LeCroy DDA 7 Zi series, Руководство оператора

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WavePro 7Zi
291
WP700Zi-OM-E-RevA
Beginning Edge Shift (BES)
Description
BES provides a measurement of the time between the beginning edge of the subject n in a specified space/pit
pair and the nearest specified clock edge. The measurement is calculated between the points where the data and
clock signals cross selected voltage thresholds. The clock period T can be entered by the user, or measured from
a user supplied clock signal, as described below.
The value calculated depends on the clock and data edges selected, as shown in the table below. The data slope
menu selects the polarity of the subject
n pit/space. If Pos (positive) is selected, the measurement is performed
from the beginning edges of positive polarity pits and categorized by the preceding space. If Neg (negative) is
selected, the measurement is performed from the beginning edges of negative polarity spaces and categorized by
the preceding pit. If Both is selected, the beginning edges of both pits and spaces are used in the calculation and
categorized by the preceding inverse polarity space/pit. The sizes of pits or spaces used in the measurement are
also determined by the range of ‘nT’ values chosen.
CLOCK
EDGE
DATA SLOPE
Positive Negative Both
Positive
time between beginning edge
of positive polarity subject pit
and nearest positive clock
edge time between beginning edge
of negative polarity subject
space and nearest positive
clock edge
time between beginning
edge of subject pits and
spaces to nearest positive
clock edge
Negative
time between beginning edge
of positive polarity subject pit
and nearest negative clock
edge time between beginning edge
of negative polarity subject
space and nearest negative
clock edge time between beginning
edge of subject pits and
spaces to nearest negative
clock edge
Near
time between beginning edge
of positive polarity subject pit
and nearest clock edge time between beginning edge
of negative polarity subject
space and nearest clock edge
time between beginning
edge of subject pits and
spaces and nearest clock
edge
The next figure shows the measurement of the beginning edge shift on a single subject 4T pit preceded by a 3T
space. In this example, the clock is specified as the positive edge. For each space/pit combination, the beginning
edge shift is calculated as the time difference between the beginning pit edge and the clock edge. Additionally,
the measurements will be sorted by the space/pit pairs. For the positive polarity pit example shown in the figure
after next, measurements t+ and t- are for a single beginning edge shift measurement configured for positive
edge, or negative edge. If nearest is selected, the smaller of t- or t+ is used.
Figure 5-1. Beginning Edge Shift measurement of subject 4Tpit