Editing Radio control (section)

==Second World War==
Radio control was further developed during World War II, primarily by the Germans who used it in a number of [[missile]] projects. Their main effort was the development of [[radio-controlled missile]]s and [[glide bomb]]s for use against shipping, a target otherwise both difficult and dangerous to attack. However, by the end of the war, the ''[[Luftwaffe]]'' was having similar problems attacking Allied [[bomber]]s and developed a number of radio [[command guided]] [[surface-to-air anti-aircraft missile]]s, none of which saw service.

The effectiveness of the [[Luftwaffe]]'s systems, primarily comprising the series of [[Telefunken]] ''Funk-Gerät'' (or FuG) 203 ''Kehl'' twin-axis, single joystick-equipped transmitters mounted in the deploying aircraft, and Telefunken's companion FuG 230 ''Straßburg'' receiver placed in the ordnance to be controlled during deployment and used by both the [[Fritz X]] unpowered, armored anti-ship bomb and the powered [[Henschel Hs 293]] guided bomb, was greatly reduced by British efforts to jam their radio signals, eventually with American assistance. After initial successes, the British launched a number of [[commando]] raids to collect the missile radio sets. Jammers were then installed on British ships, and the weapons basically "stopped working". The German development teams then turned to [[wire-guided missiles]] once they realized what was going on, but the systems were not ready for deployment until the war had already moved to France.

The German ''[[Kriegsmarine]]'' operated ''FL-Boote'' (''ferngelenkte Sprengboote'') which were radio controlled [[motor boats]] filled with explosives to attack enemy shipping from 1944.

Both the British and US also developed radio control systems for similar tasks, to avoid the huge anti-aircraft batteries set up around German targets. However, no system proved usable in practice, and the one major US effort, ''[[Operation Aphrodite]]'', proved to be far more dangerous to its users than to the target. The American [[Azon]] guided free-fall ordnance, however, proved useful in both the [[European Theater of World War II|European]] and [[CBI Theater]]s of World War II.

Radio control systems of this era were generally electromechanical in nature, using small metal "fingers" or "[[reed receiver|reeds]]" with different [[resonant]] frequencies each of which would operate one of a number of different [[relay]]s when a particular frequency was received. The relays would in turn then activate various [[actuator]]s acting on the control surfaces of the missile. The controller's radio transmitter would transmit the different frequencies in response to the movements of a control stick; these were typically on/off signals. The radio gear used to control the rudder function on the American-developed [[Azon]] guided ordnance, however, was a fully proportional control, with the "ailerons", solely under the control of an on-board gyroscope, serving merely to keep the ordnance from rolling.

These systems were widely used until the 1960s, when the increasing use of [[solid state (electronics)|solid state]] systems greatly simplified radio control. The electromechanical systems using [[reed relay]]s were replaced by similar electronic ones, and the continued miniaturization of electronics allowed more signals, referred to as ''control channels'', to be packed into the same package. While early control systems might have two or three channels using [[amplitude modulation]], modern systems include twenty or more using [[frequency modulation]].