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Quasi Zenith Satellite System Navigation ServiceInterface Specifications for QZSS


Establishment and Release of IS-QZSS Ver.1.5

JAXA is pleased to announce the publication of "IS-QZSS Version 1.5" on this QZSS/JAXA web site with our apology for taking long time to translate the document into English.

Following the publication of the IS-QZSS Draft Version 1.5 in December 2012, we gathered comments on the document from user communities, and then held a user meeting on 13 & 14 February 2013. As a result of those activities, we have made corrections and improvements as reflected in IS-QZSS Ver. 1.5.
In addition, we corrected some descriptions after issue of the draft version 1.5 from the following reasons.
(1) Correction of erroneous description caused by the difference of update timing between QZSS and GPS.
(2) Adding message type for L1-SAIF and LEX.

The major corrected parts are as follows:
1 Correction of erroneous description for equation to calculate disabled timing of ERD from NMCT by L1C/A signal.,
2 Adding information of Message Type 12 (timing information) for L1-SAIF signal.,, 6.4.1
3 Changing the update timing of Message Type 1 (PRN mask) for L1-SAIF signal.
4 Adding information of Message Type 12 (MADOCA-LEX*) for LEX signal.
* As we have already announced you, JAXA has begun test transmission of MADOCA-LEX signal from April 2013. We described the outline of MADOCA-LEX in this version of IS-QZSS because the specifications of MADOCA-LEX were not fixed (including a format etc.). We will describe for more details in the next revision of IS-QZSS. However, we would like to post the specifications on this site (QZ-vision) immediately, when they are decided.

From today's publication of IS-QZSS Version 1.5, JAXA will continue to improve the description of the system performance, the system operation, the data handling, and the generation and updating of the QZSS Navigation Messages to enhance the system's value to the user community.

JAXA always welcomes comments and questions from users as part of our commitment to continually improve both this IS-QZSS document and the QZSS. We also welcome communication with receiver manufacturers concerning the design and manufacturing of receivers.

Release of MADOCA-LEX format and Start of Test Transmission

Release of MADOCA-LEX format
JAXA releases the new LEX format (Message type ID=12: MADOCA-LEX(*1)) on QZ-vision.

This format is prepared for "Precise Point Positioning (PPP)" experiment users.
This format stores orbits and clocks correction information, etc. for GPS, GLONASS, Galileo, and QZSS.
The target accuracy of PPP using this MADOCA-LEX signal is less than 10 [cm] (RMS) (for horizontal and vertical directions).

Note: Because the format is the provisional specification for test transmission, its information is subject to change based on the result of experiments and evaluations. In addition, interruption of transmission and degradation of the transmitted orbit and clock accuracy might be occurred.

(*1) MADOCA: "Multi-gnss Advanced Demonstration tool for Orbit-and-Clock Analysis" is a software for estimating orbits and clocks of satellites (GPS, GLONASS, Galileo and QZSS) with high precision.

Start of Test Transmission of MADOCA-LEX
JAXA begins the test transmission of MADOCA-LEX signal from April 9, 2013.
From now on, JAXA is going to transmit this MADOCA-LEX signal mainly in JAXA's LEX experiments replacing Message types 10 and 11 which were transmitted here before.
For the latest information of the schedule of LEX experiments, please refer to "Experiment Schedule"(*2) on this site ("QZ-vision").
Although JAXA had updated "Experiment Schedule" for next week on every Friday till now, JAXA is going to publish the "Experiment Schedule" from next week to maximum 8 weeks from now on.

If you want to use MADOCA-LEX on the days on which JAXA is not planning the experiment or the schedule is not adjusted yet, please send an E-mail to the following address by 15th of the previous month of the preferred date. Moreover, if you want to use previous LEX signal (message types 10 and 11) on the schedule of JAXA's experiment, please send an E-mail to the following address by two weeks before the date.
After adjusting with other experiment schedules, we would deal with the request if possible.

Contact Address :QZSS-JAXA-LEX

(*2)Experiment Schedule: Experiment schedule is coordinated in "QZSS Operation Coordination Meeting" by JAXA and related organizations based on the requests in order to decide which organization is in charge of the experiments weekly. In this meeting, the fixed schedule for next month and the temporary schedule for the month after that will be decided. (For example, in the meeting in April, the fixed schedule for May and the temporary schedule for June are decided.)
(Please note that the change of the schedule after the official decision is basically difficult.)

The report of QZSS User Meeting #7

JAXA successfully held the 7th QZSS User Meeting on February 13 and 14, 2013.
On both days, about 50 participants from 26 organizations (on Feb. 13) and from 30 organizations (on Feb. 14) gathered for the meeting.
We sincerely appreciate every person who participated in the meeting.
We collected 10 comments and suggestions for improvement regarding IS-QZSS (Ver. 1.4 and Ver. 1.5 Draft) from 5 organizations in Japan and overseas. We express gratitude to all contributors and note that all comments were highly appreciated as they led to improvements in the document.

JAXA is going to establish the formal version of "IS-QZSS ver.1.5" by the end of this month (March, 2013).
After the release of IS-QZSS ver. 1.5, JAXA would be going to update IS-QZSS (and related documents) if needed.

