SATELLITE
ENGINEERING
CENTRE
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SATELLITE ENGINEERING CENTRE
Introduction
Satellite Engineering Centre (SEC) is an inter-school research centre hosted by the School of Electrical and Electronic
Engineering (EEE) with participation from the Schools of Mechanical and Production Engineering (MPE), Computer
Engineering (SCE), Civil and Environmental Engineering (CEE) and Materials Engineering (SME). The Centre was established
in July 1999. Prior to this, the School of EEE has had its Satellite Engineering Programme since 1995. SEC’s mission is to
spearhead R&D activities in new satellite systems and applications. Its core research activities include low earth orbit
(LEO) small satellite bus and payload design, fabrication and testing. Additionally SEC’s activities include the design of
LEO satellite TT&C groundstation and terminals for mobile users. SEC also undertakes consulting R&D work related to
satellite engineering for public and private sector organisations. On 1 December 2001, NTU signed an MOU with the
DSO National Laboratories to form a joint NTU-DSO Centre for Research in Satellite Technologies (CREST). CREST
comprises SEC and a group from the division of guided systems from DSO.
CREST has embarked on its flagship project since its formation – the X-Sat micro-satellite. NTU contributes $6m of
internal funding towards the X-Sat space bus development and launch. An additional $3m funding from DSO is allocated
for the earth imaging and observation payload for enhancement of the X-Sat mission. DSO also contributes its resources
and its team of full-time staff to the X-Sat project. CREST has also received additional grants in the past totalling 2.397m
from internal and external sources for academic research and consultancy projects.
LEO SATELLITE SPACE BUS AND SYSTEM DEVELOPMENT
The objective of this Research Programme is the
development of core capabilities in small satellite platforms
and mission designs for low earth orbits. The current flagship
project is the X-Sat mission.
The X-Sat would support three payloads, the primary one
being an earth imaging payload, IRIS, contributed by DSO.
The X-Sat bus, that is, the satellite shorn of the payloads, is
completely designed and developed in NTU. Currently all
prototypes of the bus have been developed. These
prototypes constitute the Engineering Model which is
currently undergoing testing.
The plan for the X-Sat project began in 2001. It was
conceived as part of a major plan to develop small satellites
and related space technologies in NTU. The X-Sat as
currently configured would be a microsatellite with
dimensions of 600mm x 600 mm x850mm and a nominal
mass of 100kg for launching into a Low Earth Orbit (LEO)
of 685km height by the first quarter of 2007.The execution
of the X-Sat mission proceeded according to the following
planned project milestones:
1. Project Kick-Off in CREST
2. System Requirement Review SRR
3. System Definition Review SDR
4. Preliminary Design Review PDR
5. Critical Design Review CDR
6. Launch Readiness Review LRR
The X-Sat structure uses honeycomb and ribbed aluminium
panels and a central column of module trays for its
construction. Two sides of the structure are fitted with
deployable solar panels, which will be deployed
immediately after launch. The structure has been modelled
using Unigraphics and AutoDesk Inventor 3D CAD/CAM
tools. Numerical analyses to study the structural integrity
during launch, such as the modal vibration modes, are
ongoing. In parallel, the thermal model of the satellite is
being established. A key requirement is the provision of a
safe operating temperature in the interior for all electronics,
optics, batteries and other components in the sub-systems.
The formal project kick-off date in CREST was January 2002.
The SRRs were held in July-October 2002 and this was
followed by the SDR in February 2003 and the PDR in
February 2004. The project is currently in the post-PDR
phase. The review processes normally include panels of
external experts and so far, the panels comprised specialists
from CNES (France) and ISRO (India).
The On-Board Computer (OBC) prototype is now ready
and is undergoing tests. It has been sized to handle all
operations such as system monitoring, safety tasks,
commands and attitude manoeuvres. The operations require
a processor bandwidth of close to 6 MIPS and the ERC-32
processor chosen for the OBC can support 10 MIPS
nominally. The ERC -32 has a number of features that make
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processor to the Flight Computer, and would provide
command packet processing and routing functions
independently of the On Board Data Handling system.
it suitable for the radiation susceptible environment in
space.
A Controller Area Network (CAN) would be used in X-Sat
as the primary means of controlling and communicating
with all the sub-systems within the satellite. The CAN bus
is dual redundant and permits the reduction in the number
of physical cabling within the satellite. The CAN bus
prototypes are now ready and are being integrated with
the key satellite sub-systems.
The X-Sat has a number of novel features, including a high
speed X-band downlink with switch beam and conical
beam antennas that can support bit rates up to 50 Mbs.
This mission data downlink allows for near-real time transfer
of image data to the CRISP ground station. The prototype
X-band transmitter is ready and is undergoing tests.
