Satellite navigation systems allow small electronic devices to determine their location (Longitude, Latitude, and Altitude) in within a few metres using time signals transmitted along a line of sight by radio from satellites. Receivers on the ground with a fixed position can also be used to calculate the precise time as a reference for scientific experiments. The Global position System is the only fully functional satellite navigation system as of 2007.
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An early predecessor were the ground based LORAN and Omega systems, which used terrestrial longwave radio transmitters instead of satellites. These systems broadcast a radio pulse from a known "master" location, followed by repeated pulses from a number of "slave" stations. The delay between the reception and sending of the signal at the slaves was carefully controlled, allowing the receivers to compare the delay between reception and the delay between sending. From this the distance to each of the slaves could be determined, providing a fix.The Third Reich's choice of priorities was always guided by prejudice rather than logic, and under the pressures of total war, the allocation of resources depended on who had the ear of the Fiihrer. The Walter programme consumed carce commodities at an alarming pace, notably skilled labour. It is typical of the way the war economy was run that the radically more advanced Type XXI 'rlectro U-boat' suf{ered delays because the most skilled workers were working on the outdated Type VII design and the various Walter designs.

Modern systems are more direct. The satellite broadcasts a signal that contains the position of the satellite and the precise time the signal was transmitted. The position of the satellite is transmitted in a data message that is superimposed on a code that serves as a timing reference. The satellite uses an atomic clock to maintain synchronization of all the satellites in the constellation. The receiver compares the time of broadcast encoded in the transmission with the time of reception measured by an internal clock, thereby measuring the time-of-flight to the satellite. Several such measurements can be made at the same time to different satellites, allowing a continual fix to be generated in real time.Post-war, both the US Navy and the Royal Navy found the cost of the fuel a major draw­back. A US Navy engineer calculated that Perhydrol was times as expensive as diesel fuel. The nature of HTP also dictated elaborate support Measures. For example, the crews of HMS Explorer and HMS F.xcnfihur never `owned a plank', and were accommodated in a tender.

Each distance measurement, regardless of the system being used, places the receiver on a spherical shell at the measured distance from the broadcaster. By taking several such measurements and then looking for a point where they meet, a fix is generated. However, in the case of fast-moving receivers, the position of the signal moves as signals are received from several satellites. In addition, the radio signals slow slightly as they pass through the ionosphere, and this slowing varies with the receiver's angle to the satellite, because that changes the distance through the ionosphere. The basic computation thus attempts to find the shortest directed line tangent to four oblate spherical shells centered on four satellites. Satellite navigation receivers reduce errors by using combinations of signals from multiple satellites and multiple correlators, and then using techniques such as Kalman filtering to combine the noisy, partial, and constantly changing data into a single estimate for position, time, and velocity.Emirates, United Kingdom, United States of America, Uruguay, Uzbekistan, Vanuatu, Vatican City, Venezuela, Vietnam, Virgin Islands, Virgin Islands, Yemen, Zaire, Zambia, Zimbabwe,

The original motivation for satellite navigation was for military applications. Satellite navigation allows for hitherto impossible precision in the delivery of weapons to targets, greatly increasing their lethality whilst reducing inadvertent casualties from mis-directed weapons. (See smart bomb). Satellite navigation also allows forces to be directed and to locate themselves more easily, reducing the fog of war.

Satellite navigation using a laptop and a GPS receiverThe teams setting U_ to work in the US and their opposite numbers in the UK doing the same for L- (HMS Meteorite) soon found that the claims for the Walter system, and for other recent designs like the Type XXI, were exaggerated. III December Captain Logan McKee wrote that the design of the turbine was needlessly complex, and suggested that German designers preferred to play safe rather than risk being sent to the Eastern Front, or worse. In the Admiralty published a secret report claiming that the designs of both the Walter boats and the Type XXI had inherent flaws. It was concluded that the increase in diving-depth was achieved at the cost of major reductions in safety-margins. We now know that the streamlined hulls of the Type XXI and Type XVII were not tank-tested to verify the hull-forms, and as a result may have offered more hull drag than necessary. Another weakness was their relatively shallow diving-depth. HMS iYlelenrife was limited to a maximum depth of ft.
In these ways, satellite navigation can be regarded as a force multiplier. In particular, the ability to reduce unintended casualties has particular advantages for wars being fought by democracies, where public relations is an important aspect of warfare. For these reasons, a satellite navigation system is an essential asset for any aspiring military power.

Dynamic position
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Offshore Support Vessel Toisa Perseus with in the background the fifth-generation deepwater drillship Discoverer Enterprise, at the Thunder Horse location. Both are equipped with DP systems.
Dynamic position (ship tracking, marine maritime building navigation shipping shipper construction fund dunding banking engineering, maritime industry)(DP) is a system to automatically maintain a ship’s position and heading by using her own propellers and thrusters. This allows operations at sea where mooring or anchoring is not feasible due to deep water, congestion on the sea bottom (pipelines, templates) or other problems.Afghanistan, Albania, Algeria, American Samoa, Andorra, Angola, Anguilla, Antarctica, Antigua, Argentina, Armenia, Aruba Australia, Austria, Azerbaijan, Bahamas, Bahrain, Bangladesh, Barbados,

The US Navy lost interest in closed-cycle machinery because it knew that nuclear propul­sion was not only feasible but also developing fast. The Royal Navy was feeling the pinch because of a national financial crisis, and also saw its nuclear propulsion progranmrr slip rapidly down the priority list.

What, then were the benefits of I-iTP-fuelled submarincs% HMS Explorer nd HMS Exia­ihur certainly contributed to the search for high underwater speed and played a useful role in the development of new anti-submarine tactics. The technology may have been ahead of its time, but the submarine world is still searching for the perfect air-independent propulsion (AIP) system.

Dynamic position (ship tracking, marine maritime building navigation shipping shipper construction fund dunding banking engineering, maritime industry)may either be absolute in that the position is locked to a fixed point over the bottom, or relative to a moving object like another ship or an underwater vehicle. One may also position the ship at a favourable angle towards wind, waves and current, called weathervaning.

Dynamic position (ship tracking, marine maritime building navigation shipping shipper construction fund dunding banking engineering, maritime industry)is much used in the offshore oil industry, for example in the North Sea, Persian Gulf, Gulf of Mexico, West Africa and off Brazil. Nowadays there are more than 1000 DP ships.Belarus, Belgium, Belize, Benin, Bermuda, Bhutan, Bolivia, Bosnia, Herzegovina, Botswana, Bouvet Island, Brazil, British Indian Ocean territory, Brunei Darussalam, Bulgaria, Burkina Faso, Burundi,
Although all methods have their own advantages, dynamic position (ship tracking, marine maritime building navigation shipping shipper construction fund dunding banking engineering, maritime industry)has made many operations possible that were not feasible before.

The costs are falling due to newer and cheaper technologies and the advantages are becoming more compelling as offshore work enters ever deeper water and the environment (coral) is given more respect. With container operations, crowded ports can be made more efficient by quicker and more accurate berthing techniques. Cruise ship operations benefit from faster berthing and non-anchored "moorings" off beaches or inaccessible ports.Cambodia, Cameroon, Canada, Cape Verde, Cayman Islands, Central African Republic, Chad, Chile, China, Christmas Island, Cocos Islands, Colombia, Comoros, Congo, Congo, Democratic