Release of IS-QZSS (Ver. 1.5) Draft

JAXA releases "IS-QZSS Version 1.5 Draft" as the revision notice of IS-QZSS (Ver.1.4) on Feb., 2012 on this QZ-Vision/JAXA web site.

Main Items to be updated
Main Items to be updated from IS-QZSS Version 1.4 (published on Feb. 2012) are as follows:
  1. Adding notes on QZSS signals to be modified according to the updating specification of GPS signals in the future IS-QZSS update.
  2. Updating information for QZS-1 based on the actual operation after the launch.
  3. Updating information in the timing of Ephemeris parameters, Almanacs and UTC parameters update.
  4. Updating information for L1-SAIF signal.
  5. Adding notes on items to be modified according to the progress of developing IMES (Indoor Messaging System).

Holding QZSS User Meeting #7
JAXA plans to hold QZSS User Meeting #7 to exchange views with the user community based on comments, questions and suggestions sent from users for improvement of "IS-QZSS (Ver. 1.5 Draft)".


Purposes of Public Release

IS-QZSS is a document to provide users with information such as interface and service performance specifications required to develop QZSS receivers and applications.

Hoping that QZSS will be utilized by many users, JAXA aims to promote development of QZSS receivers and applications based on the released information.

Content of IS-QZSS

IS-QZSS includes a system overview, a description of services, system performance specifications, RF features of positioning signals transmitted from a QZSS satellite, message specifications and recommended user algorithms.

For GPS complementary signals (L1C/A, L1C, L2C and L5), differences between QZSS and GPS are specified to make clear modifications required for GPS receivers to use QZSS signals.

Update Process and Schedule

JAXA released the IS-QZSS incrementally. After releasing each draft version, JAXA accepted comments, questions and suggestions for improvement via e-mail from the user community. Shortly thereafter, JAXA held a publicly open QZSS User Meeting to exchange views with the user community. Using this feedback, JAXA established the IS-QZSS Ver. 1.1 after official approval and signing.

JAXA will continue to improve the description of the system performance, the system operation, the data handling, and the generation and updating of the QZSS Navigation Messages to enhance the system's value to the user community as well as updating Section 7 and the Appendix of the IS-QZSS.

Same process applied during establishing the document, as shown in Figure 1, is to be applied for updating and revising the IS-QZSS after publication of a revision notice.

Below are the flow chart (Figure 1) and planned schedule for update (Figure 2).

IS-QZSS Release and Update Process

GPS-QZSS Technical Working Group(TWG) StatementGPS-QZSS TWG Statement

The GPS - QZSS Technical Working Group (TWG) was established according to a decision made by the 2nd US-Japan GPS Plenary meeting held on October 16, 2002 in Tokyo under the auspices of the 1998 US-Japan Joint Statement on Cooperation in the use of GPS. The purpose of the TWG is to exchange information and share concepts in an effort to achieve compatibility and technical interoperability between QZSS and current and future configurations of GPS.

Both co-chair agreed to announce a formal statement which describes the process for ongoing maintenance of the IS documents for both GPS and QZSS in order to maintain interoperability between both systems. (United States - Japan Technical Working Group (TWG) Statement)


* JAXA will not accept comments without your full name and contact information. Your personal information will be managed properly and used only for JAXA inquiry purposes.

* Your comments and suggestions may be anonymously published on the JAXA web site or presented for discussion at a QZSS User Meeting. Note that such public disclosures of your comments will never include your name or other personal data.

* JAXA will comprehensively examine the relevance and feasibility of your comments and suggestions and decide whether to reflect them in the subsequent revision of IS-QZSS.

* JAXA will not be able to respond to your comments and suggestions individually.

* Please refer to JAXA's official "Privacy Policy" regarding handling of collected personal information.


Ver.1.5 (English) (PDF file 7.5 MB)
IS-QZSS (English) (IS-QZSS Ver.1.5)

Ver.1.5 (English) (with Revision History) (PDF file 7.7 MB)
IS-QZSS (English) (IS-QZSS Ver.1.5(with Revision History)

Adobe Reader software is required to view and print PDF files.


MADOCA-LEX Format (Provisional)
(English) (PDF 0.4 MB)
MADOCA-LEX Format (Provisional)(English version) download (PDF 0.4 MB)

MADOCA-LEX Format (Provisional)
(Japanese) (PDF 0.4 MB)
MADOCA-LEX Format (Provisional)(Japanese version) download (PDF 0.4 MB)

Answers for Your Comments Answers for Your Comments and Suggestions for Improvement

Answers for Your Comments and Suggestions for Improvement for IS-QZSS 1.4 and 1.5 Draft

We got 10 comments, questions and suggestions for Improvement for IS-QZSS 1.4 and 1.5 Draft

Comment and Suggestions for Improvement List and Answers from JAXA.

Answers for Your Comments and Suggestions for Improvement for IS-QZSS 1.4 and 1.5Draft Download
(About 200[KB]) (Sorry, but Japanese only.)

RINEX formatRINEX 2.12 QZSS extension

RINEX 2.12 QZSS extension download

Sample data of QZSS observation data at Monitor Stations and navigation data (for RINEX2.12 QZSS ext.)

RINEX 3.01 QZSS extension

Please refer to the extension point from RINEX3.01.
RINEX 3.01 QZSS extension download

Sample data (for RINEX3.01 QZSS ext.)

Contact Us Welcome any comments


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