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ACKNOWLEDGEMENT

I extend my sincere thanks to Mr.B.S.CHANDRASHEKAR, Director, ISTRAC-ISRO

for having given me the permission to carryout the In-Plant training at ISTRAC,

Bangalore.

I am grateful to Mr.N.LAKSHMINARAYANA, HRD officer, for giving me an

opportunity to undertake the In-plant Training at ISTRAC, Bangalore. and to Smt

Seetha Madam ISTRAC-ISRO for arranging this training schedule and full support during

this training period.

I express my sincere thanks to Mr.J.V.NARASIMHAM, Manager, IBTF/GSNA,

and Mr S.Keshava Reddy Manager BL4 ISTRAC/ISRO for their constant guidance and

invaluable support.

With a sense of gratitude and respect, I would like to extend my heartiest thanks

to all those who provided help and guidance during my training period. It was pleasant

and highly educative experience to work here at ISTRAC-ISRO in Bangalore.

Shreyas G S

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CONTENTS page no.

1.0 Organization Profile(ISRO) 04

2.0 Overview of ISRO Telemetry Tracking 11

and Command Network

2.1 Operations of ISTRAC 12

3.0 Introduction to TTC Network 13

3.1 Ground Station Description & Specs 13

3.2 Processes performed at Ground Station 17

3.2.1 Uplink Chain 17

3.2.2 Downlink Chain 18

4.0 Missions Operations Complex(MOX) 20

5.0 Satellite Communication Division 21

5.1 VSAT-Very Small Aperture Terminal 22

5.2 Access methods in VSAT Communication 22

5.3 Indoor Unit(IDU) & Outdoor Unit(ODU) 25

In both HUB and Remote Side

5.4 Projects 25

5.5 Spacenet 26

6.0 Satellite Aided Search & Rescue System 27

7.0 Indian Deep Space Network (IDSN) 28

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7.1 18M antenna 28

7.2 32M antenna 29

7.3 External Network Stations 30

8.0 Indian Space Science Data Centre(ISSDC) 31

8.1 Payload Operation Centre 32

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1.0 ORGANISATION PROFILE

INDIAN SPACE RESEARCH ORGANIZATION (ISRO)

Space activities in the country started during early 1960s with the scientific investigation of upper atmosphere and ionosphere over the magnetic equator that passes over Thumba near Thiruvananthapuram using small sounding rockets. Realizing the immense potential of space technology for national development, Dr. Vikram Sarabhai, the visionary leader envisioned that this powerful technology could play a meaningful role in national development and solving the problems of common man.

Thus, Indian Space programme born in the church beginning, space activities in the country, concentrated on achieving self reliance and developing capability to build and launch communication satellites for television broadcast, telecommunications and meteorological applications; remote sensing satellites for management of natural resources. The objective of ISRO is to develop space technology and its application to various national tasks. Accordingly, Indian Space Research Organization (ISRO) has successfully operationalized two major satellite systems namely Indian National Satellites (INSAT) for communication services and Indian Remote Sensing (IRS) satellites for management of natural resources; also, Polar Satellite Launch Vehicle (PSLV) for launching IRS type of satellites and Geostationary Satellite Launch Vehicle (GSLV) for launching INSAT type of satellites. The Space Communication formulates the policies and oversees the implementation of the Indian space programme to promote the development and application of space science and technology for the socio-economic benefit of the country. DOS implements these programmes through, mainly Indian Space Research Organisation (ISRO), Physical Research Laboratory (PRL), National Atmospheric Research Laboratory (NARL), North Eastern-Space Applications Centre (NE-SAC) and Semi-Conductor Laboratory (SCL). The Antrix Corporation, established in 1992 as a government owned company, markets the space products and services

The various ISRO centres located in India are as follows :

Vikram Sarabhai Space Centre (VSSC): VSSC at Thiruvananthapuram is the major center of ISRO, where the design and development activities of satellite launch vehicles and sounding rockets are carried out and made ready for launch operations. The centre pursues research and development activities for associated technologies such as launch vehicle design, propellants, solid propulsion technology, aerodynamics, aero structural and aero thermal aspects, avionics, polymers and composites, guidance, control, and simulation, computer and information, mechanical engineering, aerospace mechanisms, vehicle integration and testing, space ordnance, chemicals and materials.

Systems reliability and quality assurance of all aspects of engineering and operations are studied and evaluated to the levels of perfection required in each field.

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Programme planning and evaluation, technology transfer and industrial coordination, indigenization, human resources development, safety and personnel and general administration groups support the centre for all its activities.

The Space Physics Laboratory at VSSC carries out research and studies in atmospheric science and other related space science activities.

The major programmes at VSSC include launch vehicle projects of Polar Satellite Launch Vehicles (PSLV), Geosynchronous Satellite Launch Vehicles (GSLV Mark II and Mark III), Rohini Sounding Rockets, Space-capsule Recovery Experiments, Reusable Launch Vehicles and Air Breathing Propulsion for Advanced Reusable Launch Vehicles.

ISRO Satellite Centre (ISAC):

ISAC at Bangalore is engaged in developing satellite technology and implementation of satellite systems for scientific, technological and application missions. ISAC is functionally organised into five major areas: mechanical systems area including structures, thermal systems and spacecraft mechanisms; digital and communications area including digital systems and communication systems; integration and power area comprising spacecraft checkout, systems integration and power systems; controls and mission area consisting of control system, mission development and computer and information; and facilities. Reliability and components area and programme planning and evaluation group provide relevant support to the centre. Project management teams co-ordinate the implementation of INSAT and IRS projects. Space astronomy and instrumentation division is engaged in space science activities. ISRO Satellite Integration and Test Establishment (ISITE) including a Comprehensive Assembly, Test and Thermo-vacuum Chamber (CATVAC) provide necessary support for qualification of sub-systems and systems to meet the requirements of space environment.

Achievements include design and development of more than 50 satellites so far of various types like scientific, communication and remote sensing.

Satish Dhawan Space Centre(SHAR):

SDSC SHAR, with two launch pads is the main launch centre of ISRO located at 100 km north of Chennai. SDSC SHAR has the necessary infrastructure for launching satellite into low earth orbit, polar orbit and geostationary transfer orbit. The launch complexes provide complete support for vehicle assembly, fuelling, checkout and launch operations. Apart from these, it has facilities for launching sounding rockets meant for studying the earth’s atmosphere.

