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www.southgatearc.org
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Sat-nav devices face big errors as solar activity risesResearchers say the Sun is awakening after a period of low activity, which does not bode well for a world ever more dependent on satellite navigation, the BBC News website reports. The Sun's irregular activity can wreak havoc with the weak sat-nav signals we use. The last time the Sun reached a peak in activity, satellite navigation was barely a consumer product. But the Sun is on its way to another solar maximum, which could generate large and unpredictable sat-nav errors. It is not just car sat-nav devices that make use of the satellite signals; accurate and dependable sat-nav signals have, since the last solar maximum, quietly become a necessity for modern infrastructure. Military operations worldwide depend on them, although they use far more sophisticated equipment. Sat-nav devices now form a key part of emergency vehicles' arsenals. They are used for high-precision surveying, docking ships and plans are even underway to incorporate them into commercial aircraft. Closer to home, more and more trains depend on a firm location fix before their doors will open. Simple geometry The satellite navigation concept is embodied currently by the US GPS system and Russia's Glonass network, with contenders to come in the form of Europe's Galileo constellation and China's Compass system. It depends on what is - at its root - a simple triangulation calculation. A fleet of satellites circling the Earth are constantly beaming a radio signal with two bits of exceptionally precise information: where exactly they are, and at exactly what time. A sat-nav receiver on Earth - or on a ship or plane - is equipped with a fairly precise clock and the means to collect signals from the satellites that happen to be in its line of sight. It then works out, based on how long it took those signals to arrive, how far it is from each of those satellites. Some simple geometry yields its position. Read the full BBC News article -
Our thanks to Lee, M0HOK for spotting this item
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