Operating instructions

LOCAL OPERATION
3-31
Arming, triggering and storing
The transient capture operation has three phases. The current phase is shown in inverse video at
the bottom right of the display.
The Armed phase is active when the transient analysis function is accessed. The level of any
signal entering the selected RF input connector at the set transmitter frequency is displayed on the
screen, if it is within the dynamic range currently being displayed.
Samples of the level of the signal displayed are stored in a circular buffer, configured to be filled
within the time of one display scan.
While in the Armed phase, the display is re-initialized if a setting is changed which could
otherwise result in an erroneous display being produced. The settings which cause re-initializing
when changed are:-
Reference level
Transmitter frequency
Display time scale
Pre-trigger.
The Triggered phase is activated by the RF level passing through the trigger level in the selected
direction.
Writing to the circular buffer is stopped after the elapse of the post-trigger time to be displayed.
When the display is complete, it will show the profile of the transmitter level transient. This starts
the Stored phase. Fig. 3-8, shows transient records of the same signal transient at Time/div
settings of 50 ms, 500 µs and 50 µs.