A usually two-element lens that is corrected to bring two specified or distinct wavelengths to a common focal point.
Note 1: The term "achromatic" literally means "without color. " This is not strictly true, however. Early lenses consisted of only a single element, and therefore could bring only a single wavelength to a given focal point; i.e., they suffered from… (Read More →)

Synonym achromat.

Synonym achromat.

1. acknowledge character.
2. acknowledge.

A transmission control character transmitted by the receiving station as an affirmative response to the sending station.
Note: An acknowledge character may also be used as an accuracy control character.
See also ACK.

1. A response sent by a receiver to indicate successful receipt of a transmission.
Note: An example of an acknowledgement is a protocol data unit, or element thereof, between peer entities, to indicate the status of data units that have been successfully received.
2. A message from the addressee informing the originator that the originator's communication has been received and… (Read More →)

Synonym [loosely] sliding window.

Architecture for Control Networks

Access Carrier Name Abbreviation

See Interexchange Access Customer (IAC Code)

1. An interface device for coupling electrical signals by acoustical means--usually into and out of a telephone instrument.
2. A terminal device used to link data terminals and radio sets with the telephone network.
Note: The link is achieved through acoustic (sound) signals rather than through direct electrical connection.