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Questions tagged [signal-analysis]

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0
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1answer
89 views

RF signals database

I'm trying to learn more about RF signal modulation/demodulation. I wanted to experiment with some real signals, but I don't have any data to work on. Is there any open database of RF signals? Like ...
0
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0answers
36 views

How can we find the signal power of $x_{out}(t)=\frac{1}{2}Am(t)\cos \theta$?

I am trying to solve the following question: I have partially worked out the problem and we have: $$x_{out}(t)=\frac{1}{2}Am(t)\cos \theta,$$ which is the output of the LPF. and $$x(t)=Am(t)\cos (2\...
0
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1answer
118 views

Time-invariant and Time-varying Systems

Determine whether the following system is time-invariant or not: $y(t)=x(t)\sin 10\pi t$ Solution: Given: $y(t)=x(t)\sin 10\pi t$ $y(t)=T[x(t)]=x(t)\sin 10\pi t$ The output due to input delayed ...
4
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2answers
80 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!
0
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0answers
23 views

Correlation of the amplitude and angle, and various modulations

I am trying to determine if a signal exists at a frequency by sampling, shifting and downsampling (to get the baseband), and autocorrelating the result. The signal is IQ samples from an SDR. I have ...
0
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0answers
29 views

DSP Hardware recommendation or is it even needed?

I'm new in embedded programming. Trying to choose a dsp, they seem very feature rich for my planned usage. I want to analyze 18 signals (simultaneously or near simultaneously) real time. I want to do ...
4
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3answers
583 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 ...
1
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3answers
82 views

Demonstrate that $x(t)$ and $\hat{x}(t)$ are orthogonal

I have to demonstrate that a function $x(t)$ and his Hilbert's transform are orthogonal, it is said: $$\int^{\infty}_{-\infty} x(t) \cdot \hat{x}(t) dt = 0$$ I have tried the exercise using Parseval'...
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0answers
129 views

How to calculate THD+N from signal

Currently writing a program to measure the distortion of audio receiving signals(FM signal). I am studying audio's signal distortion analysis. I have survey THD+N's knowledge on the Internet. But they ...
0
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1answer
94 views

Instantaneous velocity and displacement from acceleration signal using a proper filtering method

first I need to mention I'm new to signal processing. here is the situation: I have an acceleration time-series derived from an accelerometer I wanted to imply a filtering method like high pass ...
0
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1answer
42 views

filter design steps and process [duplicate]

I started to learn MATLAB and reading paper.i have faced difficulty where to start, how to start in the field of biomedical signal filtering (fNIR)?
1
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0answers
38 views

I am Confused in basics [closed]

WHAT IS signal means, how is it propagate in space or any other medium?. what power means signal amplitude increases and decreases to draw the sine wave form through a bit of time. at stable ...
0
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1answer
52 views

Recommended literature to learn essential aspects of signals and its propagation [closed]

Where can I learn about signal's features. For instance mean, power, amplitude, frequency, energy, how they propagate in space or any other medium?. What power means its amplitude increases and ...
0
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0answers
312 views

What's the difference between Chirp-Z Transform and DFT?

For a part of signal with length N $\left\{x[n]\right\}_{0\le n <N}$, I can analyze any range of frequency by using CZT. But for DFT, $\hat{x}[k]=\sum_{n=0}^{N-1} e^{-i\frac{2\pi}{N}nk}x[n]$, I ...
1
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0answers
109 views

NMSE of complex numbers

Actually I am doing an RF measurement and this includes phase and power. i generate a list of powers ranging for example from (-50 to 40) dBm, while the phase rotate to make it for example spiral ...
1
vote
1answer
146 views

FFT Frequency bin relationship

I guess this is a stupid question or it is not clear. I will try again I have a situation where I take the fft of a combined source, both at the same frequency but at different locations. I am ...
0
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1answer
94 views

