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Radio communication is a widely used form of communication that takes advantages of the characteristics of radio waves to transfer messages across wide distances. Radio messages are sent from a radio transmitter and are received by an antenna which sends them to a receiving device.
The most popular usage of radio communications today is radio broadcasting – an audio broadcasting service widely used by listeners for music and broadcast conversations. Other types of communications sent via radio waves include Morse code, and more recently DAB, or Digital Audio Broadcasting.
The two most common forms of radio broadcast include AM and FM; the two techniques used to broadcast commercial radio stations. Radio waves can also be sent and received via citizens band radio (CB radio) or even transmitted via satellites.
The fundamental idea behind broadcasting radio communications is to transmit a carrier signal which can be received by a correctly tuned receiver and then to vary that carrier signal according to the message you want to send.
A.M. stands for amplitude modulation and was the original method used to broadcast radio stations. It involves changing the amplitude of the carrier signal to send a message. It is a very simple system that does not require a lot of expensive equipment to receive a signal.
AM radio signals are subject to interference by EMI, or Electromagnetic interference. This is most notable to listeners during weather events such as lightning storms.
F.M. stands for frequency modulation and involves varying the frequency of the carrier signal to transmit a signal. This technique is used in the VHF, or “Very High Frequency”, range of airwaves.
FM Radio allows broadcasts to be made with much less interference than AM signals, and by spacing FM stations further apart they are less likely to interfere with each other. The range of an FM broadcast is not as great as an AM broadcast so they are more suitable for local radio stations.