AM vs FM radio

Have you ever thought about the history, or the differences in AM and FM radio? If your like me than you haven't. Doing research on this topic made me appreciate the differences! I think once you read this, you will have more insight about AM and FM radio stations.

AM stations were the earliest broadcasting stations to be developed. AM refers to amplitude modulation, a mode of broadcasting radio waves by varying the amplitude of the carrier signal in response to the amplitude of the signal to be transmitted. AM radio ranges from 535 to 1705 kHz. 

AM is the older an easier of the two technologies to implement. The receiver detects the changes in the carrier frequency’s amplitude and amplifies it to drive a speaker. The simplicity of the technology made it easy to build radio receivers in great quantities. The main problem associated with AM broadcasting is the fact that it is very susceptible to various weather conditions that deteriorate and distort the signal. The simplicity of the design also limits the broadcast to a single audio channel, making it inadequate for stereo sound.

FM refers to frequency modulation, and occurs on VHF airwaves in the frequency range of 88 to 108 MHz everywhere (except Japan and Russia).FM radio was invented by Edwin H. Armstrong in the 1930s for the specific purpose of overcoming the interference problem of AM radio, to which it is relatively immune.

FM is a development over AM broadcasting and it provides a lot of substantial benefits thus it is much more complex compared to AM. The first and most substantial benefit is its ability to send out two channels of information at the same time with the use of advanced algorithms. This allows the station to broadcast left and right audio channels for full stereo sound. Since most environmental factors that distort radio waves only affect its amplitude and not the frequency where FM stores the actual voice signal, the data in the FM signal doesn’t degrade as easily as AM. This also means that FM signal quality doesn’t degrade linearly as you get further from the transmitting station.

I think that these differences in AM and FM radio give FM radio a serious advantage in the radio industry. Not many people want to be subjected to the static that comes along with AM. The only time that I have listened to an AM station on the radio, was to listen to a Ravens football broadcast. Other than that I always listen to FM.

According to the  September 2011 RADAR 110 National Radio Listening Report, 1.7 million additional listeners 12 years and older tune into radio on average every week, from the 2010 report. The young demographics of radio make it very obvious to me that FM is the leading reason to this increase. How many 12 year olds that you know would tune into AM/ talk radio?

In the DC area, these are the AM and FM radio stations.