Distinguish between sinusoidal oscillations and rythmic pulses

I want to distinguish between a sinusoidal oscillations and rythmic pulses. Which method can i use to do that? I want to implement a detector that can distinguish between this two types of signals. ...
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0answers
42 views

What is meant by finite action signal

In section 1.3 from Signals, Systems and Inference, Alan V. Oppenheim, George C. Verghese. Finite-action signals, which are also called absolutely summable signals, are defined by the condition \begin{...
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2answers
270 views

Quantify the difference between two audio spectrograms

I have two speech signals of the same length. They contain the exact same speech content but are recorded from two different microphones. I want to compare the differences between them. 1) Assuming ...
-3
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1answer
72 views

Can we find the skewness of Fourier coefficients?

Can I find skewness of the Fourier coefficients (the coefficients obtained after taking FFT of a 1D signal)?
0
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1answer
126 views

Frequency extracted from MATLAB's $\tt fft$ is not very accurate

As a test I made up a sine wave in MATLAB of this form y = 5*sin((2 * pi * freq).*x + 1.4) - 6; where freq is ...
0
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2answers
85 views

Alamouti Scheme. MISO. STBC for real constellation

I have a real orthogonal design for codeword... $$ \begin{bmatrix} s1 & s2 \\ -s2 & s1 \end{bmatrix} $$ $$ s=\begin{bmatrix} s1\\ s2 \end{bmatrix} $$ $$ Y^T=\sqrt{\frac{P}{Mt}} h^T ...
1
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0answers
31 views

Sourse separation from known underdetermined mixing matrix

How to recover uncorrelated N sources from given N-1 signals and known mixing matrix M, (e.g. 9x8 matrix)? If I just use pseudo-inverse matrix M+, my source estimates are correlated with each other ...
0
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2answers
185 views

Why look at power spectral density for stochastic processes?

I have been told that for deterministic signals, it makes sense to look at their respective Fourier transforms/spectra. For stochastic processes on the other hand, I am supposed to work with power ...
0
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0answers
18 views

is there a way to separate transients by length?

Suppose we have a mixture audio signal, consisting of very short transients and some that are a bit longer (in ms, or s) along with other material, like harmonics, etc. But focusing only on transients,...
1
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2answers
98 views

Don't understand what is meant by signal dimension

I don't understand the concept of dimension of a signal. I ran into it in an explanation of Shannon Capacity, and in a paper on spread spectrum. I was hoping somebody could explain with an example. ...
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0answers
28 views

Stress analysis via Voice Signals (EMD, Hilbert Transform etc.)

I have several questions about our graduation project's voice signal processing part: 1) Is it necessary to use Hilbert Transform to get IMF's after the execution of EMD with input of WAV. file? 2) ...
0
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2answers
299 views

Understanding the definition of signal's bandwidth

In class, we have defined bandwidth of a signal as the difference between the maximal and minimal frequency. Also, our tutor explained that the bandwidth indicates how fast the signal is changing. ...
0
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0answers
64 views

Frequency Response Question on LSI System

Someone please explain me the question its seems very complicated to me. I just want know what the question asking and how to solve it i dont want fully solved solution. Thank you!!
0
votes
1answer
120 views

Phase of FMCW linear chirp

I'm doing a project involving FMCW linear chirp signals. Given the phase $\phi = 2\pi\frac{k}{2}t^{2} + 2\pi f_{c} t + \theta$ where $k$ is the frequency increase rate. When transmitting ...
0
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0answers
70 views

How to recover signal after spectral subtraction

I have done spectral subtraction on noisy speech signal. I want recover original signal after the spectral subtraction. I have done reverse of FFT and deframing of signal using following code but ...
-1
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1answer
47 views

Finding number of independent samples using autocorrelation

I have a pressure signal (y) with 512000 samples and with a sampling frequency ...
0
votes
1answer
136 views

how we can prove that the Variance of (white Gussian noise) is average power of the noise? [duplicate]

White Gaussian Noise PSD is fixed No/2. So how we can investigate that noise variance is average power of the noise?
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0answers
12 views

