Multi-GNSS precise point positioning for precision agriculture

Abstract

The main objective of this research was to examine the feasibility of Multi-GNSS precise point positioning (PPP) in precision agriculture (PA) through a series of experiments with different working modes (i.e. stationary and moving) under different observation conditions (e.g. open sky, with buildings or with canopy). For the stationary test carried out in open space in the UK, the positioning accuracy achieved was 13.9 mm in one dimension by a PPP approach, and the repeatability of positioning results was improved from 19.0 to 6.0 mm by using Multi-GNSS with respect to GPS only. For the moving test carried out in similar location in the UK, almost the same performance was achieved by GPS-only and by Multi-GNSS PPP. However, for a moving experiment carried out in China with obstruction conditions, Multi-GNSS improved the accuracy of baseline length from 126.0 to 35.0 mm and the repeatability from 110.0 mm to 49.0 mm, The results suggested that the addition of the BeiDou, Galileo and GLONASS systems to the standard GPS-only processing improved the positioning repeatability, while a positioning accuracy was achieved at about 20 mm level in the horizontal direction with an improvement against the GPS-only PPP results. In space-constrained and harsh environments (e.g. farms surrounded with dense trees), the availability and reliability of precise positioning decreased dramatically for the GPS-only PPP results, but limited impacts were observed for Multi-GNSS PPP. In addition, compared to real time kinematic (RTK) GNSS, which is currently most commonly used for high precision PA applications, similar accuracy has been achieved by PPP. In contrast to RTK GNSS, PPP can provide high accuracy positioning with higher flexibility and potentially lower capital and running costs. Hence, PPP might be a great opportunity for agriculture to meet the high accuracy requirements of PA in the near future.

Positioning Methods and the Use of Location and Activity Data in Forests

“…Data downloaded from the IGS can be used in real-time or for post-processing correction [63,71]. With PPP, GNSS devices can correctly position within 5 cm in open areas and less than 0.5 m under forest canopies (Table 1) [67,70]. In a Satellite-Based Augmentation System (SBAS) (left panel), reference stations located at precisely-surveyed points receive and forward their GNSS signals to the master station, which then calculates corrections.…”

Unmanned Aircraft System (UAS) Technology and Applications in Agriculture

“…Generally, this will include a global navigation satellite system (GNSS) receiver which is in communication with satellites. A few common GNSS systems include: GPS from the United States, Global Navigation Satellite System (GLONASS) from Russia, Galileo from the European Union, and BeiDou from China [89,105]. A GNSS is extremely useful for georeferencing images, providing better accuracy than photogrammetric methods alone [9,18,20,40,89,106].…”

Helmert Variance Component Estimation for Multi-GNSS Relative Positioning

“…In the Multi-GNSS context, the International GNSS Service (IGS) initialized the Multi-GNSS EXperiment (MGEX) in 2014 [7], aiming to provide Multi-GNSS products such as precise orbit, clock and satellite bias. Since then, MGEX products have enabled Multi-GNSS applications, such as global ionosphere modelling [8], water vapor determination [9], precise agriculture [10], crustal deformation [11] and GNSS-Reflectometry-based altimetry [12].…”