In the photosphere, i.e., visible disk of the Sun, a dark marking that manifests a magnetic anomaly that is associated with interference with radio communications on Earth.
Note: Sunspot activity, i.e., the number of sunspots occurring at a given time or on a given day, is cyclic. The period of a cycle, from maximum through minimum and back to maximum… (Read More →)

See electromagnetic spectrum.

A class used in deriving another class by specialization. [T1.260-1998]

[The] process of encrypting encrypted information.
Note: [This process] occurs when a message, encrypted off-line, is transmitted over a secured, on-line circuit, or when information encrypted by the originator is multiplexed into a communications trunk, which is then bulk encrypted. [INFOSEC-99]

1. In T-carrier, a synchronization frame that delineates 12 DS1 frames. [J. Beaty, FAA]
2. A DS1 framing format that assembles 12 individual DS1 frames into a single superframe with a 12-bit fixed frame pattern. [T
1. Rpt25-1993]

See group, multiplex hierarchy.

In frequency-division multiplexing (FDM), the distribution frame that provides terminating and interconnecting facilities for group modulator output, group demodulator input, supergroup modulator input, and supergroup demodulator output circuits of the basic supergroup spectrum of 312 kHz to 552 kHz.

See National Information Infrastructure.

A light-emitting diode in which there is stimulated emission with amplification but insufficient feedback for oscillations to build up to achieve lasing action.

In a gain medium, amplification of spontaneously emitted radiation characterized by moderate spectral line narrowing and moderate directionality.
Note: Superradiance is usually distinguished from lasing action by the absence of positive feedback, and hence the absence of well-defined modes of oscillation.