Remote control systems are increasingly popular, and the introduction of pre-tuned radio modules, and their steadily falling prices has made radio a viable alternative to infrared control. The advantage of radio is the ability of the signal to pass through objects and walls. Its range is also impressive, 100 meters or more (in free space) being typical.

No license is required in the UK, providing the radio modules operate on the 418MHz waveband, and there are a number of conditions, one of which is that setting up and tuning is carried out by a DTI (Department of Trade and Industry) approved company. Hence, if the module is purchased from such a company, the home constructor can enjoy the benefits of radio remote control.

This article describes how to use the radio modules in a similar way to those in the Reliable Infrared Remote Control system, which was published in EPE Online Nov/Dec '98. We will examine both AM and FM (amplitude modulated and frequency modulated) systems, and begin with a brief outline of the difference between these.