Walkie-talkies

A walkie-talkie (more formally known as a handheld transceiver, or HT) is a hand-held, portable, two-way radio transceiver. Its development during the Second World War has been variously credited to Donald L. Hings, radio engineer Alfred J. Gross, and engineering teams at Motorola. First used for infantry, similar designs were created for field artillery and tank units, and after the war, walkie-talkies spread to public safety and eventually commercial and jobsite work.

Typical walkie-talkies resemble a telephone handset, with a speaker built into one end and a microphone in the other (in some devices the speaker also is used as the microphone) and an antenna mounted on the top of the unit. They are held up to the face to talk. A walkie-talkie is a half-duplex communication device; multiple walkie-talkies use a single radio channel, and only one radio on the channel can transmit at a time, although any number can listen. The transceiver is normally in receive mode; when the user wants to talk he presses a "push-to-talk" (PTT) button that turns off the receiver and turns on the transmitter.

Canadian inventor Donald Hings was the first to create a portable radio signaling system for his employer CM&S in 1937. He called the system a "packset", although it later became known as a "walkie-talkie". In 2001, Hings was formally decorated for the device's significance to the war effort. Hings' model C-58 "Handy-Talkie" was in military service by 1942, the result of a secret R&D effort that began in 1940.

Alfred J. Gross, a radio engineer and one of the developers of the Joan-Eleanor system, also worked on the early technology behind the walkie-talkie between 1938 and 1941, and is sometimes credited with inventing it.

...
Wikipedia