black box

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black box

1. a self-contained unit in an electronic or computer system whose circuitry need not be known to understand its function
2. an informal name for flight recorder

Black Box


(in Russian, chernyi iashchik), an object of study whose internal structure either is unknown or is too complex for any conclusions about the behavior of the object to be drawn on the basis of the properties of the object’s elements or on the basis of the structure of the connections between the elements. In Russian, the term chernyi iashchik is also used to refer to the method of studying such objects.

The black-box method is used in cases where an outside observer knows only the input to an object and the object’s response; in such cases, the processes occurring within the object are unknown. The study of a multiterminal network whose internal circuitry is unknown provides a very simple example of the use of the black-box method. By observing the behavior of such an object for a sufficiently long time and, if necessary, by carrying out active experiments on the object (that is, by changing the input in some specific manner), a level of knowledge about the properties of the object may be achieved such that changes in the object’s behavior in response to any given input may be predicted. However, no matter how thoroughly the behavior of a black box is studied, an unambiguous conclusion about the internal structure of the object cannot be reached, since the same behavior may be characteristic of different objects.

The black-box method is widely used to solve problems in the modeling of controlled systems—for example, in the study of integrated systems—especially in cases where the behavior rather than the structure of a system is of interest.

black box

[′blak ‚bäks]
Any component, usually electronic and having known input and output, that can be readily inserted into or removed from a specific place in a larger system without knowledge of the component's detailed internal structure.

black box

black boxclick for a larger image
A typical recording of an earlier version of flight data recorder (FDR). Modern FDRs can record many more parameters.
black box
A typical flight data recorder/voice recorder. These are colored orange.
i. The generic name given to crash data recorders and voice data recorders. Although called black boxes, they are orange. They can withstand very high temperatures and high impact.
ii. Any unit, usually an electronic or avionic device such as an amplifier, that can be mounted in, or removed from, the aircraft as a single package.

black box

An abstraction of a device or system in which only its externally visible behaviour is considered and not its implementation or "inner workings".

See also functional testing.

black box

(1) See black box testing and Black Box Corporation.

(2) An electronic device that records airplane flight data. Officially a "flight data recorder," the unit is highly protected and can emit a signal for up to 30 days after a crash, even underwater. First used in the late 1950s, Australia was the first country to require them. Dating back to the late 19th century, a "train event recorder" or "on-train monitoring recorder" (OTMR) is the equivalent device in a locomotive.

(3) An electronic device that records driving data in motor vehicles, most notably their speed. Officially an "event data recorder," automotive black boxes were first used in the late 1990s.

(4) Any custom-made electronic device can be called a black box, typically made to solve some interfacing problem. Such devices were named black boxes because they were often housed in plain containers, and their purpose may even be a mystery to the experienced observer. However, yesterday's black boxes sometimes become today's off-the-shelf products. See COTS.

The Black Box
Without logos or identifying marks, a black box can be any device custom made to solve a problem.

A Little Black Box
The 10-ounce device lying on top of this CD changer is an Apple TV set-top box. See Apple TV.