Tech Chat | How To Site A CORS Station?

As introduced in the previous blog, CORS (Continuous Operational Reference System) continuously collects high-quality GNSS raw observation data through reference stations, providing mobile terminal users with high-precision positioning services at the millimeter to centimeter level. From navigation and positioning to land surveying, disaster prevention and mitigation, smart cities, autonomous driving, etc., in which the CORS system plays a huge role. In general, users only need to purchase a CORS account to easily obtain differential data for use in various scenarios.

With such importance in our daily life and work, local CORS networks have also begun to be built around the world. When setting up a CORS system, selecting an appropriate geographic location is an important factor in obtaining accurate data results. If the construction site does not meet the construction indicators, the data signal of the CORS station will be poor (expressed as a low fixed rate and insufficient accuracy of the mobile station). If your CORS has multiple reference stations, then one station with poor signal will affect the accuracy and fixed rate of the entire CORS network. 

Therefore, select a reasonable site is the first step of the CORS construction. So what is the process of building a CORS network? What are the requirements for site selection? What should be pay attention to when building a CORS network?

The process of CORS system station setup

1. Site network selection on the map
2. Field visit
3. Data collection
4. Data quality analysis

CORS Network Station Location Selection Requirements

Geographical location requirements for site selection on the map

1. Carry out site distribution design within the coverage scope of CORS station network.
2. The distance between CORS stations can reach more than 60km in the high latitude region where the ionosphere changes gently and the climate changes gently. However, in the low latitude region, due to the influence of active ionosphere and drastic changes, the distance between CORS reference stations is reduced according to the demand, and it is generally recommended to be around 40km.
3. In terms of site distribution composition, CORS sites generally adopt triangular network layout.

Geographical location requirements for site survey stations

1. Site requirements:

• The distance from the ground objects (such as tall buildings, trees, water bodies and water-prone areas) with multi-path effect should be greater than 200 meters.
• There should be a satellite visibility condition with an altitude Angle above 10°. Under difficult conditions, the height angle can be relaxed to 15°, and the horizontal projection range of occlusions should be less than 60°.
• The distance from the radio transmitting station, high voltage line through the electromagnetic interference zone should be greater than 200 meters.
• Avoid mining areas, railways, highways and other easily shaken areas.
• In consideration of future planning and construction, the area with small changes in the surrounding environment is selected for construction.

2. The geological environmental requirements: if the reference station construction on the ground, then the regional geological environment condition of location to the pier standard construction should make reference on the stable tectonic block, to avoid the geologically unstable region, such as fault zone, prone to landslides local deformation and subsidence area) and water or underground water level changes in the larger region.

3. Site requirements:

• Facilitate access to public or private communication networks.
• With stable, safe and reliable power supply.
• Convenient transportation, personnel exchange and vehicle transportation.
• Good civil construction conditions. With construction land and basic infrastructure.
• Good security environment, which is convenient for personnel maintenance and long-term preservation of the site.

Precautions for setting up CORS system

1. Precautions for site selection in the figure: Pay attention to spatial uniformity and baseline distance, that is, to conduct spatial uniformity site selection according to the plane and elevation of the covered area.
2. Precautions for test data acquisition: The same type of receiver and antenna used for the construction of the station shall be used for data acquisition, and the test time shall be 24 hours of continuous acquisition, the sampling rate shall be 1 Hz, and the cutoff height Angle shall be 10 degrees.
3. Notes for data quality analysis: Data quality should be observed through software to determine whether the selected site is really suitable for CORS construction (whether it meets the standards). The next step of the construction plan can only be started if the target requirements stipulated by the state are met.

Learn more about SingularXYZ SV100 CORS solution
https://www.singularxyz.com/SV100_CORS.html