| 词条 | Laser airborne depth sounder |
| 释义 |
The Laser airborne depth sounder (LADS) is an aircraft-based hydrographic surveying system used by the Australian Hydrographic Service (AHS).[1] The system uses the difference between the sea surface and the sea floor as calculated from the aircraft's altitude to generate hydrographic data.[1] The lack of progress made in surveying Australia's territorial waters, most of which was unsurveyed or relying on Age of Sail-era charts prompted the Royal Australian Navy to seek a method of effectively surveying large areas from the air in the 1970s.[2] The Defence Science and Technology Organisation developed the LADS system, with feasibility trials beginning 1977.[1][2] The LADS system is built around a YAG laser, which emits an infra-red beam at 990 hertz.[2] The beam is frequency doubled to produce a green laser.[2] This is split into two beams, one infra-red, one green, by an optical coupler, with the infra-red beam aimed directly below the aircraft, and the green beam directed across the target area with a scanning mirror.[2] The infra-red laser does not penetrate the water's surface, and its reflected pulse indicates the height of the aircraft above the surface.[2] However, the green laser penetrates to the ocean floor, and the return pulse from the green laser indicates the height of the aircraft from the ocean floor; the difference between the two values is used to calculate the water's depth.[2] The data from the lasers is not processed aboard the aircraft, but instead by a ground support team, with aircraft flight data and global positioning system information used to help generate hydrographic readings.[2] The aircraft makes multiple, overlapping passes of the target area to ensure accurate data is collected.[2] The LADS system is capable of taking 990 soundings per second, with data points positioned {{convert|2|to|6|m}} apart across a swath up to {{convert|288|m}} wide.[2] The system is capable of working with waters up to {{convert|70|m}} deep, and can be modified to perform land surveys of areas with an altitude variance less than {{convert|50|m}} LADS entered service with the AHS in 1993.[1] The equipment was initially fitted to a Fokker F27 Friendship aircraft.[1] In 2010, the system was installed in a de Havilland Canada Dash 8 aircraft.[1] This is operated by the Laser Airborne Depth Sounder Flight of the Royal Australian Navy. Citations1. ^1 2 3 4 5 Slade, in Oldham, 100 Years of the Royal Australian Navy, p. 171 2. ^1 2 3 4 5 6 7 8 9 {{cite web|url=http://www.hydro.gov.au/aboutus/lads.htm |title=LADS II (laser airborne depth sounder) |publisher=Australian Hydrographic Office |accessdate=26 June 2011}} References
2 : Hydrography|Military equipment of the Royal Australian Navy |
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