Questions tagged [signal-analysis]

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1answer
185 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 ...
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0answers
31 views

Minimum statistics noise estimate - how to calculate the underestimation factor?

I have implemented a basic noise estimator using the minimum statistics method. Noise power estimate is obtained as a minimum of the short time power estimate within a window of subband power samples. ...
5
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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) ...
4
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5answers
4k views

How to separate a low amplitude signal of same frequency but different phase

I have a signal consisting of two sine waves of same frequency but have different phase (and also a lot of HF noise). Their amplitudes differ by about $120\textrm{ dB}$. How to I go about separating ...
4
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3answers
396 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)...
4
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3answers
474 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 ...
4
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3answers
7k views

Processing Accelerometer Vibration Data With FFT

For a project I am attempting to use an accelerometer to measure vibration in an RC aircraft and determine frequency from the result. To do this I am using an MPU-6000 accelerometer sampling @ 1000Hz. ...
4
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2answers
385 views

Sum of sines sound wave using microcontroller

I need to produce a signal which contains only several frequencies, for example, 17KHz, 17.2 kHz,17.6 kHz. The components I'm using are microcontroller (PIC16F1783 by microchip) which works at 80 kHz ...
4
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2answers
2k views

Extracting audio track to determine the song beat

I'm completely new to this field. Perhaps I'm calling it by a wrong name, but I want to analyze an audio track and retrieve a timestamp to beat mapping. Is there an open source 3rd party library ...
4
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1answer
26k views

How to calculate Signal-To-Noise Ratio

I am doing some analysis in python working with a photodiode. The signal is more or less periodic with some phase shifting in certain areas that give rise to faster or slower periods but overall still ...
4
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2answers
7k views

Feature extraction from spectrum to aid categorisation

i have two sets of signals whose spectrum looks like shown in the figure. The first column of signals belongs to category 1 and the second belongs to category 2. Looking at the spectrums I want to ...
4
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2answers
4k views

Detecting outliers/noise from sensor data

I am trying to detect outliers/noise as indicated on the diagram below from sensor data. Can anyone advice how to go about it? I can only do this in python, so are there libraries in python that I can ...
4
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2answers
18k views

What is the rms value of a signal and how to use it

In some papers/books I found infos about a signal given as RMS value. What is the RMS value and what information does it contain? How can I compute it? Moreover, if they say that the signal is a ...
4
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4answers
2k views

How do I compare chords played on a guitar with a known sample?

I want to create a project that will recognized the chords that i played in guitar. I recorded a raw sound to be compare to the one that the user will input. Example I have a recorded sound chordA ...
4
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1answer
1k views

Corner detection using Chris Harris & Mike Stephens [duplicate]

I am not able to understand the formula, What is $W$ (window) and intensity in the formula mean, I found this formula in opencv doc http://docs.opencv.org/trunk/doc/py_tutorials/py_feature2d/...
4
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1answer
157 views

Guess the frequency response of a filter with little information

I have a processing unit that does a nice EQ filtering on soundfiles. The only thing I can do is : I give the original .wav file, and the processing unit gives me back the filtered .wav. I have no ...
4
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2answers
4k views

infomation about Stockwell Transform

I need some information about Stockwell transform (also known as the S-transform): How can I implement it in MATLAB? *Does it give you the damping ratio $\zeta$ of a signal like the complex Morlet ...
4
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2answers
4k views

Main differences to take into account between continuous and discrete time signals

I started studying DSP and the first things that came out were the differences between continuous and discrete time signals. So, I was wondering if I understood well these concepts before I keep going ...
4
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3answers
722 views

How to Prove a System Is Invertible?

what i know is that for a system to be invertibel it should be one-one , but I am confused that if i am given a transfer function of a LTI system how can I prove or verify if it is invertible. ...
4
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2answers
97 views

Why are LTI filters not able to output frequencies not present at the input?

I know this a very basic question but I'm just having troubles understanding why. Thanks in advance!
4
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3answers
2k views

Removing unwanted peaks from signal

I have a signal which looks something like: The 12 main round peaks is what I'd like to keep. However, the peak detection algorithm I apply is picking up the in-between noisy peaks. Any strategies I ...
4
votes
1answer
413 views

The meaning of $k \delta (t)$

Reading the signal literature I often come across the expression $k \delta (t)$ where $k$ is a constant. I presume this is a notation to suggest we are referring to the area or strength of the Dirac ...
4
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2answers
1k views

How to preprocess signals prior cross-correlation?

Problem Description I have two devices which are measuring the same inputs and are using them to calculate the same (non-periodic) output signal. The process generating the inputs is deterministic. ...
4
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2answers
769 views

Does “keying on” a sine wave at a zero-crossing reduce its bandwidth?

I understand that a pure sine wave of infinite duration occupies no bandwidth, i.e. it is only the modulation of a carrier that gives it sidebands. Does the exact timing of a sudden modulation make ...
4
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2answers
6k views

Removing drift from integration of accelerometer data

I am trying to get a positional data from the accelerometer data using the following steps: Re-zero the accelerometer value Removing mean from accelerometer value First integration of accelerometer ...
4
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3answers
1k views

Large sample rate or large number of cycles when estimating frequency?

