Development Of Modular & Digital Atmospheric Pressure Altimeter And Preliminary Research Of Positioning Method With GPS Double-star

The basic role of satellite navigation is to offer real-time, accurate, continuouslocation, speed and time information to each kind of user and mobile platform. Satellitenavigation location technical now have basically replaced astronomical measure and otherlocation technology. It becomes the universal adopted navigation location in humanactivity. As the pioneer of satellite navigation system, Global Positioning System (GPS) whichis used widely now, have superior navigation performance. And it is the important factor tocontinuous development in the future. However, in some special occasions, when GPSantenna is sheltered by terrain or artificial structure, there are less than four stars viewable,and GPS will reduce location precision or even invalid. BEIDOU Satellite Navigation andPositioning System of our country have advantages such as few satellites and simple userterminal etc. It needs two satellites to position only. But BEIDOU System works by activelocalization mode, which makes it limited in user capacity, concealment ability andcompatibility and so on. The research and development direction of BEIDOU System inthe future is necessarily to realize passive location. Based on above reasons, this paper is going to do preliminary research work inadvance for the feasibility of GPS double-star positioning. We have designed a double-starlocalization scheme, which studies the feasibility and precision of using double satellitesand one GPS receiver with precise clock, as well as the self-made atmospheric pressurealtimeter to realize three-dimensional location. This paper begins at the development of themodular & digital atmospheric pressure altimeter, goes to the structure and scheme ofdouble-star system, and the method of making simulation software and error analysis . Thedesign characteristic of the altimeter is that it adopts atmospheric pressure sensor whoseresistance changes with pressure, which can change atmosphere pressure into electricalsignal, instead of the traditional vacuum bellows. The altimeter realizes modularzation,miniaturization and intelligent error compensation by using C8051F SCM andcommunications with UART and SPI etc. Experiment shows that, the precision of altimeterinfluences that of system much. If we raise the precision of altimeter, the precision ofsystem will be improved within sixty meters.