– Global Navigation Satellite Systems – is an acronym that you may not commonly hear in the precision ag discussion. However, this is the general term for satellite navigation systems that you likely hear quite often, such as GPS or GLONASS.
GPS and GLONASS are both satellite navigation systems specific to the country or region that developed and runs them (GPS is the U.S. satellite system and GLONASS is the Russian satellite system). Before discussing the specific systems, it’s important to understand the general concept behind them and how this relates to precision farming.
GNSS is the standard term used to refer to a group of navigational satellites providing signals for global positioning worldwide.
So how does GNSS calculate your position?
A GNSS receiver – such as the Ag Leader GPS 1500 – communicates with global positioning satellites to determine your receiver’s distance from the satellite. In order to accurately map your position, your GNSS receiver needs to communicate with at least three satellites through a process called “triangulation”. This process measures your distance to three known satellites, and your location can be mapped based on the intersection of the three points on earth.
GNSS
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Because you need at least three satellites to accurately map your position, having more satellites available to communicate with your receiver will make it easier to receive and maintain a strong signal. If you have strong, consistent satellite communication, you can map your fields with better accuracy and consistency. This means that as precision ag technologies progress, receivers will be capable of communication with multiple GNSS – not just GPS, but also GLONASS and possibly even other systems as they become available. As new technologies are developed that allow receivers to communicate with more than just GPS satellites, GNSS will become more widely used in the precision ag vocabulary to describe receivers that can communicate with multiple satellite systems.
GPS (Global Positioning System) is the United States’ constellation of 24 satellites, developed by the U.S. Department of Defense. Traditionally, GPS has been the most commonly used navigation system for precision farming. However, as other GNSS become more advanced and accurate, we could rely on additional navigation systems in order to have access to more satellites.
GLONASS (Global Navigation Satellite System) is the Russian Federation’s GNSS consisting of 23 satellites. GLONASS is quickly becoming a popular supplement to GPS in the U.S. When you are in locations that have poor GPS signals, GLONASS will increase the number of satellites available to help your receiver maintain a strong signal. The newest precision ag receivers will have the capability to communicate with these GLONASS satellites.

While GPS and GLONASS are the most advanced GNSS, several others are in the development process. Galileo, when complete, will be the European GNSS. Galileo will consist of 30 satellites, and the European Space Agency hopes to fully launch Galileo by sometime in 2013. China is currently working on developing a GNSS called Compass, and other countries, including India and Japan, also have GNSS that they are working to develop.