LeCroy DDA 7 Zi series, Operator'S Manual

Page: 474 / 544

WavePro 7Zi
473
WP700Zi-OM-E-RevA
Local baseline and local baseline separation if not last local feature
Baseline identified
peak-to-trough
(PTBase)
Baseline identified
trough-to-peak
(TPBase)
Local Baseline
Baseline
Separation
yes yes average of TPBase PTBase – TPBase
yes no PTBase 0
no yes PTBase 0
no no
midpoint of local peak and
trough
0
Setting Hysteresis
Hysteresis must be set for all local parameters. The determining factors for a hysteresis value are:
1. The maximum peak-to-peak noise in the waveform
2. The minimum local feature amplitude
The value should be somewhere between the first and second factors to ensure that noise is not mistaken for a
local feature, and that all local features are recognized.
Local Parameters
The local parameters group offers measurements of common disk drive waveform parameters.
Local Parameter Definition
lbase baseline of local feature
lbsep separation between peak-to-trough and trough-to-peak baselines
lmax maximum value of local feature
lmin minimum value of local feature
lnum number of local features displayed
lpp local feature’s peak-to-trough amplitude
ltbe time between peak-to-trough or trough-to-peak
ltbp local feature’s time between peaks
ltbt local feature’s time between troughs
ltmn time of local feature’s minimum value
ltmx time of local feature’s maximum value
ltot local feature’s time over a % threshold
ltpt time between local feature peak-to-trough
lttp
time between trough-to-following peak
ltut local feature’s time under a % threshold
Note: The DDA’s variable hysteresis setting is essential to identifying peak-trough pairs.