GPS auto-steer systems are now synonymous with farm machinery coming onto the market. Many tractors and sprayers already have the components fitted to the new machine, however an older machine retrofitted with a new GPS system may also suit your needs. 

But what is GPS? How does it work? And what are the things a grower or spray applicator needs to consider when purchasing or upgrading a sprayer? Making a purchase decision can be confusing, especially when much of the sales literature looks the same. 

There are three main components of a GPS auto-steer system that will be discussed in this module:

• obtaining the position on the Earth’s surface (using GPS) and ways to improve its accuracy;

• the screen in the cab and what it can and can’t do; and

• the method of steering the spray rig.

These three parts are discussed in the following sections of this module.