4.6 Navigation Satellite System
237
much bigger and costlier than similar GPS receivers. In the late 2010, there were
only a handful of GLONASS receivers on the market, and few of them were meant
for ordinary consumers. To improve the situation, the Russian government had been
actively promoting the GLONASS for civilian uses, taking a series of measures, such
as increasing the import duty on all GPS-capable devices including mobile phones,
demanding the car manufacturers in Russia to use the GLONASS starting from 2011,
funding the development of the GLONASS navigation base-band chips, developing
new supplemental technologies, and maintaining navigational maps to attract more
GLONASS users.
As of April 2020, there are 27 satellites in the GLONASS constellation, where 24
are normally operational, 2 are in-orbit spares and 1 is in flight test phase. In addition,
a revised version of the GLONASS-K satellite, GLONASS-K2, is being expected
to place into the constellation in 2020, with a mass of about 1800 kg and a design
life of 10 years. The GLONASS-K2 will transmit eight navigation signals, L1OF,
L1SF, L1OC, L1SC, L2OF, L2SF, L2SC and L3OC, where “O” stands for the open
signal (standard precision), “S” for the obfuscated signal (high precision), “F” for the
FDMA and “C” for the CDMA. Furthermore, a modernized GLONASS-K satellite,
known as GLONASS-KM, is being designed at present, which will transmit the
legacy FDMA signals on L1 and L2 and CDMA signals on L1, L2 and L3, and also
do the CDMA signals on the GPS L5 frequency at 1176.45 MHz. According to the
current schedule, the GLONASS-KM series will not be deployed to the constellation
until 2025.
4.6.3.3 BeiDou System
In the early 1980s, China began to actively explore the space-based navigation system
suitable for its own national conditions, known as BeiDou Navigation Satellite
System (BDS). In accordance with the development idea of “first region, then global”
[10, 11], the BDS is implemented on the following three phases.
The first phase is from 1994 to 2003, to build BeiDou navigation satellite test
system. In 1994, the Chinese government initiated the construction of the BeiDou test
system project, known as BDS-1. Two BDS-1 satellites were successfully launched
in October and December 2000, respectively, which marked the BeiDou test system
was built, and thus China became the third country in the world with independent
navigation satellite system. In May 2003, the third BDS-1 satellite was sent into the
predetermined orbit to further enhance the performance of the BeiDou test system.
The BeiDou test system is a regional navigation and timing service system for
China’s territory and surrounding areas, and consists of three parts, space segment,
ground segment and user segment. The space segment is a constellation with three
Geostationary Orbit (GEO) satellites, which are located, respectively, at 80°E,
110.5°E and 140°E over the equator. The ground segment consists of one control
center and many calibration stations, which are used to determine the BDS-1 satellite
orbits, measure the distances between the satellites and ground stations, correct ionosphere, determine the BDS-1 user’s locations, exchange the user’s short messages,
237
much bigger and costlier than similar GPS receivers. In the late 2010, there were
only a handful of GLONASS receivers on the market, and few of them were meant
for ordinary consumers. To improve the situation, the Russian government had been
actively promoting the GLONASS for civilian uses, taking a series of measures, such
as increasing the import duty on all GPS-capable devices including mobile phones,
demanding the car manufacturers in Russia to use the GLONASS starting from 2011,
funding the development of the GLONASS navigation base-band chips, developing
new supplemental technologies, and maintaining navigational maps to attract more
GLONASS users.
As of April 2020, there are 27 satellites in the GLONASS constellation, where 24
are normally operational, 2 are in-orbit spares and 1 is in flight test phase. In addition,
a revised version of the GLONASS-K satellite, GLONASS-K2, is being expected
to place into the constellation in 2020, with a mass of about 1800 kg and a design
life of 10 years. The GLONASS-K2 will transmit eight navigation signals, L1OF,
L1SF, L1OC, L1SC, L2OF, L2SF, L2SC and L3OC, where “O” stands for the open
signal (standard precision), “S” for the obfuscated signal (high precision), “F” for the
FDMA and “C” for the CDMA. Furthermore, a modernized GLONASS-K satellite,
known as GLONASS-KM, is being designed at present, which will transmit the
legacy FDMA signals on L1 and L2 and CDMA signals on L1, L2 and L3, and also
do the CDMA signals on the GPS L5 frequency at 1176.45 MHz. According to the
current schedule, the GLONASS-KM series will not be deployed to the constellation
until 2025.
4.6.3.3 BeiDou System
In the early 1980s, China began to actively explore the space-based navigation system
suitable for its own national conditions, known as BeiDou Navigation Satellite
System (BDS). In accordance with the development idea of “first region, then global”
[10, 11], the BDS is implemented on the following three phases.
The first phase is from 1994 to 2003, to build BeiDou navigation satellite test
system. In 1994, the Chinese government initiated the construction of the BeiDou test
system project, known as BDS-1. Two BDS-1 satellites were successfully launched
in October and December 2000, respectively, which marked the BeiDou test system
was built, and thus China became the third country in the world with independent
navigation satellite system. In May 2003, the third BDS-1 satellite was sent into the
predetermined orbit to further enhance the performance of the BeiDou test system.
The BeiDou test system is a regional navigation and timing service system for
China’s territory and surrounding areas, and consists of three parts, space segment,
ground segment and user segment. The space segment is a constellation with three
Geostationary Orbit (GEO) satellites, which are located, respectively, at 80°E,
110.5°E and 140°E over the equator. The ground segment consists of one control
center and many calibration stations, which are used to determine the BDS-1 satellite
orbits, measure the distances between the satellites and ground stations, correct ionosphere, determine the BDS-1 user’s locations, exchange the user’s short messages,