Columbia Encyclopedia

(Encyclopedia) endorphins ĕndôrˈfĭnz [key], neurotransmitters found in the brain that have pain-relieving properties similar to morphine. There are three major types of endorphins: beta endorpins, found primaril...

(Encyclopedia) distortion, in electronics, undesired change in an electric signal waveform as it passes from the input to the output of some system or device. In an audio system, distortion results in poor reproduct...

(Encyclopedia) demodulation: see modulation.

(Encyclopedia) carrier wave: see modulation.

(Encyclopedia) key. 1 In music, term used to indicate the scale from which the tonal material of a given composition is derived. To say, for example, that a composition is in the key of C major means that it uses as...

(Encyclopedia) broadcasting, transmission, usually using radio frequencies, of sound or images to a large number of radio or television receivers. In the United States the first regularly scheduled radio broadcasts ...

(Encyclopedia) modem [modulator/demodulator], an external device or internal electronic circuitry used to transmit and receive digital data over a communications line normally used for analog signals. A modem attach...

(Encyclopedia) Western Union Telegraph Company, enterprise created (1851) to provide telegraphic communications services in the United States. Originally known as the New York and Mississippi Valley Printing Telegra...

(Encyclopedia) automatic tuning control (ATC), method or device to keep a radio or television receiver automatically tuned to a desired frequency or channel. Assuming that the receiver is at least approximately tune...

(Encyclopedia) communication, transfer of information, such as thoughts and messages, as contrasted with transportation, the transfer of goods and persons (see information theory). The basic forms of communication a...