Glossary

Altimeter	An aircraft device for measuring altitude.
Antrac	A term often used for radio relay equipment. It is derived from the nomenclature AN/TRC—Army Navy Transportable Radio Communications—assigned to several types of radio relay and other radio sets.
Azimuth	Direction, in terms of horizontal angle, measured clockwise from north.
BLADE	An Allied armored task force formed for the drive to capture Tunis.
BLUIE	Greenland.
Boehme	High-speed radio transmission of Morse code signals by means of perforated tape which can mechanically key a transmitter at speeds up to 400 words a minute.
BOLERO	Build-up of American forces and supplies in United Kingdom for cross-Channel attack.
Breadboard model	A display of electronic equipment assembly in which the wiring and components are spread out over a horizontal surface for ease in making changes in the circuitry; employed both in development laboratories for experimental work and in school instruction.
Carrier	Carrier method, whether involving wire or radio, is a technique which permits many messages, many separate signals, to travel simultaneously without mutual interference over a single circuit.
Cathode ray tube	A vacuum tube with a picture screen, on which the electron beam emitted from the cathode produces a visual indication. See Oscilloscope.
Chain Home	British long-range aircraft detecting radar.
Chain Home Low	British radar able to detect aircraft flying at low elevations.
Cipher	A method of secret writing which retains the letters but transposes them, or replaces them with substituted letters, according to a plan or key.
Code	A method of communication in which predetermined symbols or terms are substituted for the words of the message text.
Common battery	A switchboard which provides, from a central power switchboard supply located at the board, the current needed to operate the telephones connected to the board. Opposite to local battery switchboard, which see.
Continuous wave	A method of radio communications employing radio waves in which successive cycles are of constant amplitude. The method of transmission may be by hand key or by machine signals.
Crash construction	Rapid hand-construction of equipment by laboratory and engineer personnel.
CRIMSON	Project for airfields in central and northeastern Canada.
Cryptanalyst	One who recovers an original message text from an encoded or enciphered cryptogram, without knowing the key; also one who reconstructs such a key.
Cryptography	The process of putting message texts into meaningless letters or symbols by means of code and/or cipher systems.
CRYSTAL	Weather station.
Dah-dit	The dash-dot, or long and short, signals of Morse code, variously grouped to spell out letters of the alphabet.
Derax	An early name for radar.
Dielectric	An insulating material placed between the two plates of a capacitor.
Dipole	A T-shaped antenna, such as the familiar television antenna, used with VHF radiations.
Direction finding	Determining, by means of a radio receiver and special antennas, the direction and location of a transmitter to whose radiations the receiver is tuned. See also Goniometry (radio).
Dynamotor	An electrical rotary device which is usually employed in the power supply of a vehicular radio set and which converts the low voltage of a vehicular storage battery to the higher voltages required by radio operation.
Electromagnetic wave	A radio or radar radiation traveling in space at 186,293 miles per second; also heat, light, X-, gamma, and cosmic rays, which are all alike except in frequency and wave length.
Frequency	The number of cycles per second which characterizes any electromagnetic wave or radiation.
Goniometry (radio)	Measuring or taking angles, by means of radio receivers and directional antennas, on radio or radar radiations so as to determine the location of the transmitter. See also Direction finding.
Gun laying	The process of aiming a gun, often at a target which cannot be seen or which is moving, requiring complex calculations.
GYMNAST	Early plan for invasion of North Africa, referring to either the American idea of landing at Casablanca or the British plan for landing farther eastward on the Mediterranean coast.
Hams	Amateur radio operators and enthusiasts.
Handie-talkie	A hand-carried infantry radio transceiver, the SCR-536 during World War II.
Hand-key	In manual radiotelegraph sending, the key (operated by the hand or fingers) is a kind of switch capable of being opened or closed rapidly in order to form the dots and dashes of Morse code signals.
High frequency	3-30 megacycles.
High-speed radio	See Boehme.
Interrogator	A pulsed transmitter whose signals challenge and automatically elicit an identifying reply from a transponder in a distant craft; part of the IFF radar system.
Ionosphere	The outer layer of the earth's atmosphere which reflects the sky wave component of radio waves of the high frequency band, enabling long-distance signals.
Key	See Hand-key.
