WebPPP

PPP (Precise Point Positioning) is a high-precision satellite positioning method that uses precise ephemerides and clock corrections to determine coordinates without requiring data from a base station.

Unlike differential methods (RTK, DGPS), PPP operates globally and can provide millimeter-level positioning accuracy in post-processing.

RTK (Real-Time Kinematic) requires a nearby base station (up to 20–30 km away) to achieve high accuracy.

PPP is independent of base stations, operates globally, and is suitable for remote areas, providing millimeter-level accuracy in post-processing mode.

RINEX (Receiver Independent Exchange Format) is a standardized data-exchange format that stores GNSS observation and navigation data recorded by a receiver and is widely used for post-processing

A detailed description of the current version of the format is available via this link.

Currently, the service uses precise ephemeris and clock information (POD products) from three Russian sources — IAC KVNO, SVO ECI, and SDCM.

POD products are classified by latency (and therefore expected accuracy) as Ultra-rapid, Rapid, and Final:

A solution based on Ultra-Rapid products is available on the same day.

A solution based on Rapid products becomes available after 2 days.

A solution based on Final products becomes available after 4–5 days.

After registration, the service lets you check POD products availability and download the files used in the positioning solution.

Yes. WebPPP can process observations in both static and kinematic modes (e.g., from drones, cars, etc.).

A public API is available to automate observation file processing.

The WebPPP service has a number of requirements for submitted observation files:

- A RINEX file (versions 2.01–4.02) or Hatanaka-compressed RINEX (CRX)

- Static and kinematic observations at one or more frequencies are supported

- Multi-day observation files and arbitrary sampling intervals are supported

- File size up to 350 MB

- Uploading archived files is allowed

The recommended minimum observation duration for a static site is 60 minutes.

The accuracy of the estimated coordinates can depend on many factors, including:

- The selected type of ephemeris and clock information — Ultra-Rapid, Rapid, or Final

- The amount and quality of observations

- The number of observed satellites and their geometry

- The availability of multi-frequency observations

- The quality of the regional ionospheric model/grid (for single-frequency solutions)

- Applying ocean tide loading (OTL/BLQ) corrections

- Using antenna calibration files in ANTEX format

- The accuracy of correction products (Rapid vs Final)

- Multipath and other types of interference

In WebPPP, you can either upload your own BLQ file or generate one directly on the website in the Services section.

BLQ generation is performed using the modern FES2022b ocean tide model.

Applying BLQ corrections is especially important in coastal areas and typically has the strongest effect on the vertical component of the solution.

The service supports user-provided antenna calibration files in ANTEX format (.atx).

The ANTEX format is used to store information on the characteristics and phase center offsets of satellite and receiver antennas.

Yes. By default, the service returns coordinates at the observation epoch.

However, you can select an epoch to which the estimated coordinates will be propagated.

Epoch propagation is performed using the ITRF2020-PMM plate motion model and GSRM v2.1.