GPS Errors and Biases
GPS pseudorange và vận chuyển pha đo được cả hai bị ảnh hưởng bởi một số dạng sai sót ngẫu nhiên và những thành kiến (lỗi hệ thống). Những lỗi này có thể được phân loại như những người có nguồn gốc ở các vệ tinh, những người có nguồn gốc ở người nhận, và những người được do để tuyên truyền tín hiệu (khúc xạ khí quyển) . Hình 3.1 cho thấy các lỗi khác nhau và những thành kiến.
Differential GPS (DGPS) is a technique for reducing the error in GPS-derived positions by using additional data from a reference GPS receiver at a known position. The most common form of DGPS involves determining the combined effects of navigation message ephemeris and satellite clock errors [including the effects of selective availability (SA), if active] at a reference station and transmitting pseudorange corrections, in real time, to a user's receiver. The receiver applies the corrections in the process of determining its position ....
The Global Positioning System(GPS) is a satellite-based navigation system
that was developed by the U.S. Department of Defense (DoD) in the early
1970s. Initially, GPS was developed as a military system to fulfill U.S. mili-
tary needs. However, it was later made available to civilians, and is now a
dual-use systemthat can be accessed by bothmilitary and civilian users .
GPS Data Errors
SELECTIVE AVAILABILITY ERRORS
Prior to May 1, 2000, Selective Availability (SA) was a mechanism adopted by the Department of Defense (DoD) to control the achievable navigation accuracy by nonmilitary GPS receivers. In the GPS SPS mode, the SA errors were speci®ed to degrade navigation solution accuracy to 100 m (2D RMS) horizontally and 156 m (RMS) vertically. In a press release on May 1, 2000, the President of the United States announced the decision to discontinue this intentional degradation of GPS signals available to the public. ...
We now consider the following, practical aspects of Kalman ®ltering applications: 1. how performance of the Kalman ®lter can degrade due to computer roundoff errors and alternative implementation methods with better robustness against roundoff; 2. how to determine computer memory, word length, and throughput requirements for implementing Kalman ®lters in computers; 3. ways to implement real-time monitoring and analysis of ®lter performance;
The demand of vehicle navigation and guidance has been urgent for many years. The idea of integrating multisensor navigation systems was implemented. The most efficient multisensor configuration is the system integrating an inertial navigation system (INS) consisting of MEMS based micro sensors and a global positioning system (GPS). In such system, the GPS is used for providing position and velocity whereas the INS for providing orientation. The estimation of the system errors is performed by a Kalman...