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Questions tagged [signal-analysis]

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0answers
64 views

About the variance of the white noise process

I saw such an example in a book. Assume that the $w(t)$ is a white Gaussian noise with zero-mean and power spectrum density $N_0/2$. Now, consider the sample function: $$n(t)=\sqrt{2\over T}\int_{...
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1answer
21 views

Can I use SINAD for THD+N measurements? Are they inverse of each other?

I'm looking for a clarification, which I haven't really been able to find. It's probably obvious but I'd like to be absolutely sure of what I'm calculating. I noticed that the formula that calculates ...
0
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1answer
31 views

Channel estimation

In single-carrier systems, at the receiver, when we need to do channel estimation and equalization? Do we need to do before timing synchronization and CFO correction or before it? And, please let me ...
0
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1answer
39 views

About the variance of the coefficient of narrowband noise when using signal-space representation

Assume that n(t) is a white Gaussian noise process with zero-mean and power spectrum density $N_0/2$. By using the signal-space representation, it can be expressed as: $$n(t) =\sum_{j=1}^N n_j \...
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2answers
45 views

Energy of a signal

Suppose that $E(k)$ be the energy distribution of a signal in spectral domain with a finite total energy. Is there anyway to concentrates all the energy of signal around a specific point?
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0answers
37 views

How do I window my pwelch function on matlab. I only get an average of the first window

I am implementing a signal processing algorithm to determine tremor and non tremor activity in a signal. The tremors of interest are in the range of 4-8Hz and I need to find the max value for each ...
-2
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1answer
19 views

Signal with spectrum invariant under translation

Is there a signal with a spectrum limited in frequency and invariant by translation: $S(\nu)=S(\nu + \alpha), \alpha \in \mathbb{R}$?
0
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1answer
43 views

Incorrect dominant frequency from FFT

DATA source: Bearing vibration data FEMTO IEEE PHM 2012 challenge. DATA context: Sample rate: 25.6 kHz Sample period: 0.1 Seconds (2560 points) Motor runs at 1800 rpm Steps taken: Low pass butter ...
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0answers
25 views

Methods for subtracting gravity from accelerometer data

This could feel like a repeated question, but please bear with me. In my work we want to compare different methods of subtracting gravity from an accelerometer data to decide on the better way and ...
0
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0answers
23 views

Eigenvalue based detection threhsold of sub-sampled signal

At the receiver side, I have an observed signal sampled at a rate much lower than the Nyquist rate. I would like to know how many frequency components there are in the signal. I applied the singular ...
3
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2answers
128 views

How to find a variance of sample sequence

I have a sequence such as $$r[n] = y[n]v[n]$$ $y[n]$ and $v[n]$ are zero-mean and statistically independent. I need to find a variance of $r[n]$ and show that it is white and equal to $\sigma ^2_y\...
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0answers
34 views

Separating Ultrasonic signal from echo at the receiver

A transducer is acting as a transmitter and a receiver. It keeps on sending pulses which can hit an object placed at 5cm. Echo comes back and hits the transducer while it is continuously sending ...
0
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0answers
27 views

Problem with Spectral Correlation Function for cyclical signal analisis

I am using the autofam() function in Matlab for the Spectral Correlation Function (link: https://github.com/sayguh/MastersProject/blob/master/matlab/sandbox/autofam.m) for a BPSK modultated chirp ...
0
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2answers
99 views

Algorithms for detecting the difference between two signals

If I have two signals $X$ and $Y$, where $X$ is a clean signal and $Y$ is the same signal with linear white Gaussian noise and an amplitudes of $10^{-4}$. How could one use an algorithm to detect if ...
0
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0answers
45 views

retrieving complete 2d autocorrelation function from 2d power spectral density function (numpy.fft.ifft2)

My question is at the boundary between signal processing and python. I have a 2d power spectral density function (PSDF) constructed on Nx/2 + 1 and ...
0
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0answers
28 views

What is wrong with my PSD computation?

