Questions tagged [signal-analysis]

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37 views

How to find the filter coefficient of matched filter to detect the pulse of a signal?

I would to understand how to find the coefficient of a matched filter. Let's consider we have a signal and the signal is buried in the following noise. we want to find the coefficient of a matched ...
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10 views

Looking to simulate sound level meter (read microphone audio signal into 1/3 octave)

I am looking to pull audio from a microphone and analyse the 1/3 octave data. Can anyone suggest a software library to do this that I could then build a software interface on top of? Initially looking ...
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20 views

Analysis of linear acceleration and angular velocity, how to?

Excuse me If you don't feel that this question is good enough, but at the moment this is my level of entry knowledge. Imagine that you have 200 recordings from the sensors, and information that you ...
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100 views

I want to plot a gaussian pulse in MATLAB in the frequency domain, with its centre at the highest value

I have tried one way but i am getting 2 peaks at the edges as shown in the picture. I have used 1 part of my code for the signal generation where i used the gauspuls command (reference: www.simsonic....
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19 views

Signal ECG , collecte & visualize data

I am currently working on a sensor that visualizes an ECG signal and visualizes its data. Its principle is that it has 3 electrodes that must be placed in specific parts of the body .... I would like ...
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1answer
31 views

Higher side lobe levels in linear array beam pattern

I am working on beam forming of high frequency (>400 KHz) linear array for imaging sonar. I have gathered sensor data of 80 channel linear array sub merged halfway in 8 m deep water tank with a ...
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159 views

Why does power spectral density of OFDM signal changes with number of zero subcarriers

I am trying to plot the power spectral density (PSD) of an OFDM signal with $N_{dsc}$ subcarriers and $N_{zeros} = N_{fft}-N_{dsc}$ zero subcarriers. I am using the matlab function pwelch() to plot ...
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1answer
101 views

Please help me understand this paper about Discrete Wavelet Transform!

I am trying to understand this paper says. I have found this paragraph to be vague: (a) Preprocessing Stage. The first step in this stage was to apply the Discrete Wavelet Transform (DWT). This ...
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48 views

processing a very noisy signal

I work on an ECG signal that I collect from a sensor, and it is very noisy. Having researched it above I read that FFT or so Nyquist-Shawon's casting theories were advised, being novice in the field ...
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47 views

Drawbacks of kalman filter

What are the drawbacks of kalman for attitude angels estimation...or what are advantages of mahony filter over kalman filter for attitude angels estimation?
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68 views

How enhance amplitude of audio signal without distortion?

After FFT I've set to zero some frequencies and I'd like to enhance the amplitude in order to recover the leak. I'd like to do a normalization in order to avoid distortion. I've done in this way but ...
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26 views

Impulse response of discrete time system

I am learning about discrete systems and in this derivation something struck me as quite odd. Solving for $A_0$ in this equation seems dubious as it ignored all other values of $n$. For example, at $n=...
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41 views

Is it possible to analyze this microphone data and what to do if not?

I just created an account here because I really need some help. I'm using a microphone pmodmic3 with a development board called Ublox C030-U201 which uses the mbed OS. The microphone is working for ...
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1answer
70 views

GPS Code Phase usage

During Cross-correlation process: xcorr=ifft(fft(a)fft(b)∗) we have frequency offset and code phase offset. How is it used later in the process of finding a ...
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43 views

histogram bin size vs. data sampling rate

I have a set of numerical signals that give me a set of zeros calculated based on some numerical procedure. I make a histogram of those zeros. Here, a following problem arises: If the histogram ...
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38 views

Help to create basic sound compressor in sigmastudio

I need create own mono compressor in Sigmastudio from basic blocks. It will be only hard knee. For RMS level I want use RMS detector. I need set only next parameters over SPI: - Threeshold (0-90 dB) -...
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63 views

Please explain Multiplication property in Z transform?

I am having problem visualizing contour any example will be great help. As far as as where I need it I was trying to find Z transform of a contracted signal by first multiplication by impulse train.
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1answer
81 views

How to detect the maximum resolvable spatial frequency of camera?

I am trying to calculate the minimum line pixel width that can be distinguished from noise as shown in the camera test chart in Figure 1 where the thinner lines on the left are getting more and more ...
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40 views

Interpreting Auto correlation results

I used xcorr function in Matlab to compute the autocorrelation of my signal. I obtained a graph, which is shown below. How to interpret this? I read that autocorrelation helps in finding the patterns ...
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120 views

Working principal of MIMO(2 by 2)-OFDM (802.11n)

I have gained basic knowledge on MIMO-OFDM from online sources and in process of building 802.11n standard in GnuRadio+USRP B210. My goal is to analyze the channel state information and play with it ...
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44 views

How to low pass very few samples

I'm asking myself what is the best way to low pass a signal which only has a few hundred samples? Or is there a proper way at all? It must not be a sound signal but I used Audacity to display the ...
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338 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
59 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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52 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 ...
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30 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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29 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 ...
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40 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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55 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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176 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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30 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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48 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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36 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 ...
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20 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, ...
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103 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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1answer
187 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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59 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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22 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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1answer
172 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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133 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
160 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 ...
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80 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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15 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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41 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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52 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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42 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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30 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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46 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 ...
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1answer
48 views

EEG Sampling, Which Order should cover my result?

I have EEG data sampling rate is 250 Hz and I want to band pass this data in ( 0.5-3 Hz & 3-8 Hz & 8-13 Hz & 13-30 Hz & 30-40 Hz). Currently, the data is in the frequency range of ...
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1answer
87 views

Figuring magnitude and phase response

I've got a linear time-invariant system $$y[n]=\frac{8}{9}y[n-1]+x[n]$$ which I transformed into a transfer function $$Y(z)=\frac{8}{9}Y(z)*z^{-1}+X(z) =>\frac{Y(z)}{X(z)}=\frac{1}{1-\frac{8}{9}*z^{...
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1answer
233 views

How to determine fundamental frequencies (beats/minute) of heartbeat? (matlab)

read = matfile('ECG.mat'); [cor, lags] = xcorr(read.ecg, read.ecg); read.Fs; So i have read.ecg (signal) and ...