Comparison Gps Glonass Galileo Plnraju2

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Module 2 – GPS (EDUSAT based Trg.)

Comparative study of NAVSTAR GPS/ GLONASS/GALILEO/ Augmented Positioning Systems P.L.N. Raju, Geoinformatics Division IIRS Email – [email protected]

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Module 2 - GPS Introduction

Global Navigation Satellite Systems (GNSS) involve satellites, ground stations and user equipment to determine positions around the world and are now used across many areas of society

GNSS

GPS (USA), GLONASS (Russia),

Galileo(Europe), Augmentation Systems (SBAS, GBAS), IRNS (India), QuasiZenth (Japan) Fuelling growth during the next decade will be next generation GNSS that are currently being developed.

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Outline of my Talk

Comparison of – GPS – GLONASS – GALILEO

Augmented SBNS – – – – – – –

WAAS MSAS EGNOS GAGAN GBNS (NDGPS/LAAS) Chinese Beidou System IRNSS, India’s Navigation System

iirs GPS Constellation Plane F E D C B A

D2

E1

B3

C2

B2

D1

F3

F1 C1

A2 F2

A1

C3 E2 C4

E3

ea n

E4

B4

A4

M

D3

B1

an om

a ly

F4 A3

160°

40°

Equator

0°

320°

280° 240° 200°

D4

120° 80°

17° 137° 257° 77° 197° 317°

satellite operational spare

Right ascension of ascending node Inclination 55° Semimajor axis 26561.75 km (altitude above Earth 20183,6 km) Excentricity nominally e = 0, generally e < 0,02

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GNSS SYSTEM

GPS Modernization •

Improved code on the L2 frequency of GPS (called L2C) – •

ionospheric error,

•

more immune to RF interference and

•

multipath.

•

The first Block IIR-M during October 2005.

•

Under currently published plans, that is not expected to occur until 2013 or beyond.

•

A third civil frequency at 1176.45MHz (called L5) on the Block IIF satellites. Full operational capability is unlikely until 2015.

•

GPS-III, (extra L2 and L5 signals of the Block IIR-M and Block IIF satellites), Thirty GPS-III satellites are planned for launch from about 2013 until 2018.

iirs GLONASS Constellation

24 satellites (8 satellites in each of 3 planes) e ~ 0 (circular orbit) inclination 64.8° altitude 19 100 km, orbit period 11h 15m angular spacing between orbits 120°

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About GLONASS

GLobal NAvigation Satellite System Beginning in 1982 Belongs to USSR (Now Russia) No onboard atomic clocks Precise timing on the ground Few years of life 12 Satellites in orbit Three orbital planes

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About GLONASS

GLONASS receives similar navigational data GPS + GLONASS combined receivers Mostly secrete (till 1988/1989) Works on two frequencies like GPS Few years back receivers were with GPS + GLONASS, latest no receiver with GLONASS

13 12 11 8 7

2004

10

2002 2003

12 12 12

2000 2001

14

1998 1999

16

1996 1997

1995

1993 1994

12

1991 1992

1990

9

1988 1989

1987

iirs GLONASS Constellation history

26 22 16 10

8

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About GLONASS

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GLONASS Future Plans of Russia GLONASS-M (L1 and L2 bands ) satellites with an improved 7year design lifetime. 2007 to 2008 planned to launch GLONASS-K satellites with improved performance, also transmit a third civil signal (L3). Stated intention is to achieve a full 24-satellite constellation transmitting two civil signals by 2010. Full constellation is planned to be broadcasting three sets of civil signals by 2012. Indian Government announced at the end of 2004 that it would be contributing funds to assist Russia to revitalize GLONASS.

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Galileo from the European Union

Constellation of 30 satellites, increased altitude (approx. 3000km higher than GPS) which will enable better signal availability at high latitudes. Exact signal structure is still liable to change, Galileo satellites broadcast signals compatible with the L1(E5a E5b) and L5 GPS signals. Galileo will also broadcast in a third frequency band at E6; which is not at the same frequency as L2/L2C of GPS.

