Questions tagged [signal-analysis]
The signal-analysis tag has no usage guidance.
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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 ...
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1answer
18 views
Signal with spectrum invariant under translation
Is there a signal with a spectrum limited in frequency and invariant by translation: $S(\nu)=S(\nu + \alpha), \alpha \in \mathbb{R}$?
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1answer
25 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
18 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 ...
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0answers
18 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
111 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
32 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 ...
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0answers
12 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 ...
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2answers
77 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 ...
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0answers
26 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 ...
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0answers
26 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 ...
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1answer
48 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 ...
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0answers
22 views
Multipath propagation: pass loss [closed]
1) I read that the path loss exponent depends on an height of antenna, frequency, polarization, climate.
And also the post Question about path loss exponent estimation from measurment
Ms MBaz wrote ...
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0answers
31 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, ...
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0answers
29 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
17 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 ...
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0answers
14 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
22 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
37 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
32 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 ...
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0answers
24 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
18 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 ...
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2answers
45 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
14 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 ...
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0answers
5 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
18 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 ...
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0answers
38 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
72 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 ...
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2answers
74 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 ...
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1answer
30 views
-1
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1answer
51 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
55 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....
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0answers
44 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 ...
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2answers
72 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
61 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
27 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 ...
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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 ...
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0answers
22 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 ...
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0answers
27 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 ...
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0answers
13 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 ...
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2answers
32 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
43 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
49 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 ...
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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 ...
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0answers
17 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
33 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 ...
0
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1answer
41 views
How to build a realtime simple audio spectogram? [closed]
I'm trying to build a spectogram view of history time of 4 seconds and I'm stuck at the part where you load/draw FFT vectors into the 2D bitmap. I just don't know how to do that, but i got the FFT in ...
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1answer
21 views
Correct form of discrete-time Fourier series representation
As I see in this slides, Fourier series representation for discrete-time signal $s[n]$ with period $N$ is $\sum_{k = 0}^{N-1} c_k e^{j2\pi k n / N}$
According to Wiki, Fourier series representation ...
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0answers
36 views
Advances in Blind SNR estimation beyond $M_2M_4$
In Pauluzzi and Beaulieu, various SNR estimation methods are compared. Among the blind methods considered, the $M_2M_4$ estimator seemed to be unambiguously the best. However, it has been shown that ...
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1answer
64 views
Is there an example of an infinite signal? [closed]
In the real world, Is there an example of an infinite signal?
