The document describes GRAMSAT, a proposed Indian communications satellite dedicated to rural development and tele-education. GRAMSAT would use a Ku-band regenerative transponder payload to provide interactive training, broadcasting services, computer interconnectivity, and telemedicine to villages across India via small ground terminals. Key aspects of the proposed satellite include using spot beams, BPSK modulation for audio signals, and differential demodulation or DSP-based receivers on the ground. The goal of GRAMSAT is to help bring e-governance, disaster management, and educational opportunities to rural communities through satellite connectivity.

1. GRAMSAT
For Rural Development &
Tele-education
PREPARED BY
DARSHAN BHATT JINAL SHAH
(150320705001) (150320705013)
M.E (EC) – SEM 2 M.E (EC) – SEM 2
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2. Content
PART – 1 – Basic Concept & specifications
Introduction
Requirements
Features
Specifications
Components
Concept of GRAMSAT
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3. PART – 2 – Technical Details
Frequency band selection
Types of payload
Modulation and access scheme
Transponder configuration & technology
Differential demodulator and DSP
Ground terminal
Conclusion
References
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4. PART 1
BASIC CONCEPT & SPECIFICATIONS OF
GRAMSAT
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5. Introduction
 A satellite based system is needed to cover various components of
rural development programmes such as health, hygiene, agriculture
practices and environment etc.
 Guided with these views a dedicated satellite called - GRAMSAT
(‘Gram’ means village in Hindi language and ‘Sat’ is used for
satellite) is being planned for rural development and tele-education
in india.
 The Department of Space and Ministry of Rural Development,
Government of India has sponsored the GRAMSAT programme,
which is operating in Orissa.
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6. (cont)
 The GRAMSAT was introduced in the year 2000 to bring
Government of Orissa closer to the people.
 GRAMSAT was the first ever satellite based training in Karnataka
launched with a total budget of Rs. 65 million.
 The project was operational on 2 stages. Stage 1 is completed in Feb
2004 and Stage 2 was suppose to end in 2005.
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7. Requirements of GRAMSAT
 We can organise interactive training programme for village level
workers, school teachers, industrial workers and medical personnel
has to be planned effectively.
 Some of the other important needs of rural mass are, telegrams,
timely warning of cyclones, floods and other weather related data
and should also be made available to the villages.
 It is required for interactive training programmes (ITP) such as talk
back facility for questions and answers etc is available to the user.
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8. Features of GRAMSAT
 Its communications networks are at the state level connecting the
state capital to districts, blocks and enabling a reach to villages.
 It is also providing computer connectivity data broadcasting, TV-
broadcasting facilities having applications like e- governance,
development information, teleconferencing, helping disaster
management.
 Providing rural-education broadcasting. However, the Gramsat
projects have an appropriate combination of following activities.
(i) Interactive training at district and block levels employing suitable
configuration
(ii) Broadcasting services for rural development
(iii) Computer interconnectivity and data exchange services
(iv) Tele-health and tele-medicine services.
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9. (cont)
 Simple, sleek and effortless way of communication.
 Interactivity – A very high degree of interactive programme.
 One can air his/her question, opinion, suggestion and query and get
immediate response.
 Communication in the local language.
 Flexibility – The schedual of programme is at convenient hour.
 Generates high degree of participation.
 Facilitates one to one communication.
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10. Specifications
Launch Date 18-04-2001
Launch vehicle GSLV-D1
Launch site Sriharikota, India
Mission Communication
Weight 1530 kg
Orbit Sun synchronous Geo stationary orbit (GSO)
Manufacturer ISRO (Indian Space Research Organisation)
Owner ISRO (Indian Space Research Organisation)
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11. Components
 The GramSat program will have the following components.
- Space segment.
- Ground terminals.
- Network control.
- Software production & training
- Feedback analysis.
 It is also planned to use polarization discrimination for the ad-jacent
spot beams, so that frequency spectrum can he used efficiently. The
tentative coverage of spot beams over the country (India) is shown
in Fig.2.
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12. FIG:1A
GRAMSAT
CONCEPT
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13. FIG:1B
GRAMSAT
SYSTEM
CONFIG
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14. FIG – 2
Coverage of
spot beams
over India
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15. PART 2
TECHNICAL DETAILS
OF
GRAMSAT
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16. Frequency band selection
 The selection of Ku-band for the system has been made, based on
the comparative link calculation for Ku and C-hand.
