Triggering on Waveforms
TDS 500B, TDS 600B, & TDS 700A User Manual
3–83
rate of pulse (see above). You set the slew rate setting indirectly by setting
the ratio of delta voltage to delta time as:
+
!
Substituting the threshold and delta time settings for the setup in Fig-
ure 3–46:
+
!
+ ń
The trigger bar indicators (long horizontal bars) point to the upper and lower
thresholds. The pair cursors, which are aligned to threshold levels, read out a
delta voltage of approximately 4 V and a delta time of 200 ns between the
threshold levels. Therefore, the slew rate of the pulse edge triggered on is:
+
+
+ ń
The Trigger When side menu indicates the oscilloscope will trigger on pulses
with slew rates slower than the slew rate setting. Since the pulse edge slews
at 20 mV/ns, which is faster than the slew rate setting of 16 mV/ns, the
oscilloscope triggers.
The trigger point indicator shows where the oscilloscope triggers. For a slew
rate triggered waveform, the trigger point is always at the threshold crossed last
(the upper threshold for positive polarity settings; the lower for negative
settings).
Set the Mode and Holdoff. Mode and holdoff can be set for all standard trigger
types and classes. To set mode and holdoff, refer to Set Mode & Holdoff on
page 3–61. To learn more about trigger mode and holdoff, see Trigger Modes
and Trigger Holdoff on page 3–53.
When you select the pulse class Timeout, the TDS oscilloscope will trigger on a
pulse change that does NOT occur within the specified limits. That is, the trigger
will occur when, depending on the polarity you select, the signal stays higher or
stays lower than the trigger level for the timeout value. To set up for timeout
triggering, do the following procedures.
Select Timeout Triggering. Press TRIGGER MENU ➞ Type (main) ➞ Pulse
(pop-up) ➞ Class (main) ➞ Timeout (pop-up).
Select the Source. Press TRIGGER MENU ➞ Type (main) ➞ Pulse
(pop-up) ➞ Source (main) ➞ Ch1, Ch2, Ch3, or Ch4 (side). The source
selected becomes the trigger source for all four trigger classes.
Trigger Based on
Pulse Timeout
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