23 June 1995

Awheel step forward for

yield mapping

YIELD mapping continues to attract the attention of the industry – being a radical development which could prove to be an important management aid in the future.

But just how yield maps should be interpreted so their full benefit is realised is still open to conjecture, and the subject of research by a number of institutions.

In the meantime, the hardware continues to be developed and refined. A key part of a satellite navigation system is a base station. Used to improve the positioning accuracy of the combine harvester in the field – down to about 1m – it adds cost to a system which, for many, is already "on the expensive side".

Latest development from RDS Technology is to dispense with individual ground stations and use high powered base stations sited at locations throughout Europe.

Intended primarily for military use, these stations continually transmit positioning correction data which can be used by navigation systems fitted to vehicles. A charge of £200/year is made for the service – significantly less than the cost of a "domestic" groundbase which, as an unlicensed transmitter, has a limited range and needs to be recalibrated when moved.

In operation, the combine harvesters navigation system locks on to the strongest signal, automatically changing to another transmitter if the signal weakens.

Seen at the cereals event fitted to a John Deere combine, the RDS system allows the data logging unit to be removed and fitted to another vehicle – a John Deere Gator buggy was so equipped at the show which could, says the manufacturer, be used for early season weed mapping.