Questions tagged [signal-analysis]

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347 views

Flattening out a power spectral density

The situation is as follows. I am generating a white noise voltage signal with a certain power spectral density amplitude of choice, from 0 to some cutoff frequency, for example 200 MHz. This proceeds ...
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48 views

Mean of the product of a signal with its conjugate

I have to find $E\{s_m\cdot s_n^*\}$, where $E$ denotes mean or expected value; $s$ is a signal at $m \in [1\ldots M]$ elements and $^*$ denotes its conjugate. I am doing it by dividing it into two ...
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47 views

Orthogonality of pseudo random basis functions

I was reading about Matching Pursuit and it struck me that you might use a dictionary simply consisting of uniformly distributed bipolar pseudo random vectors, instead of, say, Gabor atoms or windowed ...
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164 views

Variation of Pulse width with center frequency in Pulse Compression technique

Assume a chirp with BW = 1 Hz (frequency range 0-1 Hz) for a period of 700 sec. The pulse compression technique (obtained through auto correlation function) applied on the chirp generates a pulse ...
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330 views

BFSK modulation what signal the transmitter actually sends?

I am trying to understand how modulation with carriers works(transmission part). I will express my question in terms of BFSK for simplicity. Let us condiser BFSK modulation with symbols {1,2}. Then ...
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52 views

noise in signal

I am trying to add phase noise in signal. However, when i see the graph in frequency domain the spectrum is not broading. Can anyone tell me what mistake i am making? ...
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405 views

Detailed Analysis of Phase Delay of an Audio Signal

I write this question as a new reference point because it is difficult to find something exhaustive regarding this topic. I'm talking about the calculus and interpretation of the phase delay of a ...
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244 views

Cross spectrum using `cpsd` (matlab) of 2D matrices

I'm struggling with cpsd for 2D matrices. In my test, I've generated two 100x100 matrices (sine waves) s1 and ...
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397 views

Generating Wavelet family matrixes

We have unnormalized Haar matrix which, is for example, H4=[1 1 1 1;1 1 -1 -1;1 -1 0 0;0 0 1 -1] After normalizing it, we use for haar transform. I know how to ...
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554 views

Effect of pathloss on signal power

Consider I have two transmitters $tx_1$ and $tx_2$ at say a distance of $d_1=5\text{ m}$ and $d_2 = 15\text{ m}$ respectively from a receiver. Now, if I consider the effect of path loss in such a ...
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127 views

PID Control - process variable / setpoint

I'm trying to design a PID controller but I have a problem in the following case: The process variable can only be between 0 and 1. The setpoint can be close to one, for instance 0.97. Hence the ...
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98 views

Zero Crossing rate

Is it possible to have negative zero crossing rate? (can rate be negative?!?) Because I saw a figure which the signal has been broken in frames each of 10msec, with the plot of zero crossing rate ...
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47 views

Goertzel filter Poles on unity circle influence of a behavior of a signal at high frequency

I'm trying to apply a goertzel filter on my sound data of 20500 Hz with sampling rate of 44100[samples/sec]. My bit duration which is passed to the goertzel function is returning a very low magnitude ...
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55 views

Changes of phase in high frequency makes the speaker “clicks”

I modulate some data over sound in a 17.7Khz and 17.8Khz. It works like an FSK with a pulse duration of 0.015sec. When playing a string the speaker gives a very strange noise that it seems to be the ...
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96 views

Getting the frequency of a 0.33Hz to 3Hz signal

I read a noisy signal from an accelerometer which is attached to the pedal of a stationary bike and need to find the frequency of the signal/ speed of the person cycling. I taught of the following ...
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166 views

MATLAB, recover a signal that has a cosinusoidal interference and that has been AM modulated

I have a signal which has been AM modulated but the channel also added a cosinusoidal interference A cos(2 * Pi * f0 * n * Tc + Phase), at the same ...
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445 views

Correlation between two graphs in Matlab

I am trying to make a system that detects footsteps. First I filter and decimate the original signal, then I make a convolution between the filtered signal and a single footstep, then I extract the ...
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38 views

What is the physical meaning of the s-space?

In my audio processing lecture, the term s-space came up. My instructor basically told us that it's a space where we perform calculations that couldn't be ...
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322 views

extrapolate turning points for a sine weighted moving average?

On a stationary signal a sine-weighted moving average is calculated (SWMA: the coefficient vector looks like the first (>0) part of a sinusoid). The SWMA looks like this: very smooth: The future is ...
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39 views

Is there a principled way to distinguish between these signals?

Consider these two signals: They both describe a biological process going on in the same subject. The blue one is obtained at rest and the red one after the subject is perturbed. Is there a ...
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784 views

Classification SVM

I have a problem with Support Vector Machine classification. I have two classes of children (boys and girls). I use a MFCC function for training (for each class I have 24 coefficients, number of ...
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225 views

Complex Morlet Wavelet piano sound analysis

my project is monophonic music transcription I am using complex Morlet wavelet but over the 1000 Hz complex Morlet does not give all results right, my code is like that ; ...
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6k views

How to check whether a continuous signal is periodic or not?

How to check if a continuous signal is Periodic or not? My notes says $\cos(\frac{3}{2}\pi t)$ is periodic because $T=4/3$. And $\cos(\frac{3}{2}t)$ is not periodic as $T=4\pi/3$.
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319 views

Trying to understand the gold-rabiner pitch detection algorithm

I am currently in the process of taking on implementing the Gold-Rabiner pitch tracking algorithm, and I came across what seemed like a good explanation of it in David Meehan's "A Code Excited Linear ...
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16 views

Suppose we have the following data. How can we calculate the channel capacity and R?

