The Magic Of R/C (Radio Control)

Radio control (often abbreviated to R/C or simply RC) is the use of radio signals to remotely control a device. The term is used frequently to refer to the control of model vehicles from ahand-held radio transmitter. Industrial, military, and scientific research organizations make use of radio-controlled vehicles as well.

The first general use of radio control systems in models started in the early 1950s with single-channel self-built equipment; commercial equipment came later. The advent of transistors greatly reduced the battery requirements, since the current requirements at low voltage were greatly reduced and the high voltage battery was eliminated. In both tube and early transistor sets the model's control surfaces were usually operated by an electromagnetic escapement controlling the stored energy in a rubber-band loop, allowing simple rudder control (right, left, and neutral) and sometimes other functions such as motor speed.^[1]

Crystal-controlled superheterodyne receivers with better selectivity and stability made control equipment more capable and at lower cost. Multi-channel developments were of particular use to aircraft, which really needed a minimum of three control dimensions, (yaw, pitch and motor speed) as opposed to boats, which can get away with two or one.

As the electronics revolution took off, single-signal channel circuit design became redundant, and instead radios provided coded signal streams which a servomechanism could interpret.

More recently, high-end hobby systems using Pulse-Code Modulation (PCM) features have come on the market that provide a computerizeddigital bit-stream signal to the receiving device, instead of analog type pulse modulation.

In the early 21st century, 2.4 gigahertz tramsissions have become increasingly utilised in high-end control of model vehicles and aircraft.

Remote control military applications are typically not radio control in the direct sense, directly operating flight control surfaces and propulsion power settings, but instead take the form of instructions sent to a completely autonomous, computerized automatic pilot. Instead of a "turn left" signal that is applied until the aircraft is flying in the right direction, the system sends a single instruction that says "fly to this point".

Some of the most outstanding examples of remote radio control of a vehicle are the Mars Exploration Rovers such as Sojourner.