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This requires either two separate radio channels or channel sharing methods such as time-division duplex (TDD) to carry the two directions of the conversation simultaneously on a single radio frequency. [2] The first two-way radio was an AM-only device introduced by the Galvin Manufacturing Corporation in 1940 for use by the police and military ...
MDC (Motorola Data Communications), also known as Stat-Alert, MDC-1200 and MDC-600, is a Motorola two-way radio low-speed data system using audio frequency shift keying, (AFSK). MDC-600 uses a 600 baud data rate. MDC-1200 uses a 1,200 baud data rate. Systems employ either one of the two baud rates.
Marine VHF radio is a worldwide system of two way radio transceivers on ships and watercraft used for bidirectional voice communication from ship-to-ship, ship-to-shore (for example with harbormasters), and in certain circumstances ship-to-aircraft.
The CB Radio Service spectrum is divided into 40 numbered radio frequency channels from 26.965 to 27.405 MHz. Channel spacing is 10 kHz between channel centers with exceptions where CBRS channels are adjacent to Radio Control Radio Service. The initial channel allocations had a gap equal to two channel spaces between channels 22 and 23.
A trunked radio system is a two-way radio system that uses a control channel to automatically assign frequency channels to groups of user radios. In a traditional half-duplex land mobile radio system a group of users (a talkgroup) with mobile and portable two-way radios communicate over a single shared radio channel, with one user at a time ...
CCIR (Consultative Committee on International Radio) functions have largely been taken over by ITU-R. One common type of CCIR selcall used in VHF and UHF FM two-way radio communications, is a 5-tone selective calling system mainly found in some European countries and used by the Swedish Police and the Turkish Police .
The General Mobile Radio Service (GMRS) is a land-mobile FM UHF radio service designed for short-range two-way voice communication and authorized under part 95 of the US FCC code. It requires a license in the United States, but some GMRS compatible equipment can be used license-free in Canada. The US GMRS license is issued for a period of 10 years.
Amateur radio operators can transmit two-way amateur television (and voice) in the 2.4 GHz band—and all ISM frequencies above 902 MHz—with maximum power of 1500 watts in the US if the transmission mode does not include spread spectrum techniques. [18] [19] Other power levels apply per regions.