How to Interpret a Scope Waveform
Oscilloscopes are widely used in electronics circles to examine the waveform produced by electrical currents. These waveforms, or traces, form a graphical representation of what is going on with the signal. Experienced technicians look at these representations, determining what they represent at a glance. Often, these waveforms reveal problems in electrical signals, which is useful in diagnosing problematic electronic components.
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Instructions
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Examine the waveform on the face of the cathode-ray-tube screen. Normal traces appear as a wave, traveling from the top to the bottom of the screen.
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Look at horizontal (x-axis) and vertical (y-axis) lines on the screen. The vertical line represents voltage, while the horizontal line depicts time. Note that the vertical line is bisected by a third line, representing zero phase. This third line represents the starting and stopping point when measuring one complete cycle.
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Check the distance between the zero phase line heading "up" on the vertical voltage line. This first arch represents amplitude.
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Look at the line as it descends below the zero phase line. One full arch above and inverted arch below the zero line represents a full cycle. This is known as a "time period," measured in seconds and milliseconds.
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Examine the upper apex of an arch above the zero phase line. The distance between the apex and the bottom of the scope's measurement graph represents peak-to-peak voltage.
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Tips & Warnings
There are dozens of wave traces possible on an oscilloscope. It is useful to print and keep a reference sheet on hand when testing components.
Never open an oscilloscope to examine the internals. High voltages are always present, whether the unit is on or off.
Use caution when moving a scope to prevent damage to the tube inside.
References
Resources
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