|
The Lorenz beam was blind-landing radio navigation system developed by C. Lorenz AG in Berlin. The first system had been installed in 1932 at Berlin-Tempelhof Central Airport, followed by Dübendorf in Switzerland (1934) and others all over the world.〔For example at Essendon Airport (Australia) in November 1936, according to: (The 33Mc 'Lorenz' Radio Range System )〕 The Lorenz company referred to it simply as the Ultrakurzwellen-Landefunkfeuer, German for "ultra-short-wave landing radio beacon", or LFF. Prior to the World War II the Germans had deployed the landing aid system at many Luftwaffe airfields in and outside Germany and equipped most of their bombers with the radio equipment needed to use it. The RAF continued using the system as late as 1955, under the name Standard Beam Approach (SBA).〔Walter Blanchard, "Hyperbolic Airborne Radio Navigation Aids", ''The Journal of Navigation'', Volume 44 Number 3, September 1991〕 The basic idea behind the short-range LFF system was later developed into a long-range system for air navigation known as Elektra. Further development produced a system that worked over very long distances, hundreds or thousands of kilometres, known as Sonne (or often, Elektra-Sonnen) that allowed aircraft and U-Boats to take fixes far into the Atlantic. The British captured Sonne receivers and maps and started to use it for their own navigation under the name Consol. ==Description== The blind approach navigation system was developed starting in 1932 by Dr. Ernst Kramar of the Lorenz company.〔http://www.radarworld.org/flightnav.pdf〕 It was adopted by Deutsche Lufthansa in 1934 and sold around the world.〔Louis Brown, ''A Radar History of World War II: Technical and Military Imperatives'', CRC Press, 1999, p. 113〕 The Lorenz company was founded in 1880 by Carl Lorenz and is now part of ITT. Lorenz used a single radio transmitter at 33,33 MHz (Anflugfunkfeuer) and three antennas placed in a line parallel to the end of the runway. The center antenna was always powered, while the other two were switched on and off in turn, fed from a common signal. With two of the antennas powered, the presence of the third resulted in a "kidney" shaped broadcast pattern centered on one of the two "side" antennas. The broadcast was switched so that the left antenna, as seen looking toward the runway on approach, was turned on only briefly, sending a series of "dots" 1/8 of a second long repeating once a second. When the left antenna was switched off the signal was sent to the right antenna instead, broadcasting a series of 7/8th second long "dashes". The signal could be detected for some distance off the end of the runway, as much as 30 km. The Lorenz obtained a sharper beam than could be created by an aerial array by having two lobes of signal.〔R. V. Jones, ''Most Secret War: British Scientific Intelligence 1939-1945'', Hodder and Stoughton, 1979 ISBN 0-340-24169-1 Chapter 11 ''The Crooked Leg''〕 A pilot approaching the runway would tune his radio to the broadcast frequency and listen for the signal. If he heard a series of dots, he knew he was off the runway centerline to the left (the ''dot-sector'') and had to turn to the right to line up with the runway. If he was to the right, he would hear a series of dashes instead (the ''dash-sector''), and turned left. The key to the operation of the system was an area in the middle where the two signals overlapped. The dots of the one signal "filled in" the dashes of the other, resulting in a steady tone known as the ''equi-signal''. By adjusting his path until he heard the equi-signal, the pilot could align his aircraft with the runway for landing. Two small marker beacons were also used: one 300 m off the end of runway, the ''HEZ'' (Haupteinflugzeichen), and another 3 km away, the ''VEZ'' (Voreinflugzeichen), both were broadcast on 38 MHz and modulated at 1700 and 700 Hz, respectively. These signals were broadcast directly upward, and would be heard briefly as the aircraft flew over them. To approach the runway, the pilot would fly to a published altitude and then use the main directional signals to line up with the runway and started flying toward it. When he flew over the VEZ he would start descending on a standard glide slope, continuing to land or abort at the HEZ depending on whether or not he could see the runway. Lorenz could fly a plane down a straight line with relatively high accuracy, enough so that the aircraft could then find the runway visually in all but the worst conditions. However it required a fairly constant monitoring of the radio by the pilot, who would often also be tasked with talking to the local control tower. In order to ease the workload, Lorenz later introduced a cockpit indicator that could listen to the signals and display the direction to the runway centerline as an arrow telling the pilot which direction to turn. The indicator also included neon lamp to indicate when the aircraft crossed over the marker beacons. Later derivatives of the system had signals of equal length in the pattern left-right-silence, to operate a visual indicator in the cabin. The Lorenz system was similar to the Diamond-Dunmore equi-signal radio guidance system, developed by the US Bureau of Standards in the early 1930s.〔H. Diamond and F. Dunmore, ("A Radio System for Blind Landing of Aircraft in Fog" ), ''Proceedings of the National Academy of Sciences'', Volume 16 (19 September 1930), pp. 678-685〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lorenz beam」の詳細全文を読む スポンサード リンク
|