How does a high precision GNSS RTK antenna overcome signal obstruction in a complex urban environment?
Publish Time: 2025-05-07
In modern urban environments, high-rise buildings, bridges, tunnels, and dense trees can cause serious obstruction and reflection of GNSS (Global Navigation Satellite System) signals, resulting in reduced positioning accuracy or even failure to work properly. This signal interference is particularly critical in high-precision applications such as drone GPS mapping. However, through a series of advanced technologies and strategies, high precision GNSS RTK antennas can effectively overcome these challenges in complex urban environments and ensure continuous and stable high-precision positioning services.
1. Multipath effect and its impact
The multipath effect means that GNSS signals not only reach the receiver directly from the satellite, but also reach the receiver after being reflected by buildings or other obstacles. These reflected signals will be superimposed on the direct signal, causing the receiver to receive incorrect location information. In urban environments, due to the height and density of buildings, the multipath effect is particularly significant, which seriously affects positioning accuracy.
In order to deal with this problem, modern high precision GNSS RTK antennas use a variety of technical means to reduce or eliminate the impact of multipath effects. First, the antenna design uses special shapes and materials, such as the choke antenna design, which can effectively suppress reflected signals from the ground and other low-angle directions. Secondly, the advancement of software algorithms also enables the receiver to identify and filter out multipath signals, thereby improving positioning accuracy.
2. Enhanced signal reception capability
In addition to hardware improvements, enhancing signal reception capability is also one of the important means to overcome signal obstruction. Modern high precision GNSS RTK antennas usually support multi-band and multi-constellation reception, which means that they can simultaneously receive signals from multiple satellite systems (such as GPS, GLONASS, Galileo, and BeiDou). By increasing the number of available satellites, even if some satellite signals are blocked, the system can still obtain enough data from other satellites for accurate positioning.
In addition, some high-end devices are also equipped with smart antenna technology, which can dynamically adjust the direction and gain of the antenna according to the current environment to maximize the effective signal strength received. This method is particularly suitable for mobile platforms such as drones, providing greater adaptability in rapidly changing urban environments.
3. Application of differential correction and RTK technology
RTK (Real-Time Kinematic) technology is one of the key technologies to improve GNSS positioning accuracy. By using a fixed-position base station to send differential correction information to a mobile station (such as a drone), the positioning accuracy of the mobile station can be greatly improved to the centimeter level. In an urban environment, although the distance between the base station and the mobile station may be far, the differential correction information can still maintain a high accuracy through the Internet or a dedicated communication link.
To further improve reliability, many systems use Network RTK technology. Network RTK uses a virtual reference station network composed of multiple widely distributed base stations to provide accurate differential correction information over a wider coverage area. This method can not only effectively solve the problem of limited coverage of a single base station, but also better handle signal obstruction in cities.
4. Combined with Inertial Measurement Unit (IMU)
In extreme cases, when the GNSS signal is completely lost, the inertial measurement unit (IMU) can be used as a supplementary means to maintain navigation accuracy for a short period of time. The IMU measures acceleration and angular velocity to calculate the velocity and attitude changes of the carrier, and then infers its position. Although IMU has the problem of cumulative error when used alone, it can provide valuable transition data to the system in the case of intermittent interruption of GNSS signal until reliable GNSS signal is regained.
The integration of high precision GNSS RTK antenna and IMU forms the so-called GNSS/INS combined navigation system. This system not only improves the overall navigation performance, but also provides higher robustness and reliability in complex environments.
In short, in complex urban environments, high precision GNSS RTK antenna successfully overcomes the challenges brought by signal obstruction by adopting multipath suppression technology, enhancing signal reception capability, applying RTK differential correction, and integrating with IMU. This not only improves positioning accuracy, but also provides solid technical support for application scenarios such as drone GPS mapping.