I wish to determine the frequency, amplitude and phase of a sine wave with some noise and I can only have a fixed number of samples. Should I go for many cycles and a small sample rate or a few cycles ...
4
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3answers
3k views

Filtering with STFT

I have sucessfully implemented a STFT (+inverseSTFT with perfect reconstruction of original signal, with overlap add, etc.) in order to work on audio files. Using this STFT / iSTFT framework, I have ...
4
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1answer
2k views

Comparing multiple signals for similarity

I have multiple (between 2 and 100) signals and need to determine when a significant number diverge from the rest. We're exploring machine learning techniques, but we also want tackle this as a signal ...
4
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3answers
3k views

Need a better step detection algorithm

I have a time series with lots of steps/jumps (data file here). A plot is given below. I would like to subtract an appropriate value for each of these square wave features to bring them back down to ...
4
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2answers
865 views

How can understand periodicity of a Signal from frequency domain representation?

Is it possible to say a signal is periodic from its frequency domain representation? A periodic signal is sum of its sinus and cosinus. Frequency translation of sinus and cosinus functions are ...
4
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2answers
838 views

Response of a system to a step function (heaviside)

I'd like to compute the response to a step function of a electrical/thermal system. Generally I can "easily" compute the transfer function $H$: $$H(\omega) = \frac{V_{out}(\omega)}{V_{in}(\omega)}$$ ...
4
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2answers
4k views

OFDM transmitter bandwidth

Theory Suppose an OFDM transmitter with four subcarriers is implemented using the structure shown below. If the serial data input rate is 40 bps, each parallel stream will run at 10 bps. ...
4
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1answer
437 views

Estimate the Discrete Fourier Transform / Series of a Signal with Missing Samples

Assuming we have a discrete signal $ { \left\{ x \left[ n \right] \right\}}_{n = 1}^{N} $. Which has a Discrete Fourier Transform / Series. Now, assume I'd like to estimate its Discrete Fourier ...
4
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2answers
586 views

Comb-like peaks in frequency spectrum

I am currently working on a project which involves measuring the sound produced by the onset of a vapour bubble in boiling water. All the experiments went perfectly well and I'm now trying to obtain a ...
4
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2answers
474 views

Convolution of an Image with a Kernel That Is a Product of Two Functions

Suppose that $G(i,j)$ is a Gaussian decay function on the distance between points $i$ and $j$ of an image. In addition, $D(i,j)$ is the difference between the VALUES of the image at those points. Now,...
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3answers
7k views

How to Remove the Periodic Oscillations from a Signal

The task that I have is to remove the annual and semiannual oscillation from a set of temperature measurements, taken over several years, by means of least squares method. I found the method ...
4
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1answer
49 views

Damped spring mass system - parameter estimation

I've tried to calculate the parameters of a damped spring mass system of the form $m~ y''(t)+d~y'(t)+c~y(t)=F(t)$ but I have some problems determining the mass m of the system. The damped ...
4
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2answers
354 views

Removing step-function like noise from signal, knowing when the step functions occur

So I currently have a system which is fit for very short time measurements. Whenever a measurement is long, however, there is a need to continuously update the reference, which, each time, will ...
4
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1answer
3k views

Calculating SNR from Frequency Domain

As I am newbie to signals, I have collected an appliance signal in frequency domain as follows: (PSD- Power Spectral Density). So, I need to calculate the SNR (Signal to Noise Ratio) and BER (Bit ...
4
votes
3answers
930 views

Determine if two signals are the same?

I'm pretty new to signal processing. My data is the $(x,y,z)$ acceleration of someone walking with a smartphone in his/her pocket. Goal Given two signals, determine if it's from the same person ...
4
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3answers
138 views

Classifing audio signals to detect fault

The basic idea i'm working on is automatic fault detection using audio signals captured from Motor. I have like set of sample audio signal which are recorded when there is no fault and with fault at ...
4
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2answers
2k views

Digital filters in LabVIEW

I am very new in signal processing and using digital filters. I have to use a low-pass filter to analyze my data in LabVIEW and have a question about it. Any help and advice is appreciated. I am ...
4
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4answers
3k views

Oscillations on Hilbert envelope

I am trying to extract the decay properties of an oscillating time history. The obvious method for doing this is to use a Hilbert transform. The figure shows an example of a theoretical decay and the ...
4
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1answer
168 views

Signal Processing using Fourier Transform

How can I derive the fourier transform of ...
4
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2answers
743 views

how were DTMF frequencies determined exactly and how can I extend them?

I've been playing with DTMF frequencies and the Goertzel algorithm, and would like to know exactly HOW the DTMF frequencies were determined. I understand that they were chosen such that none of the ...
4
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2answers
8k views

What are Autoregressive Coefficients?

Can anyone explain what are Autoregressive Coefficients? What is their meaning that is. Consider a method: ...
4
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1answer
2k 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 ...
4
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1answer
2k views

Measuring the open loop transfer function in closed loop: what's the better approach?

Considering the closed loop system; $C$,$G$, and $H$ all linear and stable transfer functions, If I chose to excite $\bf r$ and measure $\bf e$, I get the Sensitivity Function, $S$ $$S=\frac{1}{1+CGH}...
4
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1answer
474 views

Can someone let me know linearity, time-invariance, causality, memory characteristic of the system?

The input/output system is $$ \frac{dy(t)}{dt}+2y(t)=2x^2(t) $$ I want to know this is linear? causal? time-invariant? memoryless? According to solution, the answer is 'Linear if zero initial ...
4
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3answers
2k views

Removing unwanted square-wave noise from a signal

I have a signal, s, given at the end of this message. I need to remove the square wave shape from it. The desired signal is actually very small and it has been contaminated by a strong square-shape ...

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