HP 54540 Series - Page 239

See also
Figure 13-5
Measurements
Calculating Thresholds
Calculating Thresholds
Top and base are are used to calculate the threshold levels used for timing
measurements. These thresholds may be the IEEE values of 10, 50, and 90
percent, or values in percentages or volts that you set. These thresholds are
called upper, middle, and lower thresholds in the measurement menu.
These thresholds are used by all timing measurements as they are needed to
determine the presence of a rising or falling edge. In addition, the thresholds
are used by various measurements. For example, rise time is measured from
the lower threshold to the upper threshold of a rising edge. Period and
frequency measurements use the middle threshold as shown in figure 13-5.
Chapter 8, "Define Measure Menu," for information on manually setting the
thresholds.
_data [o] build histogram
istogra
,
ax
90%
top
50% 4 =
10% aoe _top,base.clip _
min Lo 4
Pea
Vmin, Vmax, Vpp
Vboase,Vtop, Vamp
70%,50%,90% O%
The oscilloscope calculates the 10, 50, and 90 percent thresholds
13-8