Four Levels of Accuracy

Differential GPS with EGNOS or OmniSTAR® correction

The vehicle with a GPS antenna receives signals from the GPS satellite constellation. The EGNOS or OmniSTAR® services, which have a number of ground based GPS receivers spread across the area for which they deliver a correction, receive the same GPS messages as the vehicle. They are able to calculate the real time position error and send this as a message to control stations, which then upload the message to a geostationary satellite. The geostationary satellite receives the correction message, and re-transmits it back to the receiver on the vehicle.

  Pass-to-pass Year-to-year
EGNOS +/- 20cm +/- 90cm
OmniSTAR® XP* +/- 7cm +/- 12cm
OmniSTAR® HP* +/- 5cm +/- 10cm

New Holland cannot guarantee performance and availability of EGNOS and OmniSTAR® services. *OmniSTAR® correction requires subscription to OmniSTAR® service.

RTK (Real Time Kinematic)

This is a highly precise technology that results in 2.5 cm year-to-year accuracy. This accuracy can be achieved with two communication technologies, depending upon your needs in terms of working area coverage:

  Pass-to-pass Year-to-year
RTK +/- 2.5cm +/- 2.5cm

RTK uses a local ground based station which receives the same position data as the mobile unit. By comparing the received position to its known actual position, the real time error can be calculated. This error is then transmitted via short wave radio to the mobile unit. By combining GPS and Glonass constellation input, accuracy can be further improved. Radio repeaters can be positioned to fill in any areas of signal loss from the base station. Signal loss could be caused by rugged terrain or thick vegetation.

VRS (VIRTUAL REFERENCE STATION)

This is a highly precise technology which uses a GPRS (mobile phone) signal that results in a 2.5cm year-to-year accuracy.

  Pass-to-pass Year-to-year
RTK +/- 2.5cm +/- 2.5cm

The system uses data provided by national network of British Ordnance reference stations. The data is streamed 24/7 into a network operation centre where a sophisticated software permanently analyses the data. Using a on board SIM card and modem the tractor/combine connects to this network operation centre and identifies its approximate position. A dedicated correction signal is provided back to the on-board SIM card and modem to determine its precise position. VRS provides a highly accurate repeatable signal for precise field operations on a national level ideal for Farm contractors covering a large area.