Types of Oscilloscope Waveforms

Most waveforms on digital storage oscilloscopes are easy to identify: there are sine, square, rectangular, triangle, sawtooth, step-, and pulse-shaped waves.

Good Ol’ Sine Waves

Sine waves are the fundamental waveform because of their prevalence and their harmonious mathematical properties. (It’s the same sine wave you had to learn in high school math class.) The voltage from your wall’s outlet makes a sine wave. Test signals from a signal generator’s oscillator circuit make sine waves. AC power sources make sine waves. You get the picture.

Then there’s the damped sine wave. You’re likely to see this in a circuit that oscillates while winding down over time. Whereas an ordinary sine wave rolls up and down with regularity, a damped sine wave rolls up and down while getting decreasing in amplitude — the wave gets closer to zero the longer it goes on.

Square and Rectangular Waves

Square waves are almost as common as sine waves. A square wave is, in essence, a voltage that turns on and off — or abruptly alternates between high and low — at recurring intervals. Television, radio, and computer circuitry frequently uses square waves for timing signals.

Rectangular waves are similar to square waves, save for the fact that the high and low intervals aren’t equal lengths.

Sawtooth and Triangle Waves

Linearly controlled voltages result in sawtooth and triangle waves on the digital storage oscilloscope. The voltage levels of these types of waves transition at a constant rate, and these transitions are called “ramps”.

Step- and Pulse-Shaped Waves

Signals like steps or pulses that occur just once are called single-shot or transient signals. A step represents a sudden change in voltage — it’s what you’d see if you flipped a power switch. If you flipped that power switch on and then off, then you’d get a pulse.

Computer components communicate with one another using pulses. Pulses are common in x-ray and communications equipment as well.