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13 Jun 2012
A two-way radio is a radio that receives and transmits content. The operator in possession of the radio can engage in a conversation with other operators having a two-way radio, which operates on the same frequency or channel. A two-way radio is also referred to as a walkie-talkie.

The 2 way radio system works in a half-duplex mode, meaning that the operator can either transmit or listen at the same time. If he is listening, and wants to talk, then he must push a button (called a Push To Transmit button). A mobile phone works on a full-duplex mode - meaning that the operator can receive and transmit conversation at the same time. This is because mobile phones work on two frequencies - whereas a two-way radio works on only one frequency.

Two-way radio systems can operate only on specified frequencies. Every country assigns this specified frequency for such radios and therefore these frequencies differ from country to country. For example, America has assigned a whole block of twenty-two channels to the general Mobile Radio Service. Operators can communicate on their two-way radios using any of these frequencies.

The government allocates the frequency based on its own policies and regulations and on a number of factors. First, it checks the traffic-per-frequency and determines the frequency availability. Then it checks the topography and checks how radio signals will travel in forest and urban areas. It calculates congestion, noise intrusion and takes into account other technical considerations. Finally, it creates a proposal that must be approved by a special technical committee.

After getting the approval, the government then assigns the frequency. Numbers and titles are given to frequencies for easy recall, - for example, Channel 10 is easier to recall than 27.695 MHz. The frequency assigned for two-way radios acts as a bridge between two-way radios. Utility companies and government departments like the police have many frequencies assigned for their use. This is necessary because these organizations provide critical services and their two-way radios must always be ready for use at any and every point in time. Though utility companies and other organization use channel numbers for easy identification of frequencies, amateur radio operators tend to work with different frequencies because they are not bound by any law that requires them to use fixed channels.

The quality of the conversation between two-way radios depends the robustness of the frequency. The range of a two-way radio system depends on many factors such as the height at which the antenna is situated, noise in the atmosphere, antenna characteristics, atmospheric refraction and reflection, type of receiver, transmitter power, and the signal-to-noise ratio.

Most 2-way radio systems operate in the UHF and VHF bands of the radio spectrum, which is what mobile systems use. Two-way radios depend on line-of-sight broadcast and therefore tall buildings within the line-of-sight can block communication. Other factors that can impact the conversation quality are weather, atmospheric noise and the frequency used. Two-way radios are used in a variety of applications - hobbyists, cops, utility company workers, hotel employees, and many other professionals and amateurs use two-way radios.

These are the basics of two-way radios.