How Sound Is Transmitted Via Radio

of course you don't really hear the sounds that are being made in the studio what you hear is a translation of the sounds the microphone responds to the vibrations of sound waves that strike it converting those vibrations of sound into similar vibrations of electrical energy this minute electrical current now called an audio wave travels over wires to the studio control room where if we could see it it might look something like this in this form though the wave contains all the elements of the program it is not strong enough to do its job so it is Amplified or strengthened until it is this size now is it ready to be sent over the air oh no it's still in the studio building so let's follow the wave on a long journey perhaps many miles to the transmitting station the wires over which this audio wave travels are specially designed so that none of its tone frequencies or vibrations will be lost though some of its power will [Music] be the transmitting station is usually located outside of the city so as to take advantage of the best possible transmitting conditions also its towering antenna requires ample space for many guy wires to hold it in place behind those Sleek metal walls are wires vacuum tubes electrical condensers coils switches relays and much other complex apparatus that represents years of technical research and development but let's get back to our audio wave here it is but not as strong as when it left the studio building or some of its power has been lost on the way so immediately it gets a r strengthening until it looks like this moving along to another amplifier it passes through and comes out like this once more it is Amplified now it is powerful enough but it isn't the right kind of wave to travel over the air to reach your radio set it's going to need some help so over here in what is known as a crystal oscillator we generate another wave a highspeed wave having perhaps as many as a million vibrations per second that would look something like this if we could see it this must likewise be [Music] Amplified on it goes into a final amplifier and it comes out a strong far-reaching carrier wave capable of transporting a program round the world in a sth of a second this wave is ready for the air except for one thing it has no program on it you wouldn't hear anything if we were to broadcast just a plain carrier wave so we go back and pick up the audio wave that we left a moment ago and we use this to control the strength of the carrier wave in technical language we are now modulating the carrier wave the combination looks something like [Music] this it is now a complete radio wave here is a picture of what we just saw take place striking the microphone sound waves are converted into electrical energy this energy or audio wave is Amplified first in the studio control room then again in the master control room now it travels over special wires to the transmitting [Music] station here it is Amplified once twice three times meanwhile another wave of very high frequency the carrier wave is being generated by the oscillator this too is Amplified once twice now the audio wave is made to control the carrier wave modulating or impressing its own pattern of sounds music and voices onto the high frequency wave producing the complete radio wave this changing radio wave is now ready for business it's in these wires now on its way to the [Music] tower up up up and then it hurled out into space with the speed of light now our program actually is on the air caught by your aerial the wave sets up currents in it and your receiving set when you tune your radio to the same frequency as the transmitter's carrier wave these currents traveling through your set's various circuits and louds speaker will give a true reproduction of the studio program all day the radio station is roting programs out to the transmitter from its various Studios and from remote sources millions of listeners profit from the relaxation each program offers for on radio's elaborate Bill Affair there are programs to fit every desire and [Music] need