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For certain precision agriculture applications such as row crop bed preparation and planting or topographic map generation, using Real-Time Kinematic (RTK) can give you even greater centimeter accuracy as well as huge savings in time and money. The CNH base station is an RTK receiver designed and built for agricultural applications. With RTK, you need a base station placed on a known, surveyed point, and one or more mobile receivers within a ten-kilometer range of your base station. The base station transmits corrections via radio to the mobile receivers in the field. Radios operate best within 8 miles line of sight or with a repeater around obstacles such as trees or hills.

The GPS receivers used in CNH RTK systems are Trimble dual-frequency receivers. Dual-frequency receivers are a must in high accuracy applications, such as precise guidance along crop rows or collecting GPS elevation data for topography mapping. As well as using the standard code and carrier phase GPS signals like all other GPS receivers, CNH's dual-frequency receivers also track the second carrier phase signal. It is this signal that enable CNH RTK receivers to lock into the higher accuracy, and initialize more quickly.

Initialization is the process a receiver performs to get the information it needs from the satellites to generate high accuracy positions—typically about one minute with a CNH system. However, other manufacturer’s base stations generally take significantly longer to initialize—in some cases up to 30 minutes! CNH's RTK receivers also output data at rates of ten times per second.

Difference between GPS & RTK
It can be difficult to distinguish between RTK and GPS. Here's a quick review the differences:

• RTK is a correction source for GPS. However, not all RTK systems are created equal! CNH systems deliver sub-inch accuracy and initialize in one minute. Other manufacturer’s systems only offer 3 to 4 inch accuracy and can take up to 30 minutes to initialize.
• To get initialized, RTK needs a minimum of five satellites. After that it can operate with four. GPS needs a minimum of three, though at least four are required for sub-meter accuracy.
• For RTK, you need a dual frequency GPS receiver. Single frequency receivers are sufficient for GPS—but not for sub-inch accuracy.
• For RTK, your GPS receiver must be capable of On-the-Fly initialization (obtaining centimeter accuracy while moving).
• With CNH RTK, it takes one minute to initialize.
• To obtain RTK corrections for GPS, you need your own base station or to subscribe to an RTK network in your area. For GPS, you can use your own base station, a correction service provider, or make use of the free radio beacon broadcasts in many regions.

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