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Scope and Multimeter Operations Control Panel and Settings
121
9.9.15 Threshold Auto/Manual (GMM Only)
NOTE
The Threshold function is only available in the Graphing Meter function for
specific tests. These functions may also be referred to as Auto Threshold
Select (ATS) or Manual Threshold (MT).
The Threshold function can be used, to display and obtain a more accurate
measurement when measuring signals (e.g. Frequency, Duty Cycle, MC Dwell and
Pulse Width) that may be difficult to display or have noise or other undesirable
variations in the signal.
When Auto Threshold is selected, the Threshold function automatically sets a
trigger and determines a threshold level in the middle of the signal range
(calculated from the Min and Max measurements) to be used as a reference point
to calculate the measurement. The falling edge (slope) of the signal is used in
determining the threshold level. Once selected, the Threshold function remains
active until the test is exited.
Selecting Manual Threshold , allows you to manually set the value and slope.
Figure 9-37
The following examples are provided, showing some common setup issues you
may experience when using this function
If after enabling the Threshold function the signal is displayed as a flat line at
zero (0) (
Figure 9-38
), reduce the vertical scale setting, as it may be set too high.
Figure 9-38
Scale at 1000Hz, frequency appears to be zero (is actually 7.7Hz)
If the scale is changed to 50Hz, it is easier to see the signal at 7Hz (
Figure 9-39
).
Figure 9-39
Scale at 50Hz