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Map matching is the process which work for location measurement and also find out appropriate route for smooth traveling on the road network, but map matching accuracy fully depends on GPS trajectory data and electronic map of the road network. Unfortunately, GPS data is not accurate because, it's through weak GPS signaling and low quality GPS devices. So, it is difficult to calculate accurate location of movements.This work provides, a map mapping algorithm for simplifying appropriate path, including curves on road network and also, we proposed Frechet distance computing algorithm with road Preliminaries for network simplification. [ABSTRACT FROM AUTHOR]

Local Area Augmentation System (LAAS) is an augmentation to GPS, for providing aircraft precision approach and landing. LAAS relies on Hatch filter for code smoothing but its filtered range is affected by code-carrier divergence occurring during ionospheric storms. Substituting traditional Hatch filter by optimized filter reduces this effect to a considerable extent. The objective of this paper is to estimate code-carrier divergence and mitigate it using the optimized filter. The performance of both Hatch and optimized filters is analyzed for different ionosphere conditions such as the geomagnetic storm of October 2003 over a low latitude station. Investigations showed that the optimized filter outperforms Hatch Filter for disturbed day data, whereas for quiet day data, it does not provide any additional advantage. The results obtained are agreeing with the results published elsewhere and are encouraging. [ABSTRACT FROM AUTHOR]

Presently, the global positioning system (GPS) satellite constellation consists of 40% older Block IIA and IIR space vehicles and 60% newer IIR-M and IIF satellites. Only newer GPS satellites are capable of transmitting the L2C signal which is in quadrature to the legacy L2P(Y) signal being broadcast by all satellites. The data format RINEX-2 is not prepared to contain carrier phase observations of both L2 signals, but should contain either one or the other. If a mix of unaligned L2P(Y) and L2C carrier phase observations are stored in a RINEX-2 file, the quarter cycle bias causes the file to be defective and not usable for precise positioning purposes. Algorithms that detect such files are presented in this study. They are mainly based on the analysis of widelane fractional ambiguities and were applied to RINEX-2 files of 2624 reference stations. Seventy-two station files (2.7%) were found to be defective since they contained mixed and unaligned L2P(Y) and L2C carrier phase observations. If such files are used for precise positioning with ambiguities being fixed to integer values, resulting coordinate errors in long baselines can reach centimeter levels. Unaligned L2 observations often prevent ambiguity fixing, especially in short baselines. [ABSTRACT FROM AUTHOR]