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About GALILEO

Galileo

Galileo Constellation

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About GALILEO

GIOVE - standing for 'Galileo In-Orbit Validation Element

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Galileo services

Open Service(OS) The OS is free and provides a GPS – like service, but with enhanced accuracy. Playing an active role in the integration of Galileo OS with GSM/UMTS systems Safety of Life Service (SoL) This service is intended for aircraft navigation.

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Galileo services

Commercial Service (CS) Galileo CS provides enhanced accuracy compared to OS, and transmits restricted access broadcasts to subscribers Public Regulated Service (PRS) Galileo PRS is an encrypted service intended for emergency and defense use.

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Galileo services

Search and Rescue Service (SAR) Each Galileo satellite will have a receiver to receive alert message communicated by International Search and Rescue Network and transmit on Galileo SAR signals

iirs Different services and accuracy of position

iirs Satellite Based Augmented Systems • WAAS (Wide Area Augmentation System) • GAGAN (GPS Aided Geo Augmented Navigation) • EGNOS (European Geo-stationary Navigation Overlay Service ) • MSAS (Multi-Functional Satellite Augmentation System) • NDGPS (National level Differential Global Positioning System) • GBAS (Ground Based Augmented System) Chinese Beidou System ~ (NDGPS/LAAS) • India’s IRNSS

iirs Satellite Based Augmented Systems

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How Position Accuracy improved with SBAS?

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About WAAS

The Federal Aviation Administration (FAA) and the Department of Transportation (DOT) have developed the WAAS program for use in precision flight approaches. Currently, GPS alone does not meet the FAA's navigation requirements for accuracy, integrity, and availability. WAAS corrects for GPS signal errors caused by ionosphere disturbances, timing, and satellite orbit errors, and it provides vital integrity information regarding the health of each GPS satellite.

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How WAAS Works?

WAAS consists of approximately 25 ground reference stations positioned across the United States that monitor GPS satellite data. Two master stations, located on either coast, collect data from the reference stations and create a GPS correction message. This correction accounts for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere. The corrected differential message is then broadcast through one of two geo-stationary satellites, or satellites with a fixed position over the equator. The information is compatible with the basic GPS signal structure, which means any WAASenabled GPS receiver can read the signal. Note: 1 – 3 m accuracy obtained with WAAS support

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How WAAS Works?

iirs Ground Based Augmented Systems

iirs NDGPS To ensure greater accuracy and improved integrity, the US Department of Transportation is deploying the Nationwide Differential Global Positioning System (NDGPS) service. This service uses ground reference stations to determine the differential between the GPS solution and the true solution. This differential is then broadcast on a low frequency carrier for users to access, free of direct user charge. NDGPS provides accurate dynamic navigation information to travelers with 1- to 2- meter accuracy (and possibly better in the future).

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About GAGAN

GPS Aided Geo Augmentation Navigation India and US cooperation to integrate GPS for ground based positioning To improve air traffic and other civil navigation Joint venture of ISRO and AAI for 110 cr 8 reference stations Master Control and Uplink facility

iirs EGNOS

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iirs Quasi Zenith Satellite System

iirs Augmentations SBAS Constellation

GAGAN EGNOS

MSAS MTSAT

WAAS

INMARSAT ARTEMIS

INMARSAT

GPS

iirs Local Area Augmentation System It is an all-weather aircraft landing system based on real-time differential correction of the GPS signal. Local reference receivers send data to a central location at the airport. This data is used to formulate a correction message, which is then transmitted to users via a VHF data link. A receiver on an aircraft uses this information to correct GPS signals, which then provides a standard ILS-style display to use while flying a precision approach.

iirs Chinese Beidou navigation system Geostationary satellites Mainly for China Four satellites launched so Far 10 m accuracy Open services by 2008 Covers North side 5° to 50° N Latitude and 70°E to 140°E Receiver sends signal, satellite estimates based on time of it

iirs IRNSS – India’s own Navigation System Indian Regional Navigation Satellite System (IRNSS) With seven satellites GEO/ elliptical orbit To be Build and launch by ISRO Costs 16 billion rupees First meeting held in July 2006

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References

• Wikipedia the free online encyclopedia for GPS, EGNOS, WAAS, LAAS, NDGPS, Beidou Navigation System • Coordinates monthly Indian News Letter • GPS World Magazine

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