A walkie-talkie is a hand-held portable, bi-directional radio transceiver. The first walkie-talkies were developed for military use. Major characteristics include a half-duplex channel (only one radio transmits at a time, though any number can listen) and a push-to-talk switch that starts transmission. The typical physical format looks somewhat like a telephone handset, possibly slightly larger but still a single unit, with an antenna sticking out of the top. Where a phone's earpiece is only loud enough to be heard by the user, a walkie-talkie's built-in speaker can be heard by the user and those in his immediate vicinity.
The first radio receiver/transmitter to be nick-named "Walkie-Talkie" was the backpacked Motorola SCR-300, created by an engineering team in 1940 at the Galvin Manufacturing Company (fore-runner of Motorola). The team consisted of Dan Noble, who conceived of the design using FM technology, Henryk Magnuski who was the principal RF engineer, Marion Bond, Lloyd Morris, and Bill Vogel. Motorola also produced the hand-held AM SCR-536 radio during the war, and it was called the "Handie-Talkie" (HT).
Al Gross also worked on the early technology behind the walkie-talkie between 1934 and 1941, and is sometimes said to actually have invented it.
Hand-held transceivers became valuable communication tools for police, emergency services, and industrial and commercial users, using frequencies assigned for these services. Walkie-talkies are also popular with some amateur radio operators, operating with an amateur radio license in several different frequency bands.
Since even a powerful commercial walkie-talkie is limited to a few watts of power output and a small antenna (the physical size of the package limits both battery capacity and antenna size), hand-held communication range is typically quite short, with a typical range not exceeding the line-of-sight distance to the horizon in open areas, and much less in built-up areas, within buildings, or underground. Many radio services permit the use of a repeater which is located at some high point within the desired coverage area. The repeater listens on one frequency and retransmits on another, so that reliable hand-held to hand-held unit range can be extended to a few score miles (kilometers) or further, using repeaters linked together.
Low-power versions, exempt from licence requirements, are also popular children's toys. Prior to the change of CB radio from licensed to un-licensed status, the typical toy walkie-talkie available in retail stores in North America was limited to 100 milliwatts of power on transmit and the 27 MHz citizens' band channels using AM amplitude modulation only. Later toy walkie-talkies operated in the 49 MHz band, some with FM (frequency modulation), shared with cordless phones and baby monitors. The lowest cost devices are very crude electronically, may employ superregenerative receivers, and may lack even a volume control, but they may have elaborate packaging. Unlike more costly units,low-cost toy walkie-talkies may not have separate microphones and speakers; the receiver's speaker typically doubles as a microphone while in transmit mode.
The personal walkie-talkie has now become popular again with the new U.S. Family Radio Service and similar unlicensed services in other countries (PMR446 in most of Europe) While FRS walkie-talkies are also sometimes used as toys because mass-production makes them low cost, they have proper superheterodyne receivers and are a useful communication tool for both business and personal use. Operation in the Family Radio & PMR446 Service is restricted to walkie talkies limited to 500 milliwatts of effective RF power. Some FRS models also include the surrounding GMRS channels, which require a license.
Handie Talkie refers to Mototorla portable products only. According to the US Patent and Trademark Office, Handie Talkie became a trademark of Motorola, Inc. on May 22, 1951. The application was filed June 24, 1948 and the trademark registration number is 71560123.
The abbreviation HT is commonly used to refer to portable handheld ham radios (from any manufacturer) in the UHF and VHF ranges. Fun and free to run walkie talkies are great for business and pleasure!