Seiler

High Accuracy GPS Mapping and VRS

Lanny Schnipper

Seiler Instrument

2008 IGIC Conference

Indianapolis, IN

VRS in Action

• No base setup – get to the job– dial in– Check– start working

• MWRTK VRS in Indiana– save time– save money

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

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

VRS Data Flow

Reference stations data streams back to the server through LAN, Internet, or radio links

VRS Data Flow

User’s receiver sends an NMEA string back to server using cellular modem. Virtual Reference Station position is established.

NMEA—GGA

VRS

VRS Data Flow

Server uses VRS position to create corrected observables and broadcasts them to the user end.

RTCM or CMR+

VRS

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

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

Indiana MWRTK

26 Stations

…and growing!

Indiana MWRTK

www.mwrtk.net

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)

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

Connecting to VRS

• Internet connection to the VRS server– GPRS-capable cellphone– WiFi Hotspot

• Serial cable connection– Data radio

• Start Settings Connections

– Make connection to your Phone or other device

– Test Internet Explorer to insure connection was successful

Outside TerraSync

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

Accuracy

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

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)

Seiler

Questions?