Questions tagged [spectrum-estimation]

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46 views

Running window design for irregular or nonuniform time series

I have to deal with multiple time series $X_n$ that are non-uniformly or irregularly sampled at increasing times $\Theta=\{t_k\}_{k\in \mathbb{Z}}$ ($ t_k<t_{k+1}$). In case this could help, this ...
2
votes
0answers
196 views

Welch Method FFT Python - Scaling factor?

I've been implementing a Welch method FFT and I am trying to work out the correct scaling factor that should be applied to the output of the function so the PSD is accurate because at the moment it's ...
2
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0answers
259 views

How to derivate in the frequency domain

I have two Time Domain functions, $f_1(t)$ and $f_2(t)$. I have both Fourier Transforms, $F_1(\omega)$ and $F_2(\omega)$. Functions $f_1$ and $f_2$ are not independent and, in fact, $f_1$ is also a ...
2
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1answer
581 views

A few questions about the output value of dsp.SpectrumAnalyzer

I am testing the output values of dsp.SpectrumAnalyzer for a sine wave mixed with white noise. The $\sigma^2$ of the white noise is 1e-4, so I use 0.01*randn(1024,1)...
1
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0answers
75 views

Wrong amplitude in the FFT for 10 seconds measured signal

I measured a signal with the Osziliscope that I generated with a signal generator. The signal is a pure sine wave with a frequency of 1 kHz and a peak amplitude of 2.5 V, I measured the signal for ...
1
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0answers
51 views

Interpreting scipy spectrum from audio signal

I have recorded some audio and would like to obtain a spectrum from it. As the audio is a real valued signal, I figure that I could perform a FFT with some window and obtain a spectrum for that period....
1
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0answers
2k views

Power spectral density vs. Fourier Transform

I am trying to understand the difference between the Power Spectral Density and the Fourier transform. Specifically, I am trying to understand why the power spectral density is useful and in what ...
1
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0answers
40 views

Complex Spectral Phase Evolution (CSPE) Performance depending on signal windowing?

I am look into CSPE. "Signal Analysis Using the Complex Spectral Phase Evolution (CSPE) Method" The method is simple. It compares the original signal's FFT and shifted signal FFT in phase domain so ...
1
vote
0answers
130 views

Second moment properties (covariance) of lag window estimator

We know that the lag window estimator of the spectral density is defined as: $$S^{(lw)}(f)=\int_{-f_{(N)}}^{f_{(N)}}W_m(f-\phi)\hat{S}^{p}(\phi)d\phi=\sum\limits_{\tau=-(N-1)}^{\tau=N-1}w_{\tau,m}s^{(...
0
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1answer
27 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-...
0
votes
2answers
39 views

Difference in signal Spectrum

[ Here are two figures from the same signal, the 2nd one(B) is after digital predistortion at transmitter end. How can you describe it? What are the improvements and advantages of this technique? Much ...
0
votes
1answer
202 views

Carrier frequency offset estimation for QPSK and asymmetrical spectrum

I am working on estimation of carrier frequency offset for QPSK data from a satellite. From my understanding, there are two main approaches: either remove data from the carrier (by taking the fourth ...
0
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1answer
73 views

frequency/phase offset estimation in satellite DOA beamforming applications

In satellite QPSK demodulation, we first estimate and remove the phase offset introduced by the channel. Then, we demodulate the baseband information bits (I & Q channels). In satellite DOA ...