MSAS Signal Structure

MSAS
Title	MSAS Signal Structure
Author(s)	GMV.
Level	Basic
Year of Publication	2011

The Multi-functional Satellite Augmentation System (MSAS) is the Japanese SBAS System: a GPS Augmentation system with the goal of improving its accuracy, integrity, and availability, and that uses the Multifunctional Transport Satellites (MTSAT) owned and operated by the Japanese Ministry of Land, Infrastructure and Transport and the Japan Meteorological Agency (JMA). Tests had been accomplished successfully, and MSAS for aviation use was commissioned on September 27, 2007.

MSAS receives GPS signal at the Ground Monitor Stations and the Monitor & Ranging Stations, checks operational status of GPS, analyze GPS error and ionospheric delay, and then broadcasts augmentation information through MTSAT (Multi-functional Transport Satellite) from the Master Control Stations. Those satellites, MTSAT, broadcast the correction messages back to Earth, where MSAS-enabled GPS receivers use the corrections while computing their positions to improve accuracy.

MSAS Signal Structure

• Signal characteristics are compliant with ICAO SARPs:

– Frequency ; L1 = 1575.42MHz.

– Bandwidth ; L1 ±2.2 MHz band.

– Data Rate; 500 symbols per Second, 1/2 convolutional encoded with a Forward Error Correction (FEC) code (250 effective bits per second).

– Signal strength on the earth surface >-161dBw at 5 degrees elevation.

• The future lines for MSAS signals are:

– Band width expansion for L1.

– L5 signal.

– Compatibility & Interoperability achivement.