Questions tagged [power-spectral-density]

The Power Spectral Density (PSD) is the distribution of signal power over frequencies.

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13 views

How to calculate the average power of each frequency band?

I have EEG data from 30 participants, each recording is about 3 mins, and I'm trying to calculate the average power of each frequency band. I tried using Welch's or multitaper functions, but my values ...
14 views

How to select parameters suitable parameters for a spectrogram

I have a limited background in DSP but I need to generate a spectrogram of an electrocardiography (ECG). I am using the scipy.signal.spectrogram and I need to set ...
45 views

Given a power spectral density of a signal. How to find mean of the signal?

Given a stationary process signal with PSD $$S_u = \Lambda(f)$$ How to find the mean, power, and variance of the signal? I know how to find power given PSD (integrating from -inf to inf over f). ...
302 views

Conversion of dBm/Hz into watt

I have a noise power density of -174dBm/Hz and a bandwidth of 180kHz. How to convert the resultant noise into watt. I am confused. First, multiply (-174dBm/Hz) by 180000, then convert the result into ...
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I also did't understand why they propose a scaling factor of simply 1/N to the FFT, while the matlab function for PSD using periodogram method scales the FFT by 2/(Fs*N)? Scaling psd is not ...
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Welch PSD Calculation with energy bands

I am working on a Stress Prediction project using the SRAD Dataset. The dataset contains measured signals such as ECG, EMG, Galvanic Skin Response, Heart Rate, and Respiration. Before any personal ...
52 views

Measure Frequency-Response of Sensor using a Signalsource and Reference-Sensor

Cheers, I want to measure the frequency response of an acceleration sensor. I have: A signal source (device similar to a loudspeaker that shakes the acceleration sensor), of which I do NOT know the ...
75 views

How plausible is undetectable (covert) radio communication?

Ever since I found out that coding gain allows you to receive a signal that is well below the noise floor I have been fascinated with the idea of covert radio signals (low probability of detection). ...
31 views

Is this an appropriate way to calculate power and relative power for individual spectral bands (EEG, MATLAB)?

I apologize in advance if this is a dumb question, I'm really new to this kind of analysis. Essentially I have my EEG signal (EEG1) and I'd like to calculate the power and the relative power in each ...
34 views

Obtain PSD data from a noisy signal

I have a noisy source (like a wheel rotating constantly) and I would be measuring signals when the wheel is running. I looked into how I could convert this signal into a PSD and came across Welch ...
92 views

Find some signal x[n] whose auto-correlation function is R[k] [closed]

I want to write a MATLAB code for generating a random message signal 𝑥[n] where its autocorrelation function is: R[k] = sinc^2 [1/4 k] where k is an integer. (Hint: Generate a process where ...
39 views

Sample rate vs noise floor in power spectral density measurement

I am trying to measure the noise floor of my picoscope. I want to generate a PSD in volts per root hz that I can compare with specs from other equipment, e.g. a preamp. I gathered some data from my ...
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Units of a Fourier Transform (FFT) and Spectrogram [closed]

I am very interested in analyzing signals in the frequency domain. Units of a Fourier Transform (FFT) when doing Spectral Analysis of a Signal 1.In the previous question, answer the unit for the ...
30 views

Noise Power Spectrum from Log Video Amplifier

I know that if I use a square law detector on band limited noise - let's assume it's rectangular - the noise power spectrum becomes the convolution of the input power spectrum. After lowpass-...
65 views

Computable Time-Frequency Distribution without Cross-Terms

Context: I have a single receiver that is receiving multiple signals. Each signal has a few strong harmonics, but I don't know the fundamental frequency. I would like to display them on a spectrogram ...
50 views

Having trouble working understanding a noise shaping filter

As context, I'm trying to understand and implement this Von Karman turbulence model in a simulation I'm working on. In order to generate turbulence velocities on the fly using the model, a ...
24 views

Infinity values in statistical analysis of minute frequency data

I'm trying to extract statistical features from power spectral density values in Python. My data is actigraphy data with sampling rate 1/60 Hz (once per minute). This is a sample from my data, "...
43 views

Is "Introduction to Statistical Signal Processing" by RM Gray good for starting?

