Flight Planning and Navigation GPS Navigation Global Positioning
Flight Planning and Navigation GPS Navigation
Global Positioning System (GPS)
Global Positioning System (GPS) • Cloud of 24 GPS satellites orbit the Earth • Satellite positions are accurately known • GPS device receives satellite signal with ‘time-sent’ information • Device calculates distance to satellite • Intersection point of multiple satellites defines device location
Satellite Precision One satellite limits possible GPS receiver location to a spherical location Two satellites limits possible GPS receiver location to a circular location
Satellite Precision Simplified diagram Three satellites limits possible GPS receiver location to two locations One location is impossible due to location and speed
GPS Orbital Configuration • 24 satellites • 20, 000 km (Approximately 12, 500 mi) above Earth • Orbits take 12 hours • Cover entire Earth
GPS Orbital Configuration Tracks Across the Earth
GPS Accuracy • Within 100 meters (328 ft) – Original GPS • Within 15 m (49 ft) – Selective Availability removed • 3 -5 m (10 -16 ft) – Differential position (GDPS) • < 3 m (10 ft) – Wide Area Augmentation System (WAAS)
GDOP - Geometric Dilution of Precision
GPS Augmentations • Systems to increase GPS accuracy – Nationwide Differential GPS System (NDGPS) – Wide Area Augmentation System (WAAS) – Continuously Operating Reference Station (CORS) – Global Differential GPS (GDGPS) – International GNSS Service (IGS)
NDGPS – Nationwide Differential GPS System • Accurately surveyed locations used for reference • Corrects GPS for increased accuracy for users on land water • Developing system for 10 -15 cm accuracy
WAAS - Wide Area Augmentation System • Operated by FAA (U. S. Federal Aviation Administration) • Aircraft navigation for all phases of flight
Benefits of WAAS • • • Primary means of navigation More direct routes Approach with vertical guidance Decommission older equipment Simplify onboard equipment Increased capacity
References • Federal Aviation Administration (2009). Retrieved from http: //www. faa. gov/ • i. Stockphoto. Retrieved from http: //www. istockphoto. com/stock-photo 5975040 -woman-using-a-gps. php
References • National Aeronautics and Space Administration (2009). Retrieved from http: //www. nasa. gov/ • National Executive Committee for Space. Based Positioning, Navigation, and Timing (2009). Retrieved from http: //pnt. gov/
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