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MSAS Signal Structure

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Title MSAS Signal Structure
Edited by GMV
Level Basic
Year of Publication 2011
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The MTSAT Satellite Augmentation System (MSAS) is the Japanese Satellite Based Augmentation System (SBAS) System:[1] a GPS Augmentation system with the goal of improving its accuracy, integrity, and availability. First tests were accomplished successfully, and MSAS system for aviation use was declared operational in September 27, 2007,[2][3][4] providing a service of horizontal guidance for En-route through Non-Precision Approach.[1][2][5] The SBAS signal used to be transmitted from MTSAT (Multi-functional Transport Satellites) operated by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT). The SBAS signal that is made by MLIT is now transmitted from the QZS-3 GEO satellite using the QZSS SBAS transmission service since April 2020.[6]

MSAS Signal Structure

Signal characteristics are compliant with ICAO SARPs:[5][7]

  • 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 of improvement of MSAS signals are:[5]

  • Band width expansion for L1.
  • DFMC L5 SBAS experiments are being conducted successfully, confirming that L5 SBAS augments multi-constellation of GPS + GLONASS + Galileo + BeiDou + QZSS. [8]

For an introduction on the signal structure, please refer to the article The EGNOS SBAS Message Format Explained.