IRNSS Satellite Navigation System: Explained

Introduction

Since the beginning of time, human beings have looked to the sky to determine their whereabouts. Traditionally, the Sun and the pattern of fixed stars have been their guides. But in the second millennium, constellations of man-made satellites have taken over as beacons to guide the way.

What is satellite navigation?

Using the fixed stars, you can determine your position anywhere on the Earth’s surface to within a few hundred meters provided the weather is fine. But navigation satellites can tell you where you are to the nearest few meters or better, whatever the weather. Enhanced instruments can even pinpoint the position of a stationary object to within a few centimeters by measuring the object’s position many thousands of times over several hours and then working out the average of the measurements. Sophisticated new receiver technology picks up signals transmitted by navigational satellites. The receiver technology is small enough to be incorporated into the electronics of a car or mobile phone, and all our lives are changing as a result.

A satellite navigation is a system of satellites that provide autonomous geo-spatial positioning with global or regional coverage. The signals also allow the electronic receivers to calculate the current local time to high precision, which allows time synchronisation. A satellite navigation system with global coverage may be termed a global navigation satellite system or GNSS.

American Global Positioning System (GPS) technology is widely available for vehicles and smartphones. GPS was originally developed in the United States for defense related applications, way back in the 1970s, GPS services became available to civilians in the 1990s. The technology is based on the user's receiver picking up precisely timed radio signals from orbiting satellites, and calculating its distance from each source. Since the signals also communicate the position of each satellite in its orbit, the device can combine the information to pinpoint the location of the user in three dimensions. The precise time signals from the constellation of satellites - 32 in total for GPS - can also provide accurate time and synchronization data for mobile phones and networks.

Some of the major Satellite Navigation Systems are the Global Positioning System (US), GLONASS (Russia), Galileo (Europe), Indian Regional Navigation Satellite System (IRNSS), Quasi-Zenith Satellite System (Japan), Doppler Orbitography and Radio-positioning Integrated by Satellite-DORIS (France) and BeiDou-2 (China).

Indian Regional Navigation Satellite System (IRNSS)

Satellite Navigation service is an emerging satellite based system with commercial and strategic applications. ISRO is committed to provide the satellite based Navigation services to meet the emerging demands of the Civil Aviation requirements and to meet the user requirements of the positioning, navigation and timing based on the independent satellite navigation system. To meet the Civil Aviation requirements, ISRO is working jointly with Airport Authority of India (AAI) in establishing the GPS Aided Geo Augmented Navigation (GAGAN) system. To meet the user requirements of the positioning, navigation and timing services based on the indigenous system, ISRO is establishing a regional satellite navigation system called Indian Regional Navigation Satellite System (IRNSS).

(a) GPS Aided GEO Augmented Navigation (GAGAN):

This is a Satellite Based Augmentation System (SBAS) implemented jointly with Airport Authority of India (AAI). The main objectives of GAGAN are to provide Satellite-based Navigation services with accuracy and integrity required for civil aviation applications and to provide better Air Traffic Management over Indian Airspace. The system will be interoperable with other international SBAS systems and provide seamless navigation across regional boundaries. The GAGAN Signal-In-Space (SIS) is available through GSAT-8 and GSAT-10.

(b) Indian Regional Navigation Satellite System (IRNSS)

This is an independent Indian Satellite based positioning system for critical National applications. The main objective is to provide Reliable Position, Navigation and Timing services over India and its neighbourhood, to provide fairly good accuracy to the user.

IRNSS will provide basically two types of services:

• Standard Positioning Service (SPS)
• Restricted Service (RS) 

Space Segment consists of seven satellites, three satellites in GEO stationary orbit (GEO) and four satellites in Geo Synchronous Orbit (GSO) orbit with inclination of 29° to the equatorial plane. All the satellites will be visible at all times in the Indian region. The first satellite is scheduled to be launched in 2013 and the total seven satellite constellation is scheduled to be in place by 2016. Ground Segment is responsible for the maintenance and operation of the IRNSS constellation. It provides the monitoring of the constellation status, computation of the orbital and clock parameters and navigation data uploading. The Ground segment comprises of TTC & Uplinking Stations, Spacecraft Control Centre, IRNSS Timing Centre, CDMA Ranging Stations, Navigation Control Centre and Data Communication Links. Space segment is compatible with single frequency receiver for Standard Positioning Service (SPS), dual frequency receiver for both SPS & RS service and a multi mode receiver compatible with other GNSS providers.