Kilocycle	One thousand cycles per second.
Kilowatt	One thousand watts.
Local battery	A switchboard which interconnects telephone sets, switchboard each having its own dry batteries to provide the talking current. Opposite to common battery switchboard, which see.
Loran	Long-range aid to navigation: a highly accurate system employing beacons and aircraft or ship receivers, the receivers determining the position of the beacons from their radiations.
Low frequency	30-300 kilocycles.
Magnetron	An electronic tube in which the electron flow is controlled by an externally applied magnet and which is capable of producing powerful oscillations at microwave frequencies.
Manual radio	Transmitting Morse code dah-dits by hand key.
Megacycle	One million cycles per second.
Microwave	Radio waves which radiate at frequencies above 300 megacycles with a wave length of 50 centimeters (20 inches) or less.
Morse	Morse code: communications according to the code, employing combinations of dashes and dots (dahdits ) to spell out the letters, as in radio or wire telegraphy.
Open wire line	A pole line carrying bare wires, usually galvanized iron or bare copper, for telephone and/or telegraph communications.
Oscilloscope	A cathode ray tube (which see) used, like a television picture tube, in a radar receiver to display visually target echoes.
Phantom circuit	An additional channel of communications which can be superimposed upon two physical pairs, that is two pairs of telephone wires already carrying two channels of communications.
Piezoelectric effect	The effect of producing an electrical voltage in a crystal by compressing or twisting it.
Pipsqueak	An airborne radio transmitter employed in the British system of aircraft control by DF, used to identify and track friendly craft.
Point-to-point	A term used of radio operation between two stations (generally fixed, with directional antenna arrays) signaling between each other only. Compare with radio broadcast operation, when a transmitting station signals to all receivers in its net, which are tuned to the frequency employed by the transmitting station.
Radio compass	A receiver which determines the direction of received radio waves and registers the direction visually on a meter or compass scale.
Radio range beacon	A radio transmitter radiating a narrow directional guide beam on which craft may "home."
Range	The distance from a gun or an observer to the target.
Rectifier	An item of equipment which converts, or rectifies, alternating current ( AC ) to produce a desired direct current ( DC ).
Responsor	The receiver of an IFF radar system, used with an interrogator, which see.
Rhombic antenna	A large transmitting antenna utilized by fixed long-range radio stations. The antenna wires, extended between four poles or towers, form a diamond-shaped or rhombic pattern, capable of directing powerful electromagnetic waves in a definite direction.
ROUNDUP	The name by which plans for cross-Channel invasion were known until the summer of 1943.
Shoran	A short-range navigation system employing electronic methods similar to Loran, which see.
Sky wave	That portion of a radio wave transmitted from an antenna which travels upward and is reflected down to earth by the ionosphere, which see. Used in the high frequency band by long-range military radios, the sky wave under favorable conditions enables communication over very long distances.
Spiral-four	A rubber-covered field cable of four conductors especially constructed for the transmission of multiple telephone and/or telegraph signals by means of wire carrier techniques.
Steatite	A form of talc used in the manufacture of high-grade insulators and dielectric parts.
Theodolite	A telescope, similar to the tripod-mounted transit of a surveyor, by which an observer can follow moving objects, such as a weather balloon, reading its elevation and azimuth from moment to moment.
TORCH	The Allied invasion operation in North Africa, November 1942.
Traffic	Passing of messages over wire circuits or radio channels.
Transceiver	A radio transmitter and receiver combined in one unit, portions of its circuits being used for both functions.
Transponder	A combined receiver-transmitter employed in the IFF radar system. The receiver on being challenged by a distant interrogator, stimulates the transmitter to send back coded identification signals. See also Interrogator and Responsor.
TRIGGER	Plan to set up a model air defense sector in the United States with RAF aid.
Ultrahigh frequency	300-3,000 megacycles.
V-mail	A method by which personal mail was microphotographed on 16-mm. film for ease and economy of transportation. At the destination the filmed messages were enlarged and reproduced for delivery.
Very high frequency	30-300 megacycles.
Walkie-talkie	A portable radio set adapted for carrying on a soldier's back, having a longer range than the smaller handie-talkie. The standard walkie-talkie during World War II was the infantry's SCR-300, replacing the original walkie-talkies, the SCR's-194 and 195.