# Tag Info

### Interpreting sensor noise data

Assumption 1 is usually a good assumption: just make the measurement noise covariance matrix diagonal. If all the sensors are the same, then this will just be $\sigma^2 I$ where $I$ is the identity ...
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### Weird Pattern in the Power Spectrum diagram (i.e. the frequency domain of the signal)

Two possible reasons: A low pass filter is active. The ripple looks like a typical filter stopband ripple. It is due to the way the spectrum is calculated. Check the settings and play around with ...
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### Conversion between Eb/N0 and SNR in spread-spectrum modulation like LoRa CSS?

You are using log with base 12, also in the code you mentioned about css for plotting, but you didn't used it anywhere else.

### why need de-correlated signal for measuring phase noise in laser

Because you can't measure absolute phase -- you can only measure the phase difference between your unit under test and a reference. If you have a reference that's perfectly correlated to your unit ...
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Let's look at one coefficient of the correlation $$c_l = \mathbb{E} \left[ x_k x_{k+l}^* e^{1j (\theta_k - \theta_l)}\right]$$ $$c_l = \mathbb{E} \left[ z_{k,l} e^{1j (\theta_k - \theta_l)}\right]$$ ...