BeiDou, QZSS, and NavIC Navigation Satellite Systems

Vocabulary terms and definitions from the lecture notes covering the development, configuration, and signal characteristics of China's BeiDou (BDS), Japan's QZSS, and India's NavIC satellite navigation systems.

BeiDou Navigation Satellite System (BDS)

A global navigation satellite system independently developed and operated by China, designed to be compatible and interoperable with other GNSS constellations.

BDS Space Segment

A mixed constellation containing 5 GEO satellites and 30 non-GEO satellites, which include IGSO and MEO satellites.

Trilateration

The positioning mechanism used by BDS, similar to GPS, GLONASS, and Galileo.

Beidou-1 System (BD-1)

The experimental phase of the BeiDou project (1994) that utilized the radio determination satellite service (RDSS) technique and two-way active ranging for positioning.

Beidou-2 System (BD-2)

The regional navigation satellite system phase (started in 2004) that provided passive three-dimensional positioning, velocity measurement, and timing to the Asia-Pacific region.

Radio Determination Satellite Service (RDSS)

A service unique to BDS among GNSS providers that offers rapid positioning, short-message communication, and precise timing via GEO satellites.

China Geodetic Coordinate System 2000 (CGCS2000)

The coordinate system used by BDS, which is a global geocentric coordinate system consistent with the International Terrestrial Reference System (ITRS).

BeiDou Time (BDT)

The time reference system for BDS that adopts the International System second ($SI$) as the basic unit and has an initial epoch of Hour $00$ Minute $00$ Second $00$ on January 1, 2006 (UTC).

B1 Signal (BDS Regional)

A navigation signal with a carrier frequency of $1,561.098\,MHz$ that provides both public (B1I) and authorized (B1Q) services.

Quadrature Multiplexing BOC (QMBOC)

A modulation technique for the BDS global B1 signal that modulates BOC(1,1) and BOC(6,1) components onto two orthogonal phases to improve compatibility with GPS and Galileo.

Asymmetric Constant Envelope BOC (ACE-BOC)

A multiplexing technique for BDS B2 signals that utilizes orthogonal data and pilot components to form an integral signal with a constant envelope.

Quasi-Zenith Satellite System (QZSS)

A regional civil SATNAV system operated by JAXA on behalf of the Japanese government, designed to complement and be interoperable with the U.S. GPS over Japan.

Michibiki

The nickname for QZSS satellites, meaning "guiding light," which operates in an inclined-elliptical-geosynchronous orbit.

DS2000

The standardized 3-axis stabilized spacecraft bus manufactured by Mitsubishi Electric used for the QZSS satellites.

QZSS Time (QZSST)

A continuous time scale independent of leap seconds maintained by the master clock at the MCS in Tsukuba Space Center.

L1S Signal

A QZSS submeter-class augmentation signal at $1,575.42\,MHz$ designed to be interoperable with GPS-SBAS and provide disaster and crisis management messages.

Navigation with Indian Constellation (NavIC)

Formerly known as IRNSS, it is a regional SATNAV system operated by ISRO providing coverage approximately $1,500\,km$ around India.

NavIC Frequencies

A dual-band system transmitting navigation signals in both the L5-band ($1,176.45\,MHz$) and the S-band ($2,492.028\,MHz$).

IRNSS Network Time (IRNWT)

The continuous time scale for NavIC traceable to Indian National Time (UTC NPLI) with a start epoch of August 22, 1999.

Standard Positioning Service (SPS)

The public positioning service provided by NavIC that uses Gold codes with a length of $1,023$ chips and a chipping rate of $1.023\,Mcps$.