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1500 questions
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2 answers

Frequency resolution and timestep in DFT

I am learning DFT and I am not sure I understand it correctly. I am just going to write out the process of DFT and I am asking you to tell me if I am thinking the right way. Suppose we have a signal on which we run DFT to get the frequencies…
c0dehunter
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IIR Filter for Smoothing (Low Pass Filter)

I am using IIR filter for smoothing $$y[n] = ax[n]+(1-a)y[n-1]$$ My question is, if I add another IIR filter, will it be the second order of IIR filter? If not, what it can be called? My second filter is $$y_2[n] = ay[n] + (1-a)y_2[n-1] $$
user4234
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Derivation of fixed-point $\tt atan2$ with self-normalization

I'm trying to understand the maths behind this Fast fixed-point $\tt atan2$ calculation with self-normalization. In particular, equation $(2)$ for theta1 appears to provide a first-degree expansion of some series. Similarly, equation $(2a)$ under…
bcs
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FFT-based fast convolution vs IIR filtering

I'm doing an multichannel audio equalizer system on a chip, which is parametric EQ, usually implemented in cascaded biquad IIR filters. My problem is that I use a lot of IIR filters due to multiple frequency bands (such as 10 bands), and I'm…
DSP novice
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1 answer

What is the relationship between beamforming and Independent Component Analysis (ICA)?

My first inclination when thinking about the Cocktail Party Problem would be to use adaptive beamforming to isolate different signals, but this does not seem to be how the problem is commonly thought about. Indeed, basic ICA assumes the signals all…
Gillespie
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Clear understanding of compressed sensing

I am trying to get a clear understanding of how compressed sensing works. A continuous signal $x(t)$ is under-sampled (less samples are collected than the numbers required by the Nyquist theorem). The signal is sampled using a random matrix $\Psi$:…
Brett Cooper
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Vehicle segmentation and tracking

I've been working on a project for some time, to detect and track vehicles in video captured from UAV's, currently I am using an SVM trained on bag-of-feature representations of local features extracted from vehicle and background images. I am then…
Jono Brogan
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Scanning from Book - Gradient Removal

This sample image: is warped on the left side. I don't want to dewarp, but just to remove shadow gradient (caused by book's spine). I guess gradient can be calculated from upper part of the image and that information can be used for reconstruction.…
zetah
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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 very different colors and if I look at the histogram…
Ann Orlova
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2 answers

How to soft decode DQPSK?

I'm successfully soft-decoding D-BPSK by taking the dot-product of the constellation-position of the symbol and of the previous symbol. If the result is >= 1, then the symbol phase hasn't changed and the bit is a zero. If the result is <= -1 then…
Dan Sandberg
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What is the exact meaning of unstable system in DSP?

In physical systems I understand what is the meaning of stability or unstability. An operational amplifier for example, if working in positive feedback will either saturate or start osscilating (i.e will not have any stable state). thats clear to…
gpuguy
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What does a "vector" in a hidden Markov model mean?

I know that a Hidden Markov Model (HMM) is used in speech recognition and understand it to some degree. However, what I don't know is how input (speech) is "transformed" to a vector which in later used in HMM. How do you get a vector from a sound…
StupidOne
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What is the definition of a "Symbol"

I’m looking for the simplest, precise definition of a Symbol e.g. The symbols found within a signal The signal has a N symbols per second I'm following this tutorial. The fellow defines the term symbol informally as "different states" and I do…
user13764383
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DSP programming in C/C++

I have exposure to MATLAB and have some basic exposure to signal processing and plotting in MATLAB... but I am more comfortable with C/C++ than MATLAB because I have been working in Image processing with OpenCV... I was just curious: Is there any…
rotating_image
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PC-to-PC data communication over Sound FSK / PSK / DSSS

For fun and work I've to implement a java based application that can Encode text or data to sound and transmit using PC's speaker and on the receiving side is a microphone with decoder software. I was thinking of using FSK (syn or async or suggest)…
geeknizer
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