Multi-GNSS Centimeter-Level PPP-RTK Augmentation Service Debuts from QZSS - Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design

Multi-GNSS Centimeter-Level PPP-RTK Augmentation Service Debuts from QZSS

Japan’s new Centimeter Level Augmentation Service (CLAS) now broadcasts a signal for nationwide open PPP-RTK service in Japan, providing centimeter positioning accuracy in a minute.

With this introduction of a highly efficient atmospheric correction message, the number of available GNSS satellites will be increased up to 17: GPS, Galileo and Quasi-Zenith Satellite System (QZS) satellites all-in-view will be corrected by the QZS L6 signal. This is expected to improve performance considerably, particularly in urban areas.

The QZS CLAS Compact State Space Representation (SSR), a highly efficient RTCM-compatible open specification for PPP/PPP-RTK. Compact SSR is accepted as PPP-RTK standard in 3GPP LPP, the mobile communication standard for LTE/5G. There are plans for it also to be applied for Galileo’s High-Accuracy Service (HAS). The detailed information is described in the ION GNSS+ 2020 paper, “Open Format Specifications for PPP/PPP-RTK Services: Overview and Interoperability Assessment,” by Rui Hirokawa, Deputy General Manager, Space Systems Department of Mitsubishi Electric Corporation; and Ignacio Fernández-Hernández, technical lead of the authentication and high-accuracy services of Galileo first-generation at the European Commission.

Since SSR corrections can be easily distributed over L-Band satellite communication channels and over IP, it will facilitate scalable business-to-business (B2B) models for high-precision mass-market applications such as in automotive sector.

Official broadcast of the augmentation information compliant with IS-QZSS-L6-003 from all the Quasi-Zenith Satellites (QZS-1, 2, 3, and 4) began on November 30. The signal complies with IS-QZSS-L6-003. In order to use CLAS, it may be necessary to update the receiver’s firmware to comply with IS-QZSS-L6-003.  For this, contact the receiver manufacturer.

For further technical documentation, refer to the Interface Specification (IS-QZSS-L6-003, Aug. 20, 2020) of the Centimeter Level Augmentation Service.