Questions tagged [terminology]

For questions about words, phrases and definitions that are specific to signal processing.

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26
votes
5answers
7k views

Is there a technical term for this simple method of smoothing out a signal?

Firstly, I am new to DSP and have no real education in it, but I am developing an audio visualization program and I am representing an FFT array as vertical bars as in a typical frequency spectrum ...
17
votes
1answer
5k views

What's the difference between the Gabor and Morlet wavelets?

The Gabor wavelet is a kind of the Gaussian modulated sinusoidal wave (source)   Gabor wavelets are formed from two components, a complex sinusoidal carrier and a Gaussian envelope. (source) ...
16
votes
1answer
16k views

Terminology: spectrum, spectrogram, spectrograph, sonogram, etc

In term of proper or accepted naming conventions of DSP graphics or instrumentation output, what is the difference between the words spectrum, spectrogram, spectrograph, and similar terms, and what ...
10
votes
3answers
2k views

What Does It Mean Exactly When Two Parts of a Signal Are Correlated?

I stumble quite often upon the notion that two or more parts of a signal are correlated to describe semi-formally that they belong together. For example in image processing, two pixels on an edge ...
9
votes
1answer
3k views

Scalogram (and related nomenclatures) for DWT?

My understanding of the scalogram is that, for a particular row, the scores of the projection of the input signal with the wavelet at a particular displacement is shown. Across rows, the same thing ...
8
votes
2answers
12k views

What is the relation between the PSDs of filter input and output called? $R_Y = |H|^2R_X$

If a wide-sense stationary signal $X$ is fed to an LTI filter with the transfer function $H$, the power spectral density (PSD) of the output $Y$ can be expressed as: $$R_Y(f) = \left|H(f)\right|^2R_X(...
5
votes
3answers
467 views

What is energy in image processing?

There are several web articles on the topic, but, after having read them, I still don't know what "energy" is, in the context of computer vision (CV) and image processing (IP). It is related to ...
4
votes
5answers
299 views

Verb for subtracting the mean?

Is there a verb for removing the mean or DC component of a signal? I am trying to name a flag for doing just that. "Normalize" can mean many things, so I don't think that would be a good choice.
4
votes
2answers
660 views

What is the meaning of channel capacity?

If the transmitted information signal takes values from a modulation constellation, then is there a way to know what the channel capacity is? Is there a connection between the modulation kind and ...
4
votes
3answers
4k views

What does 'canonical' mean?

What does 'canonical' mean? e.g. 'write IIR or FIR in canonical form' I get the gist of it but maybe someone here has a precise definition. In a non-DSP context it would mean something like '...
4
votes
1answer
164 views

Is there a name for $f(x) = |x|^n \cdot \operatorname{sgn}(x)$?

I'm looking for a name for the following function $$f(x) = |x|^n \cdot \operatorname{sgn}(x)$$ which is the exponent function, but with the sign stripped from the input and reattached to the output....
4
votes
1answer
214 views

Is there a “first” Fourier transform?

Every time I've read "first Fourier transform", I've assumed it to be a misspelling of the fast Fourier transform. Recently though, I saw the term in both the title and keywords of an article from a ...
4
votes
1answer
1k views

What does double hat mean in Spectral theory?

I was confused about the double hat notation $\hat{\hat .}$ and my teacher and I thought it probably means an estimate of an estimate most of the time, but we could not be 100% sure of its meaning. ...
3
votes
1answer
102 views

Clarifying some notation in Bishop book

In Bishop book, page 4, section 1.1, there's a notation I don't seem to understand what's meant by it. The whole paragraph, with which the section begins, is: We begin by introducing a simple ...
3
votes
1answer
255 views

What do you call it when you add zeros between the elements of a vector?

What do you call it when you add zeros between the elements of a vector? let's say you have x =[1 2 3 4] and ...
3
votes
1answer
57 views

Is there a name for the procedure of taking the FT over separate consecutive small time-blocks?

