GNSS SOC GDOP. A satellite selection algorithm in complicated GNSS signal environments

Transcription

1 32 1 Vol Journal of Harbin Engineering University Jan 2011 doi /j issn GNSS SOC GNSS GDOP 80% 70% A A satellite selection algorithm in complicated GNSS signal environments CHEN Mohan ZHENG Rui WANG Yun CHEN Jie Institute of Microelectronics Chinese Academy of Sciences Beijing China Abstract An efficient satellite selection algorithm was proposed for a global navigation satellite system GNSS in complicated signal environments The algorithm used the simplified residual sum of square as the statistic indicator and was able to reflect the pseudorange measurement error of a single satellite An operational approach was also proposed to choose a satellite combination for positioning by detecting and excluding single or multiple false measurements based on the proposed indicator Tests demonstrate that the proposed algorithm is able to significantly reduce possibility of positioning errors in complicated environments compared with the conventional geometric dilution of precision GDOP method The availability of the proposed algorithm is up to 80% on average in static tests and 70% in dynamic tests Keywords GNSS complicated signal environment satellite selection pseudorange error carrier-to-noise density ratio GNSS GDOP GNSS global navigation satellite system GDOP GNSS AA momohanchen@ gmail com GDOP RAIM receiver autonomous integrety monitoring RAIM

2 ΔX^ = H T H -1 H T Δρ 3 GNSS ΔX GNSS W = X^ - X = ΔX^ - ΔX = H T H -1 H T ε 4 ε 8 0 σ 2 N 0 σ 2 FPGA 8 GPS i 0 ε i ~ N b i σ 2 GPS UERE 8 80% 70% b i GDOP 1 A = H T H - 1 H T A i A i 1 1 x u y u z u Err p = 槡 W 2 x + W 2 y + W 2 z = 槡 A 2 1i + A 2 2i + A 2 3i b i t u 4 6 A 2 1i A 2 2i A 2 3i A i 1 2 ρ j = s j - u + ct u 1 3 ρ j 1 2 n n H s 槡 A 2 1i + A 2 2i + A 2 3i ECEF s ECEF c t u GNSS ΔX Δρ = HΔX + ε 2 2 Δρ Δρ = Δρ 1 Δρ 2 Δρ n n 1 ω = Δρ - H H T H -1 H T Δρ = a x1 a y2 a z3 1 a x2 a y2 a z2 1 H = n 4 a xn a yn a zn 1 ΔX = Δx u Δy u Δz u - cδt u T ε n 1 ΔX W = W x W y W z W t T = H T H -1 0 b i 0 T = A i b i 5 I - H H T H -1 H T Δρ = I - H H T H -1 H T HΔX + ε = I - H H T H -1 H T ε 7 4 ω' = I - H' H' T H' -1 H' T ε' 8

3 1 GNSS 87 S = I - H' H' T H' -1 H' T 9 Δρ' = Δρ max5 Δρ max6 Δρ maxn n SISS 6 i i = 1 2 n j 1 Δρ H' = a xmax5 a ymax5 a zmaxx5 1 a xmaxn a ymaxn a zmaxn 1 H n n j j H ε' - j m + 1 = 0 m n - 4 n ε SISS statistic indicator of satellite selection SISS = 槡 ω T ω 10 ε i b i SISS SISS = 槡 ε' T Sε' = 槡 Sii b i 11 S ii S i i SISS 6 SISS Fig 1 Flow chart of satellite selection method proposed σ 2 N 0 σ 2 SISS 1 + C 1 n C 1 n C n 3-2n n - 96 FLOPS 1 7 Ns = 5 k = 5 1 GDOP 4 1 FLOPS Table 1 Computation load comparison for different n 2 n SISS 5 i i = j 1 j 1 = 0 1 n j SISS 5 min n - 4 n SISS 5 max > N SISS 5 min N SISS 5 max SISS 5 min SISS 6 max > N SISS 6 min N SISS 6 min SISS 6 min 1 n GDOP

4 GPS ARM9 GPS ARM RS232 PC Matlab 2 Fig 2 Availability for different range errors GPS GNSS GNSS Sprint R STR4500GPS 24 h s 50 ~ 200 m 8 3 WGS GoogleEarth s 46 04% % m m Fig 3 Position estimates using different algorithmspart of the route 2 Table 2 Position errors in static tests s m 46 /m X % 17 Y Z D

5 1 GNSS 89 4 GPS J ZHANG Chao CHEN Tianqi A new selecting-star algo- 4 GoogleEarth rithm in GPS J Experiment Science and Technology Fig 4 Position estimates using different algorithms-part of the route on GoogleEarth SAIRO H AKOPIAN D TAKALA J Weighted dilution of precision as quality measure in satellite position J IEE Proc-Radar Sonar Naving KIHARA M Study of a GPS satellite selection policy to improve positioning accuracy C / /IEEE Position Location and GNSS Navigation Symposium Las Vegas GDOP 7 J ZHANG Qiang ZHANG Xiaolin LI Hongwei et al Satellite selection algorithm for combined receivers J Journal of Beijing University of Aeronautics and Astronatics % 73 01% 1 PHATAK M S Recursive method for optimum GPS satellite selection J IEEE Transactions on Aerospace and Electronic System GDOP J LIU Huijie ZHANG Naitong Performance research for GDOP based optimum positioning constellation J High Technology Letters GPS J ZHANG Guiming HUANG Shunji A new satellite selection algorithm for GPS navigation J Journal of University of Electronic Science and Technology of China GNSS 8 KAPLAN E D HEGARTY C J Understanding GPS principles and applications M London Artech House KUUSNIEMI H LACHAPELLE G Position and velocity reliability testing in degraded GPS signal environments J GPS Solution DIGGELEN F D BROWN A Mathematical aspects of GPS RAIM C / /IEEE Position Location and Navigation Symposium Las Vegas MACGOUGAN G D High sensitivity GPS performance a- nalysis in degraded signal environments D Calgary The University of Calgary PARKINSON B W SPILKER J J Jr Global positioning system theory & applications M Washington DC American Institute of Aeronautics and Astronautics