page_title: Two-way radio
hierarchical_section_title: Two-way radio
caption_attribution_description: Français&#160;: Radios commerciales VHF et UHF English: P25-compliant portable radios from a variety of manufacturers
context_page_description: A two-way radio is a radio that can both transmit and receive radio waves, unlike a broadcast receiver which only receives content. It is an audio transceiver, a transmitter and receiver in one unit, used for bidirectional person-to-person voice communication with other users with similar radios. Two-way radios are available in stationary, mobile, and hand-held portable models. Hand-held two-way radios are often called walkie-talkies, handie-talkies or hand-helds. Two-way radios are used by groups of geographically separated people who need to keep in continuous voice communication, such as aircraft pilots and air traffic controllers, ship captains and harbormasters, emergency services personnel like firemen, policemen, and ambulance paramedics, taxi and delivery services, soldiers and military units, fast food and warehouse employees, and radio amateurs.
  Two-way radio systems usually use a single radio channel and operate in a half-duplex mode: only one user on the channel can transmit at a time, so users in a user group must take turns talking. The radio is normally in receive mode so the user can hear all other transmissions on the channel.
context_section_description: A two-way radio is a radio that can both transmit and receive radio waves (a transceiver), unlike a broadcast receiver which only receives content. It is an audio (sound) transceiver, a transmitter and receiver in one unit, used for bidirectional person-to-person voice communication with other users with similar radios. Two-way radios are available in stationary (base station), mobile (installed in vehicles), and hand-held portable models. Hand-held two-way radios are often called walkie-talkies, handie-talkies or hand-helds.  Two-way radios are used by groups of geographically separated people who need to keep in continuous voice communication, such as aircraft pilots and air traffic controllers, ship captains and harbormasters, emergency services personnel like firemen, policemen, and ambulance paramedics, taxi and delivery services, soldiers and military units, fast food and warehouse employees, and radio amateurs.
  Two-way radio systems usually use a single radio channel and operate in a half-duplex mode: only one user on the channel can transmit at a time, so users in a user group must take turns talking.  The radio is normally in receive mode so the user can hear all other transmissions on the channel.  When the user wants to talk he presses a "push-to-talk" button, which turns off the receiver and turns on the transmitter; when he releases the button the receiver is activated again.  Multiple channels are provided so separate user groups can communicate in the same area without interfering with each other. Other two-way radio systems operate in full-duplex mode, in which both parties can talk simultaneously.  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.  A cell phone is an example of a full-duplex two-way radio. During a phone call, the phone communicates with the cell tower over two radio channels; an incoming one to carry the remote party's voice to the user, and an outgoing one to carry the user's voice to the remote party.
caption: Several portable two-way radios designed for public services (police, fire, rescue) compatible with the Project 25 digital radio standard
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