1998: A YEAR OF INNOVATION IN (THE) Richard B. Langley Geodetic Research Laboratory University of New Brunswick Invited presentation at the Association of New Brunswick Land Surveyors Annual General Meeting, Fredericton, N.B., 23 January 1999 Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
January GPS Accuracy: Lies, Damned Lies, and Statistics F. van Diggelen, Ashtech, Inc. ¥ Popular accuracy measures Ð r.m.s. (vertical) Ð circular error probable Ð r.m.s. (horizontal) Ð R95 (horizontal 95%) Ð 2 d.r.m.s. Ð r.m.s. (3D) Ð spherical error probable ¥ Common misconceptions Ð r.m.s. precisely equals 1 sigma Ð 2 d.r.m.s. means Òtwo-dimensional r.m.s.Ó Ð 2 d.r.m.s. is exactly equivalent to a 95% probability level Ð r.m.s. is perfectly comparable with a 68% probability level Ð the error distribution really is Gaussian Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
January, contÕd. Accuracy Measures Dimensions Accuracy Probability Typical usage measure (dimensions) 1 r.m.s. 68 vertical 2 CEP 50 horizontal 2 r.m.s. 63-68 horizontal 2 R95 95 horizontal 2 2 d.r.m.s. 95-98 horizontal 3 r.m.s. 61-68 3D 3 SEP 50 3D Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
January, contÕd. Measured and theoretical DGPS horizontal errors from 2 million data points Measured Theoretical CEP = 42 cm r.m.s. = 52 cm R95 = 91 cm 2 d.r.m.s. = 104 cm m 0.0 0.2 0.3 0.4 0.5 0.7 0.8 0.9 1.0 1.2 1.3 1.4 Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
February The UTM Grid System R.B. Langley, UNB ¥ Coordinates and Projections ¥ MercatorÕs World Ð Adopting the ellipsoid ¥ A Universal Projection Ð UTM Ð The grid ¥ British National Grid ¥ 500 km squares → 100 km squares → x,y coordinates ¥ Tower of London: TQ 336805 or 33.6 km E, 80.5 km N of SW corner of TQ Ð Military grid reference ¥ UNB Gillin Hall ref. point: (WGS 84) 682,725 m E; 5,091,225 m N, zone 19T = MGRS 19TFL8272591225 Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
February, contÕd. 84 ° 69 ° W 6 W 6 ° ° 2 W 7 UTM zone 19 extends from 86 ° to 72 ° west longitude. As with ~680,000mE ~320,000mE 500,000mE all UTM zones, the scale factor 0mN and is 0.9996 on the central meridian increasing northward 0 ° 0 ' 0 " and true (unity) on two slightly Scale increases 10,000,000mN and increasing curved lines approximately 180 southward km to either side. The shape of Scale decreases the zone has been exaggerated Exact scale Exact scale for clarity. Scale factor = 0.9996 80 ° Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
March Pseudolites: Enhancing GPS with Ground-based Transmitters S. Cobb and M. O’Connor, Integrinautics Corp. ¥ What is a Pseudolite? ¥ Primary Pseudolite Uses Ð Code-based ranging augmentation Ð Code-phase differential ranging Ð Carrier-phase differential ranging ¥ Ambiguity resolution Ð Indoor pseudolites ¥ The Near-far Problem Ð Signal pulsing Ð P-code use Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
March, contÕd. Antenna Mixer Microwave VCO Loop PLL C/A Code L 1 Filter Divider Generator Filter Reference TCXO Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
March, contÕd. Integrity Beacon Landing System Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
April Cellular Telephone Positioning Using GPS Time Synchronization R. Klukas, Cell-Loc, Inc. and G. Lachapelle and M. Fattouche, U. of C. ¥ E-911 Cell Phone Positioning Ð FCC requires horizontal cell phone position to 125 m d.r.m.s. by 2001 ¥ TOA Estimation Ð A system to horizontally position cellular telephones using analogue AMPS (Advanced Mobile Phone Service) ¥ System Description Ð Time tagging with GPS Ð Full correlation with MUSIC (Multiple Signal Identification and Classification) Ð Position estimation ¥ Field Tests Ð Simulations used approximately 40 sites within a Calgary cellular network; field tests with 4 sites Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
