# Questions tagged [signal-analysis]

The processing of signals for the purpose of extracting a parameter or property embedded in a signal. Signal goes in and far fewer numbers come out.

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66 views

### Method for splitting time-sampled signal into two signals

Update: the yellow area in the graph below can be ignored, it shows power produced. I'm only interested in the blue line, and how to separate power consumed by the heating system from the rest. I have ...
95 views

### Understanding FFT output oscillation around y-axis

I am looking at the output of the FFT and trying to understand the meaning of the real and imaginary parts of the output. My signals (real in time) are comprised of tonal peaks and the magnitude of ...
51 views

### Why HRV is considered as "irregularly time-sampled sequence"?

HRV is heart rate variability. As far as I understood, it is the time interval between two consecutive R peaks in the ECG signal. So an HRV dataset may contain two columns, one containing the interval ...
211 views

### Finding the maximum frequency deviation and phase deviation

I'm trying to solve a problem regarding communication and I'm stuck. The questions asked me to find the maximum frequency deviation are usually written in cos or sin wave. But this question isn't, so ...
343 views

### Real time FFT - Wouldn't zero-padding a signal at the end distorts the output?

I have looked at previous similar questions, but I am still not very clear on this. Most real-time or otherwise fft functions suggest adding zeros at the end of the input to make the sample size an ...
52 views

### Origin of the definitions of 16 types of discrete normalized/non-normalized Sine and Cosine transforms

I am a Ph.D in pure math. In the literature of signal processing, I observe that 16 types of discrete normalized/non-normalized Sine and Cosine transforms are being extensively studied. They have some ...
1 vote
1k views

### Discrete Time Signals - Time Scaling and Time Reversal

On the top graph, we can see a discrete-time signal $x[n]$. I don't understand how for the signal $x[3-n]$, the impulses with magnitude $1$ still are at the positive indices $n = 1, 2, 3, 4$. Why ...
1 vote
65 views

### Emperical mode decomposition problem

I am using Empirical Mode Decomposition (EMD) algorithm to decompose a vibration signal generated by outer race bearing defect using case western réserve University data. I am facing a problem: unlike ...
366 views

### What is inverse Fourier transform of real spectrum?

I am trying to retrieve the origin signal in time domain (or path-length domain) from a spectrum obtained by CCD-matrix of interferometer. I understand how to transform a real signal in the time ...
1 vote
13 views

### VNA based calibration of RF equipment relative to discreet time domain measurments

I am looking for methodology on how to correct data for losses present in RF signal paths. The basis for my objective is to convert an discreet time domain signal into the frequency domain with an FFT,...
1k views

### FFT of signal data with windowing, overlapping and averaging

This is my first ever question here so the help is really appreciated. I am performing FFT on a signal. I want to perform windowing, 50% overlapping and averaging to the signal. There is a function <...
86 views

### USRP Frequency Drift Measurement

I trying to measure the frequency drift between two N210 USRPs using GNURadio Companion. I used one USRP as a TX and the other one as an RX. The transmitted signal is a complex sinusoidal. The issue ...
132 views

### What does the signal of $y(n) = x(n^2)$ look like?

The original signal is at a) in the image below, and I'm confused as to what the exponent on the dependent variable does to the signal, so can anyone point me to where I go wrong and how do I actually ...
90 views

### Represent a sinusoid by other sinusoids of different frequencies

Can a sinusoid with unknown frequency be constructed from other sinusoids with known frequencies? Are there any theorems for this problem?
812 views

### The normalization of the autocorrelation function and how it changes the definitions you've learned about signal analysis in communication systems

Since this question is book-oriented, I will kindly ask you to accompany it with a book that is considered by many researchers the bible of Digital Communication: Proakis - Digital Communications, one ...
394 views

### Why is ARMA preferred instead of AR?

ARMA basically is an AR model which considers past inputs to the filter as well. But what is the benefit of taking past inputs to the filter if we are considering real-time processes which are all ...
39 views

### Significance of poles in a Transfer Function

Sorry for asking this basic question, but I am new to signal processing and have this doubt for a long time. I have been studying signal modelling and have $$H(z) = B_q(z)/A_p(z)$$ where $A_p(z)$ ...
30 views

### How can I get a single object's audio response from a pair of colliding audio?

Problem and backgroud Two objects $A$ and $B$ are colliding and produce audio response $x_{AB}(t) = x_A(t) + x_B(t)$, where $x_A(t)$ and $x_B(t)$ are audio produce by these two objects individually. ...
371 views

### Why do we have a negative gain after a certain point in frequency domain for a channel filter?

Why do we have a negative gain(i.e. not negative as in polarity but gain < 1) after a certain point (1500 Hz). What is the reason and purpose for this. Why is that point the same for both DC and AC ...
1 vote
2k views

### Detecting and Removing Noise from Signal using Python

Through this platform, I want to ask that how can I remove unwanted noise from the signal when you do not have much information regarding the frequency at which they appear? Data is collected from an ...
45 views

### How to normalize Loudness on different Android Smartphones playing same audio simultaneously?

I have been working on a conference solution based on a smartphone grid. Right now, I am stuck on Android Smartphones. Although I have managed to normalize loudness programmatically when it gets ...
202 views

### Construct complex signal from a real-valued time series and Hilbert transform

I have a time series measurement $v(t)$ from a physical nonlinear system and its power spectrum $E(f)$ look like the following From a theoretical point of view, the solution of the system is modeled ...
168 views

### Calculate noise variance from a given SNRdB

I was analyzing the following code for the MRC scheme from the book MIMO-OFDM Wireless Communications with MATLAB. Here, I am not able to understand based on what logic the sigma value calculated <...
96 views

### What is the difference between Yule Walker and Modified Yule Walker Equation that used in Stochastic Signal Modeling?

