Heliograph (message transmission)
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A heliograph or graph , or mirror telegraph , uses a mirror to reflect sunlight to a distant observer . When the mirror moves, the distant observer sees flashes of light that can be used to transmit information using predefined signal coding .
history
The first recorded use of a heliograph was in 405 BC. . Instead, Chr than the Greeks in ancient times polished shields used to transmit signals in battles to transfer and was designed by Xenophon in his work Hellenika documented.
The Roman Emperor Tiberius used a heliograph to steer the Roman Empire from Villa Jovis on the island of Capri , sending orders to the mainland eight kilometers away every day.
In 1820 Carl Friedrich Gauß developed the so-called heliotrope for surveying purposes , which is based on the functional principle of the heliograph and which allows a (sunlight) point to be aimed at a target over great distances.
use
The French , British and US military used the principle as a field telegraph to transmit information using a Morse code . Heliographs were also used by the protection force in German South West Africa (now Namibia ) in Halali , on the Dikwillem or on the protection force tower near Klein Nauas , for example during the suppression of the Herero uprising and during the First World War . The transmission range was over 70 km. Heliographs were also used by the protection forces in German East Africa to transmit messages.
The heliograph remained a standard equipment of the military in Australia and Great Britain until 1960 , as it was considered to be relatively secure against eavesdropping .
The last time heliographs were used was in 1980 by the Afghans during the Soviet invasion of Afghanistan. They are often still included in survival kits in order to be able to carry out a simple minimal signal transmission in an emergency, in particular to e.g. B. to be able to draw attention to search aircraft by means of "flashes of light". This version, called a sun mirror , usually consists of a polished, flat metal plate. There is a hole in the middle for aiming at targets.
literature
- Christopher H. Sterling (Ed.): Military Communications. From Ancient Times to the 21st Century . ABC Clio, Santa Barbara 2008, ISBN 978-1-85109-732-6 .
See also
- Optical telegraphy
- Heliography of the protection force in German South West Africa
- Turn signals (military)
Web links
- Heliography (Communicating with Mirrors) ( Memento from February 20, 2012 in the Internet Archive )
- MILITARY HELIOGRAPH
- The Heliograph in the Apache Wars
- practical description of messaging
Individual evidence
- ↑ Company - Short Biographies, Rudolf Fuess ( Memento of the original from November 29, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ In the English literature of Ernest Lisle Reedstrom: Apache Wars , An Illustrated Battle History, Sterling Publ. New York, 1990, ISBN 0-8069-7254-8 , (Reprint, Barnes & Noble Books, 1995, ISBN 1-56619- 959-X ) on pages 170–175 (The Heliograph) the hunt for the Apache Geronimo using a heliograph is described.
- ↑ Veit Didczuneit: Sun flashes in the desert - The light telegraphy in German South West Africa 1899-1915. In: The archive - magazine for communication history. Edition 2, 2017, pp. 14-27.
- ↑ Baltzer: Heliographen , in: Heinrich Schnee (Hrsg.): Deutsches Kolonial-Lexion. Volume II, Quelle & Meyer, Leipzig 1920, p. 55.