Two GPS receivers will be used on-board X-Sat for its onboard navigation system. SEC has recently signed an MOU
with the German Space Centre (DLR) to develop a precision
X-Sat Navigation System (XNS) as the secondary GPS
receiver for X-Sat.
The Telemetry and Tele-command (TT&C) System is the
primary communication system in the X-Sat micro-satellite,
allowing it to receive commands from ground controllers
and send results back to end-users. The uplink is 4 kbps
BPSK on a 16 kHz sub-carrier. BCH block codes are used
to protect command packets from the ground station. The
downlink is variable rate, supporting up to 1 Mbps, using
optional Convolutional and Reed-Solomon coding.
The X-Sat development will go through three stages: the
Engineering Model, Qualification Model and Flight Model.
Currently the X-Sat project is at the Engineering Model build
stage and the flat satellite testing activities are ongoing until
March 2005 when the first stage of the critical design review
of the project will be held before proceeding to the
Qualification Model build.
X-Sat would be flying a hardware-based command and
telemetry processing unit. This packet command and
telemetry (CCSDS) protocol processing unit is implemented
using one or more FPGAs. This unit would act as a co-
LEO SATELLITE PAYLOAD AND APPLICATION DEVELOPMENT
The objective of this Research Programme is the
development of core capabilities in Satellite Payload and
Applications for satellite missions.
ADAM is designed for communicating with small ground
terminals.
These terminals could be ocean buoys or
permanently mounted to vehicles or other platforms,
relaying telemetry information across the globe from remote
and/or mobile platforms back to monitoring stations in
Australia, Korea and Singapore.
The current primary focus of the programme is to support
the X-Sat mission. In this respect, there are three main
payloads under development:
The ADAM payload supports full duplex communication
in the UHF band. In addition, Turbo Coding is used to
support communication to very low power terminals. The
engineering model of the ADAM payload is ready and is
currently being interfaced to the X-Sat bus.
1. IRIS Primary Payload
The IRIS camera is a 10-meter Ground Sampling Distance
(GSD) Multi-spectral camera. This camera is being
developed by SaTReCi, Korea, for DSO National
Laboratories. The primary responsibility of this programme
is to jointly define and implement a suitable electrical,
mechanical and thermal interface to protect the payload
during launch loads and the harsh operating environment
once X-Sat reaches its operational orbit.
3. PPU Parallel Processing Experiment
The Parallel Processing Unit (PPU) is an experiment to
realise a High Performance Parallel Processor for Space use.
The core of the PPU comprises up to 20 commercial
StrongArm processors, interlinked by FPGAs.
The PPU
would be able to support high precision Attitude
Determination and Control operations, high speed
communications and real time imaging processing
applications. This unit would be integrated into X-Sat,
providing it with the ability to process sensor information
directly on board the satellite without ground support. The
engineering model of the PPU is ready and is currently
being integrated to the X-Sat bus.
2. ADAM Communication Payload
The Advanced Data Acquisition and Messaging Payload is
a communication payload originally developed by CRCSS,
Australia, for the Fedsat satellite. As part of the UN ESCAP
Common Payload Initiative, the Korean KIASTSAT-4 and
Singapore’s X-Sat would also be flying the same payload,
providing enhanced system capacity and availability.
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LEO SATELLITE GROUNDSTATION AND MOBILE TERMINAL
DEVELOPMENT
The objective of this Research Programme is the
development of core capabilities in satellite ground system
technologies for LEO satellite missions.
CREST has also embarked on a tri-partite collaboration with
SaTReC of Korean Advanced Institute of Science and
Technology (KAIST) and ITR of University of South Australia
(UoSA) to develop the mobile ground terminals for
accessing the services provided by the ADAM payload. NTU
is contributing to the digital system design and
implementation for the mobile terminal.
The major ground segment work on LEO satellite system in
the past involved the design and development of a mobile
LEO Satellite Ground Terminal. A VHF/UHF terminal for
the UoSAT series micro-satellites was designed and
developed. This low cost mobile satellite terminal has
considerable commercial potential. NTU led the low cost
satellite groundstation task force of UNESCAP’s RWG/SSTA
and completed its work in 2000.
X-Sat Internal View
NTU-DLE Meeting on GPS Receiver for X-SAT March, 2004
Currently CREST is undertaking the design and development
of a CCSDS-compatible TT&C satellite groundstation in
NTU which serves as the mission control and operation
centre for the X-Sat mission, as well as any other cooperating
satellite missions. The 6-metre dish antenna and transceiver
are currently being installed at the rooftop of the NTU
Techno Plaza building. The main X-Sat mission control and
operation room is situated at Level 4 of the Techno Plaza
Building. The focus of this research programme is on the
novel satellite groundstation software architecture for
implementing complex ground system design using
distributed object technology. Distributed computing
provides system scalability, interoperability, reconfigurability and rapid recoverability in mission critical
applications while the use of component-based object
model ensures the adoption of rigorous software
engineering practices throughout the project life cycle.