Our Professor couldn't explain the clear difference between the Yule Walker equation and the Modified version of it that is used in Stochastic models. Please explain both the equations and why we ...
180 views

### How to detect signal in spectrum without empirical data

Let's say, I have got a spectrum of a signal with noise using fft: For a human it's pretty obvious that there is a signal with a frequency of about 51Hz. But what is the mathematical apparatus behind ...
1 vote
134 views

### How are discontinuities in quadrature modulated signal QAM physically produced?

In quadrature modulated signals, for instance: I am unclear how the "discontinuities" in the waveform at the junction of each data point can be physically produced? Taking a speaker as an ...
99 views

### Synchronization of two noisy sinusoidals signals

I have two noisy sinusoidal signals and I am currently investigating solutions to synchronize them using python. Here is an example I made to illustrate my goal, supposing that I generate these two ...
1 vote
70 views

### FFT vs Harmonic Analyzer

I watched this video by Engineer Guy and decided to build the same, but digital. I did it, but I decided to also calculate the sine, to have a complete complex number and be able to calculate the ...
42 views

### If I have this discrete time sinusoid composed of a sine and a cosine, how do I find its period?

$$x \left[ n \right] = 3 \sin \left( 4 \pi n \right) + 2 \cos \left(0.36 \pi n \right), ~~~ 0 \leq n \leq 100$$ The fact that my signal is composed of both sine and cosine makes it tricky for me.
1 vote
81 views

### Conceptual clarification of Sampling theorem

I am new to signal processing. We were introduced to the sampling theorem and intuitively I am struggling to make sense of it: There are 3 points I am struggling to comprehend: The analog signal: the ...
59 views

### Measurement of blocking artifacts in images

I want to define a threshold for maximal blocking artifacts in an image. What is a good key value to measure blocking artifacts? I have no reference image non natural image Example: I looked into ...
45 views

### how to differentiate between random and impulse signals using MATLAB or python?

I have data collected from an experiment of shaking a 4-storey steel frame using a shaker and responses were recorded using accelerometer sensors. I realised that in the dataset some of the signals ...
123 views

### Best signal processing method for recognising changes in accelerometer results?

I am new to signal processing and trying to build a gadget that hits an object and recognizes fractures and weaknesses in it using an accelerometer attached to a hammer. I have some initial results ...
245 views

### Can we detect WiFi from Spectrograms using signal processing?

I'm looking for some suggestions on detecting wifi using spectrograms (abs magnitude only) . My project involves a wifi driver which outputs a spectrogram whenever it scans the channel . Can we use ...
243 views

### Phase Unwrapping Issue of IQ data sample in Radar Signal Processing

I am doing radar sensor signal processing. The radar sensor gives iq data corresponding to the range (sweeps). I want to detect micro motion so that phase analysis is used. Sweep is the distance ...
51 views

### What are some approaches / algorithms for reducing size of numerical data of large size with redundancies?

I'm dealing with bunch of .asc(ascii) files that are the output of continous monitoring of various electronic equipments for certification purposes. We monitor various parameters of the equipments ...
2k views

### How do you find the null to null bandwidth for the signal below?

My tutor does not explain it very well. Can someone please explain to me the reasoning and what null to null bandwidth actually is?
150 views

I am trying to generate a simple Gaussian pulse that has a 1 ns pulse width. However, when I generate the pulse, I realized that I did not meet the condition that calculates Rayleigh Bandwidth (1/...
98 views

I am trying to create a sine wave in PLL output with Simulink. But I get a square wave from the VCO block even though PFD, charge pump and loop filter outputs are correct. The VCO block says that only ...
236 views

### A self-supervised learning technique to denoise my specific signal

So I work in this domain of biophysics that has to do with a light-based detection for measuring small movement of molecules (nanometer and piconewton scale) via a Quadrant Photodiode. This signal ...
215 views

### Detecting and measuring flatness of an analog waveform

I acquire an analog waveform and I expect it to have some local flatness (post-filtering). The waveform's exact shape is unknown but some rough characteristics (peak amplitude, duration, rise time, ...
979 views

### Wavelet transformation to analyse time series

I am new to wavelet transformation. I am learning it as a tool for signal processing. I have a time series that I want to analyze. I tried to learn wavelet transformation by applying it to a periodic ...
777 views

### Odd artifacts after sinc interpolation

I am trying to upsample a signal using sinc interpolation. I have written a way to do this in python. ...