ground station design for stsat-3

5/13/2018 Ground Station Design for STSAT-3 - slidepdf.com

http://slidepdf.com/reader/full/ground-station-design-for-stsat-3 1/5

Copyrightⓒ The Korean Society for Aeronautical & Space Sciences 283 http://ijass.org pISSN: 2093-274x eISSN: 2093-2480

Technical PaperInt’l J. of Aeronautical & Space Sci. 12(3), 283–287 (2011)

DOI:10.5139/IJASS.2011.12.3.283

Ground Station Design for STSAT-3

KyungHee Kim*, Hyochoong Bang*, Jang-Soo Chae**, Hong-Young Park** and Sang-Hyun

Lee**

*Division of Aerospace Engineering, Korea Advanced Institute of Science and Technology, Daejon 305-701, Korea

**Satellite Technology Research Center, Korea Advanced Institute of Science and Technology, Daejon 305-701, Korea

Abstract

Science and echnology Satellite-3 (SSA-3) is a 150 kg class micro satellite based with the national space program. Te

SSA-3 system consists o a space segment, ground segment, launch service segment, and various external interaces including

additional ground stations to support launch and early operation phases. Te major ground segment is the ground station atthe Satellite echnology Research Center, Korea Advanced Institute o Science and echnology site. Te ground station provides

the capability to monitor and control SSA-3, conduct SSA-3 mission planning, and receive, process, and distribute SSA-3

payload data to satisy the overall missions o SSA-3. Te ground station consists o the mission control element and the

data receiving element. Tis ground station is designed with the concept o low cost and high eciency. In this paper, the

requirements and design o the ground station that has been developed are examined.

Key words: Science and echnology Satellite-3, Ground station, Low cost and high eciency

1. Introduction

Te objectives o Science and echnology Satellite-3(SSA-3) showed in the gure 1 are to optimize technologies

proven through the previous small satellite program developed

by Satellite echnology Research Center, Korea Advanced

Institute o Science and echnology (SaReC KAIS) to

demonstrate the advanced spacecrat bus and payload

technologies, and to train employees o the space technology

elds. Te main payloads o SSA-3 are: Multi-purpose

Inrared Imaging System (MIRIS) and the Compact Imaging

Spectrometer (COMIS). Te MIRIS system is to measure

inrared (IR) imaging o the Galaxy (at 1-2μm wavelengths)

and COMIS is to observe the hyper-spectral imaging o the

Earth’s surace (in the visible and near IR bands at 0.4~1.05

μm wavelengths). Te advanced spacecrat bus technologies which are to be proven through SSA-3 in the space consist

o six items: 1) Li-ion battery, 2) multiunctional complex

structure, 3) high perormance on-board computer, 4) small

solar power control regulator, 5) hall thrusters, 6) array

antenna (Korea Aerospace Research Institute, 2007).

Te ground station o SSA-3 provides the capability tomonitor and control SSA-3, to conduct SSA-3 mission

planning, and to receive, process, and distribute SSA-3

payload data to satisy the overall missions o SSA-3 (Korea

Aerospace Research Institute, 2008).[Ed: Please ensure

when ormatting nished document that all columns end in

** Professor, Corresponding author

** E-mail: khkim@[email protected] Tel:82-42-350-3758 Fax:82-42-350-3710

** Another Senior Researcher

Fig. 1. The structure of Science and Technology Satellite-3.

Received: April 05, 2010 Accepted: September 11, 2011



DOI:10.5139/IJASS.2011.12.3.283 284

Int’l J. of Aeronautical & Space Sci. 12(3), 283–287 (2011)

appropriate places. For example, at the end o a page.]

Te ground station consists o the mission control element

(MCE) and the data receiving element (DRE). In this paper,

the requirement and design o the ground station which is

being developed are examined.

2. Ground Station Design

2.1 Operational concepts

Te goal o the ground station development or SSA-3

is to control SSA-3 or its successul mission using the

low cost and the high eciency concept. For this goal, the

MCE and DRE will be re-used or upgraded with the SSA-2

ground station heritage. Te ground station o the SaReC

KAIS has accumulated its heritage through ground station

development or ve low earth orbit micro satellites and theoperation o our low earth orbit micro satellites since 1992.

Figure 2 shows the basic operational concept o the

ground station or SSA-3 and the payload user groups. In

the gure, user groups request the mission to the MCE. Next,

the MCE veries the requests, converts them into command

sequences, and uploads to SSA-3. Ater carrying out themission, SSA-3 downloads the measured mission data to

the DRE. Te DRE archives the downloaded data and then

transers to the data server. Te user groups nally obtain the

distributed data and utilize the data or their research.

