QUESTION: I cannot seem to grasp the difference between jitter and wander. Can you explain?
ANSWER: Somewhat arbitrarily, all the energy/power above 10 Hz is called "jitter" and below 10 Hz is called "wander". So jitter and wander are, in some sense, the same entity but differentiated based on spectrum. The 10 Hz demarcation point arose because, historically, it was determined that PLLs could be used to filter out this energy and available oscillators were capable of providing cut-off frequencies of 10 Hz (the lower the cut-off, the more expensive the oscillator!)
When looking at clocks, the key entity is the period (usually referred to in normalized units as 1 UI). If I compare two clocks, I can line them up at some point in time (which we usually consider the time origin) and look at the relative positions of their rising edges (any particular, specific point within the cycle is OK).
The time difference in rising edges (essentially the same as phase, with two-pi radians corresponding to 1 UI) is called the TIE (Time Interval Error). The leap of faith is to view the TIE as a time-varying signal. The Fourier transform of the TIE then gives the spectrum of the time interval error.
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