Glossary of Test Equipment Terminology

When dealing with highly technical equipment such as optical, electrical and chemical test devices it's always helpful to have a firm understanding of the industry terminology. Please note that this glossary is a very much a work in progress and will be regularly updated.

Ammeter - A meter which measures the flow of electrical current in amperes or amps. Ammeters are sometimes referred to as ampmeters or amp meters.

Attenuator - A device which attenuates or decreases the strength or amplitude of an electrical signal. One common example of an attenuator is a volume control.

Autocollimator - An instrument which combines the functions of a telescope and a collimator. An autocollimator measures very small deviations in a light beam.

Autosampler - An autosampler is a liquid sampler which takes samples automatically based on either a programmable time schedule or based on conditions that are read from sensors such as flowmeters. For instance, an autosampler could take a sample when a flowmeter indicates a heavier flow of water than normal, such as after a rainstorm.

Cable Locator - An instrument used to locate underground cables, wiring and pipes. Cable locators can be used not only to locate the cabling but to estimate the depth of the wiring. They are essentially specialized metal detectors.

Calibrator - A device used to calibrate a precision instrument. Calibration consists of comparing measurements of the instrument with a standard and making adjustments to bring the instrument into compliance with that standard. Proper use of a calibrator ensures that the instrument is as accurate as possible.

Chart Recorder - A device which records an electrical or mechanical input trend onto a paper chart. An electrocardiogram (ECG or EKG) or a lie detector are good examples of such a device.

Clamp Meter - A clamp meter, clampmeter or clamp-on ammeter is an ammeter which allows you to measure electrical current without having to disconnect the wiring to take the measurement. A clamp meter measures the current through the wire insulation.

Collimator - A collimator is a device which takes a beam of waves or particles and causes it to become more aligned or parallel. In essence a collimator produces a parallel beam.

Data Logger - A data logger or data recorder is the electronic or computer equivalent of a chart recorder. Instead of logging the data on a paper chart the data is displayed on a screen or stored in a file or database.

Disturbance Analyzer - An instrument which measures AC and DC power disturbances such as voltage outages, voltage surges, and voltage drops or sags. Some disturbance analyzers in addition to taking measurements also record and print the results.

Extensometer - An extensometer is a device which measures changes in the length of an object.

Fiber Cleaver - A fiber cleaver is a precision device used to cut a fiber optic cable leaving an end which is perfectly flat and smooth. This is done in preparation before splicing two fiber cables together using a fusion splicer. If the cable ends are not perfectly flat then you cannot achieve a perfect splice.

Fiber Optic Cable - A cable comprised of many optical fibers which is coated with a transparent cladding. Fiber optic cabling is used extensively in the telecommunications and networking industries to transmit data. It is superior to metal cabling because it can transmit much more data due to its increased bandwidth. It is also much less susceptible to interference compared to metal cable. It's quite common to see "fiber optic" combined into the single word, fiberoptic.

Flow Meter - A flow meter or flowmeter measures the rate of flow of a liquid or gas past a given point or location.

Frequency Counter - An electronic instrument which displays the frequency of a signal. Frequency counters typically work by the means of a counter which counts the number of events which occur within a specified period of time.

Frequency Standard - An oscillator which is used as a reference source for calibrating frequency measurements. A frequency standard generates a very precise and accurate fundamental frequency. The harmonics of this fundamental frequency are then used to supply reference points for calibration purposes.

Function Generator - A type of signal generator which generates an electronic waveform. Examples of common waveforms include sine, square, triangle, and sawtooth waveforms.

Fusion Splicer - A precision instrument which splices optical fibers together by fusing them, usually by the means of an electrical arc. See "What is a Fusion Splicer?" for a full explanation of how a fusion splicer works.

GPIB - GPIB is short for General Purpose Interface Bus, a digital bus specification which allows automated test equipment devices to communicate with each other. It was originally known as HP-IB (Hewlett Packard Interface Bus) and is also currently known as IEEE-488.

