What Are The Main Applications Of Radio?
The earliest use of radio in the sailing, the use of Morse telegraph in the ship and land transfer information between. Now, radio has a variety of applications, including wireless data networks, a variety of mobile communications and radio and so on.
The following are the main applications of some radio technologies:
The earliest form of sound broadcasting is the nautical radio telegraph. It uses a switch to control the transmission of a continuous wave, thereby generating an intermittent sound signal at the receiver, i.e., the Morse code.
AM broadcasts can spread music and sound. AM broadcast using amplitude modulation technology, that is, the greater the volume received by the microphone, the radio is also the greater the energy emitted. Such signals are susceptible to interference such as lightning or other sources of interference.
FM radio can spread music and sound more than fidelity broadcasts. For frequency modulation, the higher the volume received at the microphone, the higher the frequency of the transmitted signal. FM radio work in very high frequency (Very High Frequency, VHF). The higher the band, the greater the frequency bandwidth it has, and thus can accommodate more radio stations. At the same time, the shorter the wavelength of the radio wave propagation is also closer to the light wave linear transmission characteristics.
FM radio sidebands can be used to spread digital signals such as radio stations, program name profiles, web sites, stock market information, and so on. In some countries, when moved to a new area, the FM radio can automatically automatically find the original channel based on the sideband information.
Nautical and aeronautical use of voice stations using VHF AM technology. This allows aircraft and ships to use light antennas.
Government, fire, police and commercial use of radio stations are usually used in special frequency band narrowband FM technology. These applications typically use 5KHz of bandwidth. Relative to FM radio or television sound 16KHz bandwidth, fidelity had to make sacrifices.
Civil or military high frequency voice service uses shortwave for communication between ships, airplanes or isolated locations. In most cases, single-sideband technology is used, which saves half the frequency band relative to AM technology and makes more efficient use of transmit power.
Terrestrial Trunked Radio (TETRA) is a digital trunking telephone system designed for special departments such as military, police, emergency and traffic.
Cellular phones or mobile phones are the most commonly used wireless communications. The cell phone coverage area is usually divided into multiple cells. Each cell is covered by a base station transmitter. In theory, the shape of the cell is a honeycomb hexagon, which is also the source of the cell phone name. Currently widely used mobile phone system standards include: GSM, cdmaOne and TDMA. Operators have begun to provide the next generation of 3G mobile communications services, the dominant standards for CDMA2000 and UMTS.
Satellite phones exist in two forms: INMARSAT and Iridium systems. Both systems provide global coverage services. INMARSAT uses geostationary satellites that require directional high gain antennas. Iridium is a low-orbiting satellite system that uses mobile phone antennas directly.
The TETRA system has the capability of a wireless telephone.