User Manual

58 ISSUED: June 2013 923133 Rev A
PASYM PIT ASYMMETRY
Description
Pit Asymmetry provides a measurement of the asymmetry of the middle voltage level for the high
nT index pits/spaces compared to the middle voltage level of the low ‘nT’ index pits/spaces. The
measurement calculation is compliant with the definition of Pit Asymmetry as defined by IEC
908:1987 Section 3.1. The negative value of the measurement is referred to as Pit Symmetry as
defined by ISO/IEC 10149:1995 (E) Section 12.2. Pit Asymmetry is calculated by the formula:
PASYM
pmidl pmidl
paa
high n low n
high n
=
−
⋅
__
_
100%
whe
re paa is the average peak-peak amplitude. The low (smallest) and high (largest) ‘nT’ values to
use in performing the calculation are provided by the user through the associated measurement
configuration options. Midpoint designates the midpoint value between the average top and base for a
specified ‘nT.’ The value shown is in units of percent.
Display Options
ORM parameter calculations can be displayed, histogrammed, and trended in a variety of ways.
DISPLAY TYPE VALUE DISPLAYED
Parameter Statistics Off
Single value of the asymmetry for the last acquisition.
Parameter Statistics On
Average, minimum, maximum and sigma of the single
asymmetry value calculated per acquisition for all acquisitions
since the last C
LEAR SWEEPS operation.
Histogram Function
Histogram of asymmetry value calculated per acquisition for all
acquisitions since last C
LEAR SWEEPS operation.
Trend Function
Trend of single asymmetry value calculated per acquisition for
all acquisitions since last C
LEAR SWEEPS operation.