Observations -Accuracy Assessments

Abstract

Observations -Accuracy Assessments

Vijayalakshm D,VNR Vignan Jyothi Institute of Engineering And Technology
Murali Krishna, IV, Head, Centre for Spatial Information Technology, JNTU, India
Rajan EG, Department of E C E, Vasavi College of Engineering, India
Email: psridhar_babu_2k@yahoo.com, iyyanki@icorg.org, rajaneg@yahoo.co.in

Abstract:
The degree of conformance between the estimated or measured position, time, and/or velocity of a GPS receiver and its true time, position, and/or velocity is to be compared with a constant standard. Radio navigation system accuracy is usually presented as a statistical measure of system error and is characterized The prime objective of the study is estimation of accuracy and corrections to be applied to GPS observations. For this purpose GPS observations are made at different locations in Hyderabad city at different times of the day. The objective of these observations is to access the extent of variation of signal due to urbanization, day temperatures and GPS satellite positions. Depending on the status of GPS satellite, GPS receiver, time and position of observation points, several types of errors are identified.

Depending on the study of GPS satellite, GPS receiver , time and position of observation points, several types of errors are identified. These errors are quite a few and can be grouped into 3 categories as found in the literature. Out of these, the ambience essentially resulting in the form of varied signal strengths, additions or deletions contributes to Multipath errors. The time of observation in a public place of down town area is very important because there is great scope for the signals undergoing scattering and multiple reflection due to heavy traffic or areas close to large buildings. There are several methods to apply corrections to both systematic and non-systematic errors. The factors influencing GPS accuracy are basically due to biases and errors. The factors influencing GPS accuracy are basically due to biases and errors. The bias is a lateral shift of value effecting all measurements made by the receiver by same amount. The GPS data is collected at down town area at Abids in Hyderabad City. The observations indicate that the variation of differences is random in general. But certain tendencies could be delineated in terms of effect on latitude, longitude and altitude with reference to the observations made during peak time and off peak time.