The CBS transponder Testing by the EGSE
Jin-Ho Jo, Dong-Han Shin, Jong-Heung Park, Seong-Pal Lee
Electronics and Telecommunications Research Institute(ETRI)
Yusong P.O box 106, Daejon, KOREA
Abstract: Electrical Ground Support Equipment(EGSE) is used to check out satellite payload during the development
prior to launch. The main task of EGSE is to check out satellite systems, at system or subsystem level, during
integration and validation phases of their life-cycle. This paper represents the EGSE design configurations we
implemented for the Communication and Broadcasting Satellite(CBS) transponder performance testing and test results
of CBS transponders by the EGSE.
Key Words: CBS transponder, EGSE, CTS, PCTS, EQM, FM
1. Introduction
Ka-Band
Communication Services
According to the space development plan of Korean
Multimedia service
government, CBS payload development project is under
Trunk service
cooperating between Electronics & Telecommunications
VOD service
Research Institute(ETRI) and industry in Korea.
Broadcasting Services
CBS payload is consists of Ku/Ka band transponders and
DTH service
antennas. In CBS payload development project, ETRI
plan to develop EQM(Engineering Qualification Model)
Table 2 shows the payload specifications of the CBS. The
and FM(Flight Model) payload from May 2000 to
Fig. 1 shows the CBS transponder configurations.
December 2005.
This paper represents EGSE design configurations which
Table 2 CBS payload specifications
was used for the CBS transponder testing and test results
Ku-Band
of CBS transponder testing by the EGSE.
Ka-Band
EIRP
52dBW
55.5dBW
G/T
9.4dB/K
9.4dB/K
2. CBS Payload Overview
Channel BW
36MHz
100MHz
The CBS is a GEO satellite for the communication and
Service life
Over 15 years
broadcasting service over the Korea peninsula area. The
No. of Channel
3 channels for EQM
Table 1 shows the available services requirements by the
Redundancy
3 active, 1 backup
Antenna type
Offset Gregorian
CBS.
Table 1 Available service by the CBS
Transponder
Ku-Band
The CBS transponder input coupler and output coupler
Services
are used for the system verification. All the stimulus
Communication Services
signals are connected to the input test coupler port and all
SCPS-QPSK-FDMA(64kbps)
the output response signals are monitored at output test
HDR(up to 25Mbps)
coupler port in the system testing phase.
Trunk service(up to 60Mbps)
All equipments are redundancy configurations. The LNA
VSAT
are 2:1 and channel amplifiers and TWTA are 4:1
Broadcasting Services
redundancy configuration. The channel amplifier have
Analog FM-NTSC color TV
two operation mode, one is Fixed Gain Mode(FGM) and
MPEG-2 SDTV
the other is Automatic Level Control(ALC) mode. All the
MPEG-2 HDTV
equipments of the CBS transponders are monitored and
1
controlled by the ground TT&C interface.
automatic performance measurement, and simultaneously
performs the function for routing the output signal to the
measurement instrumentation. Transponder performance
measurement can be executed accurately as well as fast
by using this RF switch matrix. CTS controller has builtin program required for measurement, and appropriately
sets the parameters for various instruments according to
each measurement, and provides the function for
automatic measurement by controlling the various switch
operations of switch matrix. CTS controller stores the
measurement results in the DB, and compares the results
with the specification, and also printout the results.
Ku/Ka CBS Transponder
Fig.1 CBS Ka band payload block diagram
Stimulus
LO
Response
PCTS
CTS
2. EGSE Overview
70VDC CMD TLM
RF Switch Matrix
Test Point Box
The main task of EGSE is to check out satellite systems,
at system or subsystem level, during integration and
validation phases of their
life-cycle. Through a
combination of hardware and software elements, EGSE
Control Stimulus LO Response
DC Power Supply
Payload
Interface
Unit
RF Stimulus & monitor
Instrumentation
GPIB
GPIB
MIL-1553B
supports manual, semi-automatic and fully automated
testing. Automation is achieved by offering users simple,
yet powerful means to write their own test application
programs (test sequences) in high-level, test-oriented
language and to run them in a strict real-time
CTS Controller
(C1)
PCTS Controller
(C2)
Fig.2 EGSE configuration
environment. The core of this environment is a userconfigurable real-time database, containing all the
PCTS controls the parameters of various transponder
information needed to calibrate acquired data, check
equipments as well as performs the function for
them against predefined thresholds, automatically react
monitoring each equipment operation status. PIU
to out-of-range conditions, display data using animated
receives transponder control command generated from
graphics or synoptic windows, and so on.
