Positioning technology support

If you're a surveyor or working with infrastructure, make the most of your investment in GNSS positioning technology with our online tools and technical articles for professionals.

Whether you're looking for Rinex data, benchmarks or translations between referencing systems, you'll find them all here. Technical articles include our introduction to surveying with OS Net Free services, and our guide to coordinate systems in Great Britain.

OS Net online tools

OS Net RINEX data
Find stations and request data.

OS Net Rinex data batch search
Find the nearest active stations to a batch of coordinates.

Coordinate transformation tool
Transform coordinates from ETRS89 TO OSGB36 National Grid and vice versa.

Passive stations
Search our database of some 900 passive GPS stations in Great Britain.

Search by coordinate or grid reference for OS survey marks around the country which were made to record height above Ordnance Datum.

Height levelling datum
Learn about the Liverpool and Newlyn geodetic levellings in the 1840s, 1910s and 1950s, then find the correction that should be applied to spot heights readings, depending on the location in Great Britain.

Triangulation stations
Find where triangulation stations are located, Search by coordinates, OS Landranger Map sheet number and more.

OS Net information

Surveying with OS Net free services
These guidelines are intended for surveyors who are acquainted with GPS surveying. We outline the national coordinate systems in Great Britain, describe the national positioning infrastructure and much more.

Surveying with OS Net free services – an overview
Learn why OS Net is so important, and what the RINEX data server and online coordinate transformer provide.

OS Net accuracy
Find out just how accurate OS Net is, expressed as standard error distances in metres.

Antenna phase centre offsets
A GPS baseline is measured between the phase centres of two antennae. Find out the various antennae and offsets currently used in the active network.

Spreadsheet for coordinate calculations
Our coordinate calculations spreadsheet enables you to carry out common calculations with coordinates. It includes a full set of Transverse Mercator projection functions.

A guide to coordinate systems in Great Britain (PDF)
Learn about the concepts of coordinate systems to help you use coordinate data and mapping coordinate systems in Great Britain.

Understanding the meaning of technical terms relating to OS Net and global navigation satellite systems.

Grid InQuest coordinate transformations software
Grid InQuest transforms between the ETRS89 (WGS84) and OSGB36 National Grid coordinate systems using the same transformation models (OSTN02/OSGM02) as the online coordinate transformer. OSTN02 and OSGM02 for Developers

OSTN02 and OSGM02 for Developers
We are pleased to make OSGM02 and the OSTN02 and OSi/OSNI Polynomial transformation models available to software developers for incorporation into their software.

OSTN02 data in NTv2 format
Since the plane grid form of OSTN02 is not easily compatible with some GIS systems, some of them use a transformation data format known as NTv2.  We are pleased to provide a download of OSTN data in NTv2 format.

Local levelling data
Our full list of all the known local levelling datums in Great Britain. Newlyn and Liverpool are two of them.

OS Net and GNSS
A comprehensive FAQ for expert navigation data users.

GPS information

An overview of GPS
Find out more about GPS (Global Positioning System) and how this satellite powered system provides vital information for a wide range of customers.

A beginner's guide to GPS
Learn about GPS, how it works, the levels of accuracies you can expect, how you can use GPS as a surveying tool and how our Active GPS Network can help.

Using GPS with OS maps
GPS and Ordnance Survey maps use different models for the earth and coordinate systems. Learn about the problems this can cause and how to overcome them.

Satellite navigation in the future
Satellite navigation in the form of GPS is a system we currently rely on, yet it is not the only 'eye in the sky' – other systems are also in use above us.

Sat nav and GPS devices FAQ
Questions asked by the publc about in-vehicle sat navs and the issues they can cause.