First ,we need to know the word:
Frequency Modulation (FM),
Amplitude modulation (AM),
Long wave (LW),
Medium wave (MW),
Short wave (SW)
In general the radio or cassette player on both AM and FM bands, I believe we are already familiar with, these two bands are used for you to listen to country radio, if there SW bands on the radio, then in addition to domestic shortwave radio beyond You can also listen to radio programs around the world.
To make use of your radio a better understanding, the following is what is AM, FM, SW, MW, LW for a simple explanation.
Indeed AM and FM radio science refers to the two different modulation. AM: Amplitude Modulation called amplitude modulation, and FM: Frequency Modulation called FM.
Just general MW Broadcast (MW: Medium Wave) using amplitude modulation (AM) way, unknowingly, MW and AM equate between.
MW fact many of AM modulation is a broadcast, as in the high frequency (3-30MHz) in international shortwave radio modulation method is used for AM, FM radio or a higher frequency than the aeronautical communications (116 - 136MHz) also use the AM mode, but our daily said the AM band refers MW Broadcast (MW).
That FM do? It is also similar to the fate of the same MW. We used to refer to the general use FM FM radio (76-108MHz, the country is 87.5-108MHz, Japan 76-90MHz), in fact is a FM modulation, even in the short wavelength range of between 27-30MHz , as an amateur radio station, space, satellite communications applications the band, there is also an FM (FM) mode.
The SW is? In fact, it can be said is a simple short call, the correct statement should be high-frequency (HF: High Frequency) is more appropriate.
The shortwave This name is how come? The wavelength, the wave (MW) ranging from 200-600 m (meters), and the wavelength of the HF is 10 to 100 m (meters), compared with the above-mentioned wavelength, HF of wavelength is indeed a bit short, so they made known HF Shortwave (SW: Short Wave).
Similarly, a lower frequency than the AM MW between 150KHz-284KHz this period as the broadcast spectrum is used, the wavelength is concerned, it is about 1000 to 2000 meters (m), and between 200 MW - 600 m compared to apparently “long” and more, so put this radio spectrum called longwave (LW: Long Wave).
In fact, regardless of long-wave (LW), medium wave (MW) or shortwave (SW) are based on the AM modulation.