Some applications of IRNSS are:

• Terrestrial, Aerial and Marine Navigation 
• Disaster Management 
• Vehicle tracking and fleet management 
• Integration with mobile phones 
• Precise Timing 
• Mapping and Geodetic Data Capture 
• Terrestrial navigation aid for hikers and travellers 
• Visual and voice navigation for drivers

Courtesy of IDN

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Major Achievements of ISRO Year Ended 2014

Introduction

The Indian Space Programme had a modest beginning with the launch of the first sounding rockets in November 1963 from the Thumba Equatorial Rocket Launching Station (TERLS), an obscure fishing village near Thiruvananthapuram for the investigation of ionosphere using sounding rockets. The primary objective of the Indian Space Program is to achieve self-reliance in Space Technology and to evolve application program to meet the developmental needs of the country, thus ISRO was brought under the newly formed DOS in September 1972. 

Since then, over the last five decades, the ever challenging task of space technology development and utilisation, has not only graduated from experimental and demonstration phases to an operation era, but also provided its potential to address the national needs. Notable progress has been made in the design, development and operation of space systems, as well as, using them for vital services like telecommunications, television broadcasting, meteorology, disaster management support and natural resources survey and management including climate variability and change.

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The Science of GSLV

Geosynchronous Satellite Launch Booster

The glorious journey began at the magnanimous

St.Mary Magdalene Church (left),

it was the first lab and office of ISRO 

Currently maintained as a majestic Space Museum - Image: ISROHQ

THE EVOLUTION OF INDIA’S ROCKET PROGRAM

In 1962 in a rather nondescript fishing hamlet called Thumba near Thiruvananathapuram close to the sea, two stalwarts and visionaries of the Indian Space and Nuclear program were scouting for a new rocket launching facility along with other fellow scientists. One was the blue-blooded Dr. Vikram Sarabhai and the other the aristocratic Dr. Homi Jehangir Bhabha. Within a year’s time the Thumba Equatorial Rocket Launching Station (TERLS) was born. This was just a humble beginning but over the years, India achieved the capability of building its own launch vehicles, remote sensing, communication, defense and navigation satellites, launch interplanetary and lunar missions, design and develop the closely guarded and cutting-edge cryogenic engine. TERLS primarily focused on launching sounding rockets (SR) to study of equatorial electro-jet phenomena, which is a stream of electric current flowing in a narrow band on either side of the magnetic equator at a height of around 100 kms.

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2013: Space Launch Yearbook

SPACE LAUNCH REPORT FOR THE YEAR 2013

There were in total 81 spaceflight launches by 7 countries in 2013, unfortunately out of these 3 were failures. In the year 2012 there were 78 launches out of which 2 were unsuccessful. 

SPACE LAUNCHES BY FAMILY

Figure 1

Figure 1 Shows the number of launches by different family of rockets, however launches such as the Russian - Strela, European Space Agency - Vega, United States - Pegasus, Antares and Minotaur-1, Japanese - Epsilon, South Korean - Naro-1 (formerly Korea Space Launch Vehicle-KSLV) and the Chinese LV Kuaizhou is not represented because of single launch during the year. The last 3 vehicles had successful launches on debut. There were also a few inaugural launches in 2013, the Falcon 9 v.1.1, Antares, Minotaur V and Soyuz-2.1V. Interestingly, the first three are operated by private companies namely SpaceX and Orbital Sciences, this clearly reflects the general trend at least in the US of gaining commendable position by private companies in the annual commercial launches for all the sectors like the US Department of Defense, Commercial and International Space Station duties. 

There were totally three failures in 2013. The first was the failure of the Zenit-3SL carrying the Intelsat 27 satellite by Sea Launch, and then there was the dramatic accident of a "Proton-M" with three navigation satellites "Glonass-M" and finally the Chinese Long March 4B rocket failed to put the Brazilian Satellite CBERS-3 into orbit. The first two accidents were caused by the malfunction of the first stages of the launch, the last on account of failure of the upper stage.

SPACE LAUNCHES BY ORBIT

Figure 2

Figure 2 Shows the distribution of space launches by orbit. Nearly half of all the launches (40 out of 81) were to the Low Earth Orbit followed by Geostationary orbit (25 out of 81).

SPACE LAUNCHES BY SPACEPORT

Figure 3

Figure 3 Shows the number of launches attempted at different spaceports. The leader of this list is Baikonur spaceport with an impressive tally of 23 Launches by Russia (in 2012 it was 21), Cape Canaveral of the US was followed by 10.

SPACE LAUNCHES BY COUNTRY

Figure 4

Figure 4 shows Russia's leading the race with an impressive 33 launches followed way behind by the US, then Europe, China and India. Also note the entry of South Korea into the space club with its third attempt, the Korean launch vehicle (KSLV) is built with Russian help as the first stage, a semi-cryogenic engine burning Liquid Oxygen and Kerosene is developed by Khrunichev of Russia. Graphics: Viacheslav Pronskyi: - in Russian Language

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