Digital oscilloscopes 101

-February 19, 2014

If there is one course that every engineer should take it is Tom Dagostino’s Fundamentals of Digital Oscilloscope Usage course. Not only does this course touch on the fundamental differences between analog and digital oscilloscopes, it explains in less than 1 hour pretty much everything you need to know about the main features of digital oscilloscopes. And since it is pre-recorded and available online, you can watch it from your desk at your leisure.

Tom is an electrical engineer with nearly 40 years of acquired expertise in many areas including signal integrity and analysis, EDA, board layout and circuit design. He is currently VP of device modeling at Teraspeed Consulting Group and is also a regular presenter and active community member of DesignCon. In this course, Tom does a great job of describing complex digital oscilloscope features in simplistic terms. He walks through real-world application examples using an Agilent MSOX4154A  X-Series Oscilloscope to display signals generated from a DVD player in his lab.

Figure 1. Agilent MSOX4154A oscilloscope in Tom’s lab

While the basic functionality of both analog and digital oscilloscopes is to measure and display voltage against time for a particular input signal, digital scopes have come a long way from the classic analog models we all know and love. Analog scopes just display signals, whereas a digital one digitizes the signal using different acquisition and triggering modes.  Digital scopes provide increasingly advanced capabilities and features that make them exponentially more powerful than an analog one.

While these new features might seem intimidating at first, this course will help you find your comfort zone using a digital oscilloscope as it explains the basics about analog-to-digital conversion, sampling methods such as peak detection, averaging and high resolution, and how to effectively use triggering. In fact, did you know that triggering is a key differentiator between analog and digital oscilloscopes? In an analog scope, the trigger is used to start the display, but in a digital scope, the trigger stops the acquisition. This can be especially useful to show what caused an event as opposed to what happened because of an event.

I found the troubleshooting part of the course the most interesting. For example, I learned how the scope’s display and triggering capabilities can be used to find hidden problems in a serial data stream as well as hard-to-find timing problems, such as intermittent failures.

Figure 2. Screenshot from Agilent MSOX4154A oscilloscope using Setup and Hold trigger with Persistence feature

Whether you are an engineer debugging new designs or fixing assembly issues during manufacturing test, I am sure that you will find this course insightful and useful. Thanks to Tom for sharing his tricks of the trade with us. I invite you to take the course yourself and share your thoughts with me.

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