OS Net

OS Net is Ordnance Survey's national network of about 120 permanent GNSS base stations across Great Britain. The stations stream observations in real time to a central server, where OS software monitors the positional quality of every station continuously; a station whose coordinates drift is removed from the network until the cause is investigated. Station coordinates have standard errors generally better than 8 mm in plan and 20 mm in height.

The network gives access to ETRS89, Great Britain's national coordinate reference system, and together with the OSTN15 transformation it defines the OSGB36 National Grid, while the OSGM15 geoid model gives Ordnance Datum Newlyn heights. By post-processing against OS Net data, a surveyor can determine precise national coordinates with a single GNSS receiver, without establishing local control. Since an OS receiver upgrade in 2018 the network supplies GPS, GLONASS, Galileo and BeiDou observations in RINEX v3.

Recorded observations are free to everyone as hourly RINEX v3 files at a 30-second rate, kept for 45 days and downloadable from the OS Data Hub or through the OS Net API, a REST service that also returns station metadata and hour-by-hour network health. One-second data is restricted to organisations on the Public Sector Plan. OS does not sell real-time corrections itself: commercial partners, including Hexagon (SmartNet), KOREC (VRS Now), Topcon (Topnet Live), AXIO-NET (FarmRTK), SoilEssentials, Premium Positioning, Point One (Polaris) and CNH (AFS RTK+), build RTK correction services on OS Net data and set their own prices.

OS cites applications in surveying, mapping, construction, agriculture, geospatial research and automated systems, and use by the National Geographic Database, HM Land Registry and Met Office forecasting.