Achievements include establishment of launch complexes for Sounding rockets, SLV- 3, ASLV and PSLV. Launch complex augmented for GSLV.

Liquid Propulsion Systems Centre(LPSC): LPSC Valiamala is the Headquarters and the centre is entrusted with the responsibility of research and development of Earth Storable and Cryogenic propulsion and delivers Engines, stages, associated control systems and components for Launch Vehicle and Spacecrafts.

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Major Achievements include:

Liquid Rocket Stages and Control Power Plant for PSLV Liquid stage for GSLV Propulsion system for GEOSAT and IRS spacecrafts Propulsion system for SPE Transducer development and production LPSC delivered administration package of COWAA software ,which is currently

being used across all ISRO centres

Major Projects under development are Cryogenic Upper Stage for GSLV-Mk II , Liquid rocket core stage & Cryogenic Upper Stage for GSLV-M3 vehicle and Semi-cryogenic development

LPSC Bangalore- The centre located at Bangalore is responsible for Satellite Propulsion Systems Integration for GEOSAT and IRS programmes. The centre is also responsible for design and development of monopropellant propulsion system, System engineering, Transducer and Spacecraft propellant tanks. The centre is involved in R&D and TDP activities towards development of electric propulsion system, propellant gauging system for spacecraft, advanced transducers etc. Major Achievements include:

Integration of propulsion systems for INSAT, GSAT, IRS class of satellites providing propellant ervicing for launch and support for in orbit operation of the

propulsion systems Transducers development and production undertaken caters to launch vehicle,

satellite propulsion system and facility requirements. Monopropellant thruster developed and realised are used in IRS class of satellites

ISRO Propulsion Complex (IPRC), Mahendragiri is equipped with state-of-the-art- facilities necessary for realising the cutting edge technology products for ISRO’s space research program. Formerly, IPRC was known as LPSC, Mahendragiri and taking cognizance of the future growth of the space program of our nation and the concomitant expansion at Mahendragiri, it was elevated as IPRC with effect from February 01, 2014.

Following activities are currently carried out at IPRC, Mahendragiri:

Assembly, integration and testing of earth storable propellant engines for PSLV, GSLV and GSLV MKIII launch vehicles

Assembly, integration and testing of cryogenic engines and stages for GSLV and GSLV MKIII launch vehicles

Facilities for Assembly, integration and testing of Semi Cryo engine being established at IPRC, Mahendragiri

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Assembly, integration and testing of sub systems for launch vehicles such as turbo pumps, injectors, gas generators, gas bottles, umbilicals etc.

High altitude testing of upper stage engines and space craft thrusters, as well as testing of its sub systems

Production and supply of Cryogenic propellants for ISRO’s Cryogenic rocket programs

Responsible for supply of Storable Liquid Propellants for ISRO’s launch vehicles and satellites programs.

Facilities for conducting automatic testing of various subsystems of launch vehicles and satellites

Establishment of structural test facility for pressurized hardware up to 5 metre diameter.

Calibration and supply of transducers for flight stages IPRC is equipped with analysis lab where Modeling of components &facilities,

thermo structural analysis and CFD analysis of various sub systems are carried out

IPRC delivers quality products to meet the zero defect demand of ISRO space program ensuring high standards of safety and reliability.

IPRC, Mahendragiri also carries out Research & Development (R&D) and Technology Development Programs (TDP) towards continual improvement of its contribution to ISRO space program.

Space Application Centre(SAC):

Space Applications Centre (SAC) is one of the major centres of the Indian Space Research Organisation (ISRO). It is a unique centre dealing with a wide variety of disciplines comprising design and development of payloads, societal applications, capacity building and space sciences, thereby creating a synergy of technology, science and applications. The Centre is responsible for the development, realisation and qualification of communication, navigation, earth & planetary observation, meteorological payloads and related data processing and ground systems. Several national level application programmes in the area of natural resources, weather and environmental studies, disaster monitoring/mitigation, etc are also carried out. It is playing an important role in harnessing space technology for a wide variety of applications for societal benefits. The organisational structure continues to remain dynamic, responding to the needs of the hour. SAC operates and maintains Ahmedabad Earth Station and the Delhi Earth Stations. SAC is a host institution for the training programmes related to Satellite Communication, Satellite Meteorology and global change under the Centre for Space Science & Technology Education in Asia and the Pacific (CSSTEAP) affiliated to the United Nations (UN).

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National Remote Sencing Centre ( NRSC ): NRSC at Hyderabad has been converted into a full-fledged centres of ISRO since

September 1, 2008. Earlier, NRSC was an autonomous body called National Remote Sensing Agency (NRSA) under Department of Space (DOS). The Centre is responsible for remote sensing satellite data acquisition and processing, data dissemination, aerial remote sensing and decision support for disaster management. NRSC has set up data reception station at Shadnagar near Hyderabad for acquiring data from Indian remote sensing satellites as well as others. The Centre is also engaged in executing remote sensing application projects in collaboration with the users. Currently NRSC is supplying data from CartoSat - 1, 2, 2A & 2B, ResourceSat - 1 & 2, OceanSat, TES, IRS - 1D and IMS - 1 to the users. The users are ever growing and utilized about 67,000 data products during 2010-11 in comparison with that of 50,000 during 2009-10.

Master Control Facility ( MCF ) MCF at Hassan in Karnataka and Bhopal in Madhya Pradesh monitors and

controls all the geo-stationary satellites of ISRO. MCF carries out operations related to initial orbit raising of satellites, in-orbit payload testing, and on-orbit operations throughout the life of these satellites. The operations involve continuous tracking, telemetry and Commanding, special operations like eclipse management, station-keeping manoeuvres and recovery in case of contingencies. MCF interacts with the user agencies for effective utilisation of the satellite payloads and to minimise the service disturbances during special operations. ISRO Inertial System Unit (IISU) ISRO Inertial Systems Unit (IISU) at Thiruvananthapuram has been the center of excellence in the area of inertial systems for launch vehicles and spacecrafts. IISU carries out research and development in the area of inertial sensors & systems and allied satellite elements. It has facilities for precision fabrication, assembly, clean room and integration and testing. This unit has the total capability to design, engineer, develop, qualify and deliver inertial systems for the entire Indian Space programme. Laboratory for Electro Optics System (LEOS)

Laboratory for Electro Optics Systems is engaged in design, development and production of Electro-Optic sensors and camera optics for satellites and launch vehicles. The sensors include star trackers, earth sensors, sun sensors & processing electronics. Optics Systems include both reflective and refractive optics for remote sensing and meteorological payloads. Other optical elements developed by LEOS for in-house use include optics for star sensor, optics for Lunar Laser Ranging Instrument (LLRI), optical masks for sun sensors, optical filters and encoders. LEOS is actively involved in the development of new technologies for present / future satellites. This includes development active pixel sensor star tracker, Charge Coupled Device (CCD) based star tracker, Fiber Optics Gyro, Optical inter satellite link, high resolution camera optics, optical coatings and MEMS devices (magnetometer,

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accelerometer etc.). LEOS is situated at Peenya Industrial Estate, Bangalore where the first Indian Satellite Aryabhata was fabricated in 1975.