Figure 3 shows a more detailed mission operational

concept. Te user groups o the MIRIS and the COMIS

request a weekly mission plans to the ground station at least

seven days beore. Te ground station checks the validation

o the mission plans based on the status o SSA-3 and

then inorms the user groups o acceptance or rejection.

Te user groups conrm and respond with the result to the

ground station. Te ground station converts the request into

command les. Te command les are simulated, validated,reviewed, approved, and nally uploaded to SSA-3 at least

one day beore.

Fig. 3. The detailed mission operational concept of the ground station.

Fig. 5. The software integrated control scheme.

Fig. 2. The basic operational concept of the ground station interface

for Science and Technology Satellite-3 (STSAT-3) and the user

groups.

Fig. 4. The conceptual design of the tracking, telemetry and command

system of the ground station.



285

KyungHee Kim Ground Station Design for STSAT-3

http://ijass.org

For sae operation o the mission, the ground station is

designed with the concept o primary and back-up tracking,

telemetry and command (&C) systems. Figure 4 shows the

conceptual design o the &C system. Tis &C system

consists o three parts: 1) the antenna subsystem, 2) radio-requency (RF) subsystem, 3) base-band subsystem (ground

station controller, GSC). Tis GSC, which has the base-band

unctions, is designed or autonomously selecting one o the

primary downlink and the back-up downlink o the &C

systems by monitoring the packet count received rom

SSA-3. Tis concept is useul or eciently receiving the

data o the satellite using two &C systems simultaneously.

In case o the uplink, the operator can select one by

controlling the GSC ater monitoring the status o two &C

uplink systems, and the radio signal strength index (RSSI) o

SSA-3.

Te ground station, which is designed with the concept

or the low cost and high eciency, is re-used and upgradedrom the previous ground station. Further, because all o

the SSA-2 and SSA-3 should be operated together,

this ground station should be designed or simultaneous

operation. o meet this condition, the sotware integrated

control scheme studied by Bester et al. (2003) is considered.

Te scheme shown in the Fig. 5 can operate two satellites

with one ground station. Tis scheme consists o one control

PC and several operating PCs or the SSA-2 and SSA-3.

Each operating PC has unique operating programs or each

satellite. Te control PC can autonomously control each

operating PC based on a control list such as the contact time

inormation o the satellite, periodic time synchronization

and the orbital inormation. Tis scheme also includes the

external network or the control PC, and the closed loop

network or the operating PCs or their security.

2.2 Architecture of the ground station

Te architecture o the ground station is shown in Fig.

6. Te ground station has two antennas: 1) 13 m X/S-band

antenna, 2) 3.7 m S-band antenna. Te current 13 m parabolic

reector antenna can download X-band and S-band signals,

but will be upgraded to upload S-band signals as a primary antenna system. Te 3.7 m parabolic reector antenna

system can upload and download S-band signals as a ull

duplex back-up antenna system. Te 3.7 m antenna is to be

re-used rom the existent system. wo antenna systems are

ecient or saely operating the satellite. Te ground station

consists o the MCE or controlling the satellite and the DRE

or receiving the mission data. Te hardware block diagram

and the sotware block diagram o the ground station are

shown in Figs. 7 and 8 respectively.

2.2.1 Design of the hardware

Te hardware system consists o the antenna subsystem,

RF subsystem, base-band subsystem (GSC; data receiving

controller [DRC]), and operating computer subsystem.

Tese antenna subsystems can track satellites via manual,

program, and auto modes, transmit command and ight

S/W to satellites with the S-band uplink, receive telemetry

and ancillary data rom satellites with S-band downlink,

and receive the mission data with X-band downlink. Te RF

subsystem can modulate and transmit the S-band signal,

and receive and demodulate the S-band/X-band signal. Te

GSC can modulate and demodulate into FM/FSK with 9.6

and 38.4 Kbps data rates. It is also capable o data ormatting,

path control, and remote control. Te DRC can handle 16

Mbps data rate and demodulate the QPSK signal or the

mission data. Te Control PCs to operate the satellite and

the receiving PCs to download and archive the payload data

operate on Microsot Windows XP.

2.2.2 Design of the software

As illustrated in Fig. 8, the sotware system consists o,

Fig. 7. The hardware block diagram of the ground station.

Fig. 6. The ground station architecture.



DOI:10.5139/IJASS.2011.12.3.283 286

Int’l J. of Aeronautical & Space Sci. 12(3), 283–287 (2011)

OS, mission analysis, planning, and simulation (MAPS), and

DRE. Te C can control &C hardware autonomously

both in real-time and of-line. Te C also includes the

unctions or controlling tracking, Rx/x, and GSC. Te

tracking program can control antenna tracking. Te Rx/x canmonitor the status o the RF signal and control the Doppler

shit compensation. Te GSC can handle input/output data

rates o 9.6 and 38.4 Kbps and control the interace between

the antenna system and the operating system.

