The Research Of Portable Combined Positioning Terminal Technology Based On FPGA

Along with the improvement of Global Positioning System (GPS) and the enhancement of people living standard, portable positioning devices become ever-increasing popular. Therefore, it is urgent to develop a portable combined positioning device with Independent Intellectual Property.The work in this article is supported by Key Technologies R&D Programme of China"The Navigation and Monitor System For Individual Based on FPGA"(Item Number: 2005BA102C) and Key Technologies R&D Programme of HuBei"The Small Intelligent Navigation System Based on FPGA"(Item Number: 2006AA101C34).Based on the analyses of the portable positioning technology status in domestic and overseas at present, a novel implementation of a portable positioning terminal based on FPGA, in view of disadvantages of current GPS positioning device, is proposed. Whereafter, the terminal has been designed and realized.Based on SOPC technology, the hardware of terminal is realized, a Nios II soft-core professor and digital interface are designed on a Cyclone FPGA chip, and then other components such as external memory, digital compass, GPS module, GPRS module, LCD circuit and a portable power circuit are also implemented in this article.GPS signal is easy to be blocked in many areas, which usually results in inaccurate positioning. The traditional combined positioning system usually uses large volume distance sensor and course sensor, which is difficult to apply to portable products. In view of these disadvantages, a combined positioning technology using GPS and digital compass is applied to this portable system. The method to eliminating the errors of digital compass based on distribution display method is proposed at the beginning. Then by adopting DR, the position information of digital compass can be calculated. And finally, this article carries through dynamic weighting data fusion with position data of digital compass and GPS via the fuzzy possibility distribution.The results of the experiment indicate that a good positioning effect is gained by adopting the technology introduced in this article, which provides a feasible way for the development of portable positioning technology.