Corrections

More differential correction choices are available than ever seen in agriculture. That’s great for Montana because it makes accuracy more affordable and easier to receive. Growers are no longer tied to a local base station or cell phone tower to get high accuracy. Satellite correction covers all of Montana providing 1.5″ accuracy, repeatability, and more satellites are available for far less money than we ever thought possible. So take a look, it may surprise you.

About Corrections

What are Corrections?

Correction services are used to improve the accuracy and quality of the location data provided by receivers using satellite positioning services, including GPS.  Without correction, your receiver could direct you to the nearest Walmart, but wouldn’t be very accurate at guiding your tractor down the field.  Most corrections services use land-based towers as a reference in addition to algorithms that help filter out errors.  Satellite based corrections, such as Trimble RTX, use large towers across the continents to improve accuracy and availability, so the grower doesn’t have to worry about radios and communications.  Adding the right correction service to your receiver will result in better performance of all the precision ag tools on your farm.  More accuracy will cost you more money up front but will also deliver less frustration with operations in the field.

Understanding Accuracy Ratings

GPS positions will continuously drift over time, the amount of drift will depend on the correction source. The correction source is then given ratings for the amount of drift it will see in the field, those ratings are Pass to Pass accuracy and Repeatability.

Pass to Pass Accuracy

The Pass to Pass Accuracy rating is the amount of drift that can be expected in a 15 minute interval. This means in slower applications or in larger fields, more error may be seen between passes because the 15 minute window has passed.

Repeatability

Repeatability is the maximum amount of error that can be expected at any time. Some correction sources, such as WAAS, do not have a repeatability rating, it may be within inches or it may be feet off when going back to a line hours or years later.