Meteorites entering the atmosphere are glowing and producing an ionized band lasting from a few tenth of a second up to a few seconds at a hight of 80 to 120 km. Depending on the density of the charged particles, this burst will either scatter or reflect electromagnetic waves in the 40 to 100 MHz range, allowing communication to be established over distances of 400 to 2000 km [22.214.171.124]. This phenomenon was discovered in 1935, and later on, between 1950 and 1975, intensive development work has been carried out in order to determine the properties of these radio channels. The first meteor-burst system started operation in Canada, in the year 1953, and in 1967, the ANOTEL (Snowpack Telemetry) system in Alaska was put into operation. This system was used in an uninhabited area for transmitting sensing data from 500 remote stations to a central station.
The period over which communication is established is determined by the life time of the ionized band. This is taken into account by storing the data and transmitting them in burst form, so this kind of transmission is called meteor-burst transmission. This is an inexpensive system, sometimes called "the satellite of poor people", and is suitable to transmit data of a few kb/s. The Alaska system has been further developed, and in the technical literature, more civilian and military systems have been reported. One of these is the BLOSSOM system (Beyond Line-of-Sight Signaling Over Meteors) put into operation in 1986, operated in the 37 to 72 MHz band with FSK modulation and 2.4 kb/s capacity. Another tropo scatter system is operating in Egypt since 1995, transmitting water-level data of the Nile that are needed for watering, and one more station is installed at the top of the volcano Mount St. Helens, collecting data received from stations monitoring snow thickness .
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