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GLONASS

GLONASS stand for Global Navigation Satellite System, Russia, it is a space-based Global Navigation Satellite System (GNSS), operated by the Russian Federation. The GLONASS is a part of GPS System. The first GLONASS satellite was launched in 1982 and the system was declared fully operational in 1993.

GLONASS System

Orbital Constellation:
24 Satellites
(3 planes x 8 satellites)
Orbit type: circular,
H = 19 100 km,
i = 64.8°
Orbital period:
11 hr 15 min
The orbits are shifted by
120° along the equator

Fundanmental of GNSS-GLONASS

As with GPS, the GLONASS system design consists of 3 parts:

GLONASS Satellite Constellation

CapabilitiesGlonassGlonass-MGlonass-KGlonass-K2
Time of Deployment1982-20052003-20162011-20182017+
StatusDecommissionedIn useDesign maturation based on in-orbit validationIn development
Nominal Orbit ParametersCircular
Altitude – 19,100 km
Inclination – 64,8°
Period – 11 h 15 min 44 sec
Number of Satellites in the Constellation (Used for Navigation)24
Number of Orbital Planes3
Number of Satellites in a Plane8
Launchers Soyuz-2.1b, Proton-M
Design Lifetime, years3.571010
Mass, kg150014159351600
Dimensions, m 2,71х3,05х2,712,53х3,01х1,432,53х6,01х1,43
Power, W 140012704370
Platform DesignPressurizedPressurizedUnpressurizedUnpressurized
Clock Stability, as per Specification/Observed5✕10-13 / 1✕10-131✕10-13 / 5✕10-141✕10-13 / 5✕10-141✕10-14 / 5✕10-15
Signal TypeFDMAFDMA (+CDMA for SVs 755-761)FDMA and CDMAFDMA and CDMA
Open Access Signals (for FDMA Signals Center Frequency Values are Provided)L1OF (1602 MHz)L1OF (1602 MHz)
L2OF (1246 MHz)
L3OC (1202 MHz) for SVs 755+
L1OF (1602 MHz)
L2OF (1246 MHz)
L3OC (1202 MHz)
L2OC (1248 MHz) for SVs 17L+
L1OF (1602 MHz)
L2OF (1246 MHz)
L1OC (1600 MHz)
L2OC (1248 MHz)
L3OC (1202 MHz)
Restricted Access SignalsL1SF (1592 MHz)
L2SF (1237 MHz)
L1SF (1592 MHz)
L2SF (1237 MHz)
L1SF (1592 MHz)
L2SF (1237 MHz)
L2SC (1248 MHz) for SVs 17L+
L1SF (1592 MHz)
L2SF (1237 MHz)
L1SC (1600 MHz)
L2SC (1248 MHz)

Advantages of GLONASS

  • Increased satellite signal observations
  • Markedly increased spatial distribution of visible satellites
  • Reduced Horizontal and Vertical Dilution of Precision (DOP) factors
  • Decreased occupation times means faster RTK results
GLONASS development 2002 –– 2011

Phase I: Replenishment of the constellation with the existing GLONASS SV

  • Maintaining the constellation at a minimal level.

Phase II: System upgrade using GLONASS-M SV

  • Flight tests of the GLONASS-M SV in 2003.
  • Guaranteed active life of 7 years.
  • Transition to the agreed frequency band.
  • Introducing a second frequency for the civil community.
  • Test trials of elements for the advanced SNS.

Phase III: Further system upgrade using GLONASS-K SV

  • Further upgrade of the SV active life to 10 years and more.
  • Reducing the overall SV mass to provide launches of 6 to 8 SV at a time by PROTON-M rocket launchers and 2 to 3 SV by SOYUZ-2 launchers.
  • Upgrade of the ground control complex.
  • Introducing a third frequency in the L-band.
  • Improving navigation signal characteristics taking into consideration the growing navigation user requirements.
Comparison of GLONASS and GPS Characteristics
SatellitesGLONASSGPS
Number of satellites21 + 3 spares21 + 3 spares
Number of orbital planes36
Orbital plane inclination (degrees)64.855
Orbital radius (kilometers)25,51026,560
SignalsGLONASSGPS
Fundamental clock frequency (MHz)5.010.23
Signal separation techniqueFDMACDMA
Carrier frequencies (MHz)L1-1598.0625-1609.3125
L2-1242.9375-1251.6875
1575.42
1227.6
Code clock rate (MHz)C/A- 0.511
P- 5.11
1.023
10.23
Code length (chips)C/A- 511
P- 5.11 x 10 6
1 023
6.187104 x 10 12
C/A-code Navigation
Message
GLONASSGPS
Superframe duration (minutes)2.512.5
Superframe capacity (bits)7 50037 500
Superframe reserve capacity (bits)~620~2 750
Word duration (seconds)2.00.6
Word capacity (bits)10030
Number of words within a frame1550
Technique for specifying satellite
ephemeris
Geocentric Cartesian
coordinates and their
derivatives
Keplarian orbital
elements and
perturbation factors
Time referenceUTC (SU)UTC (USNO)
Position reference (geodetic datum)PZ-90WGS84

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