Development and Educational Communication Unit (DECU) is involved in the system definition, planning, implementation and socio-economic research/evaluation of satellite-based societal applications.The Major Programs, at present, of DECU – to promote the satellite-based communication systems to support development, education & training – include:

Tele-Education Tele-Medicine Gramsat Program - including Training & Development Communication Channel

(TDCC) Satcom Applications – including VRC, DMS Program (for S & T), etc.

DECU supports:

Satcom Networks - Configuration, Implementation & Utilisation Social Research & Evaluation Content Generation, Transmission, & Training Studio & Technical Facilities

DECU, as an independent entity, has a definite role in meeting the goals of ISRO in promoting usage of space technology for the benefit of common man. The continuing expansion of space applications programs like Tele-education, Tele-medicine, etc. reiterates the increasing role played by DECU in providing direct benefits to the society. Thus, DECU continues to pursue successful goals on all fronts in meeting the objectives of space-based societal applications for the national development. Five Regional Remote Sensing Service Centres (RRSSCs) established under National Natural Resources Management System (NNRMS) by DOS at Bangalore, Jodhpur, Kharagpur (recently relocated to Kolkata), Dehradun and Nagpur have been integrated with NRSC and renamed as Regional Remote Sensing Centres (RRSCs) South, West, East, North and Central respectively on December 2, 2009.RRSCs support various remote sensing tasks specific to their regions as well as at the national level. RRSCs are carrying out application projects encompassing all the fields of natural resources like agriculture and soils, water resources, forestry, oceanography, geology, environment and urban planning. Apart from executing application projects, RRSCs are involved in software development, customisation and packaging specific to user requirements and conducting regular training programmes for users in Remote Sensing Application, digital techniques, GIS and theme based applications. RRSC also provides expert advice / consultancy towards

promotion of technology in the country.

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North East SAC ( NE-SAC)

NE-SAC, located at Umiam (near Shillong), Meghalaya, is a joint initiative of DOS and North Eastern Council to provide developmental support to the North Eastern region using space science and technology. The centre has the mandate to develop high technology infrastructure support to enable NE states to adopt space technology inputs for their development. At present, NE-SAC is providing developmental support by undertaking specific application projects using remote sensing, GIS, satellite communication and conducting space science research.

Physical Research Laboratory (PRL) at Ahmedabad, is an autonomous institution supported mainly by DOS. It is a premier institute engaged in basic research in experimental and theoretical physics, astronomy and astrophysics, earth, planetary and atmospheric sciences. The activities cover a wide spectrum of competitive research in all these areas. PRL is also involved in conducting extensive academic programmes for Doctoral and Post Doctoral research and also has an Associateship programme for university teachers. It is also entrusted with the management of the Udaipur Solar Observatory (USO). Semi-Conductor Laboratory (SCL), formerly known as Semiconductor Complex Limited, is presently a Society under the Department of Space with the main objective to undertake, aid, promote, guide and coordinate the R&D in the field of semiconductor technology, Micro-Electro-Mechanical Systems (MEMS) and process technologies relating to semiconductor processing in the existing 6" wafer fab. SCL has over the years developed and supplied a number of key VLSIs, majority of which have been Application Specific Integrated Circuits (ASICs) for high reliability applications in industrial and space sectors. Steps have been initiated to upgrade the facilities to fabricate devices in 0.25 micron or better technology. SCL continues to strive for technological excellence in the field of semiconductor fabrication. National Atmospheric Research Laboratory (NARL)

NARL at Gadanki near Tirupati is an autonomous society supported by Department of Space. NARL has now become one of the prime centers for atmospheric research in the country specializes in basic atmospheric research, indigenous technology development for atmospheric probing and weather and climate modeling. NARL regularly operates a state-of-the-art MST radar, Rayleigh / Mie Lidar, Boundary Layer Lidar, Sodium Lidar, Lower Atmospheric Wind Profiler, Sodar, Disdrometer, Optical Rain Gauge, Dual frequency GPS receiver, Automatic Weather Station apart from regular launching of the GPS balloon sonde. Being relatively young, NARL's research facilities are available for national and international scientists to conduct atmospheric research.

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2.0 Overview of ISRO Telemetry Tracking and Command Network

ISTRAC is responsible for providing Space Operation services that include spacecraft control, TTC support services and other related projects and services, for the launch vehicle and low earth orbiting spacecraft and deep space missions of ISRO and other space agencies around the world. Development of RADAR systems for tracking & atmospheric applications and Establishment of Ground Segment Network for Indian Regional Navigation Satellite System of ISRO are the additional responsibilities of ISTRAC.

Indian Space Research Organization (ISRO), over the years, established a comprehensive network of ground stations to provide Telemetry, Tracking and Command (TTC) support to Satellite and Launch vehicle missions. These facilities are grouped under ISRO Telemetry, Tracking And Command Network (ISTRAC) with its headquarters at Bangalore, Karnataka State, INDIA. ISTRAC has TTC ground stations at Bangalore, Lucknow, SHAR (Sriharikota), Thiruvananthapuram, Port Blair Island, Brunei, Biak (Indonesia) and Mauritius, meeting international standards. The Indian Deep Space Network (IDSN), commissioned during the year 2008, at Byalalu village near Bangalore forms the Ground segment for providing deep space support for India’s prestigious and first Lunar mission, the Chandrayaan-1 and Mars Orbiter Mission from IDSN-32 and IDSN-18 terminals. The technical facilities in IDSN include a 32 metre Deep Space Antenna, an 18 metre Antenna Terminal, an 11 metre Antenna Terminal, Indian Space Science Data Centre (ISSDC) and a Technical Services complex. The IDSN is the first of its kind project in the country that provides ISRO the capability to handle deep space missions of India and also provides cross support to other deep space missions of external space agencies because of its inter-operable features and state-of-the-art capabilities.

