Teledyne LeCroy AORM - Advanced Optical Recording Measurements - Manual (Page 47)

AORM Software Package
923133 Rev A ISSUED: June 2013
45
The next figure demonstrates the measurement of the beginning edge shift on a single subject 4T pit
preceded and followed by a 3T space. In this example, the clock is specified as the positive edge. The
beginning edge shift is calculated as the time difference between the beginning pit edge and the clock
edge while the ending edge shift is calculated as the time difference between the ending pit edge and
the clock edge.
Beginning and Ending Edge Shift measurement of subject 4T pit
The measurement has configurable units. If absolute time is specified, the value is simply the
time, as indicated above. If percent is specified, the value of the measurement is the time
normalized to the clock period:
For all pits, a valid measurement will be obtained only when both edges of the leading and trailing
pits/spaces can be determined (that is, there is a hysteresis-qualified threshold crossing
beginning the start pit/space and ending the end pit/space of interest between the parameter
cursors)
, and there is a clock edge of both polarities surrounding the leading pit or space edge
between the parameter cursors.
Data
Signal
Clock
Signal
threshold
3T 4T
ending
edge shift
beginning
edge shift
3T
∆
∆
bees t
T
or t
T
100%
100%
= ⋅
⋅
+
−