Anritsu Field Master Pro MS2090A, Measurement Manual, Page: 13 / 46

Pulse Analyzer (Option 421) 2-4 Pulse Measurements
Pulse Analyzer MG PN: 10580-00451 Rev. A 2-7
Finding the Reference Level Instants
Instants are a specific time value within a waveform time duration. They are typically referenced relative to
the initial instant of the waveform. The following sections describe how the pulse measurements are
determined (see
Figure 2-7 and Figure 2-8 ).
Finding the Transitions
Transitions are contiguous regions of a waveform that connect, either directly or via intervening transients,
two state occurrences that are consecutive in time but are occurrences of different states. To find the
transition, begin with a filtered list of reference level instants that contain only those that cross the low or high
reference levels. Each reference level instant in the list has a corresponding index and direction (e.g. the trace
index immediately before the amplitude crossing the reference level, and direction indicating whether the trace
crosses from above to below the reference level or vice versa).
This filtered list of instants is sorted in ascending index order. Then all positive and negative transitions
(between the high/low reference levels) are found by searching for consecutive instants in the filtered list that
both have the same direction. The waveform is defined to be in the "high state" if it exceeds the 90% reference
level and in the "low state" if it drops below the 10% reference level. This is the chosen alternative rather than
using the state upper/lower boundaries (which the IEEE standard says is optional).
Figure 2-7. Positive Pulse Waveform Instants and Transitions
Figure 2-8. Negative Pulse Waveform Instants and Transitions
Time
Amplitude
S2
S1
10% Reference Level
90% Reference Level
50% Duration Instant
First Transition
} }
Second Transition
Positive Direction Reference Level Instants
Positive
Transition
Negative
Transition
Negative Direction Reference Level Instants
Time
Amplitude
S2
S1
10% Reference Level
90% Reference Level
50% Duration Instant
First Transition
} }
Second Transition
Positive Direction Reference Level Instants
Negative
Transition
Positive
Transition
Negative Direction Reference Level Instants