I am working on noise processes in electronic devices for my studies, by now Ive been doing a fairly large amount of processing of time measurements, like calculate PSD, estimate thermal, flicker ...
59 views

Extracting "frequency domain features" from signal for classification

I have a real signal with only nonnegative values (actigraph measurements). Many papers say they use "frequency domain features" for classification, such as mean, variance etc. But I'm ...
154 views

Generate a time series from power spectral density

I have a model function for a power spectral density (PSD). I want to simulate a time series with a power PSD equal to my model function. After some browsing about how to do this, I came up with the ...
124 views

How to compute the theoretical power spectrum of a first order autoregression (AR1) model

I'm trying to figure out how to compute the theoretical power spectrum of a first-order autoregression model (AR1). The AR1 model is given as $x_i = r_1 x_{i-1} + e_i$ where: $x_i$ is real-valued ...
47 views

How to Normalize a Power Spectral density?

I have a spectroscopy data representing Periodogram of 1024 pts (Periodogram estimate a theoretical PSD), however it is not normalized. How do we normalize the PSD ? The normalization I am looking ...
94 views

Does pwelch function, in matlab, adopt already the correction factor due to the window?

Does pwelch function, in matlab, adopt already the correction factor due to the window? When we use a window, like hamming or hanning, a correction factor for the amplitude or energy is needed. In ...
57 views

dB octave band spectrum

When I was at the University I did some courses about Acoustic. I always seen the dB octave band spectra, as the Fourier Transform of the dB in time. Now looking at some reference in Matlab, I noticed ...
30 views

Results do not match between manually computed PSD values and those from MATLAB pwelch function

The power spectral density (PSD) of the given input signal $x[n]$ is computed as follows: ...
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Average Power Spectral Density (1D and 2D) of multiple images of different sizes in python

I am trying to calculate avg 1D and 2D PSD of multiple image with different sizes. Any idea how can I do this? Current I'm calculating 1D psd using this function. The problem here is that each image ...
68 views

What does the intensity values on wavelet transform mean? Amplitude or power?

So when applying wavelet transform, we get a 2d plot. Each point in that 2d plot has a color, showing intensity of something. But I cannot understand if it is an amplitude or power?
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Low Pass Filtering, Welch's Method, ENBW

I am working on using Welch's method (https://www.osti.gov/servlets/purl/5688766/) to estimate a Power Spectral Density (PSD). This algorithm involves scaling a set of averaged FFTs by the equivalent ...
82 views

Estimating the SNR of respiration signal

I'm trying to evaluate the SNR of a respiration signal on Matlab environment, so the bandwidth considered is [0.04-1Hz]. The problem is that noise is overlapped on the signal, so I can't evaluate the ...
77 views

Why Bluetooth 2 use pi/4-DQPSK instead of OQPSK?

From the peak to average power ratio point of view OQPSK is better than pi/4-DQPSK. What is the advantage of pi/4-DQPSK compare to OQPSK? Why Bluetooth 2 use pi/4-DQPSK instead of OQPSK?
232 views

Converting from PSD (V^2/Hz) to dBV (1 Volt RMS reference)

I'm having difficulty figuring out how to convert from PSD (V^2/Hz) to dBV (1 Volt RMS reference). The goal is to have a 1 Volt RMS input show as 0 dBV. Essentially I calculated the PSD of a signal ...
44 views

Spectrum in real life with Spectrum in theory

as you know it is possible to measure the power spectral density ($|X(f)|^2$) of a certain voltage signal $x(t)$ through a Spectrum Analyzer. As far as I'm concerned, the simplest spectrum analyzer ...
This diagram again. This is clearly not the shape of $\log_2(1+SNR)$ but I very frequently see this instead of this: But this is also a stupid diagram because it doesn't cross at the origin. Also why ...