FM Radio Transmitter
With all the technical jargon removed, let's try to simplify the complex inner workings of FM radio transmitters. Broadcasting begins at the radio station on the sending end. A sound whether its voice or music is converted by a microphone to an electric signal which in turn is converted by an FM radio transmitter to a radio signal and sent into space through the antenna. The radio signal or wave will travel thousands of miles through space at the speed of light. When we get to the other end of the radio signal, we see that the radio receiver works in exactly the opposite manner as the FM transmitter. The radio receiver's antenna captures a portion of that radio signal, its internal electronics convert this back into an electric signal and the loudspeaker produces the sound you hear.
This is the simplest explanation of what happens. Unfortunately the receiving end isn't quite that simple. To judge the radio receiver we're examining or buying, it's good to know a little more about radio reception. The antenna gathers the weak radio signals. There are dozens of different signals from as many stations, all crowding into the radio through the doorway of this antenna. The antenna will be a wire of some sort. All radios have an antenna of some sort whether it's a wire outside the house or if it's hidden inside the radio as a "loop" wound on a flat cardboard frame. You must select the particular signal you want through a process called tuning the radio. To understand why this is necessary, you need to know that each radio signal has a frequency and a wave length. The frequency is the rate at which the signal changes its character, measured in cycles per second. Every station on the air will have an assigned frequency. You will find radio stations identified by either their frequency of transmission or the wavelength. The sound you want is encoded in the radio signal. Your radio must detect this sound signal, extracting an electrical image of the sound from the radio signal. This weak electric image must now be amplified to the point where it is strong enough to operate the loudspeaker. The loudspeaker converts the electrical signal into sound waves that resemble the original sound at the radio station and your ears do the rest. Electrical energy is required to operate the radio. This is provided by the power supply. A power supply can be a group of batteries or an electrical circuit that provides the correct energy levels from an outside power source. And that's all there is to how an FM radio transmitter works. It may sound complicated if that information is new to you but it's not at all unusual for people to build their own FM radio transmitters in their basements or garages. |