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 →)

A combination of signal communication facilities operated by the Army in the field and consisting of a communications center, telephone switching central and appropriate means of signal communications. [JP1]

1. In analog (usually audio) systems, reduction of the dynamic range of a signal by controlling it as a function of the inverse relationship of its instantaneous value relative to a specified reference level.
Note 1: Signal compression is usually expressed in dB.
Note 2: Instantaneous values of the input signal that are low, relative to the reference level, are… (Read More →)