Suppose we have a continuous time-interval $I=[a,b]$, and a signal $x \colon I \to \mathbb{R}$. A procedure that is sometimes carried out (e.g. when doing bispectral analysis) is to partition $I$ ...
3
votes
1answer
3k views

Difference between order and length of a filter

Let, the channel be modeled as a FIR model with order L. Mathematically, $y_n = \sum_{k=1}^L h_k u_{n-k} \tag{1}$ where $u$ is the data input to the channel and <...
3
votes
2answers
2k views

Radar terminology - Specific meaning of “video signal”

In the radar literature, particularly in older references, the term "video signal", "downrange video", or just "video" is used to describe the radar signal at a certain point in the processing chain. ...
3
votes
1answer
91 views

Limiter, compressor, AGC, dynamics processor?

What are the primary differences between the usage or definitions of the terms “AGC”, “compressor”, “limiter”, and dynamics processor? They all seem to be forms of playing with gain knobs.
3
votes
1answer
208 views

Help in understanding from book expression of variance of an estimator : PRBS vs real valued input

The question is based on Book : Fundamentals of Statistical Signal Processing by Steven Kay, Chapter 4 : Eq(4.21). The expression for the variance of the estimated coefficients when the input is PRN ...
3
votes
1answer
206 views

Difficulties in understanding mutual information concept

What does mutual information (MI) convey? If 2 signals are independent then MI is zero; What does this imply and mean in the case of mutual information of error, and in general definition of MI and ...
3
votes
1answer
151 views

White noise gain of uniform spline interpolation

Uniform spline interpolation is fully defined by its continuous-domain impulse response. I noticed that the integral of the square of the impulse response over its support gives the average ...
3
votes
1answer
79 views

Sinusoidal Wave Terminology

Suppose I have a sinusoidal signal of the form $x(t) = a\sin\left(2\pi b(t-c)\right) + d$. I understand $a$ is the amplitude, $b$ is the wave number, and $c$ is the phase shift. I know that the term ...
2
votes
4answers
90 views

What is the moment when all oscillators aligned to make a jump called?

Say we have a square wave and its Fourier series. When the wave doesn't jump, its oscillators aren't aligned: But if they are aligned, the wave will jump: What is this moment called? They might not ...
2
votes
2answers
3k views

White noise vs. delta pulse and Ultraviolet catastrofe

Everybody explains that white noise has all frequencies equally strong. But, this immediately means that Ultraviolet catastrofe inevitably happens if power > 0 stays constant at any frequency and, ...
2
votes
1answer
253 views

Quadrature demodulation, homodyne detection, lock-in detection - what's the difference?

Quadrature demodulation Homodyne detection Lock-in detection What is the difference between these terms? Are they all synonomous? In my mind they kind of are, so I'm never sure which to use. I ...
2
votes
2answers
86 views

Why use parametric based estimation methods - confusion regarding terms

Using the probability density function (pdf) we can estimate an unknown parameter using methods such as Maximum Likelihood estimation. If the pdf is not available, then Least Squares can be used. ...
2
votes
2answers
87 views

Why Is The Maximum Likelihood Estimation (MLE) Method Taken as the Benchmark for Comparing with Other Methods?

In many research articles the performance of an estimation method is compared to that of the ML estimation performance. If the performance of the method does not achieve the ML estimation performance, ...
2
votes
1answer
167 views

What do certain terms mean in EEG processing describing frequency bands?

I've recently started a project about detecting driver drowsiness with an EEG and came across some terms I didn't quite understood: ...increase in theta activity occur... - ...low voltage theta ...
2
votes
1answer
128 views

What does orthogonality mean in the context of adjacent channels in a filter bank?

First off, what does orthogonality mean in the context of adjacent channels in a filter bank? Secondly, I am reviewing some code in which the dot product of the transfer functions of adjacent ...
2
votes
1answer
129 views

Terminologies - lags, order in time series model

I am facing some difficulties with the terminologies - lag ($p$) and sequence length (number of data points) (N) used in time series model such as Moving average and Autoregressive model. Considering ...
2
votes
1answer
112 views

Is there a scientific name for this technique?

The following algorithm takes a set of signals, and return a complex number: For a given set of signals - $\{s_1(n),s_2(n),...,s_M(n)\}$, compute the DFT of each of them - $\{S_1(k),S_2(k),...,S_M(k)\...
2
votes
1answer
156 views

How to distinguish between the different frequency domains?

Sometimes the terms 'Fourier domain', 'complex frequency domain', 'Frequency domain' and 's domain' are used interchangeably. Take those answers here for example: http://answers.yahoo.com/question/...
2
votes
2answers
111 views

Confused in difference between sequence versus signal?

