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Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave.In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal.
Medium wave (MW) is a part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band. During the daytime, reception is usually limited to more local stations, though this is dependent on the signal conditions ...
Frequencies Modulation Frequency range Notes longwave: 148.5–283.5 kHz: amplitude modulation (AM) low frequency (LF) Mostly used in Europe, North Africa, and Asia: AM radio (medium wave) 525–1606.5 kHz, 525–1705 kHz in N. America, Australia and the Philippines. amplitude modulation (AM) medium frequency (MF)
In large urban centers, AM radio signals can be severely disrupted by metal structures and tall buildings. As a result, AM radio tends to do best in areas where FM frequencies are in short supply, or in thinly populated or mountainous areas where FM coverage is poor. Great care must be taken to avoid mutual interference between stations ...
When a broadcast reaches well outside of its intended range due to unusual conditions, DXing is possible. The local terrain can also play a major role in limiting broadcast range. Mountain ranges block FM broadcasts, AM broadcasts, and TV broadcasts, and other signals in the VHF and especially UHF ranges, respectively.
This enables AM radio stations to transmit beyond the horizon. Additionally, frequencies in the shortwave bands between approximately 1 and 30 MHz, can be refracted back to Earth by the ionosphere, called skywave or "skip" propagation, thus giving radio transmissions in this range a potentially global reach.
The radio spectrum is the part of the electromagnetic spectrum with frequencies from 3 Hz to 3,000 GHz (3 THz).Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication.
Medium frequency (MF) is the ITU designation [1] [2] for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometers (1000 to 100 m).