Radio, sometimes referred to as radio transmitters, wire transmission, or unlicensed radio communication, involves the transmission of data over wide areas using radio waves. A radio transmitter sends radio waves from a base station to an area that needs service; these signals are then received and interpreted by receivers, and the data is sent or received. In the United States, radio stations can receive data from anywhere on the earth within about 100 miles (from a transmitting tower), although international radio communications generally require a further satellite connection. Radio transmitters may be used to send personal or commercial messages; they may also be used to monitor traffic, and to locate weather balloons and aircraft. Radio operators use a variety of methods to operate their equipment, including regular channels, tone, single or multiple frequency channels, and so on.
The two main types of radio systems are satellite and regular radio. The former transmits radio waves using a satellite, while the latter uses radio waves on a regular carrier frequency. Satellite communications can be less reliable than regular carrier communications, especially in remote or poor radio environments, but they offer a more flexible option for global coverage. On the other hand, regular radio systems are less expensive and have a broader reach, including inside buildings and on mobile handsets. Most regular types of radio communications use the same channels and frequencies to transmit and receive data, although some have slightly different modes of operation. A basic distinguishing characteristic is that the satellites transmit their radio waves in an unchanging fashion across the entire sky, while regular radios use random channels and frequencies.
Most household electronics sold in the U.S. include a built-in radio receiver, and most portable devices and personal media players come with built-in radios as well. Modern mobile phones also include built-in radio receivers, and some mobile devices come with an FM radio transmitter, as well. Digital TV systems often include a radio receiver or channel. Small hand held devices such as PDA’s, pocket cameras and video recorders may also have built-in radio receivers and can scan channel channels.
There are several types of radio systems used for communication. One is the power Radio Service (PRS), which is a service using two independent channels, allowing the transmission and reception of analog (analog) radio waves. Another is the Broadcast Radio Service (BROS) which transmits on one single channel. Broadcast Radio Service usually requires a license. Fm radio, otherwise known as Family Radio Service (FRS), is a type of broadcast communication system using only one channel to communicate with multiple users.
FRS systems broadcast their radio signals by a small dedicated base unit. Unlike the other two types of radio services, FRS does not require a license to operate. In addition, FRS does not use any one single frequency to operate. Some mobile phones also operate on FRS.
There are three different types of satellite radio systems, – portable (portable dish, -) permanent magnet (PMT), and shortwave radio. Portable dishes usually have limited power and are ideal for single-use. Most of the time, portable dishes do not broadcast shortwave radio signals. On the other hand, permanent magnet dishes usually have larger power and longer lasting antennas. Shortwave radio, the type of radio that transmits on very short (solar) radio wave are ideal for car headlights, dashboards, marine buoys, emergency and distress beacons, hunting and locate devices, weather alert systems and on road vehicles.