HP 54645A, User'S And Service Manual

Page: 106 / 301

The time reference position sets the initial position of the trigger event within
acquisition memory and on the display, with delay set to 0. The delay setting
sets the specific location of the trigger event with respect to the time
reference position. The time reference setting affects the delayed sweep as
described in the following ways.
When the horizontal mode is set to Main, the delay positions the main sweep
relative to the trigger. This delay is a fixed number.
Changing this delay
value does not affect the sampling interval or sweep speed. When the
horizontal mode is set to Delayed, the delay controls the position of the
delayed sweep window inside the main sweep display. This delayed delay
value is independent of sampling interval and sweep speed.
The time reference indicates where the delay value is on the screen, and is
the point about which the screen is expanded when you change the time per
division. The delay setting sets the specific location of the trigger event with
respect to the time reference position.
Thus, because the delay can be
adjusted in the positive direction to greater than the depth of
acquisition memory, the trigger event may or may not be stored in
acquisition memory
. The range of available negative delay is less, and the
trigger will always be in acquisition memory.
MegaZoom Concepts
Changing the time reference position
4-23