Making time measurements with a DSO. (digital storage oscilloscope)

The oscilloscope is the time-honored tool of choice for measuring voltage changes over time because the waveforms on its screen are graphical representations of those changes. This article will show you how to use your digital storage oscilloscope (DSO) to your advantage when you need to make highly accurate time measurements.

Time is measured on the oscilloscope's horizontal or X axis. You can adjust the time axis by using the scope's horizontal scale or time-per-division control. In this article, we will be discussing some of the more frequently made time measurements. A similar discussion of voltage measurements was presented last month.

Common time measurements include the waveform period, frequency, pulse risetime, and pulse width. A period is the time it takes a repetitive waveform to complete one cycle or move through a series of amplitude values until the values begin to repeat. The frequency in Hertz is one divided by the period, or the period's reciprocal.

Pulse waveforms are encountered frequently. All pulses have a rising edge, a width, and a falling edge. The risetime is the time it takes the pulse to go from a low amplitude (voltage) to a high one. …