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### Is the periodogram squared-magnitude DFT or squared-average DFT?

The periodogram is simply the squared magnitude of the DFT. Since the periodogram is a rather poor estimate of the power density spectrum of a random process there are methods which use averaging of ...
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### Interpretation of Clarke's Doppler power spectral density

In addition to Carlos answer, I want to correct your general understanding: What I understand of Doppler spread is that the relative motion between Transmitter (TX) and Receiver (RX) change the ...

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### Show That the Power Spectrum Density Matrix Is Positive Semi Definite (PSD) Matrix

Pay attention that for a Scalar Random Process the Power Spectrum Density is non negative. Namely, let $y \left[ n \right] \in \mathbb{R}$ be a WSS Random process with its Auto Correlation function ...

do you see anywhere in your book where this "DTFT" is defined for your w.s.s. process, $x[n]$? the DTFT is normally defined as $$X(e^{j \omega}) \triangleq \sum\limits_{n=-\infty}^{+\infty} x[n] e^{... 5 votes Accepted ### Power Spectral Density From Variance The power spectral density is NOT the Fourier transform of the variance. For wide-sense-stationary (WSS) signals, the power spectral density is the Fourier transform of the Autocorrelation function, ... 5 votes Accepted ### Filter before or after multiplication of two signals? A personal rule: in general, it can be better to perform non-linear operations before linear ones. One reason behind that is that a lot of practical concerns are related to outliers or suspect ... 5 votes Accepted ### Is spectral density conserved after aliasing? No. The aliased component will interfere with the non-aliased components and the interference can constructive or destructive. Trivial example:$$x[n] = \sin\left(\frac\pi2n\right) If you down ...
First, multiply (-174dBm/Hz) by 180000, then convert the result into watt? Because the decibel is a logarithmic unit, you need to be careful here. $-174\mathrm{dBm}$ means $10^{-17.4} \mathrm{mW}$. ...