​ How Does Precision Agriculture Achieve Centimeter-level GPS Positioning?

Precision agriculture, also known as Precision Farming, is a new type of agricultural production method based on information technology and modern agricultural technology. The core lies in the precise monitoring and control of various factors in the agricultural production process through the comprehensive application of 3S technology (GPS positioning, GIS geographic information system, RS remote sensing) and automation technology. Among them, GPS dynamic differential real-time positioning technology is a key support for ensuring operations such as autonomous driving of agricultural machinery, precise sowing, and variable fertilization.

1. Position Differential GPS

The reference station compares its own GPS single-point positioning coordinates with the known precise coordinates, calculates the error correction value, and sends it to the mobile station (such as agricultural machinery, unmanned aerial vehicles) for real-time position correction. At the same time, the reference station and the rover station are required to receive exactly the same satellite signals; otherwise, the correction effect will decline, and its positioning accuracy can reach about 5 to 10 meters.

2. Pseudorange Differential GPS

The reference station calculates the pseudo-range values of each satellite using the known precise coordinates and satellite ephemeris data, compares them with the actual pseudo-range observations measured by the GPS receiver, and generates the pseudo-range correction number for each satellite. These correction values are transmitted in real time to the rover station to correct the pseudo-range observations of the rover station. Differential correction can also be carried out when the number of satellites received by the reference station and the rover station receivers are not exactly the same. As long as there are four identical satellites, the positioning accuracy depends on the number of differential satellites and their distribution in the air. The accuracy can reach 3 to 10 meters.

3. Real-Time Kinematic

The reference station transmits its Carrier Phase Observations to the rover station in real time through the data link. The rover station (GPS receiver) uses these observation data and the carrier phase information collected by itself to perform carrier phase positioning, achieving relative positioning with centimeter-level accuracy.

As the inevitable trend of modern agricultural development, precision agriculture provides a strong guarantee for the efficiency and sustainability of agricultural production by integrating advanced means such as GPS dynamic differential technology.

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