- Jul 24, 2017 -
In the water depth measurement work, but also to accurately determine the depth of the plane position, this work is called positioning. When the depth is measured, the plane position of the depth point is the plane position of the transducer. When the depth is measured with the depth of the measuring rod and the water mound, the plane of the depth point is the measuring rod, Rod or water mound perpendicular to the water surface) when the plane position. In the distance from the shore, the visual ability to distinguish the target distance, the general use of optical instruments, such as theodolite, flat and sextant positioning. When the mapping scale is 1: 10000 or more, usually with the theodolite or flat instrument to the front intersection method positioning; mapping scale is less than 1: 10000, usually using the sextant instrument after the intersection method (also known as the three standard two ) Positioning. For large scale mapping with high positioning accuracy, the distance measurement system (also known as circular-circular system) is used, such as a marine microwave rangefinder, or by a distance-azimuth method. On the far off the sea area, the general use of radio hyperbolic positioning system positioning. Since the 1960s, the use of artificial earth satellites has been widely used for high-precision positioning. This kind of positioning method uses the electronic computer as the data information processing center to filter the navigation information of the satellite to obtain the real-time navigation data (longitude, latitude, heading, speed, time). The use of artificial earth satellite positioning can work around the clock, the instrument system with automatic, global coverage and continuous implementation of positioning and other advantages (see satellite geodesy).
Locating points into the drawing board of the method of analysis and graphic methods are two. Analytical method is to determine the parameters of the measured formula according to a certain formula to calculate the coordinates of the point, and then points into the drawing board. This work is now available with a computer-aided map mapping system (see Computer Assisted Map Mapping). Graphical positioning refers to the grid method or with the instrument directly to the positioning point drawing board. Grid method is based on different positioning methods in the drawing board to draw a variety of forms of grid map. Radial grid, for the front intersection method positioning; isometric arc grid for rear intersection method positioning; distance grid, for distance measurement system positioning; Hyperbolic grid for radio hyperbolic Positioning system positioning.