That portion of the ionosphere existing between approximately 160 and 400 km above the surface of the Earth, consisting of layers of increased free-electron density caused by the ionizing effect of solar radiation.

Note 1: The F region reflects normal-incident frequencies at or below the critical frequency (approximately 10 MHz) and partially absorbs waves of higher frequency.

Note 2: The… (Read More →)

In laser diodes, a phenomenon in which a high field intensity of stimulated optical radiation causes degradation of the facets, i.e., those forming the cavity mirrors, decreasing reflectivity and resulting in a decrease of the internal quantum efficiency and an increase in the threshold current.

1. A fixed, mobile, or transportable structure, including (a) all installed electrical and electronic wiring, cabling, and equipment and (b) all supporting structures, such as utility, ground network, and electrical supporting structures.
2. A network-provided service to users or the network operating administration.
3. A transmission pathway and associated equipment.
4. In a protocol applicable to a data unit, such… (Read More →)

A group of interconnected equipment and transmission media uniquely identified and dedicated to a specific type of service. [T1.238-1994/97]

A two-digit code (FC) used in the exchange-carrier-to-interexchange carrier (EC-to-IC) facility/service selective signaling protocol and the IC-to-EC facility/service selective signaling protocol that identifies the type of facility requested. [T1.104-1991]

The electrically interconnected system of conductors and conductive elements that (a) provides multiple current paths to the earth electrode subsystem, and (b) consists of the earth electrode subsystem, the lightning protection subsystem, and the fault protection subsystem.

The particular group of facilities to route the call. [T1.667-1999]

The specific member of a trunk group or a multi-line hunt group. [T1.667]

1. A form of telegraphy for the transmission of fixed images, with or without half-tones, with a view to their reproduction in a permanent form. [47CFR] In this definition the term telegraphy has the same general meaning as defined in the Convention. [NTIA] [RR]
2. The process by which fixed graphic images, such as printed text and pictures, are scanned,… (Read More →)

1. In a facsimile receiver, a device that changes the signal modulation from frequency-shift keying (FSK) to amplitude modulation (AM).
2. In a facsimile transmitter, a device that changes the signal modulation from amplitude modulation (AM) to frequency-shift keying (FSK).