This value is calculated from interval time of reflected scanning laser beam between two sensors during rotation of the mirror at rated speed. Peak-peak jitter and high frequency jitter are defined as follows using the interval time T1, T2...T480.

The following graph shows a continuous measurement of jitter.
Time is measured across 2 detectors (S.O.S. and E.O.S.)
This time is then compared against the calculated average time interval and desplayed as A plus minus value.