GPS receiver SPS accuracy assessment using LS and LQ estimators for precise navigation

Global Positioning System (GPS) is the emerging technology extending its applications in the field of surveying, navigation, military etc., and these applications demands multiple levels of accuracy ranging from tens of meters to sub-millimetre level. Hence there is a need to develop systems, methods and a technique to meet the demand of high accuracy.GPS provides its services in two different standards, Standard Positioning Services (SPS) and Precise Positioning Services (PPS).The accuracy of these services is influenced by various measurement biases and random errors. Many of the biases and errors can be minimized by proper modelling of the biases, GPS technique employed and position estimate solution. This paper focuses in improving the accuracy of SPS GPS receiver by correcting relativistic and satellite clock errors in the C/A (Coarse/Acquisition) measurements. It also proposes an accurate position estimate method among Least Squares Estimator (LSE) and Linear Quadratic Estimator (LQE).The performance of these estimators are analysed with Position Accuracy Measures (PAM) and Statistical Error Measures (SAM). The practical data used for processing and analysis is collected on L1 (1575.42MHz) frequency over a period of 24 hrs from the SPS Dual Frequency GPS (DFGPS) receivers located at IISC, Bangalore (Lat/Lon: 13.01° N / 77.56° E) and Andhra University (AU), Visakhapatnam (Lat/Lon: 17.72°N / 83.32°E).