CARRIER FREQUENCY electrode and the work. No shielding is used, and pressure and filler metal may or may not be used. CARBON BLACK A black pigment produced by the incomplete burning of natural gas or oil. It is widely used as a filler or pigment, particularly in the rubber industry. Because it possesses ultraviolet protective properties, it is used in polyethylene systems such as cold-water piping and black agricultural sheet. CARBON PRECIPITATE A precipitate composed of a compound of carbon with one or more metallic elements, often found in fer- rous materials but also in aluminum and titanium. CARBON STEEL Carbon steel is classed as such when non-mini- mum content is specified or guaranteed for aluminum, chromium, columbium, molybdenum, nickel, titanium, tungsten, vanadium, or zirconium; when the minimum for copper does not exceed 0.40%; or when the maximum content specified or guaranteed for any of the following elements does not exceed the percentages noted: manganese, 1.65; silicon, 0.60; copper, 0.60. CARRIAGE STORE INTERFACE The electrical interface on the carriage store structure where the aircraft is electrically connected. This connection is usually on the store side of an aircraft-to-store umbilical cable. CARRIAGE STORES Suspension and release equipment that is mounted on aircraft on a nonpermanent basis as a store are classi- fied as a carriage store. Pylons and primary racks are not consid- ered carriage stores. CARRIAGE STORE STATION INTERFACE The electrical interfaces on the carriage store structure where the mission stores are electrically connected. This connection is usually on the car- riage store side of an umbilical cable. CARRIER (1) A wave suitable for modulation by an information- bearing signal to be transmitted over a communication system. (2) An unmodulated emission. Note: the carrier is usually a sinusoidal wave or a recurring series of pulses. CARRIER DROPOUT A short-duration loss of carrier signal. CARRIER FREQUENCY (1) The frequency of a carrier wave. (2) The frequency of an unmodulated wave capable of being modulated or impressed with a second (information-carrying) signal. Note: in frequency modulation, the carrier frequency is also referred to as the center frequency. 49