1. service access code,
2. special area code.

Either of the two circuits used to derive a phantom circuit.

Any way in which one representation differs from previous representations, but which is not revealed by the verification methods adopted, and can lead to failure to satisfy the security requirements [CESG].

In a directional antenna radiation pattern, a lobe in any direction other than that of the main lobe.

In amplitude modulation (AM), a band of frequencies higher than or lower than the carrier frequency, containing energy as a result of the modulation process.
Note: Amplitude modulation results in two sidebands. The frequencies above the carrier frequency constitute what is referred to as the "upper sideband"; those below the carrier frequency, constitute the "lower sideband. " In conventional AM… (Read More →)

See single-sideband transmission.

The sound of the speaker's own voice (and background noise) as heard in the speaker's telephone receiver.
Note: Sidetone volume is usually suppressed relative to the transmitted volume. Synonym telephone sidetone.

1. Abbreviation for special interest group.
1. Within a given technical discipline or area of knowledge, a circle of individuals or organizations having an intensified interest in a narrower facet of the general area.
2. In networking, particularly involving Internet applications, a group of individuals or organizations that sponsor, e.g., IRC channels, mailing lists, or Web sites for the purpose… (Read More →)

Acronym for signals intelligence.

1. Detectable transmitted energy that can be used to carry information.
2. A time-dependent variation of a characteristic of a physical phenomenon, used to convey information.
3. As applied to electronics, any transmitted electrical impulse. [JP1]
4. Operationally, a type of message, the text of which consists of one or more letters, words, characters, signal flags, visual displays, or special… (Read More →)