Obtaining a fixed number of wavelet coefficients from variable-length inputs

I recently discovered wavelet transforms, and have studied some work done using them to create (meta-)features for machine learning classifiers. However, all the work I've seen thus far uses images/...
0
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0answers
33 views

In NMF: How to decide which matrix can be applied group sparsity constraint

In simple setting, my signal has specific pattern peak detected at some minutes like in $V$ matrix. I have prior knowledge that $V$ can be mixed from 6 patterns which is belong to 2 groups but cannot ...
0
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0answers
68 views

I want to understand the Dual Tree Complex Wavelet Transform

I want to understand the dual tree complex wavelet transform for vibration analysis of motor faults.I search a lot of books and materials but couldn't understand Can anyone recommend me a book or ...
1
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0answers
53 views

Beamforming with NDP frames

During beamforming, the Tx first sends NDP Announcement (which is a broadcast frame) thereby reaching all Rx in its area. And then it follows by sending NDP. Is the 2nd frame (NDP) is also a ...
0
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1answer
52 views

Transmission frquency in MIMO-OFDM system

What I understand in MIMO system, the user data is broken down into several chunks and transmitted over the antennas (say 3 Tx antennas) by using same frequency Fc. In order to use the interference as ...
1
vote
1answer
254 views

Octave: Finding the mean fundamental frequency given an audio signal

I have an audio .wav file of someone's speech of which I want to find the mean fundamental frequency. Till now, all I have managed to do is load the data into a vector and (roughly) filter the silence ...
0
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1answer
36 views

Echo effect on sinusoidal input: Intuition

I am currently reading about adding echo effects on signals. I was wondering if my understanding is correct. In the attached figure, the blue line represents the original signal and the red line is ...
4
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3answers
720 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 ...
0
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1answer
90 views

Wavelets and bank filters

The wavelet transform has a problem as it gives poor time resolution for low frequencies and poor frequency resolution for high frequencies according to uncertainty conditions. This appears well ...
0
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1answer
354 views

How channel state information is calculated from Sounding Packet

What I understand is for Explicit Transmit Beamforming scenario, the Transmitter sends an NDP packet(aka HT Sounding) which consist of OFDM training symbols in packet preamble (HT-LTF) which are ...
0
votes
1answer
437 views

Determining Causality From Discrete Impulse Response

Trying to wrap my mind around the concepts of this one... Consider the following impulse response $h[n]$ for a linear, time-invariant system: $$ h[n] =\left\{\underline{1} , -2, 2, -1\right\} $$ ...
0
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1answer
50 views

Measured signal from tachometer has ripples, why and how to minimize?

I don't know if it would be straightforward enough to chalk it up to this being a real system. Thus there's friction and physical mechanics of gears and teeth pulling.
0
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2answers
193 views

Confused about how Echo filter diagram works [closed]

The picture above is the block diagram of an echo filter. My question is, how does the delay, and gain block affect the output signal? I think that when the input signal is outputted with a delay from ...
0
votes
1answer
26 views

Suggest me some good references for sonification

I need good reference books/tutorials/doccumentations on sonification. Please suggest me some books or other references from which I can learn about sonification and algorithms of sonification. ...
0
votes
1answer
42 views

Signals and Filters 101 [closed]

I am a complete novice to the world of signal processing, and I am an environmental engineering grad by degree (i.e. zero background in signals/systems). We acquired a couple sensors and a data ...
-1
votes
1answer
89 views

Weird noise floor slope when capturing with USRP E310

I'm experiencing a weird effect on my captures. It may just be due to my bad dsp understanding. I'm using an E310 SDR platform to capture a multitone (4 carriers) signal: Fc = 150 MHz Bw = 286 KHz ...
1
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2answers
222 views

IQ data QPSK Demodulation

I have an IQ data of QPSK signal , when I apply a PLL loop I obtain constellation in figure below. What is this phenomenon, and how can I obtain the good constellation?? The second figure is about ...