Meaning of AM and FM
What are AM and FM:
AM and FM, in the world of broadcasting, are acronyms that refer to two ways of modulating the carrier wave of electrical signals. AM stands for 'amplitude modulated', while FM stands for 'frequency modulated'.
AM or amplitude modulated
AM stands for amplitude modulation or amplitude modulation; It is a technique used in electronic communication that consists of varying the amplitude of the radio frequency carrier wave. As such, it was the first technique used to make radio.
The AM channel has a bandwidth that is between 10 KHz and 8 KHz. Because they are lower frequencies, whose wavelengths are longer, the range of their signal is considerably wider in relation to that of the modulated frequency.
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 well 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 stands for frequency modulated; 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 American inventor Edwin Howard Armstrong.
The modulated frequency channel has a bandwidth of 200 KHz. Such a width allows the transmitted sounds (music and speech) to have higher fidelity and quality, and to be cleaner and clearer than at modulated amplitude.
In modulated frequency, one station transmits on 101.1 MHz (that is, 101,100 KHz), and the next transmits on 101.3 MHz (that is, 101,300KHz). This means that between one channel and another there are 200 KHz free. In addition, it allows you to send a double signal, that is, a stereo signal.
However, the range of frequency modulated 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 that they travel in a straight line and quickly attenuate. Hence, it is a type of wave suitable for flat areas, where waves can be transmitted without obstacles.