# Questions tagged [power-spectral-density]

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

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### Reason for decrease in the PSD gain with increase in the number of FFT points

what is the reason for that? The gain should increase ideally I guess. This is the code I tried. As I increase the length of F by zero padding,the gain of PSD reduces. ...
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### How to transform flat-field corrected spectra to those under Standard illuminant E (ideal equal energy illuminant)

My ultimate goal is to convert a flat-field corrected hyperspectral image of reflectance (360nm-780nm) to corresponding CIEXYZ image and thus device-independent color image. By flat-field correction, ...
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### Cross Power Spectrum

Is it necessary that cross power spectrum (CPSD) should always be between power spectrum (PSD) of individual signals, irrespective of the method we compute it? The images are shown below.
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### Is there an equivalent time-domain operation to the spectrum averaging in Welch's method?

In Welch's method a time-series is segmented and then the subsequent FFTs of the segments are averaged. Is there an equivalent time-domain operation? I guess doing the the Welch estimate and ...
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### How do I modulate complex time domain signal to a carrier frequency?

I want to modulate a complex time domain signal to a carrier frequency 1880MHz but the sampling frequency is 30M which is smaller than Fs. I did upconversion using ...
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### Determining power spectral density from a sample

To start, I have absolutely no background in electrical engineering, I am a computer scientist by trade. I'm currently working on a project where I am attempting to code a function that uses the ...
735 views

### How to evaluate Spectral Density of DC component vs. AC component during computing PSD?

When computing the PSD, how to manipulate the DC component?  PSD integral is the total signal power, does it include the power of DC component? In other words, if there is one signal with DC value ...
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### Epoching Data with no Events in mne?

I am new to Python and signal processsing, and I'm trying to create a spectrogram of EEG data taken during a course of general anesthesia. I would like to use MNE's ...
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### How to choose notch frequencies for filtering line noise?

I'm using the function to filter out line noise at 60 Hz (and 120, 180 Hz) caused by electrical noise: ecogNotch In the case below I can effectively filter out the line noise with a notch filter at ...
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### Average value of power spectral density

I have a spectra of power spectral density (PSD) (vector (1:1e6)) from experimental data (blue color). However I want to plot only average value of PSD (red curve)....
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### Relationship between Wavelet transform and Fourier Power Spectral Density

Is there anyway to obtain the Fourier Power Spectral Density from a wavelet transform of a time series? I am particularly interested in this problem because I was wondering if there is any ...
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### Oversampling while maintaining noise PSD

I'm designing a digital PID for control and stabilization of laser amplitude. The noise PSD of the laser intensity is around -140dB/Hz, and I want to servo that between DC and 100kHz. I think I've ...
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### Appropriate model for IIR filter to compare with spectral ratios

A quick, basic question. I have measured spectral ratios - comparing a measured signal to an 'ideal' signal. I am fitting a specific, simple IIR filter to that data for transfer functions. So, if I'...
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### Power Spectral Density of Sigma-Delta modulator

I am simulating a 3rd order SDM and I want to plot the PSD of the output. As you may know, the output is a sequence of pulses ranging from -3 to +4. The number of samples is $N$. The way I ...
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### Confidence Interval For Frequency of Peak in Averaged Periodogram?

I am averaging periodograms from sets of ~15-25 experimentally measured timeseries all of the same length. To do this I am just summing the power in each frequency bin over all periodograms and then ...
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### Power spectrum of 2D image: result interpretation

Let's say I have an image, which is NxN pixels in size. If I calculate the fourier power spectrum of this image, I get NxN values, with the highest distinguishable frequency at +- N/2 in each ...
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### When to use cross spectral density versus cross correlation?

All my life, I've used cross-correlation to analyze the strength of the relationship between an input signal and the output signal. I use this to determine which ...
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### PIsarenko Harmonic Decomposition method for PSD estimation

i would like to present steps for estimation Power Spectrum density using Pisarneko Harmonic Decomposition i would like to present code for step 1 part ...
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### VSD in rms voltage

I am looking at a datasheet where they show a graph: $V_{RMS}/\sqrt{Hz}$ as a function of frequency = VSD (voltage spectral density). The question is: how can a spectral density be in RMS? The root ...
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### Is Spectral Coherence (MSC) dependent to the initial amplitude of the comparing signals?

Given the signals \begin{align} x(t) &= A_1\sin(\omega t)\\ y(t) &= A_2\sin(\omega t) \end{align} Do $A_1$ and $A_2$ play a role in the $C_{xy}$ coherence estimator? MATLAB's ...
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### Applying periodogram-based PSD

For plotting a Power Spectral Density graph based on FFT results, I had used two different approaches, but they produced very different results, and it'd be great if anyone knows why. Note: From this ...
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### Effects of averaged periodogram (Welch's Method) on resolution?

I'm trying to make an app(running on an android phone) that can detect the frequency of a guitar string being played. I know it'll be hard to detect that but that's a problem I'll deal with later. ...
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### Interpreting dataset of a power spectrum

I am currently working with kaldi, and are trying to make spectrogram plots of different audio files. Kaldi is a speech recognition toolkit. Kaldi frames its input in frames of 25 ms with a ...
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### How should this fft output be intepreted?

I am currently reading some code, so I can understand how this FFT output is actually been stored. I have a function which computes FFT of audio file, and stores is in the format. ...
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### How to explain this BER vs SNR behaviour?

I wrote a script in MATLAB to simulate an LDPC created using an algorithm of a colleague of mine. The parity check-matrix is regular and has dimensions $1012 \times 1518$ and the code rate is $R=1/3$. ...
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### Derivation of PSD of sampled bandlimited random process

When a bandlimited random process whose PSD $$S(\omega) = \begin{cases} \frac{N_0}{2} & -10B<\omega<10B\\[2ex] 0 & \text{otherwise.} \end{cases}$$ is ...
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### RMS averaging in spectrum analyzers

While studying spectrum analyzers I ran into the concept of RMS averaging as a mean to reduce dispersion of data without affecting power spectral density (PSD). What is not really clear to me is how ...
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### How to read off power at different frequencies

In MATLAB, consider a signal y and its Fourier transform Y: ...
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### Estimate the wavelength of an oscillatory signal

I need to estimate the dominant wavelength of a signal that is looking like this: My first attempt was using scipy.signal.argrelmin in Python in order to detect the ...
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### Scaling for a 2D Hanning Window

I am trying to find the PSD of a 2D set of data and representing it as a function of frequency in both these directions. I start with a 2D FFT and generate the 2D hanning window for a $M\times N$ ...