Abbreviation for Bose-Chaudhuri-Hochquenghem code. A multilevel, cyclic, error-correcting, variable-length digital code used to correct errors up to approximately 25% of the total number of digits.
Note: BCH codes are not limited to binary codes, but may be used with multilevel phase-shift keying whenever the number of levels is a prime number or a power of a prime number, such as… (Read More →)

Abbreviation for bit-count integrity.

Abbreviation for baud.

Border Element

See radiobeacon station.

1. The main lobe of an antenna radiation pattern.
2. A column of light.
Note: A beam may be parallel, divergent, or convergent. [After FAA]

Of an electromagnetic beam, along any specified line that (a) intersects the beam axis and (b) lies in any specified plane normal to the beam axis, the distance between the two diametrically opposite points at which the irradiance is a specified fraction, e.g., ½ or 1/, of the beam's peak irradiance.
Note 1: Beam diameter is usually used to characterize… (Read More →)

Of an electromagnetic beam, in any plane that intersects the beam axis, the increase in beam diameter with distance from the aperture from which the beam emerges.
Note 1: Beam divergence is usually used to characterize electromagnetic beams in the optical regime, i.e., cases in which the aperture from which the beam emerges is very large with respect to the… (Read More →)

Changing the direction of the main lobe of a radiation pattern.
Note: In radio systems, beam steering may be accomplished by switching antenna elements or by changing the relative phases of the rf signals driving the elements. In optical systems, beam steering may be accomplished by changing the refractive index of the medium through which the beam is transmitted or… (Read More →)

A device for dividing an optical beam into two or more separate beams.
Note: An example of a beamsplitter is a partially reflecting mirror.