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Ultra-high-frequency (UHF) radio waves are most commonly used for short-range communication systems such as two-way radios, wireless local computer network technologies such as Wi-Fi, and most cellular phones. These radio waves are also used for local broadcast media such as UHF television. Different types of UHF review devices use different frequencies within the 300 megahertz (MHz) to 3 gigahertz (GHz) range. Particular frequencies are often reserved by law for particular types of devices, with the specifics varying by jurisdiction.
Ultra-high-frequency radio, is the region of the electromagnetic spectrum encompassing electromagnetic radiation with frequencies between 300 MHz and 3 GHz (3,000 MHz) and wavelengths between 10 and 100 centimeters. UHF radio waves can be picked up by smaller antennas than lower-frequency radio transmissions require, but have much shorter range.
Most cordless telephones use UHF radio to transmit from the cordless handset to the phone's base. In the United States, most modern cordless phones transmit at frequencies of 900 MHz, 1.9 GHz, or 2.4 GHz. Early cell phones had frequencies in the low megahertz range, but these frequencies were largely abandoned because they can be easily picked up and eavesdropped on by radio scanners.
Many cellular phones use UHF transmissions. The world's most widely used mobile phone technology, the GSM (Global System for Mobile Communications, or Group Special Mobile) standard, uses UHF radio to transmit information between the cell phone and the base transceiver's station's antenna in order to connect the phone to the cellular network. Most cellular phones in the United States and most other countries of the Americas transmit to their base station at frequencies of either 824 to 849 or 1850 to 1910 MHz, with the base station transmitting back at frequencies of 935 to 1990 or 1930 to 1990 MHz. In most other parts of the world, most cellular phones transmit at 890 to 915 or 1710 to 1785 MHz and receive at 930 to 960 or 1805 to 1880 MHz.
Wireless networks are usually based on UHF radio, though some wireless technologies transmit at even higher frequencies in the super high frequency (SHF) band. Bluetooth devices transmit at frequencies of between 2402 and 2480 MHz. Many wireless local area networks (WLAN) and wireless wide area networks use UHF signals in the 2.4 GHz band. The most widely known wireless technology standard, Wi-Fi, is an example.
UHF frequencies are also used by many two-way radios. Some hand-held transceivers, popularly known as walkie-talkies, transmit at frequencies of between 400 and 500 MHz or at 900 MHz. The specific allocation of different frequencies of the UHF band is usually set by law and varies according to jurisdiction.
In the United States, for example, 14 frequencies between 462.5625 and 467.7125 MHz are allocated to the Family Radio Service, a set of unlicensed frequencies used for personal and business communications. Overlapping this is a group of eight UHF frequencies called the General Mobile Radio Service, which are also dedicated to short-range two-way devices that require a license to use. The Industrial/Business Pool in the United States has reserved for the use of businesses licensed by the FCC, or Federal Communications Commission, several sets of designated UHF frequencies, ranging from as low as 406 to 413 MHz to as high as 1427 to 1432 MHz.
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