ISTRAC activities are organized into network operations, network augmentation, mission operation and spacecraft health monitoring, communications and computers and control centre facilities and development projects. Programme planning and reliability groups support ISTRAC activities.

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2.1 OPERATIONS OF ISTRAC

The major functions of ISTRAC are to provide:

Tracking, commanding and housekeeping data acquisition as well as health

analysis and control, orbit and attitude determination and network coordination

support to all low earth orbit satellite missions of ISRO throughout their mission

life.

Telemetry data acquisition support for ISRO launch vehicle emissions from lift-off

till satellite acquisition and down range tracking support for monitoring and

determining the satellite injection parameters.

Close coordination between spacecraft and launch vehicle teams and supporting

ground stations is maintained right from planning till completion of mission.

ISTRAC is also involved in advance mission planning, scheduling, frequency

coordination, etc.

Major objectives of ISTRAC are to provide:

TTC services for ISRO’S launch vehicle machines and low earth orbiting satellites.

Spacecraft health monitoring and control operation of ISRO’s low earth orbiting

satellites.

TTC operations services on commercial basis to other space agencies.

ISTRAC facilities in Bangalore consist of:

TTC ground station(BLR) with full redundancy.

Multi mission spacecraft control centre(SCC) to carry out and control spacecraft

operations and to coordinate with the network stations.

Computer facility with distributed architecture providing independent processors

for communications handling, dedicated processors to provide real time displays

for individual spacecraft missions and off-line processors for carrying out

spacecraft data archival, analysis and orbit and attitude determination.

Communication Control Facility to establish links between SCC and ISTRAC

network stations a well as control stations for other participating external space

agencies and data reception stations through dedicated sky-links for Voice/Data

transmission.

Limited TTC facility to provide an orbit operational support to INSAT satellite as a

back up to INSAT Master Control Facility at Haasan.

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3.0 INTRODUCTION TO TTC Network :

Telemetry Subsystem: The word “Telemetry” implies that measurements are

made from a distance using telecommunications principles .This involves grouping of

data measurements (satellite status) in format that can be transmitted on a single

medium and also retrieved from the medium. Downlink data derived from the

spacecraft are monitored by the controlling earth stations.

Tracking Subsystem: Tracking can be defined as the process of detection of

position and path of satellites and involves measurements of range ,range rate, angular

position and direction. By repeated measurements of the three parameters from the

ground stations, changes in the orbit of the spacecraft can be detected.

Command Subsystem: This is a process of encoding and relaying commands to

the satellite perform a particular operation and to control certain physical parameters

on board. Used to correct the position and attitude of the spacecraft based on telemetry

and tracking data. It uplinks commands to control antenna position and switches on the

spacecraft.

3.1 GROUND STATION DESCRIPTION AND SPECIFICATIONS :

An earth station/ ground station or earth terminal is a terrestrial terminal station

designed for extra planetary telecommunication with spacecraft, and/or for reception of

radio waves from an astronomical radio source. Earth stations are located either on the

surface of the Earth, or within Earth’s atmosphere. Earth stations communicate with

spacecraft by transmitting and receiving radio waves in the super high frequency or

extremely high frequency bands (e.g., microwaves).When an earth station successfully

transmits radio waves to a spacecraft (or vice versa), it establishes a

telecommunications link.

Primary function of Ground station of ISTRAC is providing TTC support for IRS

mission and LEO satellites. Station configuration is so designed as to meet the mission

requirements in full.

A typical GS has two 10m diameter dish antenna with transmit receive feed. It

receives both RCP and LCP signals simultaneously and combines them optimally before

data detection. For transmission, either LCP or RCP can be used. Frequency band

reception is 2200-2300 MHz and for transmission is 2025-2125 MHz.

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15

GROUND STATION SPECIFICATIONS

Parameter G/S Terminal

BL-1 (East) BL-2 (West)

Receive

Freq. Band 2200-2300 MHz 2200-2300MHz

G/T 20 dB/deg K 20dB/ deg k

Polarization RCP and LCP RCP and LCP

Antenna beam width 0.9 deg 0.9 deg

Simulataneous Carrier Reception

3 2

Acq.Chain G/T -NA- -3.0dB/deg k

Acq.Chain Beam width -NA- 7.0 deg

X-band Frequency 8.0-8.5 GHz -NA-

X-Band G/T 30.0 dB/ deg k -NA-

Transmit

Transmit Frequency band 2025-2125 MHz 2025-2120MHz

Transmit Power 2.0 kW/100W 2.0kW/100W

EIRP 74 dBW/61 dBW 74 dBW/61 dBW

Polarization(Selectable) RCP or LCP RCP or LCP

Antenna Gain 43 dBi 43 dBi

Tracking System

Type of Mount Elevation over Azimuth

Azimuth Limits +/- 360 deg

Elevation Limits 0 to 90 deg

Tracking Velocity 9 deg/sec

Tracking acceleration 3 deg/square sec

Tracking modes Auto, Program,Computer-designate,slave,Manual, Slew

Pointing 0.1 deg

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Antenna System

The Bangalore ground station has two S band disc shaped antennas (east and

west chain) each of 10m diameter. Since there are two antennas, two spacerafts can be

independently tracked simultaneously. The type of mount used is the elevation over

azimuth mount. The antennas can be revolved around 360 degs in the horizontal plane

(azimuth angle) and about 90 degs in vertical plane (elevation angle).

The ground station antennas are required to have high directive gain, low side

lobe level and low noise temperature. The antenna system consists of main antenna

and acquisition antenna. The main antenna is the parabolic reflector with cassegrain

feed of 10m diameter and pointing accuracy of 0.1 degree.

The information from main antenna is transmitted to the ground station through

cables. The acquisition antenna is a combination of 4 pyramidal horns positioned in

such way that they give the performance equivalent to a 1m small dish antenna.

Because of the wide beam width, the acquisition antenna is used for initial acquisition

and afterwards the control is switched over to main antenna. The acquisition antenna

has no transmission capabilities. The test coupler has a coupling factor of 30dB and is

mainly used for chain calibration and for periodical evaluation of chain performance.

