Glossary of Electronics Test Terminology

ATE - Automatic Test Equipment. A test equipment system that is computer driven and able to run test programmes to test the unit under test.

Autorange - The ability of an instrument to automatically choose the optimum range of the instrument for the magnitude of the measurement being made.

AVO - Amps Volts and Ohms. This term is often used to indicate a type of meter. It is a trade name and their major products were robust, quality, analogue multimeters.

BIST - Built In Self Test. A facility contained within a circuit, module or unit that enables it to test itself. It will typically consist of some additional circuitry and software.

BIT - Built In Test. Another name for BIST

BITE - Built In Test Equipment. This refers to the circuitry or "equipment" that is built in to a unit of assembly to enable to undergo a self test.

CMMR - Common Mode Rejection Ratio. It is a measure of the ability of a test instrument to reject interference that is common to both of its measurement input terminals. It is expressed in decibels and it is the ratio of the actual or common signal level appearing on the two input terminals together to the measured level.

Boundary Scan - A test methodology that uses shift registers in the output connections of integrated circuits, one IC often is connected to the next. A data pattern is passed through the chain and the observed returned data stream affected by the circuit conditions gives an indication of any faults present. The system is defined under IEEE standard 1149.1 and is also often known as JTAG (Joint Test Action Group).

DMM - Digital Multimeter. This a digital meter that is capable of making a variety of types of measurement. The basic measurements that are normally made include voltage, current (both AC and DC) as well as resistance. Many meters have a variety of other measurements that can be made and these may include frequency (normally not to a high degree of accuracy), capacitance, temperature, etc.

FATE - Functional Automatic Test Equipment. An automatic test equipment that tests the operation of the UUT. This type of system is normally used in large scale electronics equipment manufacture and test.

FSD - Full Scale Deflection. This is the maximum calibrated reading for a meter.

Frequency counter An instrument for measuring the frequency of a signal accurately. It operates by 'counting' the number of crossings of the signal that occur across a certain trigger level.

GPIB - General Purpose Interface Bus. Originally known as HP-IB (Hewlett Packard Interface Bus) and also defined as IEEE 488, this bus is used for communicating between devices. One of its main uses is for automatic test applications where a computer is used to control a number of test instruments.

Multimeter - This is a form of meter that is capable of making a variety of measurements. It is normally applied to a meter that can make measurements of current, voltage and resistance, although digital versions available today may be capable of making a variety of measurements. Normally a multimeter is a small, portable and robust instrument.

Oscilloscope - a form of measuring instrument that displays waveforms of a screen, the horizontal axis being indicative of time, and the vertical providing the instantaneous amplitude at that given instant. An oscilloscope is an invaluable test tool for anyone testing or developing circuits in which there are repetitive waveforms that need to be viewed.

PPM - Parts Per Million. This is normally used to indicate the accuracy of an item. A component may be said to have an accuracy of 100 PPM. In this case its value is accurate to within 100 parts in a million or 0.01%.

Settling Time - The time required after a change for a circuit or test instrument to reach its steady state.

UUT - Unit Under Test. This a term used in commercial production testing to define the target item that is being tested.