I'm trying to calibrate the RX of my SDR Board to become a measuring receiver. I.e, by connecting it to a known source of power (in my case, a frequency generator), at a fixed frequency, I'm trying to ...
2
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1answer
67 views

What Is the Difference between Parseval's Theorem and Plancherel Theorem?

Wikipedia gives Parseval's theorem as follows. Parseval's Theorem , is the Fourier transform of x(t). And Plancheral's theorem is given as , where is the fourier analog. Plancheral ...
0
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0answers
36 views

Matlab: How to implement expectation of product of hermitian matrix

I want to implement the following equation in Matlab: $\mathbf {R}_\mathbf {z}^a(\tilde{f}) = \mathbb {E} \left[\mathbf {z}(\tilde{f}) \mathbf {z}^H(\tilde{f}+a) \right]$, $ \tilde{f} \in \left[0, ...
0
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0answers
31 views

vibration analysis in spherical coordinates

I'm trying to understand some data from a vibration sensor, in units of milli-g and in cartesian coordinates. One idea I had was to analyze the data in something like spherical coordinates, to ...
0
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1answer
24 views

response of LTI system to a Random Input Signal

what is LTI filter? what is the output when x(t) is input? let x(t) be the input signal to the system and y(t) denote the output signal. The output of the system may be expressed in terms of ...
0
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0answers
15 views

Wifi signal stability of routers

In certain routers, there is a setting that allows one to change the interference resistance, which is bounded between the limiting cases of "maximum stability" and "maximum performance." Apparently, ...
2
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1answer
30 views

Error due to downsampling an image

I have two images $I_1$ and $I_2$ suppose $I_2 = downscale(I_1)$, so for example if $I_1$ has resolution 1024x1024 $I_2$ could be 512x512. How can I measure how much quality I've lost during this ...
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3answers
44 views

How does real-time signal processing work when the signal we deal with is assumed to be known for all times?

One thing that never sat right with me after my signal processing course is that in order to do signal processing, we must know the entire signal $x(t)$. For instance, I cannot take the Fourier or Z ...
0
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0answers
42 views

Accelerometer signal processing

I'm new signal processing (this is my first pratical application), so I ask sorry if my question is simple. My challenge is to see the displacement of accelerometer when I have vibration too. I do ...
0
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0answers
41 views

Power Spectral Density of discrete White Gaussian Noise defined with variance and sampling interval

From Creighton and Anderson Chapter 7 on Gravitational Wave data analysis: Please explain where the delta t and the limit came from in this derivation.
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0answers
20 views

Reducing noise on several Transfer Function measurements

INTRODUCTION I want to obtain the transfer function of certain system (a ground "path", in this case) using an impact hammer for the excitation and one accelerometer (measuring vertical direction ...
0
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2answers
51 views

Why Coherence is not a valid metric when performing impact excitation?

INTRODUCTION I have understood that Coherence is a function that explains the linear relationship between an excitation signal and a response signal. I know how it is calculated and why it is bounded ...
0
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1answer
31 views

how is this method of proving shift invariance correct

I got this answer from here. But i don't know how this method is correct. Until now to prove shift invariance what i did was : step 1: delay output and write it in terms of input. step 2: delay input ...
0
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0answers
12 views

1/3 octave analysis and convert dB/Hz to m/s^2 / Hz

I am new to this type of analysis.I have Labview with addon Sound and Vibration and have stuck with my program. I have uff file with vibration data. In this file I have data in m/s^2(t) units. And i ...
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0answers
19 views

Expression related to Tellegen's theorem and signal flow graphs

I'm reading the paper "Signal Flow Graphs-Computer-Aided System Analysis and Sensitivity Calculations" by Arnold Y Lee and my question in about expression/equality (59) in the paper. The expression ...
1
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0answers
72 views

Basics of Normalizing Cross-Correlation with a View to Comparing Signals

I'm trying to understand how cross-correlation is used determine the similarity of two signals. This tutorial offers a very clear explanation of the basics, but I still don't understand how to use ...
2
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1answer
136 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 ...
2
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2answers
85 views

