Trigger

Introduction

This topic describes both standard and pattern triggering of a DCA-X.

Click Setup > Trigger to open the Trigger dialog. Or, click the Trigger button, located at the bottom of the screen.

To Trigger the Instrument

A trigger signal must be provided to the oscilloscope using one of the following methods:

• Connect a synchronous clock signal to the oscilloscope's front-panel Trigger connector. Click Setup > Trigger to open the Trigger dialog and specify Front Panel. This is the most often-used method (as well as the default) source for triggering. You can also press the instrument's front-panel Trigger Level knob to select Front Panel. After connecting and then selecting the trigger source click Auto Scale on the menu bar to set the trigger level to the amplitude midpoint of the trigger signal. To manually adjust the trigger level, turn the Trigger Level knob.



• On N109x-series DCA-M scopes, connect the clock signal to the DCA-M's front-panel Clock In connector.
• If a trigger signal is not available, use clock recovery to recover the clock. Click Setup > Trigger and select Left Module or Right Module to trigger from the clock recovery module. Compatible modules (that have front-panel trigger input connectors) include N1060A, 86108A/B, N107x series DCA-M, and 83496A/B modules. When an 86108A/B precision waveform analyzer module is installed, the Left Module setting selects triggering from the recovered clock and the Right Module setting selects triggering from the precision timebase. If you are using an 86107A Precision Timebase module and the time reference is set, all external trigger sources and controls are disabled.
• Trigger on the data input to a module. Split the incoming data signal and route half of the data to the instrument's trigger input. Route the other half to the module's input connector. Due to jitter and pattern dependencies this technique shows incomplete eye diagrams and approximately 75% of waveforms are never observed in a PRBS.
• In Oscilloscope and Eye/Mask modes, you can also select Free Run. This selection causes the instrument to trigger as soon as the trigger is armed; an external trigger is not used. Free run is asynchronous to the data and can be used to quickly examine a signal's amplitude without any timing information.