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Demonstration experiment

Demonstration experiment

GPAS has launched a demonstration experiment of precise satellite positioning using MADOCA technology under the framework of "Centimeter Level Augmentation Service for Experiment" with QZSS.

The augmentation message of MADOCA has been provided on L6E signal of QZSS since December 6, 2017.
This message can be used by everyone.

Please read and understand the disclaimer below before using the augmentation message.


Data Format Specification (English)

Data Format Specification (Japanese)

Notice of Modification of Correction Data (English)

Notice of Modification of Correction Data (Japanese)


QZSS Interface Specification (IS-QZSS)


Global Positioning Augmentation Service Corporation makes no warranties on the demonstration experiment provided as "Centimeter Level Augmentation Service for Experiment" with QZSS, the contents of message, accuracy, and the continuity of the message, and disclaims any responsibility or liability for any damage caused by this demonstration experiment. The provided augmentation message on L6E signal of QZSS may be changed, interrupted, or terminated without prior notice.

By using the augmentation message on L6E signal of QZSS, you shall be deemed to have accepted this disclaimer.

Flow of Providing Service

GPAS has begun technical verification of high-precision positioning correction technology MADOCA by the quasi-zenith satellite system (QZSS), which is a distribution of the correction information for the verification via L6E signal of QZSS. GPAS plans to distribute the information via the Internet.

  1. Collect observation data of navigation satellites from GNSS reference stations deployed all over the world.
  2. Based on the collected observation data, precisely calculate the error of the satellite orbit and the satellite clock.
  3. Distribute the correction information to users on the ground via "L6E signal" of QZSS.
  4. Plan to distribute via the Internet in addition to QZSS.
  5. Calculate user position in centimeter class all over the world by using the correction information.


”Multi‒GNSS Advanced Demonstration tool for Orbit and Clock Analysis”
MADOCA is being developed by JAXA(Japan Aerospace Exploration Agency) based on their technology for estimating satellite orbit and clock corrections.