Increasing Accuracy and Productivity with GNSS Receivers

When using Global Navigation Satellite System (GNSS) systems, such as GPS, for surveying, the high accuracy of the GNSS receiver's location must be considered (A Ogaja, 2022). The basic concept of GNSS technologies is to build a satellite framework in which every satellite provides transmission to receivers at a predetermined time. Is it feasible to achieve high precision with a Global navigation satellite? Assume you want dependable, precise worldwide geolocation in your solution. You conduct some studies and conclude that a multi-frequency GNSS receiver is the best answer. So you place an order for an assessment kit (Choy & Harima, 2019). Now, how can you enable your receiver to achieve the great precision that it guarantees? To attain decimeter-level precision as quickly as feasible, GNSS receivers depend on external adjustments to adjust for numerous defects known as GNSS errors.

Atmospheric errors

    The transmission from the satellites passes through the various atmospheric layers. The pace of the signal is affected by certain atmospheric layers. GNSS signals, like any other electronic transmission, usually move at the speed of light. Because the speed of light is a fundamental constant that must not vary, why is the GNSS transmission decelerated? The ionosphere is a zone of charged particles that exists at altitudes ranging from 130 to 200 kilometers (Heelis & Maute, 2020). Only in a vacuum can the speed of light stay unchanged. Traveling through many kilometers of a thick layer reduces the GNSS transmission, resulting in an inaccuracy in the proximity computation from the source node to the destination node.

    To decrease ionosphere error, employ two separate GNSS transmission frequencies and a receiver capable of picking up the two frequencies concurrently. Signals moving via the ionosphere are decelerated in proportion to their frequency. Employing the variation in the variance of pace in all transmissions, it is able to minimize the majority of the ionosphere inaccuracy. Many GNSS receivers intended for surveying employ this technology. For the ionospheres inaccuracy, receivers with lesser requirements frequently adopt a standardized approach given a typical day within average settings.

Increasing productivity

RTK method

    A client receiver in the Real-Time Kinematic (RTK) approach receives rectification information from a data access point. It then utilizes this information to remove the majority of the GNSS inaccuracies. RTK is predicated on the assumption that the access point and client receiver are near together (no more than 40 kilometers apart) and hence "find" the same mistakes. For instance, because the ionospheric lags for the client and the benchmark site are comparable, they may be canceled out of the result, enabling greater accuracy. Adjustments for a given place are obtained through the RTK approach. They transmit a rectification framework to a greater region but with significantly lesser accuracy in the PPP-RTK and PPP approaches.

PPP method

    Just the satellite clock and orbit inaccuracies are included in the Precise Point Positioning (PPP) adjustments. Because these mistakes are satellite-specific and hence independent of the client's location, just a small number of base stations are required throughout the world. Since it does not account for atmospheric faults, this technique yields lower precision. Furthermore, it can take up to 20-30 mins to set up, which may be inconvenient for some programs. PPP has always been used in the marine sector. As a straightforward technique to obtain global GNSS adjustments, it has now spread to numerous terrestrial uses like agriculture.

References

A Ogaja, C. (2022). Augmented Reality: A GNSS Use Case. In Introduction to GNSS Geodesy (pp. 3-12). Springer, Cham.

Choy, S., & Harima, K. (2019). Satellite delivery of high-accuracy GNSS precise point positioning service: An overview for Australia. Journal of Spatial Science, 64(2), 197-208.

Heelis, R. A., & Maute, A. (2020). Challenges to understanding the Earth's ionosphere and thermosphere. Journal of Geophysical Research: Space Physics, 125(7), e2019JA027497.