The Beginning
It was back in December 1894, when a young Italian scientist woke his mother from a deep sleep to have a look at his latest invention. On his strange machine, he tapped a key, sending a message in Morse code. To his mothers surprise, a bell started to ring across the room. But there were no wires connecting the two machines! The signal had been sent through the air, from one machine to the other. Because there were no wires, the young Italian, Guglielmo Marconi, called his latest invention the wireless.

Across the Atlantic
Just five years later, in 1899, Marconi had broadcast radio messages across the English Channel, from England to France. But he had a bigger goal in mind - he wanted to transmit a signal all the way across the Atlantic Ocean. It was December again, but 1901 this time, when Marconis assistants tapped out a radio signal from Cornwall, England. The signal was three dots or short beeps, for the letter S.

On the other side of the Atlantic, at St Johns in Newfoundland, Canada, Marconi waited in a small, bitterly cold wooden hut for the signal. Would it work? Then he had his answer; everyone plainly heard the message - the three dots - repeated over and over. History had been made.

Because Marconi had proved it could be done, others followed, and eventually hundreds of radio stations were built all over the world. With huge arrays of antennae (aerials), they could capture and retransmit signals from anywhere on Earth.

Speech and music
But this was still only using Morse code. Could the wireless signals carry the human voice as well? Scientists already knew that telephone wires could carry speech, so why not wireless? It was a Canadian scientist, named Reginald Fessenden, who found the way. He converted sound waves into a pattern or signal, which could be carried by the radio waves. What his discovery changed was the actual height of the radio waves. This height is called the amplitude, and this method of changing the waves is called amplitude moderation, or AM for short.

Other people soon realised that if speech could be broadcast through the air, so could music. By the 1920s there were many radio stations doing just that, sending out regular broadcasts for people at home to listen to. Radio became extremely popular, and people would gather around the wireless set at night to hear the latest news, radio plays, concerts and childrens programs.

But AM broadcasts needed careful wireless tuning to get the best sound, and the atmosphere could play funny tricks on the signal. In 1939, and American named Edwin Armstrong found another way to send radio signals. Instead of changing the height of the radio waves, he changed the distance between them. This is called frequency modulation, or FM for short. Today, for home use, FM radio is the most common broadcast method, giving the clearest sound reproduction at home or in the car.