The LNA output is brought down from the antenna.

Antenna Control

An ordered pair of two angles namely, Azimuth and Elevation gives the

antennas’s position and direction at any given time.

The explanations for these are as follows:

Line of reference: The line, which joins the point on earth to the North star is called the

line of reference. This is because the North star is situated on the Earth’s axis of

rotation. Therefore there is no relative motion of the same with respect to any point on

the earth.

Local Horizon: The plane obtained by drawing an imaginary tangent to the earth at any

given certain point is referred to as the Local Horizon.

Azimuth: This is the angle on the local horizon, which the antenna axis projection

makes with the point of reference( or line of reference).

Elevation: This is the angle , which the antenna axis makes with the local horizon.

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The azimuth and elevation uniquely determine direction and position of any object in

space(in this case satellite).

Modes of operation :

The antenna is controlled both in azimuth and elevation axis by antenna control servo

system which closes position, velocity/rate, current loops and uses two motors for each

axis in counter torque mode.

Auto Mode: In auto mode the system takes error from auto track receiver system

and after processing sends necessary signal to the drive system.

Program Mode: This mode is meant for to move the antenna in predetermined

trajectory which contains time, azimuth and elevation angle information and will be

loaded into the servo system well before the start of the Pass. Servo system will

wait at the expected position and will command the antenna system as per

trajectory angles and time.

Manual Mode: This is purely an operator’s mode for positioning the antenna in both

the axes .The movement can be achieved in steps of 0.1deg.

Slew Mode: In this case the antenna can be slewed at the max. Rate of 9deg/sec.

Slave Mode: Antenna can be slaved to an external synchro input from another

antenna.

3.2 PROCESSES PERFORMED AT GROUND STATION :

The basic block diagram of Bangalore Ground Station is as shown in the above

figure. The main processes carried out here can be classified as Uplink Chain and

Downlink Chain.

3.2.1 UPLINK CHAIN:

PCM/FSK/FM PM (70MHz) 2025-2125MHz 2KW(Power) ( 100bps/3.125&5.55KHz/70KHz ) Or PCM /PSK (4Kbps/ 32 or 8 Khz) Telecommand(up-linking) is carried out at 100bps data rate. The onboard

requirements are that the uplink system should be simple, fast and highly reliable. In

Station

computer

TTC

processor

Up-

Converter

High power

Amplifier Antenna

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this case differ the modulation scheme is chosen- PCM/FSK/FM/PM. Uplink system is

made very simple for tele-commands.

The Station computer system uses the command encoder add-on PCI card

which generates PCM/FSK/FM or PCM/PSK signal depends on up-link modulation

scheme incorporated for that particular satellite. PCM is done at 100bps.In case of FSK,

logic 0 represents 3.123KHz and logic 1 represents 5.555KHz. PCM/FSK /FM is

collectively called ‘video’.Basic Fm carrier is 70KHz. In case of PCM/ PSK scheme, PCM

data rate will be 4kbps and PSK carrier will be 8 or 32Khz) .

TTC Proccesor(70MHz modem)-tele-command video from DHS generated or

encoded by command card goes to 70MHz PM modulator. Here final PM modulation is

done.Output signal is at IF level of 70MHz.

UP-Converter-this is also called Exciter System: the output of the modem

which is 70MHz phase modulated signal will be up converted to 2025-

2125MHz(allocated TTC uplink frequency band) at low power.

High Power Amplifier(HP)- high power is needed for transmission from

ground staion. The RF signal is fed to a HPA. Here power amplification is done by four

cavity KLYSTRON microwave tube which has upto 40db gain and gives the output of

2000W.This high power RF signal is connected to the antenna through WR-430

rectangular wave guide that are hollow metallic conductors and are high frequency

filters(High pass filter) .

3.2.2 DOWNLINK CHAIN:

g

v

Antenna System- The antenna has a 10m diameter. It is a parabolic dish and

acts as a passive amplifier with a gain of around 44dB. It concentrates the

received/transmitted signals at the FEED.

Low Noise Amplifier(LNA)-It controls noise gives good signal quality. It is an

active amplifier. It has 2.2 to 2.3GHz in band signal processing ability. So it has

100MHz bandwidth. In this range there is 40 dB gain.

Multi coupler –It effectively distributes signals at high frequency levels. It

isolates and distributes the signals for simultaneous or parallel processing .Frequency

remains unchanged.

Down converter-Up to this step the signal is in the RF (from 2.2 to3.3GHz)

Low Noise

Amplifier

Multicoupler Down

converter

TTCP STC

antenna

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as it is received from the satellite. Down converter converts the RF signal to

Intermediate Frequency(IF) signal using a LO or Local Oscillator signal. The IF signal

can be in the range of 400 to 500 MHz or it can be fixed frequency of 70MHz.

TTCP-Telemetry Tracking And Command Processor:

TTCP is an integrated processor to perform all three operations, telemetry,

tracking and command from a single system. It interface with 70MHz IF input from

down converter, 5MHz station reference, reference tim9ing for synchronization, external

telecommands and PC LAN to data transfer between TTCP and General Equipment

Interface(GEI).

The system performs bit synchronization, frame synchronization, decoding and

time tagged telemetry and playback data on two different LAN connections to station

computers(STC). TTCP is the heart of the entire system as it performs tele-

commanding.

Functions of TTCP:

Telemetry: Under this function, we can monitor the input, 70 MHz IF display,

telemetry 1(TM1), telemetry 2(TM2) frame display on manual refresh, configure

for telemetry simulation, bit error rate(BER) check and receiver automatic gain

control(AGC) calibration.

Telecommand: We can set the required uplink modulation scheme, modulation

index,70MHz RF on/off, uplink sweep parameters and simulation parameters.

Range and Doppler: We can set the number of range and Doppler

measurements.

General: We can set the system IP address for TM1 and TM2 data and port

address for various data type including AGC, M and C etc. System status, boot

log messages, load/save of configuration registers is available under this

function.

STATION COMPUTER:

Station computer(STC) is a system used to communicate with TTCP and provides

support for real time operation as well as in case of offline operational need. Station

computer receives telemetry/playback/tracking data from TTC processor through LAN

connections. It reformates the data into required ISTRAC format and sends the data to

main computers for furthers processing at communication group.

