How to Use Measurement Statistics to Set Up Triggers

Figure 1.  Histogram of the different pulse widths occurring
in a pulse-width modulated rectangular pulse train.

Triggering is an essential element in all modern digital oscilloscopes.  The trigger synchronizes the oscilloscope’s data acquisition with a user-specified event on the signal, be that an edge, threshold crossing or a specific signal characteristic. Teledyne LeCroy Smart Triggers can trigger oscilloscope acquisitions based on properties such as a period, width, low signal amplitude, slew rate or signal loss. These trigger types are ideal for capturing transient events like glitches, but they require knowing at least a range of possible values for the trigger to detect.

Intermittent transient events and glitches are among the most frustrating problems to detect and solve. This is especially true if you have no idea about the nature of the transient. However, you can use the oscilloscope’s measurement tools to help locate these bothersome transients, then use that information to set up your trigger to capture them when they occur. Here’s how.

Why IEEE's Pulse Definitions and ESD Pulses Don't Mix

Figure 1: The IEEE's pulse definitions, which don't fit
the bill for measuring ESD pulses

The IEEE's pulse definitions, found in the organization's Std 181-2011 that covers transitions, pulses, and related waveforms, set the bar for how pulse measurements are determined. These definitions, which are in the DNA of all oscilloscopes, are just the thing for measuring repetitive pulses such as clock signals but not so much for ESD/EMC measurement requirements. In this post, we'll discuss why that is and what you should do differently for measuring ESD pulses.