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Appendix C: Algorithms
TVS600 & TVS600A Command Reference
C–3
LREFerence the waveform low reference or proximal level. Used in fall time and
rise time calculations. In the RELative mode, you use the command CALCu-
late:WMParameter:LREFerence:RELative to set it from 0% to 100%, with a
reset value of 10%. You can set it to a voltage level with the command CALCu-
late:WMParameter:LREFerence.
The waveform analyzer also measures several values itself that it uses to help
calculate measurements.
RecordLength is the number of data points in the waveform record.
Hysteresis reduces the effects of noise on measurements by providing a guard
band of 5% (the default) of the waveform amplitude, above and below the
midpoint value. Hysteresis can be set in the range 0% to 50%. It is used in
MCross1, MCross2, and MCross3 calculations.
For example, once a crossing has been measured in a negative direction, the
waveform data must fall below 5% of the amplitude from the MidRef point
before the measurement system is armed and ready for a positive crossing.
Similarly, after a positive MidRef crossing, waveform data must exceed 5% of
the amplitude before a negative crossing can be measured. Hysteresis is useful
when you are measuring noisy signals, because it allows the waveform analyzer
to ignore minor fluctuations in the signal.
MCross1, MCross2, and MCross3 refer to the first, second, and third MidRef
cross times, respectively. (See Figure C–1.)
The polarity of the crossings does not matter for these variables, but the
crossings alternate in polarity; that is, MCross1 could be a positive or negative
crossing, but if MCross1 is a positive crossing, MCross2 will be a negative
crossing.
The waveform analyzer calculates these values as follows:
1. Find the first MidRefCrossing in the waveform record (or the gated region).
This is MCross1.
2. Continuing from MCross1, find the next MidRefCrossing in the waveform
record (or the gated region) of the opposite polarity of MCross1. This
is MCross2.
3. Continuing from MCross2, find the next MidRefCrossing in the waveform
record (or the gated region) of the same polarity as MCross1. This
is MCross3.
Other Variables
MCross Calculations