Range
The useful direct range of a two-way radio system depends on radio propagation conditions, which are a function of frequency, antenna height and characteristics, atmospheric noise, reflection and refraction within the atmosphere, transmitter power and receiver sensitivity, and required signal-to-noise ratio for the chosen modulation method. An engineered two-way radio system will calculate the coverage of any given base station with an estimate of the reliability of the communication at that range. Two-way systems operating in the VHF and UHF bands, where many land mobile systems operate, rely on line-of-sight propagation for the reliable coverage area. The "shadowing" effect of tall buildings may block reception in areas within the line-of-sight range which can be achieved in open countryside free of obstructions. The approximate line-of-sight distance to the radio horizon can be estimated from : horizon in kilometers = 3.569 times the square root of the antenna height in meters.
There are other factors that affect the range of a two-way radio such as weather, exact frequency used, and obstructions.
Read more about this topic: Two-way Radio
Famous quotes containing the word range:
“The ideal of the self-sufficient American family is a myth, dangerous because most families, especially affluent families, do in fact make use of a range of services to survive. Families needing one or another kind of help are not morally deficient; most families do need assistance at one time or another.”
—Joseph Featherstone (20th century)
“Jane Addams, founder of Hull House, once asked, “How shall we respond to the dreams of youth?” It is a dazzling and elegant question, a question that demands an answer—a range of answers, really, spiraling outward in widening circles.”
—William Ayers, U.S. author. To Teach: The Journey of a Teacher, ch. 7 (1993)
“During the cattle drives, Texas cowboy music came into national significance. Its practical purpose is well known—it was used primarily to keep the herds quiet at night, for often a ballad sung loudly and continuously enough might prevent a stampede. However, the cowboy also sang because he liked to sing.... In this music of the range and trail is “the grayness of the prairies, the mournful minor note of a Texas norther, and a rhythm that fits the gait of the cowboy’s pony.””
—Administration in the State of Texa, U.S. public relief program (1935-1943)