Tektronix MSO 2 Series - Fall Time Measurement Algorithm

In the diagram below, the Falling Slew Rate from mid ref to low ref is calculated using the following equation:
Falling Slew Rate = (VREF - VREFLO)/ΔTF
Fall Time measurement algorithm
Fall T
ime is the time required for an edge to fall from the high reference level to the low reference level. By default the measurement is
from reference level 90% amplitude to 10% amplitude.
The following figure shows a falling edge with the two edges necessary to calculate a Fall measurement. The figure shows the default high
reference level which is 90% of Top and the default low reference level which is 10% of Base.
1. Searching from Start to End, find the first sample in the measurement zone greater than HighRef.
2. From this sample, continue the search to find the first (negative) crossing of edge of HighRef. The time of this edge is THF. (Use
interpolation if necessary.)
Figure 2: Fall Time
3. From THF, continue the search, looking for a crossing of LowRef. Update THF if subsequent HighRef crossings are found. When a
LowRef crossing is found, it becomes TLF. (Use interpolation if necessary
.)
4. FallTime = TLF – THF
Measurement algorithms
2 Series MSO MSO24 and MSO22 259