# Questions tagged [signal-analysis]

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15k views

### Is deep learning killing image processing/computer vision?

I'm looking forward to enroll in an MSc in Signal and Image processing, or maybe Computer Vision (I have not decided yet), and this question emerged. My concern is, since deep learning doesn't need ...
38k views

### Meaning of Hilbert Transform

I understand the Fourier Transform which is a mathematical operation that lets you see the frequency content of a given signal. But now, in my comm. course, the professor introduced the Hilbert ...
33k views

### What is the difference between linear and non-linear filters?

How a mean filter is called as linear filter and a median filter is called as non linear filter? I understand how a mean and median filter operates, but I was not able to relate with the term linear ...
3k views

### Show others how I hear myself

Sooo .. I've been thinking about this stuff. We all know that we sound different from what we hear of our own voice. It is easy to find out how others hear us by recording oneself and listen to it. ...
24k views

### Help calculating / understanding the MFCCs: Mel-Frequency Cepstrum Coefficients

I've been reading bits and pieces online but I just can't piece it all together. I have some background knowledge of signals / DSP stuff which should be enough prerequisites for this. I'm interested ...
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573 views

### What kind of modulation is this?

I'm trying to find out what kind of modulation and encoding is used by my window cover remote control, aiming to implement the same on a Raspberry Pi to add a bit of home automation. A colleague ...
3k views

### Why complex numbers are represents as a+ib and can't be as (a,b)?

I am confused as why do we need to represent the complex numbers with the imaginary y-axis if we can simply represent them as (x,y) ? I've read that Multiplication by i is an anti-clockwise rotation ...
380 views

### Which sections to cover for my graduation thesis on blind source separation?

I'm not sure if I'm on right place to ask a simple suggestion, so please be kind and don't downvote my question. I'm not asking someone to do it for me, I just need short guidance how should I proceed....
7k views

### When Is a Kalman Filter Different from a Moving Average?

this thread asks when a discrete time Kalman filter is better/different from a simple moving average of the observations: Why use a Kalman filter instead of keeping a running average? there's no ...
425 views

### White noise DC component

I'm really new to DSP, I'm actually studying Computer Science and took an elective on DSP so my knowledge is pretty limited. I've learned that pure white noise signal for example has all possible ...
354 views

### Acoustic Scenarios With Negative SNR

For all the practicing engineers out there: Where have you encountered a negative SNR? How negative, in dB, was it or estimated to be? Where would you expect to encounter a negative SNR? Note: I ...
4k views

### What are some methods for detecting a sinusoid in noise?

I'm looking for a broad classification on the kinds of techniques available. Something I can use to begin a literature survey. Some details: should be feasible for real-time implementation. Binary ...
3k views

### eigen values and eigen vectors of signal

What does the Eigen values and Eigen vector of a signal or function represent? What is its physical significance? I know about basis vectors of a signal which constitute the orthogonal planes where ...
3k views

### Magnitude-squared Coherence calculation inconsistence

I have to calculate the magnitude-squared coherence (MSC) between two signal. However, using a routine that uses only one taper (or no tapers at all) my result is always 1, despite the signals are ...
2k views

### Random sampling vs uniform sampling

In this paper of Lustig, he speaks about a something which appears unintuitive: sampling at random may exhibit better performance than sampling uniformly. I tried to understand this starting from page ...
3k views

### How can a signal be both periodic and random?

Do any examples of such signals exist where the signal is both periodic and random? Because as I see it, if a signal is periodic then the randomness kinda goes away because you know what the signal ...
3k views

### How to derive the results that averaging $N$ signals yields a $\sqrt{N}$-fold increase in signal-to-noise ratio?

If I have understood correctly, averaging $N$ noisy independent segments or signals increases the signal-to-noise $\sqrt{N}$-fold. How does one derive this result?
173 views

### Signal Processing for Discrete Events

This is less a specific question, and more... "what is this called" and "where can I read more about it"? Several times in my career, I've had to work with datasets with "discrete events". Lets say ...
7k views

### Generalized Cross Correlation

What is the definition of Generalized Cross Correlation? I need it for estimating the delay (time offset) between two audio signals. The time offset between the two signals might be as large as 500ms....
4k views

I've been trying to understand the concept of the Kalman Filter. I came across this great article which makes the concept sufficiently clear. However I could not understand the concept of the matrix $... 3answers 2k views ### Compressive Sensing Incoherence Principle As people acquainted with Compressive Sensing would know, incoherence and sparsity are two main principles. I've been reading about compressive sampling and developed an interest into the topic. What ... 2answers 74 views ### As of 2019, which discrete nonlinear, time-invariant systems with memory are considered “easy” to model and identify? There are several types of discrete nonlinear time-invariant systems with memory ("NTIM") which are considered "easy" to model and identify. Any such system can be represented using a Volterra series, ... 6answers 388 views ### The Least Norm Solution of Under Determined Linear System Suppose I have a matrix $$A= \begin{pmatrix} 1 & 0 & 1 & 0\\ 0 & 1 & 1& 0\\ \end{pmatrix}$$ where the variables are channel information like assume$X_1$,$X_2$,$X_3$... 1answer 4k views ### Signal filtering using Python I'm trying to create an application using python that is capable of recording an audio signal and detecting short glitches in the signal. For example, I could be recording a 1000Hz sine wave and ... 3answers 2k views ### How to remove text region in a document image? or extract image from a document image Given a document image (i.e. newspaper), how to extract photos in it or remove text region? I think traditional OCR methods may not be suitable here, as I don't need to recognize the text, and OCR is ... 3answers 155 views ### Window functions with rippleless spectra On Wikipedia I found the Hann-Poisson window, and the article claims the spectrum is smooth, but it isn't theoretically smooth, as it turns out. In practice you achieve partial smoothness by jacking ... 2answers 2k views ### Periodicity of the output of causal time-invariant systems when the input is periodic For time-invariant systems, if the input is periodic, the we can argue that the output is periodic: If we shift the input signal one period, we come up with the same signal as before, and since the ... 2answers 228 views ### Finding the maximum of a real valued trigonometric polynomial I have been posting all over SE looking for a good method of finding the maximum of a trigonometric polynomial. A trigonometric polynomial is the sum of a set of sinusoids,$$a_0 + \sum_{k = 1}^{N} ... 1answer 473 views ### Assumptions for Hurst exponent calculation Are there any general assumptions for the calculation of the Hurst exponent? Does the signal need to be stationary, for example? Does it depend on the method? What about the length of the time ... 1answer 180 views ### Representation of frame image pixels In paper Human identification using gaits Section 3.2, the authors explain how to represent a 3D image (x,y,t) into 2D image with (x,t) ; (y,t) denoted 1D signals. I have a conceptual doubt which is ... 3answers 5k views ### 1/3 Octave Analysis Good Morning! I am new in signal processing and I am trying to do a work in noise control of an electronic steering lock device (ESL). My aim is to calculate the loudness (Zwicker Method- ISO 532 B) ... 3answers 324 views ### Is Linear Prediction ever exact? I'm just learning about linear prediction and was wondering whether or not there are any signals that would produce no error if run through a linear prediction algorithm. I was thinking (maybe naively)... 3answers 472 views ### Lower digitisation rate for long distance communcation Why is it that usually lower digitisation rates are used for long distance communications? e.g. sound is highly distorted in undersea communications, is this because of the lower digitisation rate ... 3answers 1k views ### Why does signal averaging reduces noise levels by more than$\sqrt{n}\$?

I have an electrophysiology signal, which is time-based. It basically measures neural activity in the form of potential differences over time. The noise in this signal is assumed to be a random ...