1. In the radio regime, of an antenna pattern, the angle between the half-power (3-dB) points of the main lobe, when referenced to the peak effective radiated power of the main lobe.
Note: Beamwidth is usually expressed in degrees. It is usually expressed for the horizontal plane, but may also be expressed for the vertical plane.
2. For the optical… (Read More →)

See B channel.

A telecommunications service that allows transmission of user-information signals between user-network interfaces. See B channel, service access.

See heterodyne.

Synonym paging, radio paging.

A unit of measure of ratios of power levels, i.e., relative power levels.
Note 1: The number of bels for a given ratio of power levels is calculated by taking the logarithm, to the base 10, of the ratio. Mathematically, the number of bels is calculated as B = log10(P1/P2) where P1 and P2 are power levels.
Note 2: The… (Read More →)

A transmission control character that is used when there is a need to call for user or operator attention in a communications system, and that usually activates an audio or visual alarm or other attention-getting device.

Historically, any of the 22 operating companies that were divested from AT&T by court order.
Note: Cincinnati Bell Telephone Co. and Southern New England Bell Telephone Co. were not included.

1. [A] formal state-transition model of a computer security policy that describes a formal set of access controls based on information sensitivity and subject authorizations. [INFOSEC].
2. A formal state transition model of computer security policy that describes a set of access control rules. In this formal model, the entities in a computer system are divided into abstract sets of… (Read More →)

See macrobend loss, microbend loss.