The Oscilloscope

A - Z : Glossary of terms

AC: (Alternating Current) A signal in which the current and voltage vary in a repeating pattern over time.
ADC: (Analog-to-Digital Converter) A digital electronic component that converts an electrical signal into discrete binary values.
Alternate Mode: A display mode of operation in which the oscilloscope completes tracing one channel before beginning to trace another channel.
Amplitude: The magnitude of a quantity or strength of a signal. In electronics, amplitude usually refers to either voltage or power.
Attenuation: A decrease in signal voltage during its transmission from one point to another.
Averaging: A processing technique used by digital oscilloscopes to eliminate noise in a signal.
Bandwidth: A frequency range.
CRT: (Cathode-Ray Tube) An electron-beam tube in which the beam can be focused on a luminescent screen and varied in both position and intensity to produce a visible pattern. A television picture tube is a CRT.
Chop Mode: A display mode of operation in which small parts of each channel are traced so that more than one waveform can appear on the screen simultaneously.
Circuit Loading: The unintentional interaction of the probe and oscilloscope with the circuit being tested, distorting the signal.
Compensation: A probe adjustment for 10X probes that balances the capacitance of the probe with the capacitance of the oscilloscope.
Coupling: The method of connecting two circuits together. Circuits connected with a wire are directly coupled; circuits connected through a capacitor or a transformer are indirectly (or AC) coupled.
Cursor: An on-screen marker that you can align with a waveform to take accurate measurements.
DC (Direct Current): A signal with a constant voltage and current.
Division: Measurement markings on the CRT graticule of the oscilloscope.
Earth Ground: A conductor that will dissipate large electrical currents into the Earth.
Envelope: The outline of a signal's highest and lowest points acquired over many repetitions.
Equivalent-time Sampling: A sampling mode in which the oscilloscope constructs a picture of a repetitive signal by capturing a little bit of information from each repetition.
Focus: The oscilloscope control that adjusts the CRT electron beams to control the sharpness of the display.
Frequency: The number of times a signal repeats in one second, measured in Hertz (cycles per second). The frequency equals 1/period.
Gigahertz (GHz): 1,000,000,000 Hertz; a unit of frequency.
Glitch: An intermittent error in a circuit.
Graticule: The grid lines on a screen for measuring oscilloscope traces.
Ground

A conducting connection by which an electric circuit or equipment is connected to the earth to establish and maintain a reference voltage level.
The voltage reference point in a circuit.

Hertz (Hz): One cycle per second; the unit of frequency.
Kilohertz (kHz): 1000 Hertz; a unit of frequency.
Interpolation: A "connect-the-dots" processing technique to estimate what a fast waveform looks like based on only a few sampled points.
Megahertz (MHz): 1,000,000 Hertz; a unit of frequency.
Megasamples per second (MS/s): A sample rate unit equal to one million samples per second.
Microsecond: A unit of time equivalent to 0.000001 seconds.
Millisecond (ms): A unit of time equivalent to 0.001 seconds.
Nanosecond (ns): A unit of time equivalent to 0.000000001 seconds.
Noise: An unwanted voltage or current in an electrical circuit.
Oscilloscope: An instrument used to make voltage changes visible over time. The word oscilloscope comes from "oscillate," since oscilloscopes are often used to measure oscillating voltages.
Peak - V[p]: The maximum voltage level measured from a zero reference point.
Peak-to-peak - V[p-p]: The voltage measured from the maximum point of a signal to its minimum point, usually twice the V[p] level.
Peak Detection: An acquisition mode for digital oscilloscopes that lets you see the extremes of a signal.
Period: The amount of time it takes a wave to complete one cycle. The period equals 1/frequency.
Phase: The amount of time that passes from the beginning of a cycle to the beginning of the next cycle, measured in degrees.
Probe: An oscilloscope input device, usually having a pointed metal tip for making electrical contact with a circuit element and a flexible cable for transmitting the signal to the oscilloscope.
Pulse: A common waveform shape that has a fast rising edge, a width, and a fast falling edge.
RMS: Root mean square.
Real-time Sampling: A sampling mode in which the oscilloscope collects as many samples as it can as the signal occurs.
Record Length: The number of waveform points used to create a record of a signal.
Rise Time: The time taken for the leading edge of a pulse to rise from its minimum to its maximum values (typically measured from 10% to 90% of these values).
Sample Point: The raw data from an ADC used to calculate waveform points.
Screen: The surface of the CRT upon which the visible pattern is produced - the display area.
Signal Generator: A test device for injecting a signal into a circuit input; the circuit's output is then read by an oscilloscope.
Sine Wave: A common curved wave shape that is mathematically defined.
Single Shot: A signal measured by an oscilloscope that only occurs once (also called a transient event).
Single Sweep: A trigger mode for displaying one screenful of a signal and then stopping.
Slope: On a graph or an oscilloscope screen, the ratio of a vertical distance to a horizontal distance. A positive slope increases from left to right, while a negative slope decreases from left to right.
Square Wave: A common wave shape consisting of repeating square pulses.
Sweep: One horizontal pass of an oscilloscope's electron beam from left to right across the CRT screen.
Sweep Speed: Same as the time base.
Time Base: Oscilloscope circuitry that controls the timing of the sweep. The time base is set by the seconds/division control.
Trace: The visible shapes drawn on a CRT by the movement of the electron beam.
Transducer: A device that converts a specific physical quantity such as sound, pressure, strain, or light intensity into an electrical signal.
Transient: A signal measured by an oscilloscope that only occurs once (also called a single-shot event).
Trigger: The circuit that initiates a horizontal sweep on an oscilloscope and determines the beginning point of the waveform.
Trigger Holdoff: A control that inhibits the trigger circuit from looking for a trigger level for some specified time after the end of the waveform.
Trigger Level: The voltage level that a trigger source signal must reach before the trigger circuit initiates a sweep.
Volt: The unit of electric potential difference.
Voltage: The difference in electric potential, expressed in volts, between two points.
Waveform: A graphic representation of a voltage varying over time.
Waveform Point: A digital value that represents the voltage of a signal at a specific point in time. Waveform points are calculated from sample points and stored in memory.
Z-axis: The signal in an oscilloscope that controls electron-beam brightness as the trace is formed.

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Oscilloscope Training Package Programmed by Jigar C. Shah NTU Final Year Project.