HP 54620A, Руководство пользователя и сервисное руководство

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Setting Logic Levels
You can adjust the logic threshold levels used by the analyzer for
three independent groups of input signals: channels 0-7, channels
8-15, and the external trigger. Because of this, you can make
simultaneous measurements on signals from different logic families.
For example, you could connect channels 0-7 to TTL signals, channels
8-15 to ECL signals, and the external trigger to an analog signal. Then,
you can set the threshold voltages to the appropriate value for each
group.
Logic Threshold Setup
Selects the group of
channels for which
threshold will be set
Choose from preset TTL,
CMOS, or ECL thresholds, or
set a user-defined threshold
Shows the threshold
for the selected
family, or sets a
user-defined
threshold using the
Entry knob
When threshold is set
correctly, the activity
indicators show
double-headed arrows
for rapidly-changing
signals, or high or low
for static or very
low-frequency signals
Figure 10
53