Many millions of people enjoy listening to the radio every day but few of us give any thought to how it actually works. At its most basic level, radio is about transmitting signals along radio frequencies. There are two main frequencies for transmission; AM and FM. AM frequency can often feature a lot of interference and is not the smoothest signal FM frequency is a better quality broadcast than AM and can be quite crisp and clean. Traditional radio works over analogue signals. More recently, digital radio has been put into commercial use. A digital radio that is eco friendly is the Wind up DAB radio.