Oscilloscope Reference Measurement algorithms
Positive width
Timing measurement. The distance (time) between MidRef (default = 50%) amplitude points of a positive
pulse.
If MCross1Polarity =+
then
PositiveWidth = (MCross2 –MCross1)
else
PositiveWidth = (MCross3 – MCross2)
Rise time
Timing me
asurement. Time taken f or the leading edge of a pulse to rise from a LowRef value (default =
10%) to a HighRef value (default = 90%).
The foll
owing figure shows a rising edge with the two crossings necessary to calculate a Rise Time
measurement.
1. Search
ing from Start to End, find the first sample in the measurement z one less than LowRef.
2. From this sample, continue the search to find the first (positive) crossing of LowRef. The time of this
cross
ing is the low rise time o r TLR. (Use linear interpolation if necessary.)
3. From TLR, continue the search, looking for a crossing of HighRef.UpdateTLR if subsequent LowRef
cros
sings are found. If a HighRef crossing is found, it becomes the high rise time or THR. (Use linear
interpolation if necessary.)
4. Ris
eTime = THR – TLR
736 DSA/DPO70000D, MSO/DPO/DSA70000C, DPO7000C, and MSO/DPO5000 Series
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