Questions tagged [physical-units]

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Correct way of viewing negative voltages in units of dB for noise analysis

I have a voltage signal, on top of which there is some noise. I am interested in the noise components so the way I am trying to do this is to fit the known signal to the data and look at the residuals....
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2answers
72 views

Unit of Energy Spectral Density

The continuous-time Fourier Transform (CTFT) of a signal $x(t)$ (with unit $unit$) is: $$X(\omega)=\int_{-\infty}^{\infty} x(t)e^{-i\omega t}dt$$ which should be in $unit\cdot sec$ or $\frac{unit}{...
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21 views

What are the ranges of values for each audio feature/descriptor?

I need to normalize some audio feature measurements I've done with the software Wolfram Mathematica. Coming from a non signal processing background, I have some difficulties understanding what ...
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1answer
88 views

Units for a PSD from square of FT?

If I am looking to do a PSD plot on a signal $x(t)$ with units $m$ then the units I am expecting in the PSD would be $\frac{m^2}{Hz}$ but I can't seem to get this result from the following reasoning: ...
0
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1answer
36 views

Conversion between DTFT in radians/sample to DTFT in cycles/sample

I have found that most commonly the DTFT is defined as: $X(\omega) = \sum_{n=-\infty}^{\infty} x[n]e^{-j \omega n}$. However the class I am taking frequently uses the DTFT expressed in "normalized ...
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1answer
99 views

Correct SNIR computation units

I would like to know the correct units to make a SNIR computation. I am using the following formula: $$ \text{SNIR} = \frac{1}{\frac{1}{\text{SNR}} + \frac{1}{\text{CIR}}} $$ I have SNR in dB and ...
1
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1answer
66 views

Convolution Input/output Units

How come are the units of convolution for LTI system not consistent? $$y(t)= \int_{-\infty}^{\infty} x(\tau)h(t-\tau)d\tau$$ $y(t)$ unit is volt, whereas the RHS has volt.time unit!!!!
1
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2answers
162 views

Why is “$1/\mathrm{Hz}$” unchanged while converting$\mathrm{V}^2/\mathrm{Hz}$ to $\mathrm{dB}/\mathrm{Hz}$?

When computing power spectral density via Fourier transform and Parseval's theorem, one gets units of $V^2/Hz$ (e.g. Wiki). As a popular next step, the following unit conversion is widely used: $V^2/...
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1answer
80 views

Normalizing Cepstrum by Energy

I have separately computed the cepstrum and the energy of a finite discrete-time signal. If the energy of the signal is high, we would expect (on average) larger cepstral values than if the energy of ...
8
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1answer
7k views

What are the units of my data after an FFT?

Magnetometer measures the derivative of the magnetic field, or dB/dt, with an output in microvolts (mV). The Sampling rate is 128 Hz, so if we collect data for 2 minutes, $2 \times 60 \times 128=...
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2answers
11k views

What is the difference between the PSD and the Power Spectrum?

Can any one explain the difference in the amplitude between the two and what does each one represents? For example, when using the pwelch algorithm in MATLAB how ...