An example of this is the rapid oscillation of an AM signal which is very far away. We will discuss this further in Chapter 3. Noise is also an interesting phenomenon, and one which we can quantify. We can also use this to take a closer look at the maximum possible transmission rate in the presence of noise. Let's take each type in turn.
Thermal noise is assumed to be spread evenly across all frequencies.
This seems like a pretty low signal. We will have a baseline for comparison of this as we go farther in the course. The received signal level would be reduced even further by other losses, as we shall see in chapter 3.