Analysis of Causes of Measurement Error of GPS Area Measuring Instrument
The GPS area measuring instrument accurately measures the land area by high-precision GPRS positioning, and can realize real-time testing, dynamic graphic display and intelligent data processing and storage of any irregular area. This area measuring instrument is widely used in agriculture and forestry. In agriculture, the land area measuring instrument can further accurately determine the amount of seeds, fertilizers and pesticides used, and reduce the waste of resources. In the course of use, this type of measurement The results of the instrument measurements are not completely accurate, for the following reasons:
The area measurement accuracy is affected by many factors such as GPS positioning error, plot size, forest and mountain shelter. Handheld GPS receivers can effectively perform positioning as long as they can accept more than 4 satellites. When the plot area is less than 600 square meters, the area measurement error will exceed 5%. The smaller the plot, the greater the relative error. Canopy closure affects the reception of GPS signals, which in turn affects area measurements. The impact of the mountain on satellite signals is an issue that cannot be overcome by any GPS device. Positioning and area measurements are also difficult to perform in the Grand Canyon. Different observation periods have certain influence on the area measurement. The better observation period should be selected for area measurement, which can be predicted by the spatial position accuracy factor PDOP.
Since the earth is an ellipsoid, in order to accurately calculate the distance or area, it is generally converted into plane coordinates by means of projection. In China, for large scale maps, Gauss-Kruger projection is usually used for conversion, but the projection method is very complicated. It is difficult to implement in a single chip microcomputer. To simplify the calculation, we consider the earth to be a true sphere. The earth body is converted into plane coordinates for calculation, so there will be some influence in the process of measuring different terrains. The difference of the terrain not only causes signal difference, but also brings certain errors to the conversion.
Dried Green Split Peas,Whole Dried Peas,Dried Salted Peas,Green Peas Dried
Shanghai Sinospices Sourcing Ltd , https://www.garlicall.com