196
Concepts
Trigger Concepts
Figure 15-2 Frame Triggering
a. Period
Sets the period of the internal periodic timer clock. For digital
communications signals, this is usually set to the frame period of your current
input signal. In the case that sync source is not set to OFF, and the external
sync source rate is changed for some reason, the periodic timer is
synchronized at the every external synchronization pulse by resetting the
internal state of the timer circuit.
Press Trigger, Periodic Timer.
b. Offset
Adjusts the accumulated offset between the periodic timer events and the
trigger event. Adjusting the accumulated offset is different than setting an
offset, and requires explanation.
The periodic timer is usually unsynchronized with any external events, so the
timing of its output events has no absolute meaning. Since the timing relative
to external events (RF signals) is important, you need to be able to adjust
(offset) it. However, you have no direct way to see when the periodic timer
events occur. All that you can see is the trigger timing. When you want to
adjust the trigger timing, you will be changing the internal offset between the
periodic timer events and the trigger event. Because the absolute value of that
internal offset is unknown, we will just call that the accumulated offset.
Whenever the Offset parameter is changed, you are changing that
accumulated offset. You can reset the displayed offset using Reset Offset
Display. Changing the display does not change the value of the accumulated
offset, and you can still make additional changes to accumulated offset.
Press Trigger, Periodic Timer.
c. Reset Offset Display
Resets the value of the periodic trigger offset display setting to 0.0 seconds.
The current displayed trigger location may include an offset value defined
with the Offset key. Pressing this key redefines the currently displayed trigger
location as the new trigger point that is 0.0 s offset. The Offset key can then
be used to add offset relative to this new timing
Press Trigger, Periodic Timer.
To Next Page
Loading...
