last updated 14 July 2003 How It Works You talk into one radio, and your voice comes out of the other radio! Magic, isn't it? Your voice is electronically added to a radio wave by using Frequency Modulation. The radio signal is modulated by varying the frequency very slightly in sympathy with your speech. The other radio detects the radio signal, and recovers the modulation, and amplifies the speech signal to the loudspeaker. The magic part is that the receiving radio can still receive your voice even when it's kilometres away - and the received signal can be 150dB weaker than it was at the transmitting radio's antenna - that is 1,000,000,000,000,000 times weaker! Welcome to the wonderful world of radio - some of us have been playing with them for years and the magic is still as strong as it ever was!