Meaning of AM and FM

What are AM and FM:

AM and FMin the world of broadcasting, are acronyms that refer to two ways of modulating the carrier wave of electrical signals. AM stands for ‘modulated amplitude’while FM stands for ‘modulated frequency’.

AM or amplitude modulated

A.M means amplitude modulated or amplitude modulation; It is a technique used in electronic communication that consists of varying the amplitude of the radiofrequency carrier wave. As such, it was the first technique used to make radio.

The AM channel has a bandwidth between 10 KHz and 8 KHz. Because they are lower frequencies, whose wavelengths are longer, the range of their signal is considerably wider than that of FM.

In this sense, AM waves can measure between 100 meters (3000 KHz) and 1000 meters (300 KHz). This is the type of wave that reaches the ionosphere and bounces off it.

However, the sound quality of amplitude modulation (AM) is far below that of frequency modulation (FM). In addition, as they are low-frequency waves, they are more vulnerable to noise, since these are produced in the amplitudes of the waves. Despite this, it is the most advisable type of wave for mountainous areas.

FM or frequency modulated

FM it means modulated frequency; It is a technique that allows information to be transmitted through a carrier wave, varying its frequency. As such, it was patented in 1933 by the American inventor Edwin Howard Armstrong.

The FM channel has a bandwidth of 200 KHz. Such width allows transmitted sounds (music and speech) to have higher fidelity and quality, and to be cleaner and clearer than amplitude modulation.

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In frequency modulation, a station transmits on 101.1 MHz (that is, 101.100 KHz), and the next does so on 101.3 MHz (that is, 101.300 KHz). This means that between one channel and another 200 KHz are free. In addition, it allows sending double signal, that is, a stereo signal.

However, the range of FM signals is less than that of amplitude modulation. This is because the modulated frequency is transmitted between 88 and 108 MHz, that is, at very high frequencies, whose waves can measure between one meter (300 MHz) and ten meters (30 MHz). These types of waves also have considerably short lengths, so they travel in a straight line and fade quickly. Hence, it is an ideal type of wave for flat areas, where waves can be transmitted without obstacles.