by Chris Woodford. Last updated: June 3, 2020.
Do you read me, over? Yes, I read you, over. If you've never had the pleasure of communicating by walkie-talkie, you don't know how much fun you've been missing! Before cellphones became popular during the 1980s and 1990s, walkie-talkies were the most effective way to share information over short to medium ranges—and they're still widely used by police officers, military personnel, and the organizers of public events. What are they and how do they work? Let's take a closer look!
Photo: Testing, testing, 1-2-3. This naval technician is checking the communication between a pair of walkie-talkies. Photo by Raymond D. Diaz III courtesy of US Navy.
What is a walkie-talkie?
Photo: This is a typical one-way radio: it will receive things like music broadcasts from radio stations, but it can't transmit. A walkie-talkie can send and receive, so it's called a two-way radio.
Walkie-talkies are handheld, portable radios: they communicate wirelessly (using radio waves) on a single, shared frequency band. Each battery-powered unit contains a transmitter/receiver and antenna (for sending and receiving radio waves), a loudspeaker that often doubles up as a microphone when you talk into it, and a button that you "push-to-talk" (PTT). The loudspeaker/microphone works in much the same way as an intercom: because a speaker and a microphone contain essentially the same components (a coil of wire, a magnet, and a paper or plastic cone to pick up or generate sounds), you can use a single device to do both jobs essentially by switching the electrical circuit into which it's connected and reversing the current. More sophisticated walkie-talkies (like the Motorola model shown in our photos) contain separate loudspeakers and microphones.
How do you use a walkie-talkie?
Screenshot: Walkie-talkies have entered the 21st century thanks to apps like these two. Above) Walkie Talkie Standard from Indigo Penguin. It converts your smartphone (or iPod Touch) into a walkie-talkie that can communicate with others nearby. Below) Online Walkie Talkie Pro from NAVA apps for Android. You'll find lots of similar apps if you search for "walkie-talkie" in the iTunes Store or Google Play (for Android).
A group of people who are using walkie-talkies to talk to one another have to tune in to the same frequency band, which is called a channel. Their radios are all "receiving," so their microphone/loudspeaker units are working as loudspeakers and probably hissing with static, a bit like a conventional radio that's not tuned into any particular station. When someone wants to to talk to the others, they hold the push-to-talk button on their handset. Their radio goes quiet as their loudspeaker switches over to a microphone. As they talk into it, their words are converted into radio waves and beamed out on the prearranged channel (typically at a frequency around 460 MHz in the United States and 446 MHz in Europe). Since radio waves are part of the electromagnetic spectrum, they travel at the speed of light (300,000 km/second or 186,000 miles/second), so the waves are picked up almost instantaneously by the other handsets. The radio waves are converted back into fluctuating electric currents and the loudspeakers use those to reproduce the sound of the talker's voice. When the talker has finished, he or she says "over" (meaning my bit of talking is finished) and releases the push-to-talk button. The radio now switches back into listening mode and someone else can talk.
Unlike a normal radio, which will only pick up broadcast voices or music from a radio station, a walkie-talkie is a two-way radio: you can both talk and listen (send and receive). The main drawback is that the same frequency channel is used for both things, so only one person can talk at a time. When communication devices work this way, they're described as half-duplex (a single channel allows communication in only one direction at any one time), as opposed to full-duplex (where you can talk and listen at the same time, as on a telephone).