I am learning basics of signals and systems with MATLAB If i create a vector in matlab such that x=[ 2 5 10 20], will it be considered a sequence or a signal? As ...
2
votes
1answer
1k views

Lloyd Max Quantization and Clustering : Part 1

The Lloyd-Max quantizer is a scalar quantizer which can be seen as a special case of a vector quantizer (VQ) designed with the Linde Buzo Gray (LBG) algorithm. In k-means clustering, we are given a ...
2
votes
1answer
91 views

Sampling distance

In paper: A. Vlad, A. Luca, and M. Frunzete, "Computational measurements of the transient time and of the sampling distance that enables statistical independence in the logistic map," in Proc. ...
2
votes
1answer
20 views

Describing a certain quality of an image

Generally I guess I’m asking for a source of image processing terminology. Specifically here I’m trying to find the word for the quality that would identify the main difference between the Mondriaan ...
2
votes
0answers
133 views

What is the difference between an impulse response and a kernel?

It seems to me they are two terms used to refer to the same concept, but, according to the Wikipedia page on Guassian filter a Gaussian filter is a filter whose impulse response is a Gaussian ...
2
votes
2answers
684 views

Is there a difference between Image Alignment and Stereo Rectification for stereo correspondence or matching?

As far as I know, Image alignment just finds the best fit given two images of the same scene. Whereas Image rectification, with regards to stereo vision, warps the images so that the epipolar lines ...
1
vote
2answers
614 views

Why is second-order Gaussian called Laplacian Gaussian?

We usually use Laplacian of Gaussian as the filter for edge detection or blob detection. But the filter itself is essentially a second order Gaussian. So why do we call it Laplacian of Gaussian? Is ...
1
vote
1answer
2k views

Radar signal processing - Difference between range gate/range bin

In learning about radar signal processing, I see two different terms that sometimes seem to refer to the same thing, but sometimes different things: Range gate Range bin Usually, I interpret both to ...
1
vote
2answers
33 views

What is the technical term for the product of “number of pixels” and “number of channel per pixel”?

Assume I have m x n pixels of an RGB image. If I calculate 3mn, what is the name of quantity for this value?
1
vote
1answer
114 views

What is a periodic signal in image processing?

In the context of image processing (and computer vision), the concept of convolution comes up a lot. Convolution is quite related to the concept of Fourier transform and DFT. In the context of image ...
1
vote
2answers
92 views

Is there any opposite name for Decibel?

According to definition of decibel it’s “logarithmic unit of measurement used to express” So in audio we often convert linear value from range 0 to 1 to logarithmic scale for example like that: <...
1
vote
2answers
520 views

When can the impulse response become zero?

The article Efficient Use Of Sparse Adaptive Filters (Proc. Asilomar Conference, Khong et al., 2006) introduces adaptive filters for the estimation of channels or systems having a sparse impulse ...
1
vote
1answer
1k views

SNR for complex valued signal and when to use SNR and when to use Eb/N0?

This question is in continuation to the one asked earlier Help in understanding the formula of Signal-to-Noise-Ratio (SNR) - Part 1 Consider a model $$y[n] = x[n] + w[n]$$ Signal means the desired ...
1
vote
1answer
163 views

Beginner level : Help with terminologies : smooting length, length of channel, channel equalization delay, blind system identification, equalization

Say the channel model is an univariate FIR filter with true coefficients $h=[1,a_1, a_2 ]$. I am learning algorithms for system identification and channel equalization. For this, I am implementing ...
1
vote
1answer
278 views

Sample vs. sample values

Is there any difference between the terms sample and sample value in DSP? In statistics, those are very different concepts: a sample is a subset of a population: it is a set of random variables. A ...
1
vote
1answer
97 views

Is Oversampling a Signal Same as Discretizing the Signal?

I am confused about the new terminology 'oversampling' I have encountered very recently. To explain it better, I am going to use numerical examples. Now let's assume I am using a BPSK modulator and my ...
1
vote
1answer
169 views

Intuition behind cepstrum analysis terminology

In multiple books I found a parallel between spectrum-analysis terminology and cepstrum-analysis terminology that says low pass filter $\rightarrow$ short pass lifter I didn't read explicitly what ...