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The Western Union company used the term simplex when describing the half-duplex and simplex capacity of their new transatlantic telegraph cable completed between Newfoundland and the Azores in 1928. [4] The same definition for a simplex radio channel was used by the National Fire Protection Association in 2002. [5]
Naval air traffic controller communicates with aircraft over a two-way radio headset A variety of portable handheld two-way radios for private use. A two-way radio is a radio transceiver (a radio that can both transmit and receive radio waves), which is used for bidirectional person-to-person voice communication with other users with similar radios, [1] in contrast to a broadcast receiver ...
Working Channel, Marine Weather Maritime radio working channel A VTS (Ship-to-ship + port operations) Coast Guard: Radiotelephone links between ship stations and land stations of the authorities responsible for the operation of inland waterways (ship-to-shore duplex) 68: 156.425: 156.425 Non-commercial A Maritime radio working channel
The interstitial frequencies are in-between the main channels, and the 462 MHz interstitial frequencies may be used for simplex as long as the effective radiated power does not exceed 5 watts. [14] The 467 MHz interstitial frequencies have a power limit of 500 milliwatts ERP, [15] and only hand-held portable units may transmit on these channels ...
Most (30-174 MHz) systems operate simplex, with multiple radios sharing a single radio channel. Only one radio can transmit at a time. The transceiver is otherwise normally in receiving mode so the user can hear other radios on the channel. To talk, the user presses a push to talk button that turns on the transmitter of the transceiver.
In the late 1970s, the impending ban by the FCC of the sale of older 23 channel CB equipment that did not meet more stringent restrictions on newer, 40 channel units, meant that a surplus of 23 channel CB gear was on the market. This was a windfall for amateur radio enthusiasts, allowing access to fairly inexpensive radios which could easily be ...
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 ...
There are two types of radio network currently in use around the world: the one-to-many (simplex communication) broadcast network commonly used for public information and mass-media entertainment, and the two-way radio (duplex communication) type used more commonly for public safety and public services such as police, fire, taxicabs, and delivery services.