Distributed computing is also well suited to LEO satellite
mission control and operation because of the limited access
to the LEO satellites from any single geographical location
and a wide area network of participating groundstations
will add value and provide increased return from the heavy
investment in the space segment.
X-Sat On Orbit Configuration
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Staff Members
Assoc Prof Tan Soon Hie
Director
[email protected]
Prof Er Meng Hwa
Assoc Prof Kandiah
Arichandran
Asst Prof Chua Tai Wei
Assoc Prof Low Kay Soon
Asst Prof Narayanaswamy
Nagarajan
Prof Narasimhan
Sundararajan
Assoc Prof Chan Choong
Wah
Assoc Prof Chu Yun Chung
Asst Prof Tan Meng Tong
Dr Kudari Isaiah Thimothy
Research Fellow
Dr Yu Qing
Research Fellow
Dr Zhou Keliang
Research Fellow
Dr Jin Zhanli
Research Fellow
Ms Goh Swee Gein
Project Officer
Mr Yeap Yean Wei
Project Officer
Mr Shantanu Shukla
Project Officer
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Dr Ho Hai Pang
Research Fellow
Ms Lim Siok Lin, Sharon
Research Associate
Mr Deepak Mohan
Project Officer
Mr Vipul Gupta
Project Officer
Ms Cary Li Ka Yin
Project Officer
Mr Teh Eng Chuan
Project Officer
Mr Gurprakash Singh
Sandhu
Project Officer
Mr Bharath Ramesh
Project Officer
Mr Narayanan Madhusudanan
Project Officer
Ongoing Research Projects
Project Title
Principal Investigator
Funding
Distributed Computing Technologies for X-Sat Mission Control
Groundstation Software System Design
Tan Soon Hie
NTU ($422k)
X-Sat Micro-Satellite Mission
Tan Soon Hie
Goh Cher Hiang (DSO)
NTU/DSO ($20m)
X-Sat Micro-Satellite Space Bus Design and Development
Kandiah Arichandran
NTU ($300k)
Attitude Control of Micro-satellites
Chu Yun Chung
NTU ($123k)
Project Title
Principal Investigator
Funding
Engineering Model of Merlion Communication Payload and its
Related UoSAT-12 Satellite Sub-Systems
Kandiah Arichandran
NTU ($248k)
Attitude Determination and Control System (ADCS) for X-Sat
Narayanaswamy Nagarajan
NTU ($210k)
Low Earth Orbit Satellite Communications and Services Studies
V K Dubey
NTU ($250k)
Research Projects Completed in 2004
MEng and PhD Theses Completed in 2004
Project Title
Degree
Student
Supervisor(s)
Attitude Control of Micro-satellites
PhD
Luo Wencheng
Chu Yun Chung
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Courses
Name(s) of Instructor(s)
Title of Course
Course Conducted for
Jack Qian
Autodesk Inventor Professional
Satellite Engineering Centre
Selected Publications in 2004
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J.L. Kuang, and S.H. Tan, “QUEST Algorithms Case Study: GPS-Based
Attitude Determination of Gyrostat Satellite”, book chapter in
Advances in Dynamics and Control, Chapman & Hall/CRC Press,
Book in Nonlinear Systems in Aviation, Aerospace, Aeronautics, and
Astronautics Series, 2004, pp.117-136.
J.L. Kuang, P. Meehan, A.Y.T. Leung, and S.H. Tan, “Nonlinear
Dynamics of a Satellite with Deployable Solar Panel Arrays”,
International Journal of Non-linear Mechanics 39 (2004) , 2004,
pp.1161-1179.
Y.W. Yeap, L.H. Chua, and S.H. Tan, “Design of 3.5W S-band Power
Amplifier Based on Small Signal S-parameters Analysis”, Microwave
Journal, Horizon House Publications, Inc., Vol. 47, No. 7, pp 80-90,
Jul 2004.
S.H. Tan, C.H. Goh Cher, K, Arichandran, and W.E. Koh, “X-Sat
Mission: Development and Operation”, Proc. 1st Asian Space
Conference, Thailand, Nov. 2004.
K.I. Timothy, and S.H. Tan, “High Data Rate Transmitter for LEO
Satellite-Design Considerations”, Proc. VTC2004, USA, Sep. 2004.