Signals - question due to sampling

I don't have an idea how to start it. Help pls :) $$m = z(t) + \frac{\operatorname{Sa}(t-T)}{4}$$ We have some signal $z(t)=\left(\operatorname{Sa}(\frac{t}{T})\right)^2$. How often the m signal ...
0
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1answer
46 views

Amplitude and Phase spectrum of a signal [closed]

Please help me to solve this question.
-1
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1answer
60 views

Signal Denoising Uniformly in Frequency Domain

I have a noisy sparse signal containing number of frequency components. Is there any method to uniformly denoise this signal. in other words, a method that estimated and eliminates the noise power ...
0
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1answer
88 views

Threshold for peak detection of noisy signal in frequency domain

I have a noisy signal (Gaussian Noise) with a known SNR and known Noise variance. This signal contains a number of Frequency components. My ultimate objective is to detect the components of the signal....
0
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0answers
50 views

How can I calculate the Number of bins per octave?

I am trying to calculate the Constant Q Transform for Monophonic audio using Python. The Python has the library to calculate the CQT , the default value of num_bins_per_octave is 12. How would one ...
0
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2answers
78 views

why is my FFT magnitude of real time recording so volatile?

My goal is to do spectrum analysis of a gear motor. I used Python with the Pyaudio package and made a crude spectrum analyzer that displays the FFT as the sound is being recorded. I recorded 10 ...
0
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2answers
90 views

Why complex signal has no imaginary spectrum

I am learning about complex sampling. I am confused why $~e^{ j 2\pi f~ n}~$ has only a real spectrum. I would have thought the $j ~\sin(2 \pi f n)$ would produce a single spike in imaginary spectrum ...
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0answers
35 views

Decoding data hidden using “echo hiding” technique

I'm working on a little project, which centers around steganography. As part of it, I want to implement the audio echo hiding method, but the problem is, I've never done anything related to digital ...
0
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0answers
12 views

How to receive v-chip signals from digital TV stream

I'm trying to retrieve and decode V-chip data from my TV streams (NTSC/ATSC digital streams). Apparently these data are embedded somewhere in the stream itself, but I have no clue how they are ...
0
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0answers
25 views

Co-prediction of signals

Is there any plausible method to estimate or predict one signal, on the basis of known value of another signal, provided the two signals bear a strong correlation? For instance, the audio amplitude ...
0
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0answers
35 views

How to make function in time domain after fft fit with the corresponding function in frequency domain?

For example, I want to use fft to transform the simple function exp(-x.^2) defined in time domain. And the corresponding funciton in frequency domain is sqrt(pi).*exp(-k.^2/4). And I use the upper ...
0
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0answers
23 views

FM affected by AWGN

Could you give me a little help with the below question. I have plotted the FM signal and also added the AWGN on matlab but when i comes to the mathematical part it is not that simple as i thought it ...
0
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2answers
38 views

LTI and Deterministic Channel

Can someone explain me the statistical relationship of random signals with a linear time-invariant and deterministic channel to the output of the channel when having random signal as an input?
0
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1answer
52 views

Effective Nyquist frequency / signal resolution for overlapping time averaged signal samples

Say that I have a continuous signal. If I sample the signal at sampling rate f_sample, then the highest signal frequency that I can resolve without worrying about ...
0
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1answer
157 views

What is the difference between undersampling and oversampling in analog to digital conversion ?

When converting a signal from analog to digital, we observe undersampling and oversampling. Does oversampling means that the sampling frequency is greater that the signal's frequency and does ...
0
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0answers
27 views

Adaptive frequency discovery of binary signal

First of all, I'm not a signal processing expert. Actually, I'm trying to benefit from some concepts of signal processing theory in my computer science research. My problem is that, I have to find ...
0
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0answers
19 views

how to do supervised NMF source separation?

I know how NMF works by itself (unsupervised), but I am now interested in learning how it works in the supervised way. Suppose I have a clean isolated time domain signal of about 3 seconds in length ...
0
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1answer
74 views

Difference between acoustic emissions and ultrasonic waves

I need some clarification about the difference between acoustic emissions and ultrasonic waves. I have the idea that both are high-frequency signals and informative frequency bands more or less ...