Active Control Networks
Active control networks across Canada are operated by public agencies and private sector interests. In total, about 600 active control and network RTK stations have been deployed to date (Table 1).
Equipped with receivers that continuously track and record satellite signals, active control stations are sources of GNSS information that can be exploited in various ways. Satellite ranging measurements can be downloaded by users to improve the accuracy of their surveys with differential methods and connect to the national frame. The tracking data can also be contributed to global initiatives, such as the International GNSS Service (IGS), to support GNSS augmentation and the improvement of terrestrial reference frames. International collaboration facilitates the generation of continuous and reliable precise GNSS orbit and clock products that support Precise Point Positioning (PPP) applications. ACS real-time correction streams also enable precise navigation over various coverage areas as they are integrated into regional to global augmentation services.
GNSS augmentation using ACS networks can enable positioning and navigation with typical accuracy of 10 cm or better, depending on reference network configuration and density. In regions where reference station spacing is in the 10-20 km range, networked RTK solutions typically provide 3D accuracies better than 5cm at 95% confidence level.
Table 1. Number of active stations in Canada (October 2021)
|Network RTK||Active Control|
|QC1||92||18 + 4||10 (5)|
1. 4 ACS in Montreal
2. Count of stations taken 2021-05-07
Public and private agencies serving different Canadian jurisdictions and markets have chosen different models and approaches to deliver active control technologies. At the federal level, Natural Resources Canada, the Department of Fisheries and Oceans and NavCanada have been early adopters establishing stations of the Canadian Active Control System (CACS), Coast Guard Differential Global Positioning System (DGPS), and Canadian Wide Area Augmentation System (CWAAS) networks. While Canadian DGPS (CDGPS) and CWAAS stations are dedicated mainly to maritime and air navigation safety, CACS has been the main initiative to support the geodetic and scientific communities.
At the provincial level, public sector involvement and investment in ACS varies between provinces, depending on private sector offering and opportunities for partnerships. In western Canada, British Columbia is the only province with ACS operations at both the provincial and municipal levels. The prairie provinces of Alberta, Saskatchewan, and Manitoba, along with Ontario rely mainly on commercial network RTK services. Quebec and New Brunswick offer ACS references in their main municipalities. Nova Scotia and Prince Edward Island have developed partnerships with industry to operate ACS networks supporting subscriber-based real-time services and open access to post-mission data.