Positioning Of The Two Orientation Theories And Models

Navigation is a rather ancient technique. In order to ensure the safety of the ships and to navigate economically, the navigators must know the position and the direction of travel atany given moment, so that the ship could navigate along the scheduled route. The achievements in the modern science and technology have made signification progress in navigation. The successful application of the technologies such as information, computer, electronics, communications and the satellite has brought profound changes to the navigation technology, greatly enhanced and developed the scope of navigation. It could be envisaged that the twenty-first century will be completely new era for navigation.In the modern comprehensive navigation and positioning technology, currently on the global positioning system (GPS) is capable of providing accurate position of the ship and this information could be used together with electronic nautical chart。 GPS was originally established by the US defence department for military purpose, mainly used by the US military, therefore, the GSP signals have very high level of encryption. Only the parts with lower encryption is open for civil exploitation. The protect the US interests, the US government has adopted a policy of useability, artificially introduced error into to the satellite clock and calendar, intentially reduced the ppsitioning accuracy of civil GPS receivers. Meanwhile, one main controlling staion, three injection station , five monitoring stations are all located in the US or its military establishments. In a sense, GPS is a type of radio positioning based on satellites. It is a kind of electronic positioning which is prone to error. If the accuracy and use of positioning and comprehensive navigationsystems of all the other countries are also solely based on GPS, then in some special circumstances, it may results in enormous risks. It is, therefore, important for the GPS users to have a substitution method for GPS, so that he can enjoy the advanced functionality of GPS while avoiding possible risks.In this article, we investigate an alternative universal navigation method , by making use of the current scientific and technological achievements, and basing on a simple but reliable two-orientation method, and combining with electronic oceanography, to improve the positioning accuracy of two-orientation method, to reduce the positioning time and to raise the overall navigation level of ships under extraordinary circumstances. Although the precision and amount of information in this method is far less than GPS, but for certain precision condition, it can maintain the effectiveness of auto-navigation, to avoid the paralysis of the navigation system due to the loss of GPS signals.This articles contains the following seven sections: 1. the orientation-position line and its errors; 2. two-orientation positioning and its errors; 3. the mathematical modelling of the two-orientation positioning; 4. the validation of the mathematical model against mesured data; 5. the use of the two-orientation method with electronic oceanography; 6. the design and application of two-orientation positioner; and 7. the difficency and possible improvement of the mathematical model for the two-orientation positioning method.