1. High Accuracy GPS Mapping and VRS
Lanny Schnipper
Seiler Instrument
2008 IGIC Conference
Indianapolis, IN

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

3. 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

4. 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

5. VRS Data Flow
Reference stations data streams back to the server through LAN, Internet, or radio links

6. VRS Data Flow
User’s receiver sends an NMEA string back to server using cellular modem. Virtual Reference Station position is established.
VRS
NMEA—GGA

7. VRS Data Flow
Server uses VRS position to create corrected observables and broadcasts them to the user end.
RTCM or CMR+
VRS

8. 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

9. 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
Productivity lost through having to establish base station – locate co-ordinates, set up comms and power, provide security (additional person).
Radio frequency and range issues.
Battery charging.

10. Indiana MWRTK
26 Stations
…and growing!

11. Indiana MWRTK

12. 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)

13. 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

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

15. Outside TerraSync Start  Settings  Connections
Make connection to your Phone or other device
Test Internet Explorer to insure connection was successful

16. 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: for MWRTK
IP Port: for MWRTK

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

18. 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 $ per quarter and payable in advance)

19. Questions?