GPS comes of age


If you wanted to nominate the fastest-moving sector of farm machinery design, GPS guidance would have to be high on your list. Since FW did a six-make test in February 2005, prices have dropped sharply, screens have got more animated and colourful and features have blossomed.

In fact, the market has polarised. At one end are cheap-and-simple units that do everything most people would want without making a song and dance about it. At the other are sophisticated, colour-screened items that are every bit as desirable as the latest-generation sat-nav systems, mobile phones or laptop computers.

There’s a push towards steering-assist systems, too, that don’t just tell you where to go but turn the tractor wheels for you as well. And the scope for turning GPS into a management tool that can be used to meet assurance or traceability standards hasn’t been lost on the makers too.

And this year’s must-have add-on? GPS-activated auto shut-off for your sprayer boom, which is now offered by several manufacturers.

Most companies bringing in GPS guidance equipment report fast-rising sales in the UK and the vast bulk of these are for lightbars, parallel tracking equipment (see Jargon Buster, p66, if you’re struggling with some of the terminology) or other guidance-only units.

However, sales of steering-assist equipment are gathering pace too, helped by the fact that many units offer the chance to upgrade from one to the other without replacing the GPS receiver or display unit.

While many farmers are understandably nervous about making the jump straight to steering-assist, the manufacturers point out that guidance-only systems are only as accurate as the driver.

While many units quote a theoretical pass-to-pass accuracy of 150-300mm (6-12in), a really good driver may be able to drive to an accuracy of 100-150mm (4-6in) and a poor one may only be able to steer to an accuracy of 500mm (20in). Or worse, if he’s eating a sandwich or adjusting the radio volume.

Steering-assist and auto-steer systems, which steer for you, claim to do rather better than this. A full autosteer system with a base station could be capable – on paper – of accuracies of under 20mm (1in).

Our 2006 test showed that all steering-assist systems were able to achieve 200-500mm point-to-point accuracy and often averaged within 200mm of the target line. These were all better results, we reckoned, than a human operator using a lightbar could manage. Full autosteer should do even better than that.


Testing, Testing…

Staff from Farmers Weekly and Dutch farm magazine Boerderij spent last week testing a batch of six GPS guidance units that span both entry-level and more sophisticated models. 

  • Farm Works Guide Mate
  • Raven Envizio Plus
  • TeeJet Centerline 220
  • Patchwork BBGuide
  • Sirio Lightbar
  • Trimble EZ-Guide 500+

We had planned to include the DGPS 4U Jethro, but a production model was not available for the test.

We’ll be rating them for build quality, ease of installation, ease of getting under way, guidance clarity, other tricks and accuracy. Look out for the full results in early August.

You can also view our two previous tests of GPS kit, including six parallel-guidance units (published in February 2005) and four assisted-steer set-ups (Sept 2006) on our website. Just go to and all will be revealed.

Want to know more?
Farm Works 01786 465 100

Beeline 01799 520 068

Patchwork 01291 673 366

DGPS 4U 01339 883 361

TeeJet 01428 608 888 

Trimble South: AS communications

01480 860 111              

Trimble North: Precise Solutions

07850 471 216              

Outback 01635 204 190


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