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Efficient frequency offset estimation of known signals

Let's say that my receiver will be receiving known data signals that range from the very simple (tone) to the complex (known data sequence that is modulated (PSK/QAM/OFDM/etc.)). What are the most computationally efficient ways to get a reasonably…
Jim Clay
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Recommended C/C++ General Purpose DSP Libraries

I am looking to transition some of my MATLAB algorithms to C/C++ for deployment on target (PowerPC and/or ARM). Mostly 1D FIR/IIR filter in this instance. In other domains, there are well-regarded general libraries (both speed and quality) with…
Damien
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