1. OS Net ™ Ordnance Survey's RTK GPS Network Mark Greaves Geodetic Analyst, Ordnance Survey 7 th May 2006

2. What is OS Net™? National GPS infrastructure and service developed by Ordnance Survey to provide up to 1cm accuracy real-time positioning Enables positioning against OS MasterMap ® and supports Digital National Framework (DNF) principles

3. The Current OS Net Network 90 base stations in operation Density enables RTK positioning services across most of the country

4. OS Net structure RTK for Ordnance Survey surveyors via GPRS / GSM Raw GPS data in RINEX format for www.ordnancesurvey.co.uk/GPS OS Net base station network

5. Accuracy of OS Net All stations Overall rmse: east: 11mm north: 16mm height: 31mm

6. Precision of OS Net All stations

7. RTK initialisation time All stations

8. What OS Net enables Up to centimetric level positioning service for Ordnance Survey surveyors Real-time, raw GPS data feed to OS Net partners to create commercial positioning products Access to the national coordinate reference frame through free products from www.ordnancesurvey.co.uk/gps Data to the Meteorological Office to aid their weather forecasting models and for some academic studies Support to pilot studies in applications outside of agreed partner terms

9. OS Net benefits Delivering efficiency and flexibility to Ordnance Survey Supports local and national applications that require a positioning element Enables quicker easier positioning Supports interoperability of data and the use of a common coordinate system Provides a revenue opportunity

10. Commercialisation through Partners OS Net can bring significant efficiencies to any application that uses GPS Initially entering high-accuracy markets where most benefit can be realised Work to foster new market areas

11. Future direction of OS Net Short term Strengthening network and possibly extending into north west Scotland Work with partners and policy developers to develop and position OS Net Medium term Infrastructure will be renewed with dual GPS + Galileo receivers Galileo test bed in the south east. Aid internal and national understanding of what Galileo will bring Work towards the goal of ubiquitous survey quality positioning, through involvement in external projects and the development of OS Net

12. Summary OS Net used internally by 130 field surveyors Recent accuracy testing has shown 1-2cm horizontal accuracy, 3cm vertical accuracy Partners are taking the raw data from OS Net to build commercial services OS Net has the capability to support national policy initiates that require positioning Expanding OS Net into the NW of Scotland is being considered OS Net will be updated to support Galileo

13. Contact for further information Customer Contact Centre Ordnance Survey Romsey Road SOUTHAMPTON United Kingdom SO16 4GU Phone: 08456 05 05 05 Fax: 023 8079 2615 Email: customerservices@ordnancesurvey.co.uk Website: www.ordnancesurvey.co.uk