Ag Leader Technology Blog

OmniSTAR

OmniSTAR is a wide-area differential GPS service, using a network of base stations surveyed to centimeter accuracy.

OmniSTAR offers wide-area differential correction by using geo-stationary satellites to broadcast correction data over a large area. OmniSTAR differential correction is subscription-based, which allows you to pay for the level of accuracy you need. Currently, three levels of service are offered: OmniSTAR VBS offers pass-to-pass accuracies of around 6-8 inches, OmniSTAR XP is accurate to about 3-5 inches pass-to-pass, and OmniSTAR HP has 2-4 inch pass-to-pass accuracy. The level of accuracy is reflected in subscription prices. Like we mentioned in our discussion of RTK, your operation and precision farming goals can help you determine if OmniSTAR is the best choice for you and what level of subscription you need.

SBAS

Satellite-based augmentation system (SBAS) is a differential correction system that supports wide-area correction through multiple ground stations.

In North America, WAAS is the SBAS system that is used. EGNOS (in Europe) and MSAS (in Japan) are the equivalent sources for those regions – all are free, wide-area correction services available for use in precision ag.

Wide Area Augmentation System (WAAS) is a differential correction source maintained by the FAA. WAAS covers all of North America and uses both geo-stationary satellites and 24 ground reference stations to broadcast its free differential correction signal.

WAAS (Wide Area Augmentation System)

WAAS was originally developed for aviation uses, but it is also useful for precision farming. WAAS is a free signal and GPS receivers compatible with WAAS only are inexpensive. WAAS offers 6-8 inch pass-to-pass accuracy, but they may not be accurate enough for some operations. Because it is a free signal, though, it may make the most sense economically for your operation. WAAS is an inexpensive option for getting started in precision ag; ParaDyme™, for example, can be upgraded from WAAS all the way to RTK.

One important thing to keep in mind regarding WAAS it does not have the repeatable accuracy of RTK (the sub-inch accuracy from day to day, month to month, or year to year). When choosing the differential correction service you will use, keep in mind what you want to do on your operation and how differential correction will factor into that plan.

Now that we have briefly discussed several differential correction services, it is important to think about these in terms of your own precision farming plan before deciding what service is best for you. Learning about the different options and how they would work on your operation is an important step in determining which differential correction service you will use.

Image credit:  US FAA

LESSONS IN PRECISION AG: Differential Correction (Part 1)

LESSONS IN PRECISION AG: Differential Correction (Part 2)

Tags: Ag Leader, Ag Leader Technology, Global Navigation Satellite Systems, GLONASS, GNSS, GPS, OmniSTAR, precision agriculture, precision farming, Satellite-based augmentation system, SBAS, WAAS
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