What is MSAS (multifunctional satellite augmentation system)

Multifunctional Satellite Augmentation System (MSAS):

1. Overview:
   • MSAS is the Japanese Satellite-Based Augmentation System (SBAS).
   • Its primary goal is to enhance the accuracy, integrity, and availability of the Global Positioning System (GPS) signals.
   • By providing augmentation information, MSAS improves the reliability and precision of GPS-based navigation.
2. System Components:
   • Space Segment:
     • MSAS utilizes geostationary satellites to broadcast augmentation signals.
     • Initially, the SBAS signal was transmitted from MTSAT (Multi-functional Transport Satellites) operated by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT).
     • Since April 2020, the SBAS signal is transmitted from the QZS-3 GEO satellite using the QZSS SBAS transmission service.
   • Ground Segment:
     • The ground segment includes Master Control Stations (MCS) and Ground Monitor Stations (GMS).
     • These stations monitor satellite signals, compute augmentation data, and generate correction messages.
   • User Segment:
     • Receivers equipped with SBAS capability receive the augmentation signals.
     • These receivers apply corrections to improve GPS position accuracy.
3. Operational Phases:
   • MSAS V1 (Initial Performance Phase):
     • Operational with MTSAT, 2 MCS, and 6 GMS.
     • Provided horizontal guidance for en-route and non-precision approaches.
   • MSAS V2 (System Update Phase):
     • Transitioned to the GEO QZS-3 satellite.
     • Fully replaced the SBAS ground system.
     • Achieved performance equal to or better than MSAS V1.
   • MSAS V3 (LPV Performance Phase):
     • Focuses on vertical guidance (LPV operation).
     • Requires high-performance ionospheric software for low-latitude magnetic equatorial regions.
   • MSAS V4 (DFMC Validation Phase):
     • Supports ICAO SARPs validation.
     • Initial performance with LPV 200.
     • DFMC SBAS validation using QZS-2, QZS-3, and QZS-4.