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4.0 Mission Operations Complex (MOX)

The nerve centre for this Moon Mission will be the Mission Operations Complex, situated within the ISTRAC campus, Bangalore. The MOX will be responsible for all spacecraft operations during various phases of the mission viz. pre-launch, launch and early orbit phase, normal phase and terminal phase, as well as for the health monitoring of the spacecraft and payloads. MOX is authorized for up linking of commands for change of onboard configuration, payload operations and conduction of maneuvers as required. MOX facility has a number of elements that function in unison to support round-the-clock spacecraft operations. The Mission Operations Complex and the ISSDC facilities are linked through a secure network for data transfers.

Spacecraft Operations

Mission activities will be conducted from the Mission Operations Complex. The health keeping data / dwell received will be monitored in real-time to ensure good functioning of the onboard systems. Telecommands for changes of spacecraft configurations and payload operations will be uplinked after verification and due authorization. The centre will also be equipped to handle special operations and contingency recovery. Periodic orbit maneuvers will be planned and conducted to maintain the altitude /eccentricity that satisfies the payload data overlap requirements and safe altitude of the spacecraft. Periodical reports on the performance of spacecraft and payload services are generated and passed on to designers and users. The centre maintains an archive of all satellite operations, health, special operations, attitude/orbit maneuvers, anomalies and recoveries.

ISTRAC Network Control Centre (NCC)

NCC enables remote monitoring and control of all ISTRAC Ground Stations including IDSN and it is located in Peenya, Bangalore Campus. NCC also facilitates Data Service from all stations through Standard Station Computers, SLE Gateway or any other agency specific data interface through external station computers. The payload data acquisition system at IDSN also interfaces with NCC for obtaining the payload operations schedule. The multi-mission schedule system of ISTRAC provides the required schedules to NCC for day-to-day operations.

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5.0 SATELLITE COMMUNICATION DIVISION

SATELLITE ORBITS-LEO,MEO,GEO:

LEO (Low Earth Orbit): Satellite have an altitude between 250 to 1500km each orbit

takes 1.5 to 2 hours

Applications: Mobile communication, earth observation, science & military mission

MEO (Medium Earth Orbit): Satellite have an altitude between 20,000km each orbit

takes 10 to 12 hours

Applications: Commonly used for navigation (such as GPS) as well as Mobile

communication and other services

GEO (Geosynchronous Equatorial Orbit): Satellite are placed at an altitude of about

35,800km This makes an orbit period of exactly 24 hours

Application: Broadcasting, VSAT and earth observation and science mission

Frequency Band UPLINK (GHz) DOWNLINK (GHz)

C-Band 5.925-6.425 3.625-4.200

Ex C-Band 6.725-7.025 4.500-4.800

Ku-Band 14.00-14.50 10.95-12.75

Ka-Band 30.00 20.00

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5.1 VSAT-VERY SMALL APERTURE TERMINAL

VSAT is a satellite communications system that serves business users and home. A

VSAT end user needs a box (Modem like iDirect, ViaSat, Radyne modem, PolarSat) that

interfaces between the user's computer and an outside antenna with a transceiver.

The transceiver receives or sends a signal to a satellite transponder in the sky. The

satellite sends and receives signals from an earth station computer that acts as a hub

for the system.

Each end user is interconnected with the hub station via the satellite in a star topology.

For one end user to communicate with another, each transmission has to first go to the

hub station which retransmits it via the satellite to the other end user's VSAT.

VSAT handles data, voice, and video signals. VSAT offers a number of advantages over

terrestrial alternatives. For private applications, companies can have total control of

their own communication system. Business and home users also get higher speed

reception than if using ordinary telephone service or ISDN.

5.2 ACCESS METHODS USED IN VSAT COMMUNICATION

SCPC: Single Channel Per Carrier (In simple terms this is nothing but lease lines in the

sky). SCPC Channels can be either PAMA or DAMA.

Pre Assigned Multiple Access:

PAMA is an access scheme where in when 2 VSATs want to communicate with

each other a bandwidth is assigned to them exclusively. This assigned bandwidth will be

available the VSAT’s on a permanently basis. This link can either be a symmetric and

asymmetric link. It is nothing but a point to point connectivity.

Demand Assigned Multiple Access:

The DAMA scheme is very similar to a telephone connection. Whenever, there is

a need to talk to someone, you dial a number. The call lands at the telephone

exchange, and the telephone exchange connects you to the dialed number. The role of

the telephone exchange is to connect you to the desired number. This is exactly how a

DAMA network operates. The HUB plays the role of a telephone exchange, between any

two VSAT’s. network.

TDM (Time Division Multiplexing)

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TDM is a scheme for many VSATs to share one high speed “outbound” from the

hub station.

outbound carrier is broadcast to all VSAT’s from central hub

TDMA (Time Division Multiple Accesses)

TDM is a scheme for many VSATs to share one “inbound” carrier channel by

taking turns transmitting

The hub electronics sorts all the data packets from the VSAT’s and send them to

their correct destinations

MF TDMA (Multi Frequency - TDMA)

More than one frequency channel is used for the inbound links

VSAT’s Can hop from one frequency to another

HUB AND REMOTE OVER SATELLITE

Speed of Light or signal 299,762 kms

Therefore: 35,790/299,762= .119sec or 120ms (Hub to Satellite)

So Uplink delay + Downlink delay=240ms (Hub to Remote)

Delay for both Outbound and Inbound (IP ‘Ping’)

Total Round-trip Delay of 480ms

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Uplink: Transmission path from earth station to a communication satellite

Downlink: Transmission path from satellite to earth station

Outbound Channel (Out route or Downstream): Signal from the Hub to the Remote

Outbound Uplink (Hub to Satellite)

Outbound Downlink (Satellite to Remote)

Inbound Channel (In route or Up Stream): Signal from the Remote to the Hub

Inbound Uplink (Remote to Satellite)

Inbound Downlink (Satellite to Hub)

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5.3 Indoor Unit (IDU & Outdoor Unit (ODU)

Equipments operating inside the room or under roof environment are called IDU

(Indoor Unit)

Equipments operating in the outdoor or open sky environment are called ODU

(Outdoor Unit)

Few ODU’s & IDU’s that are essential part of the system are:-

ANTENNA

BUC (Block Up Converter)

LNB (Low Noise Block)

LNA (Low Noise Amplifier)

Down converter

Up converter

Antenna is a device used for transmitting and receiving radio signals.

BUC is an electronic device meant for transmitting signals through the antenna.

