7-1 answers.txt

Answers were written by Johannes Lorper

What is the defining property of Gaussian noise?

Its distribution.
The defining property of Gaussian noise is its pdf (probability density function) having a Gauss distribution.
That means that the values calculated with the pdf describe a bell shaped graph.
(Chapter 2)

What does a low-pass filter do in general?

A low-pass blocks all frequencies above a certain threshold. All frequenzies below the threshold can pass the filter.
That means, you can filter out all frequenzies above the threshold and only the ones below it remain. (Chapter 3)

Is a moving average filter a low-pass or a high-pass filter? Why?

The moving average filter can be both, depending on the signal (Chapter 15, Figure 15-1[a,b,c], page 279); it has a slow roll-of and
a poor stopband attentuation as seen in its frequency response graph (Chapter 15, Figure 15-1, page 280)
It filters outliers by averaging values with neighboring values and thus frequency outliers are effectively filtered out. This means
if the average calculated for a certain value is lower than the input value itself, its functions as a low-pass filter, if its higher
than its input value, it functions as a high-pass filter.
It can change from being a lowpass or highpass filter for different values.