An ultra-high frequency (UHF) transceiver is a device which usually houses a transmitter and receiver operating between the radio frequencies of 300 megahertz (MHz) to 3 gigahertz (GHz). Depending on the frequency used, the corresponding wavelength of a transceiver using a UHF band ranges between 3.94 inches (10 cm) to 3.28 feet (1 m). Due to the relatively short wavelength, UHF transceivers such as walkie-talkies and citizen band (CB) radios are limited to a radius of several miles.
The actual operating distance of the devices will largely depend on several factors including environmental topography, use of repeaters and antenna height. A UHF transceiver relies on line-of-sight radio propagation, which means the devices communicate with one another in a direct path. Physical objects such as trees and buildings will often weaken or even block line-of-sight propagation, decreasing communication reliability. To increase reliability, UHF transceivers will often include additional radio bands such as high frequency (HF) and very high frequency (VHF).
UHF and multi-band transceivers such as walkie-talkies and CB radios are used for short range communications between two or more parties. Walkie-talkies and CB radios are used by a variety of sectors including public, commercial and military. Public use may involve leisure activities that require communication mobile phones cannot provide due to a weak or non-existent signal. Some countries may reserve certain UHF frequencies for military use only and require a special permit to operate a UHF transceiver. In many commercial and military settings, base station repeaters are utilized to extend a UHF transceiver operating range.
Operating instructions for a UHF transceiver will most likely vary due to differing device models and settings. While there are a few differences in how to access certain features in transceiver devices, most operating principles remain the same. For example, most walkie-talkies will have a push-to-talk button which allows a person to transmit or communicate with a device on the same frequency and channel. The person will receive the message and will be able to respond after the incoming communication is done transmitting.
Care should be taken while transmitting sensitive information. Interception of a radio transmission by a third party is entirely possible, especially if the channel is not encrypted or secure. For this reason many walkie-talkie manufacturers have implemented encrypted or privacy channel options. Generally a code or a password is either entered or generated to secure a transmission session between communicating parties. In addition to privacy codes, a voice scrambling function is offered in some transceivers to ensure maximum transmission security.