April, contÕd. Baseband Baseband signal signal 45 MHz 455 kHz Digital PLL signal chip processor Lock GPS detect pulse 0 5 10 km 4000 4000 3000 3000 Sheraton Sheraton Winwood Winwood Northing (meters) Northing (meters) 2000 2000 1000 1000 Renfrew Renfrew 0 0 Franklin Franklin –1000 –1000 –1000 0 1000 2000 3000 4000 –1000 0 1000 2000 3000 4000 (a) Easting (meters) (b) Easting (meters) Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
May The Effect of Weather Fronts on GPS Measurements T. Gregorius and G. Blewitt, Univ. of Newcastle upon Tyne ¥ Atmospheric Delay ¥ The Positioning Effect Ð Height error = 3 x tropo delay error ¥ What is a Weather Front? ¥ Delay Estimation Models ¥ Fronts and GPS Precision Ð Improving repeatability Ð Vertical velocity Ð The horizontal factor ¥ Remedies and Possibilities Ð Radiosondes, satellites (GPS/MET), data editing Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
May, contÕd. direction of motion tropopause Warm Frontal Zone C R o R A I N & C L O U D COLD WARM COLD A l d ~ 10 km I F N AIR r AIR AIR o dry & n dry t C a l L Z O o n U e D 0.5 - 1º ~ 1 km ground surface ~500 km ~100 km ~100 km ~800 km Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
May, contÕd. 2.44 Warm surface front Cold surface front Total tropospheric zenith delay (m) 2.42 2.40 2.38 2.36 2.34 GPS estimates Front model: r.m.s. = 6.1 mm Standard model: r.m.s. = 11.6 mm 2.32 0 12 24 36 48 60 72 Time past 00:00 on 28 November 1996 (hours) Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
June The NSTB: A Stepping Stone to WAAS Andrew Hanson, Stanford University ¥ WAAS in Practice Ð Reference stations Ð Error models ¥ The Stanford Connection ¥ WAAS Metrics Ð Accuracy Ð Integrity Ð Availability ¥ Flight Testing Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
June, contÕd. Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
July A Primer on GPS Antennas R.B. Langley, UNB ¥ Fields and Waves ¥ Antenna Characteristics Ð Axial ratio Ð Impedance Ð Standing Wave Ratio Ð Bandwidth Ð Gain pattern Ð Ground planes Ð Phase-centre variation ¥ Low Noise Preamp ¥ Transmission Lines Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
July, contÕd. At a fixed point in space, the y electric field vector of a right- x hand circularly polarized wave rotates clockwise as seen from the wave’s source. y z x The electric and magnetic fields are transverse to the direction of t propagation, and the fields are mutually perpendicular. Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
July, contÕd. Microstrip patch Quadrifilar helix Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
September RTK GPS R.B. Langley, UNB ¥ A Fix on Accuracy ¥ Carrier-phase Positioning Ð Post-processed Ð Real time Ð Correction message formats: RTCM SC-104 ¥ RTK System Architecture ¥ The Data Link Ð Propagation distances; path loss; viability ¥ RTK Solutions Ð OTF Ð GLONASS Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
September, contÕd. GPS Positioning Surveying Navigation Standalone Differential Differential Standalone Post-processed Real-time Carrier Phase Pseudorange Static Stop and Go (RTK) (DGPS) Pseudokinematic Rapid Static Kinematic Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
September, contÕd. Reference station Rover RTK Hardware Geodetic Research Laboratory, Department of Geodesy and Geomatics Engineering, University of New Brunswick
Recommend
More recommend
