CSRS PRECISE POINT POSITIONING (CSRS-PPP)
Launched in 2003, Canada’s Precise Point Positioning (PPP) service, CSRS-PPP, continues to solidify its place as a world-class GNSS post-processing platform. Operated by the Canadian Geodetic Survey (CGS) under Natural Resources Canada (NRCan), the service enables users to obtain highly accurate coordinates from raw GNSS data without requiring proximity to a base station. Users simply upload RINEX observation files from either static or kinematic receivers, and CSRS-PPP returns positions referenced to NAD83(CSRS) or the International Terrestrial Reference Frame (ITRF). Crucially, this free and publicly accessible service is contributing enormously to the democratization of centimeter-level GNSS positioning for users around the world.
As part of the license agreement for the use of CSRS Precise Point Positioning (CSRS-PPP), with His Majesty the King of Canada, represented by the Minister of Natural Resources Canada (NRCan), RIGC implemented the processing of GNSS observations of static measurements based on the CSRS-PPP service. The basis of the processing are the accurate final (or rapid) products of the CODE (Center for Orbit Determination in Europe) processing center without the need to use the initial observations from base stations. The results of CSRS-PPP processing are adapted to the representation of coordinates in the UCS2000 system and heights in the Baltic Height System 1977.
Galileo PPP-AR Now Supported
On May 14, 2025, CGS released a major upgrade to the service that introduced support for Galileo PPP with Ambiguity Resolution (PPP-AR). This new capability applies to Galileo E1/E5a signals recorded on or after November 27, 2022, and is available when using either Rapid or Final products.
These “products” refer to high-precision satellite data; specifically, calculated information about satellite orbits, clock corrections, and signal biases, based on data collected by a global network of stations. The collected data are processed by NRCan and international partners to support CSRS-PPP’s precise positioning outputs. The recent CSRS-PPP upgrade builds on the PPP-AR support for GPS added in 2020 for data recorded on or after January 1, 2018, marking a significant step toward fully integrated, ambiguity-resolved positioning using data from multiple GNSS constellations.
Why PPP-AR Matters
The major milestone in October 2020, when ambiguity resolution was introduced to the CSRS-PPP platform, ushered in a new era of precision for users. At the core of PPP-AR is a significant shift in how satellite signals are interpreted. Traditional PPP estimates carrier-phase ambiguities as ‘float’ (real-valued) parameters because the integer number of whole carrier wavelengths between satellite and receiver remains unknown and unresolved. In contrast, PPP-AR resolves these ambiguities as fixed integers by utilizing precise satellite orbit and clock products alongside detailed modeling of satellite and receiver biases, thereby enabling reliable integer ambiguity resolution. This leap in algorithmic refinement leads to faster convergence times and enhanced accuracy, often down to the centimeter level. Ambiguity Resolution can lead to particularly noticeable improvements on east–west accuracy, which makes PPP-AR particularly valuable in applications demanding high horizontal precision.
CSRS-PPP Advances: Broader Satellite Support and Richer Output Data
Since its inception, CSRS-PPP has evolved steadily. Alongside expanded satellite constellation support, the platform’s reference frame has progressively advanced through updates from ITRF2005 to subsequent realizations, culminating in the adoption of ITRF2020. Additionally, CSRS-PPP output files now include valuable metrics such as estimated tropospheric delays, receiver clock offsets, and ambiguity resolution statistics. These enhancements provide users with more detailed insights into solution quality.
An Evolving Platform
Even as this article was being written, on July 15, 2025, CSRS-PPP announced support for GPS signals C1L, L1L, C1X and L1X, further enhancing its capabilities and reaffirming its role at the core of a modern geodetic infrastructure. As GNSS shifts toward multi-frequency, multi-constellation services, CSRS-PPP is evolving in parallel, making centimeter-level accuracy accessible to a wider user base. With robust algorithms and enriched data outputs, CSRS-PPP remains a critical tool for high-precision positioning in Canada and a model for international GNSS services.
Source - Canada’s CSRS-PPP service sets a new standard for high-precision GNSS / GPS World. URL : https://www.gpsworld.com/canadas-csrs-ppp-service-sets-a-new-standard-for-high-precision-gnss/
Canada’s CSRS-PPP - URL: https://webapp.csrs-scrs.nrcan-rncan.gc.ca/geod/tools-outils/ppp.php