AM vs. FM radio: What’s the difference?


Thanks to the digital revolution, members of Generation Z don’t spend a lot of time shooting a radio compose for the chance to hear their favorite song. Corn Millennials and their predecessors no doubt remember the experience – as well as the acronyms, A M and FMit went with it.

You probably know that A M and FM describe different types of radio stations. But how exactly are they different?

In order to process this response, it is helpful to have at least a superficial understanding of how radios produce noise in the first place. Each radio station emits what is called a carrier wave or carrier signal, which is essentially a stable electromagnetic wave whose variables, such as frequency and amplitude, do not change. That is, until a DJ starts playing a song at the station (or some other sound plays). These sound waves are converted into electrical signals that travel to your radio antenna via the carrier wave, and your radio converts them back into sound waves for your speaker to emit. When the carrier wave transmits these signals, it changes in two ways.

If it is an AM radio station, the amplitude of the carrier wave – the height of the wave – is manipulated according to the signals. As Soundfly Flypaper Reportsthis is called amplitude modulation, hence the A M. For FM radio stations, the amplitude remains the same, while the frequency – the number of complete wave cycles in a given time – changes.

frequency modulation vs amplitude modulation

FM vs. AM, shown. /petrroudny/iStock via Getty Images

FM represented frequency modulation, and is generally considered better than AM. When random electrical signals interfere with a carrier wave, they can affect its amplitude. Since FM carrier waves do not transmit signals through amplitude, such as PBS explains, it does not affect the quality of an FM radio broadcast. But changing the amplitude of an AM carrier disrupts the data it is trying to transmit, which is why AM radio generally has more static than FM. FM radio also broadcasts over a much wider range of frequencies, called bandwidth, so it is able to handle more nuances and variations in sound. If you want to stream music, you will get better quality by using FM radio.

That said, AM radio is not without its advantages. As explained in the video above, its wavelengths – the distance from one wave crest to the next – are significantly longer than FM wavelengths, helping signals travel farther and stay intact when encountering obstacles like buildings or mountains. If you want your show to reach as many people as possible, AM radio may be your best bet.

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