HP 54501A Getting Started Manual page 30

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What are Time Time interval measurements are made with one or both of the time
interval markers to determine the relationship of a specific point on a waveform to :
the trigger point. The oscilloscope automatically calculates the time
difference between the two markers. The "delta t" calculation is always
made by subtracting the time at the "start marker" from the time at the
"stop marker." Therefore it is possible to obtain negative time readings on
"delta t" if the "stop marker" is placed on the display before the "start
marker."
Measurements?
After an Autoscale, the trigger point is displayed at the center of the
display. When a time marker is placed on the left half of the display the
time for that marker is negative, indicating it is before the trigger. Any
marker to the right of the trigger point is after the trigger and its time
reading is positive. The reference for the display (trigger point) can be
changed to left, cntr (center), or right of the display in the TIMEBASE
menu.
a
Measuring a The following procedure measures the period of a complete cycle of the
Waveform
calibrator signal.
Period
e Connect the ac calibrator output to the channel 1 input.
e Press AUTOSCALE (or set up the oscilloscope display manually).
e Press At/AV menu key.
e Press At markers function key to turn on the markers.
Making Manual Measurements HP 54501A, HP 54502A and HP 54503A
5-6 Getting Started Guide