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Appendix B: Automatic Measurements Reference
B-12
CSA8000B & TDS8000B User Manual
Table B- 2: Pulse Measurements - Timing (cont.)
Name Definition
Rise Time The time interval bet ween t he low-reference level and t he high reference level crossi ngs on the
positive sl ope of the pulse.
RZ Rise Time = TcrossH – HcrossL
Where:
H TcrossH is the time of crossing of the high reference level.
H TcrossL is the time of crossing of the low reference level.
The low reference and high reference levels are adjustable and default to 10% and 90% of the
pulse amplitude. There are four Reference Level Calculation methods available for determining
these reference levels. See Measurement Reference Parameters and Methods on page B--56 or
in the online help. Also see Reference Levels Method on page 3--79.
If enabled, measurement gates constrain the measurement region to the area between the Start
Gate (G1) and Stop Gate (G2). By default the algorithm searches forward from the Start Gate
for the f irst risi ng edge, but t he Direct ion of traversal can be reversed, so that the search will be
backward from t he Stop Gate. See To Localize a Measurement on page 3--83.
RMS Jitter The time variance on the time crossings of data sampl ed at t he mid-reference level. RMS Jitter
is defi ned as one standard deviation (σ) of that variance.
RMS Jitter = Tcrossσ
Where Tcrossσ is one standard deviation of the variance of crossing times for a histogram
of the Tcross values. Tcross is the horizontal coordinate of the first positive or negative
crossing.
The mid-reference level is adjustable and defaults to 50% of the pulse amplitude.
The slope can be selected to be the fi rst posi tive, the fi rst negat ive, or the first crossing (positive
or negative) in the region.
If enabled, measurement gates constrain the measurement region to the area between the Start
Gate (G1) and Stop Gate (G2). By default, the algorithm searches forward from the Start Gate
for the first falling edge, but the Direction of traversal can be reversed, so that the search will be
backward from t he Stop Gate.
This measurement requires the use of a waveform database. When this measurement is turned
on, it will automat ically set the measurement system to use a waveform database if available.
See Use a Waveform Database on page B--70.