#TechTips | Choosing a Correction Signal

GPS technology has evolved a crazy amount over the last decade or two.  What’s even crazier is that many farmers are still utilizing the same GPS receiver and correction signal today as they did 12-15 years ago.  The phrase ‘don’t fix what ain’t broken’ may apply to lots of things in life, but GPS correction signal isn’t one of them.  Not only could using the incorrect signal for your fieldwork be costing you money in over- or underapplied product, but could also be costing you time each year recreating guidance lines for simple operations.  Read below for our recommendations on how to choose the right correction signal!

All John Deere StarFire^TM receivers come with SF1 signal in base from the factory. This is the free signal that requires no additional activations or yearly subscriptions to function, and enables you to use documentation, AutoTrac^TM, Section Control, and other guidance-related features. While the free portion of SF1 is hard to pass up, don’t forget that it may not be a fit for every operation. On StarFire^TM 6000 receivers, the pass-to-pass accuracy of SF1 is +/- 6″ – meaning your passes could be up to 6 inches apart and still be considered acceptable. Ideally, SF1 should only be used for low-accuracy fieldwork, such as tillage.

Only available on StarFire^TM 3000 receivers, SF2 is a bump up from SF1 signal. Requiring an initial activation purchase and annual subscriptions, SF2 provides more pass-to-pass accuracy with no repeatability. With a margin of +/- 2″, SF2 provides a much more reliable correction signal for operations that require some degree of accuracy – such as planting, spraying, or nutrient application. However, keep in mind that the guidance lines you create using SF2 will not be able to be reused next year.

The latest introduction to the correction signal family is SF3, only available on StarFire^TM 6000 receivers. SF3 provides pass-to-pass accuracy of +/- 1.2″ with in-season repeatability. Essentially, it’s another way to get RTK-like accuracy for guidance lines that you know you won’t reuse year after year. Similar to SF2, SF3 requires an activation and annual subscription, and is great for operations that require moderate to high levels of accuracy – such as planting, spraying, nutrient application, or even strip tilling.

The cream of the crop when it comes to correction signal, RTK combines sub-inch accuracy with year-over-year repeatability. Network towers that are placed throughout our territory on tall structures (like grain legs) allow the signal to be stronger and more reliable than using just GPS receivers in space. RTK is the only correction signal we recommend if you want to utilize boundaries for things like Section Control on your operation, because it’s the only signal that guarantees no drift over time. Because RTK is so accurate and so reliable, it does require a radio that connects to your GPS receiver and an additional subscription to our tower network.

At the end of the day, the best way to choose your correction signal is to ask yourself how accurate your field operations require you to be. Have questions about your current hardware or want to learn more about upgrading? Contact our Precision Ag Support Team today for assistance!