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LATEST ADVANCES IN GPS TECHNOLOGY
Presented by:
M. Gautam Raj
B.Tech, ECE.
Contents
Short review of GPS
Segments of GPS
Functioning of GPS
Applications
Current Technology
Future Technology
Glimpse of Future
Conclusion
Latest Advances in GPS Technology
Global Positioning System
GPS is satellite based Navigational system developed and operated by US department of Defense.
Constellation of 24+ satellites in Earth orbit
Global coverage, 24 hours a day, all weather conditions
Two classes of signals
– Civilian (free of direct user fees)
– Military (encrypted for US/allies)
Signal frequencies
– L1 - 1575.42 MHz (C/A and P-codes)
– L2 - 1227.60 MHz (P-code only)
Latest Advances in GPS Technology
Segments of GPS
• Space segment
• Control segment
• User segment
Latest Advances in GPS Technology
Space Segment
• 24 GPS space vehicles (SVs) placed in 6orbits.
• 6 orbital planes inclined at 55 degreeswith the equator.
• Satellites orbit the earth in 12 hrs.
• This constellation provides 5 to 8 SVsfrom any point on the earth.
Latest Advances in GPS Technology
Control Segment
• The control segment comprises of 5 ground stations located on equator.(4-monitor and 1-master control station)
• Monitor stations measure the distances of the overhead satellites every 1.5 seconds and sends the data to Master control.
• In Master control the satellite orbit, precise time and health of the satellite are determined and determines whether repositioning is required.
• This information is sent back to the satellites using ground antennas.Latest Advances in GPS Technology
User Segment
• It consists of receivers that decodes the signal from the satellites.
• The receiver performs following tasks:
• Selecting 3 or more satellites
• Acquiring GPS signals
• Measuring and tracking
• Acquiring navigation data
Latest Advances in GPS Technology
How does the GPS work?
Latest Advances in GPS Technology
Satellites broadcast
• Precise time
• Orbit data
• Satellite health
Receiver measures time delay from satellites, and by triangulation calculates
• Location• Elevation• Velocity
How does the GPS work?
• The GPS uses technique of "triangulation" to find location.
• To "triangulate“, a GPS receiver measures distance from the satellite using the travel timeof radio signals.
• To measure travel time, GPS needs very accurate timing, which is provided by atomicclocks used in the satellites.
• Atomic clocks are the most accurate timekeepers in the world.
• Along with distance, we need to know exactly where the satellites are in space.
• Finally we must correct for any delays
Latest Advances in GPS Technology
Triangulation
Latest Advances in GPS Technology
Triangulation
Latest Advances in GPS Technology
The receiver is somewhere on this sphere.
Signal From One SatelliteSignals From Two Satellites
Three Satellites (2D Positioning)
Three Dimensional (3D) Positioning
Differential GPS
• To obtain more accuratemeasurements than a single GPSunit, DGPS systems are used.
• The GPS unit in the field receivesdata from the GPS satellites andthe other GPS receiver on theground through a radio signal.
• The GPS error from the knownposition is compared to that of theGPS receiver in the unknownlocation.
Latest Advances in GPS Technology
Applications
• Recreation
• Navigation (Airways ,Waterways & Roadways)
• Construction
• Boundary Mapping
• Surveying
• Search and Rescue
• Precision Agriculture/Forestry
Latest Advances in GPS Technology
Current Technology
Machine Guidance and Automation
Latest Advances in GPS Technology
Guidance Systems
Unique opportunities - ability to work accurately
at night
Current Technology
Machine Guidance and Automation
Latest Advances in GPS Technology
Current Technology
Location of Soldier in War
Latest Advances in GPS Technology
Current Technology
Latest Advances in GPS Technology
Wireless and Touch Screens
Future Technology
Dust and Motes
Latest Advances in GPS Technology
Future Technology
Latest Advances in GPS Technology
GPS wrist Bands Portable GPS with Music Player
Future Technology
Latest Advances in GPS Technology
Positioning Head Gear
Autonomous Tractors
Indian Regional Navigation Satellite System
• Indian version of US GPS
-Under ISRO satellite Centre
-It would consist of a constellation of seven satellites and a support ground segment
-Hoping to have all satellites in Orbit by March 2015
• Applications
-Missile Guidance
-Navigation
-Precision Weather Forecast
-Military Applications
Latest Advances in GPS Technology
Glimpse of the future …
• GNSS (global navigation satellite system) =
Galileo + GPS + GLONASS
• SV constellation
– More than doubled when entire Galileo network is in place
– Improves precision and reliability of the constellation
Latest Advances in GPS Technology
Summary
• GPS performance is better than ever and will continue to improve
• Enhanced GPS usage
• Integration of wireless technology
• New and cheaper technology
Latest Advances in GPS Technology
Latest Advances in GPS Technology
Latest Advances in GPS Technology
T + 3Then distance between satellite and receiver = “3 times the speed of light”
T
Radio waves travel at the speed of light. If GPS signal leaves satellite at time “T”…
…and is picked up by the receiver at time “T + 3.”
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