2013年1月6日星期日

Parts of a Two-Way Radio

Transmitter
The transmitter creates the outgoing radio signals that allow two-way radios to communicate, a process known as propagation. Essentially, the transmitter takes a very simple signal produced within the radio by electric pulses that have been created from the user’s voice, and enhances them so they can be sent out to a communication tower or other radio.
Antenna
The antenna helps the transmitter send out its signal, and picks up other incoming signals with the help of a receiver. Without the antenna, the range for mobile 2 way radios would be virtually nonexistent.
Speaker
The speaker enables the user to speak into the radio and have the sounds converted to radio signals that can be sent through radio waves. Without the speaker, the radio would not be two-way at all, although there are other secondary devices that help the speaker both produce incoming sound and convert outgoing sound. When signals are incoming, the speaker takes the radio wave and converts it into sound, often with the help of an amplifier to enhance the audio. When signals are outgoing, the speaker must convert sound waves into radio waves that can be broadcast by the transmitter.
Range
There are two types of two-way radio communication, known as Repeat and Simplex. Repeat involves the use of a nearby radio tower or repeater, which takes the radio signal and propagates it even further, allowing the signal to travel miles in search of the correct person, usually in a format that most two-way radios can pick up. The exact distance depends on the power of the radio, but this method is always the most far-reaching and is used when one user is not sure where the other user is. Simplex is “simply” two radios talking to one another without the use of a repeater, which means they must be far closer together.
Tone Control: Encoder/Decoder
Many two way radios also have an encoder and decoder that allow users to privatize signals, known as tone control or private line. In PL mode, a two-way radio waits for only one type of tone, and will only activate if it picks up that particular tone. Another person trying to reach either one of the radios with a different tone will not succeed. The tone itself is basically a subaudible noise included with the transmission that acts as a type of authorization code.

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