 The realisation of spot beam is easier at Ku-hand as compared to C-
band.
 This will enable to use 0.8 m to 1.2 m ground terminal for the Ku-
band links.
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17. Types of PAYLOAD
 TRANSPONDER
• The satellite transponder which is an important element in
communication link.
• The signals are received. Frequency translated and amplified
before transmission.
• This transponder has limitation of link degradation and non-
lineary.
 REPEATER & ON-BOARD TRANSPONDER
• The regenerative repeater and on-board processing transponder
are able to make the user terminal cost effective by removing the
effect of uplink noise, improved down link.
• This will enable to have voice communication between small
terminals without hub due to regeneration.
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18. (cont)
 The regenerative repeater will reduce the transmission delay and
will utilize the satellite resources efficiently.
 It can be observed that with regenerative transponder the uplink
EIRP required is 8 dB less, the path delay is reduced by 50% and
number of channels supported by the link are increased by two
times.
 The video programmes will be generated at a few places and will be
located in selected cities, so comparatively large size ground
terminals can be used.
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19. Modulation & Access Scheme
 Modulation Scheme for video signal:
• The conventional frequency modulation scheme is selectedfor
video signal.
 Modulation Scheme for audio signal:
• For audio signal, the base band signal will be in digital form and
Bi-Phase Shift Keying (BPSK) modulation will be used as
regeneration is easier for it.
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20. (cont)
 Scheme for Uplink Audio Signal:
• The uplink signal for audio will be in SCPC-FDMA mode as
requirement of transmit uplink ElRP will be less compared to that
of Time Division Multiple Access (TDMA) mode. Due to on-
board complexity Code Division Multiple Access (CDMA) is not
preferred.
 Scheme for Downlink Audio Signal
• Down link for audio signal will be in Time Division Multiplexed
(TDM) mode as the scheme will be efficient for space segment.
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21. Communication Transponder Config.
 The required signal is selected and is upconverted to Ku-band and
amplified before transmission.
 The C-band trans-ponder provides the national coverage and can
select the signal from any of the regional transponder.
 The estimated weight and power of the communication transponder
will be 180 kg and 650 watts respectively.
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22. Technology
 Multicarrier Demodulator (MCD) and spot beam antenna systems
are being developed for the GRAMSAT.
 There are two techniques used for multi-carrier demodulator (MCD)
as follows :
1. Differential Demodulator using Single delay line
2. Digital Signal Processor based demodulator
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23. Differential Demodulator using Single delay line
 Suitable for medium data rate such as 64 kbps or above
 Does not require complex carrier recovery circuit.
 Hardware complexity reduced
 Bit Error Rate (BER) for differcnt Energy per bit (Eb) to noise density
(No) ratio of the scheme are very interesting -
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24. Digital Signal Processor based demodulator
 PSK Modem is implemented using DSP, because it is more effective
and in-expensive for low bit rate in the range of 9.6 kbps.
 With the availability of higher version of DSP for efficient
implementation of algorithms and higher frequency range, it will be
possible to use it as a multicarrier demodulator.
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25. Ground Terminal
 There are three types of ground terminal available as per the
requirement.
Type – 1
 The first type terminals will be capable of receiving the television
programmes, low bit rate messages and the warning messages etc
from the spot beam meant for that region.
 It can also receive programmes from national beam in C-band.
 It consists of 1 m diameter antenna, receiver and message decoder.
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26. (cont)
Type – 2
 The size of second type terminals will be similar to first type but
will be capable of transmitting the audio signal using 1 watt of
power amplifier.
Type – 3
 Third type terminals will be used for transmission of video
programmes and the terminal size will be approximately 4.5 m in
diameter. One such terminal will act as main station for the region.
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27. Conclusion
 For rural development and tele-education in India, GRAMSAT is
launched and dedicated regenerative type Ku band payload will be
used for rural development and tele-education in INDIA. The
GRAMSAT programme is an ambitious intiative of INDIA’s space
house ISRO, to bring villages, blocks and talukas under umbrella of
communication network at the state level.
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28. References
 A K Sisodia, K N Shankara, “Regenerative Communication Payload
for rural development and tele-education in India”, IET Conference
Publications, Digital satellite communication 1995.
 N Usha Rani, “GRAMSAT – Village satellite for empowerment of
rural people in INDIA”, Journal of communication studies, Vol 4,
No.2, pp 58-68, April-June 2005.
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29. THANK YOU
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