Y.W. Yeap, L.H. Chua, and S.H. Tan, “Design of 12W X-band Cascade
Power Amplifier”, Proc. RF and Microwaves Conference (RFM2004
Malaysia), Oct 2004.
E. Gill, O. Montenbruck, K. Arichandran, T.S Hie, and T. Bretschneider,
“High-precision onboard orbit determination for small satellites the GPS-based XNS on X-SAT”, Proc. Symposium on Small Satellite
Systems & Services, France, 2004.
D. Mohan, K. Arichandran, and I. McLouglin, “Fault Tolerant
Computer for Low Earth Orbit Microsatellites”, Proc. Symposium on
Small Satellite Systems & Services, France, 2004.
D. Lin, K.V. Ling, G.R. Hu, and N. Nagarajan, “GPS-based Attitude
Determination for Microsatellite Using Three-Antenna Technology”,
Proc. IEEE Aerospace Conference, USA, March 2004.
F. Liu, and N. Nagarajan, “Neural Network Based Orbit Propagation
for Small Satellite Missions”, Proc. 18th Annual Conference on Small
Satellites, USA, Aug. 2004.
N. Nagarajan, S.G. Goh, S.H. Tan, and K. Arichandran, “Attitude
Determination and Control System (ADCS) Design for X-SAT
Mission”, Proc. 1st Asian Space Conference (ASC), Thailand, Nov.
2004.
Y.W. Yeap, E.C. The, and T.W. Chua, “Design of Linear S-band Power
Amplifier with High Power Added Efficiency”, accepted, Microwave
Journal, Horizon House Publications, Inc.
T.W. Chua, K.I. Timothy, K.Y. Li, Y.W. Yeap, E.C. Teh, S.H. Tan, and K.
Arichandran, “X-Sat Communications System”, Proc. 1st Asian Space
Conference, Thailand, Nov. 2004.
14. B. Ramesh, T. Bretschneider, and I. McLoughlin, “Embedded Linux
Platform for a Fault Tolerant Space Based Parallel Computer”, Proc.
6th Real-Time Linux Workshop, Singapore, 2004.
15. B. Ramesh, D. Mohan, I. McLoughlin, and N. Madhusudhanan, “On
Board Data Handling System for the X-Sat Mission”, Proc. 1st Asian
Space Conference, Thailand, 2004.
16. T. Bretschneider, B. Ramesh, V. Gupta, and I. McLoughlin, “LowCost Space-Borne Processing on a Reconfigurable Parallel
Architecture”, Proc. International Conference on Engineering of
Reconfigurable Systems and Algorithms, USA, pp. 93-99, 2004.
17. A. Leonardi, B. Schottdorf, and T. Bretschneider, “Simulation-based
evaluation of design options for high performance parallel
architectures for space-borne applications”, Proc. International
Conference on Parallel and Distributed Processing Techniques and
Applications, Vol. 1, pp. 114-118, 2004.
18. Z.L. Jin, S.C. Joshi, N. Nagarajan, and S. Shukla, et al, “Challenges
in Meeting Thermal, Structural and Power Requirements for X-Sat”,
Proc. 1st Asian Space Conference, Thailand, Nov. 2004.
19. W.C Luo, Y.C. Chu, and K.V. Ling, “H-infinity Inverse Optimal Attitude
Tracking Control of Rigid Spacecraft”, accepted, AIAA Journal of
Guidance, Control and Dynamics, 2004.
20. W.C. Luo, Y.C. Chu, and K.V. Ling, “H-infinity Attitude Tracking
Control of a Rigid Spacecraft”, Proc. 23rd American Control
Conference, USA, June 2004.
21. W.C. Luo, Y.C. Chu, and K.V. Ling, “Optimal Adaptive Attitude
Tracking Control of Rigid Spacecraft”, Proc. 12th Mediterranean
Conference on Control and Automation, Turkey, June 2004.
22. K.L. Zhou, K.S. Low, S.H. Tan, D.W. Wang, and Y.Q. Ye, “OddHarmonic Repetitive Controlled CVCF PWM Inverter with Phase Lead
Compensation”, Proc. IEEE IAS 39th Annual Meeting, USA, Oct.
2004.
23. K.S. Low, K.L. Zhou, and D.W. Wang, “Digital Odd Harmonic
Repetitive Control of a Single-phase PWM Inverter”, Proc. 30th
Annual Conference of the IEEE Industrial Electronics Society, Korea,
Nov. 2004.
24. C.Y. Chua, S.S.L. Lim, and D.L. Maskell, “High performance, reliable
and flexible computing payload for space missions”, Proc. IEEE
TENCON, Nov. 2004.
25. S.S.L. Lim, and H. Schroder, “Onboard remote sensing platform based
on a mesh processing array”, Proc. Australian Space Conference,
July 2004.
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