Russian satelites(glonass)

GLONASS

GLONASS The Soviet union began development of

Glonass in 1976. In 1982 a constellation of 24 satellites

started working properly. After the collapse of Russia's economy ,

Glonass development was put on hold. In 2001 the full satellite constellation

was finally restored on 2nd October by Russian president VALDIMIR PUTIN.

GLONASS constellation

How does GLONASS work? System have 24 satellite constellations that orbit the

Earth at an altitude of 10,900 nautical miles.

These satellites broadcast their position and the exact time that they are in that position on a continuous basis. A glonass receiver compares the signals from at least three or four satellites and sent information towards the control segment.

Accuracy verificationAccuracy verification• Russian system compares values, altitude, and Russian system compares values, altitude, and

altitude rate estimates to US estimates for verification altitude rate estimates to US estimates for verification and fault detection.and fault detection.

GLONASS SATELLITEThe Russian GLONASS consists of a constellation of

24 (21 active and 3 spares) satellites and their ground based stations.

The satellites orbit the Earth once every 11hours and 15 minutes on three orbital planes separated by 120°.

Life expectancy of these satellites is 3-5 years. Next generation satellites are being developed with an expected service life of 10 years.

All ground based stations are located within former Soviet Union territory.

In December 2010,three satellites crushed during launch.

GLONASS satellite

Three segments of GlonassSpace segmentGround/Cotrol segmentUser segment

The main functions of the space segment are to transmit radio navigation signal ,to store and transmits the navigation message sent by the control segment. The mechanism of high atomic clock.

The GLONASS space segment consist mainly of 24 operating satellite distributed over three orbital plane. Each orbit consist of 8 satellites.

GLONASS Ground segment

The glonass ground segment or control segment is responsible for the proper operation of glonass.

The glonass ground segment consist of:_A system control centre located at

KRASNOZNAMENSK._The central clock situated in SCHELKOVE near

MASCOW._Two laser ranging stations, a network of four

monitoring and measuring stations(Schelkove)

GLONASS user segmentThe Glonass user segment consist on

receiver/processor and antennas which receive glonass signals, determine pseudoranges and solve the navigation in order to obtain their co-ordinates and provide accurate time.

• The time it takes for a signal to travel from the satellite to the receiver gives a direct indication of distance. This distance from the satellite is used by the receiver to fix position.

ERRORSThere are few other variables that

the receiver needs to take into account to ensure accuracy:Atmospheric errorMultipath errorSatellite geometry

GLONASS & GPS(NAVSTAR)

Both the system have their stregnths and weaknesses while GPS is generally considered the better option on most parts of the globe. Glonass is believed to have a superior accuracy in the north latitudes of the planet as the system was developed to provide the best service to Russia which extends to the highest latitudes.

Who can use GLONASS

As GPS Glonass was originally only for military.

The system was made available for public and

commercial use in 2007 although GPS has been available for civilian use since 1990.