LNB is a device meant for receiving signals (programs) transmitted from the

HUB/Remotes.

LNA This is the preamplifier between the antenna and the earth station receiver. The

LNA is especially designed to contribute the least amount of thermal noise to the

received signal.

Up converter accepts the modulated IF Carrier from modulator and translates it to the

Uplink RF frequency by mixing with a Local oscillator (LO).

Down converter receives the modulated RF in Downlink from LNA and translates it to

the IF frequency by mixing with a Local oscillator (LO).

These converters are Exclusively designed to have high stability, required conversion

Gain, less phase noise & high reliability.

5.4 PROJECTS

VRC:

Tele-education: Focus is on imparting vocational training at local level - aimed at skill

development and capacity building to catalyze livelihood support in rural areas;

supplementary teaching to rural children; and non-formal and adult education.

Tele Medicine :-

ISRO has initiated space-based telemedicine. The Telemedicine network covers more

than 700 hospitals in remote areas like Jammu & Kashmir, Andaman & Nicobar and

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Lakshadweep Islands, North Eastern Region, and remote tribal areas in central and

southern Indian states which are connected to super specialty hospitals in major cities

5.5 SPACENET

The various centre of ISRO are located at different places in India and are involved in

carrying out specific tasks related to Indian Space Program. Most of the Projects of

ISRO, like building the launch vehicles and satellites, controlling the satellites or utilizing

the satellite data are interdisciplinary in nature and are executed with team approach

and on an interactive mode with the work being distributed among all ISRO centre.

Proper execution of any project requires lot of interaction among all ISRO/DOS centre

and also exchange of information among themselves to design, develop and testing of

various hardware and software elements. Apart from this, the essential information

related to finance, purchase, administrative matters etc. are also required to be shared

among the various centre of ISRO for timely decisions and execution of projects.

So, for those requirement we are providing Video conference, Data Transfer between

centre and also VOIP phone services through

iDirect Technology:-

Totally IP based solution

Both Star and Mesh configurations to coexist in the planned network.

Multipoint video conferencing employing H.264 codec

High speed data connectivity among ISRO centers

Facility for IP-Multicasting to support multicasting applications/sessions

Facility to support voice calls from the existing exchanges

TECHNOLOGY USED :

TDM/MF D-TDMA :-

Time division Multiplexing (TDM) is a base band technique used at one location (i.e. a

transmitting earth station) to multiplex several digital bit streams into a single higher

speed digital signal. Groups of bits are taken from each of bits streams and formed in to

base band packets or frames that also contain synchronization and identification bits.

D-TDMA: Deterministic - Time Division Multiple Access (TDMA) Technique used to

prevention of collisions of remotes transmitting simultaneously Network timing provided

by synchronized burst time plan Time slot assignments provide guaranteed delivery

Improves throughput by reducing/eliminating retransmissions

D-FTDMA: Deterministic - Frequency & TDMA Allows remotes to better utilize shared

bandwidth Hub can control data traffic flow to ‘load balance’ during normal network

operations

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6.0 SATELLITE AIDED SEARCH AND RESCUE SYSTEM

India is a member of the international COSPAS-SARSAT programme for providing

distress alert and position location service through LEOSAR (Low Earth Orbit Search And

Rescue) satellite system. Under this programme, India has established two Local User

Terminals (LUTs), one at Lucknow and the other at Bangalore. The Indian Mission

Control Centre (INMCC), is located at ISTRAC, Bangalore.

INSAT-3A located at 93.5 deg East is equipped with 406 MHz Search and Rescue

payload that picks up and relays alert signals originating from the distress beacons of

maritime, aviation and land users. INSAT and GOES systems have become an integral

part of the COSPAS-SARSAT system and they complement the LEOSAR system.

Indian LUTs provide coverage to a large part of Indian Ocean region rendering distress

alert services to Bangladesh, Bhutan, Maldives, Nepal, Seychelles, Sri Lanka and

Tanzania. The operations of INMCC/LUT are funded by the participating agencies,

namely, Coast Guard, Airports Authority of India (AAI) and Director General of Shipping

and Services.

INSAT GEOSAR Local User Terminal (GEO LUT) is established at ISTRAC, Bangalore and

integrated with INMCC. The distress alert messages concerning the Indian service area,

detected at INMCC are passed on to Indian Coast Guard and Rescue Coordination

Centres at Mumbai, Kolkata, Delhi and Chennai. The search and rescue activities are

carried out by Coast Guard, Navy and Air Force. INMCC is linked to the RCCs and other

International MCCs through Aeronautical Fixed Telecommunication Network (AFTN).

The Indian LUTs and MCC provide service round the clock and maintain the database of

all 406 MHz registered beacons equipped on Indian ships and aircraft.

Development of indigenous search and rescue beacons has been completed, and is now

in qualification phase. Shortly it will be released to the Indian fishermen community.

Till date, there are about 400 registered user agencies (Maritime & Aviation) in India

with more than 5200 radio beacons in use.

Migration from LEOSAR & GEOSAR to MEOSAR system has been under taken. Design of

upcoming MEOSAR system is ready and will be implemented in 2 years.

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7.0 INDIAN DEEP SPACE NETWORK (IDSN)

The Indian Deep Space Network consists of a 18-m and a 32-m antennae that are

established at the IDSN campus, Byalalu, Bangalore. The Network is augmented with a

couple of stations in the western hemisphere in addition to the 64-m antenna in

Bearslake, Russia to improve the visibility duration and to provide support from the

antipodalpoint.

The existing ISTRAC S-Band Network stations will be used to support the mission during

Launch and Early Orbit Phase (LEOP) that includes Earth Transfer Orbit (ETO) up to a

range of about 1,00,000 km. Although the 18-m antenna is tailored for Chandrayaan-1

mission, the 32-m antenna can also support other planetary missions. The established

IDSN is a state-of-the-art system, with its base band system adhering to CCSDS

(Consultative Committee for Space Data Systems) Standards, thus facilitating cross-

support among other TTC agencies. The supporting network stations will ensure the

adequacy of the link margin for telemetry/dwell, tracking, tele command and payload

data reception. The IDSN station has the responsibility of receiving the spacecraft

health data as well as the payload data in real time. Later, conditioning of the data

takes place, before onward transmission of the same to Mission Operations Complex at

Bangalore. The tracking data comprising Range, Doppler and Angle data will be

transferred to the control center for the purpose of orbit determination. The payload

data will be transmitted to the Indian Space Science Data Center (ISSDC) as and when

received by the payload data acquisition system, located at the station.