Hipot Tester - A hipot or hypot tester is a type of electronic test equipment which allows you to check the quality of the electrical insulation in an electrical cable, circuit board, transformer or any other electrical device. Hipot is short for high potential voltage. A hipot tester is used to verify that no electricity will flow through the insulation. It works by generating a high voltage between the circuits and checking by the means of a meter to ensure that no current flows between the two points.

HP-IB - HP-IB is short for Hewlett Packard Interface Bus. HP-IB is a bus specification which was created to facilitate communication between electronic testing devices. It is now known as GPIB or IEEE-488.

Logic Analyzer - A logic analyzer is used to test digital circuits or systems. A logic analyzer displays the logic levels (0 or 1) of signals in the circuit. The logic analyzer's built-in software then converts the data into various formats which a technician can use to debug failures in the system. See "What is a Logic Analyzer?" for more information.

Manometer - An instrument which measures pressure.

Mass Fusion Splicer - A fusion splicer which can splice multiple fibers in a ribbon fiber cable simultaneously. See "What is a Fusion Splicer?" for a full explanation of how a mass fusion splicer works.

Optical Fiber - A type of fiber made of glass or plastic which is designed to allow light to travel along its length. A fiber optic cable is comprised of many optical fibers.

Optical Time Domain Reflectometer - An OTDR is a device used in the fiberoptic and communications industry to find faults, bends and splices in fiber optic cabling. An OTDR works by injecting a series of optical pulses into the fiber which are then reflected back and measured for deviations in the light wave. See "What is an OTDR?" for an in-depth explanation of how an OTDR works.

Oscillator - An electronic circuit which generates a repeating electronic signal such as a sine wave or a square wave. Oscillators are used in devices such as function generators and frequency standards.

Oscilloscope - An electronic test instrument which renders electrical signals or waveforms as a visible wave on a fluorescent cathode-ray tube screen. The wave is shown on a graph. The horizontal axis indicates time and the vertical axis shows the amplitude at that exact point. An oscilloscope lets you see how a signal varies over time. A multiple trace oscilloscope allows you to monitor multiple waveforms at the same time so you can make timing measurements or a phase comparison. See "What is an Oscilloscope?" for more information.

Signal Generator - A type of electronic equipment which generates a precisely calibrated repeating signal. The signal can be analog or digital and can be adjusted by frequency, waveform, output voltage, modulation and impedance. Signal generators are used for testing as well as designing electronic equipment.

Spectrum Analyzer - A spectrum analyzer (also known as a spectral analyzer) measures an electrical, optical or acoustic waveform and displays the frequency response curve in real time. See "What is a Spectrum Analyzer?" for more information on how one works.

Thermometer - An instrument which measures temperature.

Time Domain Reflectometer - A Time Domain Reflectometer (or TDR for short) is a device which allows you to locate faults in metal cables. A TDR works by generating an electrical pulse which is transmitted through the cable. When the pulse reaches a fault point or the end of the cable it is reflected back to the TDR. The TDR then takes a measurement of the time that it took for the signal to travel through the cable and back. This measurement is then converted into the distance to the fault point. It's actually very similar to how a radar works.

Universal Counter - A frequency counter which in addition to measuring frequency also measures other parameters such as time interval and period. They are sometimes also referred to as universal frequency counters.

Universal Disturbance Analyzer - A disturbance analyzer which not only measures power disturbances but also has the capacity to measure disturbances in radio frequency, temperature, humidity and more, by the means of individual plug-in modules. As well as taking measurements universal disturbance analyzers generally also monitor, record and print the results.

Vacuum Gauge - An instrument which measures the pressure in a vacuum.

Vibration Meter - A device which measures the amount of vibration present in a piece of machinery. Vibration meters are typically used to locate precise areas of vibration and noise in equipment such as motors, pumps, gearboxes and compressors.