Getting The Most Out Of Your Oscilloscope: Cursors and Parameters

Figure 1: Cursors (top) and parameter
measurements (bottom) are both
powerful tools in their own right

Oscilloscopes give us a wealth of tools with which to view, measure, and analyze the performance of a circuit. Broadly speaking, two classes of such tools are cursors and parameter measurements. Taken on their own, both classes afford the user a great deal of capability. Put them together, though, and you can really start to gain deep insights into what's going on with a waveform.

The Challenges of GFCI Measurements

Figure 1: An example
of a GFCI

The ubiquitous ground fault circuit interrupter (GFCI), a fast-acting circuit breaker, has saved countless individuals from serious injury or death when they've inadvertently entered the low-resistance ground path of an electrical device or outlet. It's important to measure precisely the amount of time that elapses from when the 60-Hz cycle is present to when the GFCI disables the ground path. Other tests include determining the start, stop, and duration of the GFCI's tripping time. Let's take a look at the challenges these measurements present.