The American Surveyor

UPDATED – JAVAD GNSS Tracks QZSS Satellite and its New L1C Signal

Another first from Javad: On the afternoon of Friday October 29, 2010, JAVAD GNSS engineers in Moscow tracked Japan’s first QZSS satellite and its new L1C signal. The signals looked as expected. The company will present technical details on Monday.

Most of the current JAVAD GNSS receivers, including OEM boards, ALPHA, DELTA, SIGMA, TRIUMPH-1 and TRIUMPH-VS can track QZSS signals with a software update. The software upgrade may be released as early as next week.

About QZSS
The Quasi-Zenith Satellite System (QZSS), is a proposed three-satellite regional time transfer system and enhancement for the Global Positioning System, that would be receivable within Japan. The first satellite ‘Michibiki’ was launched on 11 September 2010. Full operational status is expected by 2013.

Authorized by the Japanese government in 2002, work on a concept for a Quasi-Zenith Satellite System (QZSS), or Juntencho in Japanese, began development by the Advanced Space Business Corporation (ASBC) team, including Mitsubishi Electric Corp., Hitachi Ltd., and GNSS Technologies Inc. However, ASBC collapsed in 2007. The work was taken over by the Satellite Positioning Research and Application Center. SPAC is owned by four departments of the Japanese government, the Ministry of Education, Culture, Sports, Science and Technology; of Internal Affairs and Communications,; of Economy, Trade and Industry; and the Ministry of Land, Infrastructure and Transport.

QZSS is targeted at mobile applications, to provide communications-based services (video, audio, and data) and positioning information. With regards to its positioning service, QZSS can only provide limited accuracy on its own and is not currently required in its specifications to work in a stand-alone mode. As such, it is viewed as a GNSS Augmentation service. Its positioning service could also collaborate with the geostationary satellites in Japan’s Multi-Functional Transport Satellite (MTSAT), currently under development, which itself is a Satellite Based Augmentation System similar to the U.S. Federal Aviation Administration’s Wide Area Augmentation System (WAAS).

The satellites would be placed in a periodic Highly Elliptical Orbit (HEO). These orbits allow the satellite to dwell for more than 12 hours a day with an elevation above 70° (meaning they appear almost overhead most of the time) and give rise to the term "quasi-zenith" for which the system is named. Similar orbits are used by the Sirius Satellite Radio system (Tundra orbit). As of June 2003, the proposed orbits ranged from 45° inclination with little eccentricity, to 53° with significant eccentricity. Source: Wikipedia

UPDATE – Michibiki satellite has a periodic Highly Elliptical Orbit (HEO). In Moscow its day track is shown in figure on left. On November 1, 2010, during 2 hours (from 10:00 to 12:00 UTC time), starting from 13 deg elevation and stopping at 3 deg elevation, L1C signal was tracked.

Shown are pseudorange (in chips, right) and SNR (relative numbers, bottom) plots for this period of time. It appears that Japanese engineers turn standard L1C code on when satellite approaches Japan area and turn it off when it goes  far away. Note that only L1C pilot signal was analyzed.

  

 

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