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Statistical evaluation of GPS error. Amalia Doebbert Ninfa Bennington. Problem. Assumed uncertainties in GPS systems: s HH < 10 m s DGPS < 1 m. Big questions: Do uncertainties we observe in real data agree with these estimates? Are the distributions of these data Gaussian?. Data used.
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Statistical evaluation of GPS error Amalia Doebbert Ninfa Bennington
Problem Assumed uncertainties in GPS systems: • sHH < 10 m • sDGPS < 1 m • Big questions: • Do uncertainties we observe in real data agree with these estimates? • Are the distributions of these data Gaussian?
Data used Field exercise 26 April, 2008 DGPS: • 3 Trimble rcvrs • 10 sec. epochs HH GPS: • 3 HH rcvrs • ~10 min. tracks • Variable epochs
HH absolute position histograms m =43.0709º s =3.19 m
DGPS relative position histograms m =1.1574 m s =.1286 m
Z-distribution (HH) • Z=(x-m)/s • Hist(Z)
Z-distribution (DGPS) • Z=(x-m)/s • Hist(Z)
c2 (Goodness of fit) c2 = S[(O-E)/s]2
Conclusions • Positions from DGPS better fit to Gaussian distribution than HH • Assuming Gaussian distribution: • sHH between ±0.21 m and ±5.06 m • sDGPS,vert < 0.2839 m & sDGPS,NorE < 0.1822 m • DGPS positioning more precise than HH positioning • Both DGPS and HH have uncertainties w/in estimated uncertainty