Te OS includes the unctions or monitoring and

controlling the on-board computer (OBC), telecommand and

telemetry (CM) and attitude and orbit control subsystem

(AOCS) in real-time. Te OBC sotware that controls the

satellite in real-time can upload the commands to control

the tasks o the satellite and to perorm the mission, as

well as download the les generated rom the satellite. Te

CM sotware can receive, process, display, and archive the

telemetry and upload the raw commands instead o throughthe on-board computer o the satellite as a contingency.

Te AOCS sotware can monitor and control the attitude o

the satellite. Te MAPS, which has the unction o mission

planning and analysis, includes the unctions o real-time

log, status o health (SOH), and SSA-3 simulation (S3SIM).

Te unction o the real-time log is to monitor the log such

as the status o the on-board computer, tasks, and units o

the satellite. Te SOH has the unction o analyzing the

telemetry. Te S3Sim can veriy commands beore uploading

them and also analyze anomalies detected by the satellite.

Te DRE sotware includes the unctions o tracking, RX, and

receiving and archiving system (RAS). Te RAS can receive

and archive the mission data.

Te sotware o the ground station has a part in common

with the sotware o the electrical ground support equipment

(EGSE) to veriy the perormance o the satellite. o reduce

the development time and cost, this common part can

be designed together or both the ground station and the

EGSE. Tis sotware uses serial line internet protocol (SLIP)

protocol or processing the packet.

Te S/W structure shown in Fig. 9 includes the ollowing

unctions:

- Graphical user interace or controlling and monitoringthe satellite

- Commands processing

- ask processing including the status o the satellite

- Event processing or monitoring and controlling ground

station H/W

- Database managing and data archiving

- Packet processing or the communication interace

Tis graphical user interace has unctions or processing

various input data, including user and script-based command

les. Tis script-based interace can perorm command le

autonomously during the operating time. Tus, its interace

can reduce operating errors and replace changed commands

easily. Te commands processing unction provides denedinput commands decoding, processing, and verication

using the command database. Te unction also includes

raw commands processing or basic commands, single

commands processing or each single command, and macro

commands processing or multiple commands. Te task

processing unction can monitor and process the telemetry

data using the satellite status database. Tis task processing

also has the unction o monitoring and controlling the unit,

OBC, le, attitude, payload, and scenario o the satellite.

Te event processing unction can monitor and control the

Fig. 8. The software block diagram of the ground station.

Fig. 9. The structure of the ground station S/W.



287

KyungHee Kim Ground Station Design for STSAT-3

http://ijass.org

ground station H/W according to acquisition o signal and

loss o signal events o the satellite. Te packet processing

unction can process data to transmit and receive the

signal through the ground station equipments. Tis packet

processing uses the SLIP protocol or communication.

3. Conclusions

Te ground station has been developed and operated

successully since the SaReC KAIS was established in 1989.

With this heritage, the existent ground station will be re-used

and upgraded to reduce the cost, risk, and development

time (Kim et al., 2003). Te sotware integrated scheme was

considered to make it possible to simultaneously operate

more than two satellites with one ground station or cost

eciency. Most o all, it is known that some sotware o the

ground station can be compatible with the EGSE sotwarethrough previous development experiences. Tereore,

these common unctions o the sotware will be able to be

developed and used or both the ground station and EGSE

(Kim et al., 2008). Consequentially, the ground station

sotware will be developed and veried saely through the

development and verication o the EGSE sotware, and the

cost, time and risk rom both developments will be reduced

considerably.

Te perormance o the designed ground station will

be proven throughout the launch, and early operation o

SSA-3.

Acknowledgements

We acknowledge that this paper was supported by SSA-3

program.

References

Bester, M., Lewis, M., Quinn, ., and Rauch-Leiba, J.

(2003). Automation o operations and ground systems at U.C.

Berkeley. Proceedings of the 5th International Symposium

on Reducing the Cost of Spacecraft Ground Systems and

Operations, Pasadena, CA.

Kim, K. H. (2003). Te development o the ground station

or the SSA-1. Proceedings of the Korean Space ScienceSociety , Jecheon, Korea, p. 53.

Kim, K. H. (2008). Te EGSE S/W conceptual design o

SSA-3. Proceedings of the Korean Space Science Society ,

Cheong-Ju, Korea, p. 39.

Korea Aerospace Research Institute. (2007). STSAT-3

SRR Systems Engineering . Daejeon, Korea: Korea Aerospace

Research Institute. pp. 68.

Korea Aerospace Research Institute. (2008). STSAT-3 PDR

Ground Station Section. Daejeon, Korea: Korea Aerospace

Research Institute. pp. 1-57.

ground station design for stsat-3

Documents