High Accuracy GPS Mapping and VRS

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High Accuracy GPS Mapping and VRS

• Lanny Schnipper
• Seiler Instrument
• 2008 IGIC Conference
• Indianapolis, IN

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VRS in Action

• No base setup
• get to the job
• dial in
• Check
• start working
• MWRTK VRS in Indiana
• save time
• save money

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Overview

• Review GPS
• Discuss use of Virtual Reference Stations (VRS)
• Obtaining highly accurate GIS/GPS positions
• Continuously Operating Reference Stations (CORS)
• Real-Time differential results

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What is VRS?

• GPSNet, DGPSNet, RTKNet
• Links a network of reference stations
• Provides quality control of incoming data
• Logs files for post-processing
• Network modeling of systematic errors
• Real time broadcast of true network DGPS and RTK
  solutions

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VRS Data Flow
Reference stations data streams back to the
server through LAN, Internet, or radio links
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VRS Data Flow
Users receiver sends an NMEA string back to
server using cellular modem. Virtual Reference
Station position is established.
VRS
NMEAGGA
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VRS Data Flow
Server uses VRS position to create corrected
observables and broadcasts them to the user end.
RTCM or CMR
VRS
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Why use VRS?

• Eliminates the need for Users to establish DGPS
  base/reference station(s)
• More reference stations shorter vectors/
  baselines
• Shorter baselines less atmospheric errors
• Network atmospheric modeling
• Extended operating range with improved accuracy

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Why use VRS?

• VRS provides integrity monitoring
• All users in common, established coordinate frame
• Eliminates the dependency on single
  base/reference station
• Graceful degradation should a reference station
  fail
• Uses established communications

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Indiana MWRTK
26 Stations and growing!
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Indiana MWRTK
www.mwrtk.net
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Real Time in TerraSync/ArcPad

• External correction source
• Data radio
• Beacon-on-a-Belt (BoB) receiver
• GeoBeacon
• SBAS (WAAS)
• TerraSync Version 2.30 (2/03) added VRS
• Network VRS
• Single base
• GPSCorrect Version 1.1 (4/05)

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Support VRS corrections

• GeoExplorer CE series with GPS firmware version
  1.03
• GeoXT
• GeoXM
• GeoXH
• GPS Pathfinder with firmware version 1.52 or
  later
• GPS Pathfinder Power
• GPS Pathfinder Pro XRS
• GPS Pathfinder Pro XR
• GPS Pathfinder ProXH
• GPS Pathfinder ProXT

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Connecting to VRS

• Internet connection to the VRS server
• GPRS-capable cellphone
• WiFi Hotspot
• Serial cable connection
• Data radio

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Outside TerraSync

• Start ? Settings ? Connections
• Make connection to your Phone or other device
• Test Internet Explorer to insure connection was
  successful

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Inside TerraSync

• Start TerraSync
• Select Setup section
• Set Real-time Settings
• Choice 1 field select External Source.
• Configure the external source
• From the Type field, select VRS
• or select the Single Base option
• Connection Method field, select Internet
• Address field, enter the IP address or URL of the
  VRS server.
• IP Address 64.123.250.18 for MWRTK
• IP Port 2101 for MWRTK

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Accuracy

• Submeter with a GeoXT/XH
• Usually subfoot
• We have even seen less than 6 inches!
• No post-processing required

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Subscription

• VRS is a paid subscription
• Seiler provides Logon and password
• MWRTK.NET
• Single Day - 20 per day, 3-day minimum per month
  maximum monthly charge 200(Billed monthly)
• Single Month- 150(Billed monthly and payable in
  advance)
• Single Quarter- 375 (125 per month)(Billed
  quarterly and payable in advance)
• One Year- 1,200(Billed 225.00 per quarter and
  payable in advance)

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Questions?