A channel has a bandwith of 5MHz. If signal strength to spectral noise density S/N0 is 107 Hz, calculate the channel capacity C and R. The problem is that I can use Shannon-Hartley theorem because ...
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46 views

Calculating the modulation based on the coordinates in the constellation diagram

A constellation diagram has points at the following coordinates: (2,2), (2,-2), (-2,2), <...
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62 views

comparing different signals

I have some noise measurements and 4 different models that can generate a similar noises using estimated parameters from the real measurements. To compare the estimated noises I calculated the PDF, ...
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288 views

Comparing two wav in matlab using NullTest

i have a legacy processed audio wav file. Another UN-processed copy of the source is processed by my algorithm. From both processsing blocks i get processed wav files as output. Now i want to do null ...
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217 views

Bandwidth required for orthogonal and antipodal signals

What is the bandwidth required to transmit baseband modulated signals like an antipodal and orthogonal signals?
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908 views

CWT for filtering / feature extraction

I had asked a question last night in regards to how to process my data (Noise rejection / feature extraction) but I have a more specific question now that I hope someone can answer. As mentioned in ...
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62 views

Signal Acquisition Game?

I read from Wikipedia that signals obey the uncertainty principle. The product of the measured uncertainty in frequency times the measured uncertainty in time is greater than a constant. The ...
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37 views

Matlab:Sampling Curve into Frames and Plotting

I have a Output Curve of following characteristics http://i.imgur.com/hABfsiC.jpg Following is the data which represents the output curve cited above ...
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520 views

Online FFT of simulated signal

it is a couple of weeks that I am thinking about the following: I have a tool which is able to simulate the dynamic behavior a steel tower exhibites due to the coupled action of wind and waves. ...
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153 views

TDOA using demodulated signal

Is it possible to find time delay of arrival using demodulated signals (of bandwidth ~200hz)? I have a setup in which I receive (multiple receivers, of course) modulated signal from a source. I want ...
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238 views

Why the number of poles and zeros for a RHS signal in the Z domain is equal?

I can not understand the reason why the following sentence is true: If we have a Right-Hand signal(RHS) x(n), X(z), the Z-transform of x(n), has the same number of poles and zeros except at z = ...
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456 views

Analyzing an undersampled recording from an antenna with matlab?

I'm trying to analyze the power spectral density of a signal recorded from a Ham radio antenna. The signal is about 30 seconds long, recorded at a 48 kHz sample rate. The frequency is center frequency ...
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62 views

Common mode noise from two ADC results

I am sampling two sinusoidal analogue signals that are phase separated by $\frac{2\pi}{3}$, and there appears to be a significant amount of common mode noise in my samples. What, if any approach can I ...
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177 views

Constant phase for each frequency?

FFT of some signal $x$ has two parts: $|x|$, which is the magnitude spectrum and $arg(x)$, which is the phase spectrum. I want each frequency to have the same phase. Is there a way to accomplish this?
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112 views

understanding windowed fourier ridges

I am studying windowed Fourier ridges for my project. I know that it computes the instantaneous frequencies and amplitudes from the spectrogram. But I don't really know how it relates to signal ...
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140 views

How to measure the short-time change in an audio signal?

The choice of frame length for calculating the Mel Frequency Cepstral Coefficients of a signal, depend on the how much the signal change over a small time scale. I guess that human speech change ...
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1answer
46 views

Basic question regarding third octave filters

I would like to use third octave filters on a time signal. Do I have to apply all third octave filters to a single frequency or do I only need to apply the one that has its center frequency the ...
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1answer
342 views

Kiss fft does not work after giving it more than 32 samples

I am trying to take data from an accelerometer and apply Kiss FFT to the samples. I'm using a Freescale Kinetis FRDM-K22F board. I want to use 64 samples, but when I run the program I get an error ...
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1answer
3k views

Calculating SNR for ECG signals

I'm reading through the literature for finding the best way to calculate SNR for a ECG signal. While there are many algorithms for improving SNR, I couldn't find any that details any standard ...
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1answer
64 views

Counter design for audio signals

I am designing a schematic in which a Counter is to be increased whenever a particular band of frequencies is received at the Audio input. We are receiving the audio input as electrical Signal and I ...
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1answer
30 views

Data Adaptive technique

I am doing data analysis. I used the wavelet transform and now I am trying the Hilbert–Huang transform (HHT). In the literature, I read that Hilbert–Huang transform (HHT) is an adaptive technique. I ...
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17 views

What is definition of cross correlation function?

I mean there are three different formulas for cross correlation that I have studied f and g are two functions whose correlation has to be found 1.For Energy signals 2.For Power signals 3.For ...
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1answer
130 views

Why do we need the power spectral density?

Since the power spectral density is just the squared of the fourier transform, why is it useful ? Can't I just replace every solution that requires the psd with the fourier transform ?
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1answer
157 views

Spectral Subtraction python implementation error

I am trying to implement Spectral subtraction in python. I am new to DSP. I used this article as reference and below code is what I can come up with. Of course I did not get the expected output. I ...
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1answer
126 views

Quadtree decomposition of Discrete Wavelet Transform using bio4.4/CDF wavelet

My problem is pretty basic but fundamental. It relates to the way discrete wavelet transform behaves for biorothognal 4.4 or CDF wavelets. When using most wavelets (e.g., CDF 9/7 or bio4.4 or ...
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1answer
264 views

Alignment of signals for ensemble averaging? Something else?

I have been applying ensemble averaging (adding signals of different trials to obtain one signal) to improve Signal to noise ratio in my data. I have achieved good results in terms of classification ...