Best Practices for using a Real-time GPS Network Ken Bays, PLS Lead Geodetic Surveyor Oregon Department of Transportation B B Best GPS Practices Panel GPS Nuts & Bolts Workshop Oregon GPS Users Group Albany, OR 11 January 2012 http://www.ogug.net/Presentations/Best_RTN_RTK_Practices_OGUG_11_Jan_2012_Bays.pdf
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Best Practices for using a Real-time GPS Network
Ken Bays, PLS Lead Geodetic Surveyor
Oregon Department of Transportation
BB
Best GPS Practices Panel GPS Nuts & Bolts Workshop Oregon GPS Users Group
Overview Advantages of Using a Real-time GPS Network What you should know about your RTN Best Practices for Using an RTN Other information sources on RTK best practices
Less equipment to purchase Less time searching for passive marks No base set-up time Less crew time GPS baby sitting Stable base stations Automatic tie to the NSRS & a defined coordinate system Better accuracy than single base RTK
Advantages of Using a Real-time Network Operator sets up on wrong station Wrong coordinates for base are entered into data recorder Wrong height of antenna measurement Wrong antenna type picked Antenna not plumb over point Subject to tripod movement or disturbance (wind, bumped, etc.) • Subject to interference with GPS signal (trucks
How are positions of the RTN CORS sites computed? • What datum realization? • Is it tied to the NSRS?
What percent of the RTN’s stations are NGS CORS stations? Site installations • Pre-installation QC Data Sets performed? • Antenna Mount Stability? • Sky Visibility? • Photos available? • Site Logs Current?
Best Practices for Using an RTN Check out the RTN you intend to use Check cell coverage in project area • Visit the site • Vendor data coverage maps are unreliable Planning • Mission planning software • Check NANU’s • Check space weather: 2013 Max • Check RTN operational status Consider and test OCRS zone for project • OCRS web tool
Best Practices for Using an RTN Check equipment before and after job • Tribrachs, level bubbles, rod tips, antenna adapters
If not fixed height rod or tripod, measure HI in ft and meters Check rover configuration • Send GGA • NTRIP user ID and password • Set reference station sensor as: unknown • Set reference antenna to: Null or ARP (NGS diagram ARP vs PC)
Check into fiducial points on project Observe redundant measurements • Independent occupations • NGS: “RT positioning of important data points cannot be done reliably
without some form of redundancy. “ NGS User Guidelines for Real Time GNSS Positioning
Perform site calibration/localization as needed to match passive control