Analysis of the Combined Positioning Accuracy using GPS and GLONASS Navigation Satellites

Abstract

Due to inaccurate safe navigation estimates, maritime accidents have been occurring consistently. In order to solve this, the precise positioning technology using carrier phase information is used, but due to high buildings near inland waterways or inclination, satellite signals might become weak or blocked for some time. Under this weak signal environment for some time, the GPS raw measurements become less accurate so that it is difficult to search and maintain the integer ambiguity of carrier phase. In this paper, a method to generate code and carrier phase measurements under this environment and maintain resilient navigation is proposed. In the weak signal environment, the position of the receiver is estimated using an inertial sensor, and with this information, the distance between the satellite and the receiver is calculated to generate code measurements using IGS product and model. And, the carrier phase measurements are generated based on the statistics for generating fractional phase. In order to verify the performance of the proposed method, the proposed method was compared for a fixed blocked time. It was confirmed that in case of a weak or blocked satellite signals for 1 to 5 minutes, the proposed method showed more improved results than the inertial navigation only, maintaining stable positioning accuracy within 1 m.Keywords: carrier phase based positioning, carrier phase statistics, weak signal environment Therefore, it is necessary to determine the air clearance for safe navigation using the precise positioning technology.Carrier phase measurements should be used together with code measurements for precise positioning. For the pseudorange measurements, the distance between the satellite and the receiver on the ground is predicted using the time delay of C/A code, but for the prediction of distance by carrier phase measurements, changes in carrier phase generated by the satellite is used. Since the wave length of carrier is significantly shorter than the length of C/A code, the distance measured using the carrier phase is more precise than the distance measured using codes. But, Integer ambiguity which is carrier phase wavelength value existing between the satellite and the receiver in the carrier phase measurements, and It is necessary to obtain this integer ambiguity to measure an accurate distance. It is important to obtain and maintain the integer ambiguity in the carrier phase based precise positioning (Parkinson & Spilker 1996). But, a satellite signal may become weak or blocked for some time due to high buildings and mountain INTRODUCTIONCurrently, the global positioning system (GPS) of the United States and the global orbiting navigation satellite system (GLONASS) of Russia are global navigation satellite systems that can perform positioning and provide time information. GPS satellites have been continuously operated as a navigation system since 1980. However, for GLONASS satellites, the service was interrupted for a short period of time due to the financial problem of Russia. Then...

Multi-GNSS Standard Point Positioning using GPS, GLONASS, BeiDou and QZSS Measurements Recorded at MKPO Reference Station in South Korea

“…The results indicated that the 'GPS+GLO' combination had a larger RMS value for the position error than 'GPS-only'. Choi et al (2013) reported that the GPS and GLONASS combination did not show improved positioning performance within the Korean Peninsula compared to GPS-only positioning. These results of the present study are consistent with the results of the previous study.…”