7.1 18M-ANTENNA

The 18-m dish antenna is configured for Chandryaan-1 mission operations and payload data collection. The antenna is established at the IDSN Campus, Byalalu, situated at the outskirts of Bangalore with built in support facilities. A fibre optic / satellite link will provide the necessary communication link between the IDSN Station and Mission Operations Complex (MOX) / Indian Space Science Data Centre (ISSDC).

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This antenna is capable of S-Band uplink (2 kW) and both X-Band and S-Band downlink. This system has provision to receive two downlink carriers in S-Band and one carrier in X-Band (RCP and LCP) simultaneously, whereas, the uplink is either RCP or LCP. The system will have a G/T of 30/39.5 dB/K (45º elevation, clear sky) for S/X-Band. The base-band system will adhere to the CCSDS Standards. The station can be remotely operated from ISTRAC Network Control Centre (NCC). The above figure depicts the 18-m antenna. 7.2 32M-ANTENNA

The wheel and track 32-m antenna is a state-of-the-art system that will support the Chandrayaan-1 mission operations and beyond. This is co-located with 18-m antenna in the IDSN site at Byalalu. A fibre optics / satellite link will provide the necessary connectivity between the IDSN site and Spacecraft Control Centre / Network Control Centre. This antenna is designed to provide uplink in both S-Band (20/2 kW) and X-Band (2.5 kW), either through RCP or LCP. The reception capability will be in both S-Band and X-Band (simultaneous RCP & LCP). It can receive two carriers in S-Band and one carrier in X-Band, simultaneously. The system will have a G/T of 37.5/51 dB/K (45° elevation, clear sky) for S/X-Band. The base-band will adhere to CCSDS Standards facilitating cross-support among the space agencies. The station is also equipped for remote control from the ISTRAC Network Control Centre (NCC).

Existing S-Band ISTRAC Network

Indian lower earth orbit satellites are controlled by the ISRO Telemetry Tracking and

Command (ISTRAC) Network stations. The Elevation over Azimuth 10/11/12-m dish

antennae at the existing ISTRAC network stations (Bangalore, Lucknow, Mauritius,

Bearslake, Biak, Brunei, Trivandrum and Port Blair) will be augmented to serve the

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Chandrayaan-1 mission during Earth Transfer Orbits and Lunar Transfer Trajectory up

to a range of about 1,00,000 km. All these antennae are configured for two-carrier

reception (RCP&LCP) and uplink, in either RCP or LCP in S-Band. The G/T of the

stations is 21/23 dB/K. The base-band will adhere to CCSDS Standards, facilitating

cross-support among the TTC agencies. The stations are being equipped for remote

control from the ISTRAC Network Control Centre (INCC). These stations are linked to

MOX by dedicated communication links.

7.3 External Network Stations

External network stations APL, JPL (Goldstone, Canberra, Madrid), Hawaii, Brazil

(Alcantara, Cuiaba) are requisitioned in for the purpose of extended visibility of Launch

and Early Orbit Phase (LEOP) operations, as well as to gain the near continuous

visibility during the normal phase operations. All the external stations will ensure the

required compatibility to communicate with the spacecraft.

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8.0 Indian Space Science Data Centre (ISSDC)

Indian Space Science Data Center (ISSDC) is a new facility being established by ISRO, as the primary data center for the payload data archives of Indian Space Science Missions. This data center, located at the Indian Deep Space Network (IDSN) campus in Bangalore, is responsible for the ingestion, archive, and dissemination of the payload data and related ancillary data for Space Science missions. The principal investigators of the science payloads as well as scientists from other institutions and general public will use this facility. The facility will be supporting Chandrayaan-1, ASTROSAT and Megha-tropiques and any other future space science missions.

Payload data from the satellites will be received at the data reception stations and subsequently transferred to ISSDC for further processing.

The raw payload data received through the data reception stations is further processed to generate Level-0 and Level-1 data products that are stored in the ISSDC archives for subsequent dissemination. Automation in the entire chain of data processing is planned. Raw payload data / Level-0 data/ Level-1 data for each science payload is transferred to the respective Payload Operations Centers (POC) for further processing, analysis and generation of higher level data products. The higher level data products generated by the POC’s are subsequently transferred to ISSDC archives for storage and dissemination. The data archives for Level-0 and higher products are organized following the Planetary Data System (PDS) standards.

The dissemination of data from ISSDC to the payload operations centers / principal investigators, scientists and general public is supported through private WAN connections and Internet.

Software packages developed by software development teams in the different centers of ISRO, by the principal investigator’s teams / payload development teams are to be deployed at ISSDC to support these functions.

ISSDC data archival and distribution functions follow the data policy guidelines of ISRO. The data transfer system at ISSDC, with suitable security systems, provides for distribution of science data (as per data policy). After a pre-specified proprietary period, ISSDC would make the data available to public users who can access the archives through the Internet.

ISSDC supports six primary services; viz Access Services, Interchange Services, Archive Services, Support Services, Operations Services and Maintenance Services.

ISSDC interfaces with Mission Operations Complex, Data reception centers, Payload designers, Payload operations centers, Principal investigators, Mission software developers and Science data users to execute its functions.

The primary facilities for ISSDC have been established at the IDSN site, Byalalu at Bangalore.

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8.1 Payload Operations Centre (POC)

Payload Operation Centres focus on the higher levels of science data processing, planning of payload operations, performance assessment of the payload and payload calibration. POC is authorized to interact with MOX in conducting the payload operations. These centers are co-located with the institutions/laboratories of the Instrument designers, Principal Investigators and will be processing and analysing data from a specific payload. POCs will pull relevant payload (level 0 and level 1) and ancillary data sets from the ISSDC dissemination server and process the data to generate higher level products. These products will be archived in ISSDC after qualification.

Payload Operations Centers are planned at SAC, Ahmedabad (TMC, HySI), ISAC, Bangalore (C1XS, HEX, LLRI), SPL,VSSC, Trivandrum (SARA, MIP), APL, Maryland, USA (MiniSAR), Brown University, JPL, USA (M3), Max Planck Institute, Germany (SIR-2), RAL,UK (C1XS), Swedish institute of Space Physics, Kiruna, Sweden (SARA).