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The Global Positioning System Advanced Tools. Sources of GPS Error. Standard Positioning Service (SPS ): Selective Availability: 0 to 100 meters Ionosphere: 5.0 to 7.0 meters Troposphere: 0.5 to 0.7 meters Satellite clocks: < 1 to 3.6 meters Orbital errors: < 1 meter
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Sources of GPS Error • Standard Positioning Service (SPS ): • Selective Availability: 0 to 100 meters • Ionosphere: 5.0 to 7.0 meters • Troposphere: 0.5 to 0.7 meters • Satellite clocks: < 1 to 3.6 meters • Orbital errors: < 1 meter • Receiver noise: 0.3 to 1.5 meters • Multipath: undetermined • User error: Up to a kilometer or more • Errors are cumulative!
Dual Frequency Positioning L1 C/A Code L2 P(Y) Code Signal propagates through atmosphere at different rates due to different frequencies. This time difference can be calculated and used to correct for Ionospheric and Tropospheric created errors.
Receiver DGPS Site Post-Processed Differential GPS
Post-Processed Differential GPS Trimble’s Pro XR Trimble Geo CE XT and XM Trimble GPS Pocket
Receiver DGPS Receiver DGPS Site Real-Time Differential GPS
NDGPSNationwide Differential Global Positioning Service • Advantages: • 1 meter, 95% real-time accuracy when the user is within 100 miles of station • Optimized for surface (maritime and terrestrial) applications with medium frequency, “ground hugging” signal and is not line-of-site dependent • Fully operational in areas of coverage
NDGPSNationwide Differential Global Positioning Service • Disadvantages: • Accuracy degrades at a rate of approximately 1 meter per hundred nautical miles • More user equipment needed for most receivers • Can be susceptible to RF interference • Accuracy and usage are distance dependent • System is operational but the coverage not completed yet
GPS / NDGPS Beacon System Trimble’s “BoB” CSI’s MBX3 Beacon Receiver
WAASWide Area Augmentation System Advantages: • < 7 meters real-time accuracy • Accuracy not distance dependent • No additional receiver needed • Inexpensive
WAASWide Area Augmentation System • Disadvantages: • Does not work well in canopy cover • Satellite are geo-stationary over equator • Not declared operational yet
Garmin GPSMap 176 Trimble’s Pro XR Trimble Geo CE XT and XM Garmin GPSMap 76 and V WAAS / Beacon / Omnistar / GPS Receiver System CSI’s DGPS Max
Why Should You DoDifferential Corrections? • Improved Accuracy ( still have atmospheric degradation of sv signals ) • Positional Integrity ( Are you where you say you are? ) • Geodetic Tie to NGS Monumentation Network
What’s Coming for GPS System? • Better, smaller and less expensive receivers • Closer integration into existing equipment, watches, cell phones, data collection devices, etc. • Dual Frequency, C/A Code • FAA satellite based differential service - Wide Area Augmentation System, WAAS • Double coverage of NDGPS for CONUS
Garmin GPSMap 76s Garmin GPS V Casio GPS Watch Trimble GPS Pocket Latest GPS Technology Trimble Geo CE XT and XM CSI DGPS Max and MiniMax
Garmin’s NavTalk GSM Wireless Phone Latest Communication Technology Garmin Rino FRS / GRSM Radio and GPS Reciever
Latest Communication Technology CSI GT300 GPS Enabled Digital Cell Telephone Racal Project 25 Voice / Data Radio
TerraSync ERSI’s ArcPAD Latest Mapping Technology
Handheld Mapping In-the-fielddata collectionand informationdisplay. Display valuabledata sources Combine datasets Query attributeinformation
Data Collection Softwares • Trimble TerraSync • ESRI ArcPad • Fieldworker • TDS Solo CE • Various PalmPilot Softwares
Minimum Suggested Handheld Requirements (August ‘03) • Min. 206 Strong Arm chipset • 32 Mbs of RAM • PC Card (or compact flash) expansion capability • Daylight viewable screen! • Ruggedized (if possible)
Examples: Panasonic Toughbook 01 • Panasonic Toughbook 01 (32 Mbs of RAM) • Serial AutoSync cable • 1 gig IBM Microdrive and / or 512 mb Secure Data card • Extra removable battery • with charger Approximate cost: $2000.00
3D Marketing’s Photo Link and GPS Tag Software Latest GPS Imaging Technology Trimble’s Media Mapper
Digital Camera/GPS Imaging Systems • Latitude and Longitude • Datum • Elevation • FMSS Facilities information • Archeological descriptions • Viewing direction • I&M database unique identifiers • Basically, anything that you want to watermark on photo.