A circuit that can be used simultaneously either for telephony and dc telegraphy or for telephony and signaling.
Note: Separation of the two may be accomplished by frequency discrimination. Synonym voice-plus circuit.

1. A document represented by a software file that is composed of more than one element; e.g., text, graphics, voice, video.
2. The software file itself.

In ac signaling, a signal consisting of the simultaneous transmission of more than one frequency.
Note: An example of compound signaling is dual-tone multifrequency (DTMF) signaling.

See data compaction, data compression, signal compression.

Video that has been encoded so as to reduce the number of bits required for storage or transmission.

See data compression, signal compression.

1. In signal compression, the ratio of the dynamic range of compressor input signals to the dynamic range of the compressor output signals.
Note: The compression ratio is usually expressed in dB. For example, a 40-dB input range compressed to a 30-dB output range would be equivalent to a 10-dB compression.
2. In digital facsimile, the ratio of the total… (Read More →)

A nonlinear analog device that has a lower gain at higher input levels than at lower input levels.
Note: A compressor is used to allow signals with a large dynamic range to be sent through devices or circuits with a smaller dynamic range.

1. The known or suspected exposure of clandestine personnel, installations, or other assets or of classified information or material, to an unauthorized person. [JP1]
2. The disclosure of cryptographic information to unauthorized persons.
3. The recovery of plain text of encrypted messages by unauthorized persons through cryptanalysis methods.
4. Disclosure of information to unauthorized persons or a violation of the… (Read More →)

In cryptography, a key state in which the secrecy or integrity of the key is suspect. [After X9.17/95]