the PCTS controller, and transfers it to the transponder
Fig.2 shows the configuration of EGSE being developed
after transforming to the suitable command format. PIU
for CBS EQM transponder testing. EGSE comprises two
also receives the operation status as telemetry, and
parts, namely CTS and PCTS. CTS perform the function
transfers this message to the PCTS controller by
for accurate automatic testing of transponder RF
transforming to MIL-1553B format. PCTS controller also
performance.
provides operator GUI environment, and interfaces with
RF stimulus & monitor instrumentation module of CTS
PIU for command generation and monitoring of
consists of signal generator and signal measurement
transponder. PCTS also supplies DC power required for
device, which generates various signals required for
the operation of transponder equipments.
transponder performance measurement, and analyzes the
CTS controller and PCTS controller have connected by
transponder output signals.
TCP/IP, and share various information required for test,
RF switch matrix routes and transfers the signal to the
control and monitor of transponder.
transponder generated from RF stimulus & monitor
3. EGSE H/W Design
instrumentation suitable to each measurement item for
3.1 CTS H/W Design
CTS H/W comprises three parts: RF stimulus & monitor
supply function, and command & telemetry function for
instrumentation, CTS controller, and RF switch matrix.
the equipments of Ka/Ku-band transponders.
RF stimulus & monitor instrumentation consists of CW
overall PCTS configuration is shown in Fig.4.
generator, Sweep generator, Spectrum analyzer, Vector
The PCTS has a DC power supply for providing +70 V
network analyzer, Power meter, Attenuator & switch
system power to Ka/Ku transponders during the ground
driver and Data acquisition unit. These equipments GPIB
test.
interfaced with CTS controller, and operation parameters
power to D/C, TWTA, and also for generating the
of the equipments are controlled as well as monitored by
secondary
the CTS controller.
transponder.
CTS controller configured with PC of windows98
The PIU of PCTS will provide command(CMD) and
environment. CTS controller has a built-in test sequence
telemetry(TLM) function for configuring the components
program for transponder performance testing, and
of transponder during the ground test. In general, these
provides functions for collecting and storing transponder
CMD & TLM I/O interfaces are used to distribute
measurement results, and printing out the results of
commands to the payload and to gather telemetry from
comparisons
controller
the payload. For this function, PCTS has the PCTS
interfaces with PCTS controller through the hub, and
controller and the PIU which are connected with MIL-
shares the data each other.
STD-1553B data bus.
The RF switch matrix module located in the EGSE, will
command data which will be sent to the PIU and
serve as a central interface between the measurement and
monitors the telemetry data which will be sent from the
stimulus equipment and the Unit Under Testing(UUT).
PIU, and the PIU is used to distribute commands to the
All signal connections to the UUT will be made through
payload and to gather telemetry from the payload.
this switch matrix at all the test modes. The RF switch
data between the PCTS controller and PIU is transferred
matrix will contain the necessary circuitry for switching
via the MIL-STD-1553B data bus, with the PCTS
and routing the UUT stimulus and response signal to and
controller acting as the bus controller and the PIU acting
from the appropriate measurement instrumentations. It
as remote terminal.
with
specifications.
CTS
The
The +70 V will be used for providing primary
voltages
will also provide external auxiliary ports, where
in
DC/DC
converter
of
the
The PCTS controller generates
All
Fig.4 PCTS Configuration
appropriate, for injection or monitoring of special signals.
Fig.3 shows the CTS configuration.
Ku/Ka band CBS Transponder
Fig.3 CTS Configuration
TLM
Ku/Ka CBS
Transponder
CW Gen.
Test Point
Box
Switched
70VDC
Payload Interface
Unit (PIU)
Input Test Coupler
Sweeper
Spectrum
Analyzer
CMD
MIL-1553B
RF Switch
Matrix
LO Test CPL
To CTS
Controller
ethernet
GPIB
70VDC
70VDC
PSU
PCTS Controller
4. EGSE S/W Design
VNA
Ouput Test Coupler
Power
Meter
The EGSE software was designed in a hierarchical
structure. This was implemented by building standard
functions that perform discrete tasks. These functions are
CTS Module
Atten/SW
Control
Data
Acquision
then called at many points in the software, the reuse of
GPIB
these functions minimizes the size and complexity of the
CTS Controller
3.2 PCTS H/W Design
The PCTS is used to provide the +70 V Main power
total system. Code that is modified is automatically
updated in all modules that use the specified routines,
additionally this allows for easier maintenance of the
accessible from program control, which includes, but is
system software. The EGSE software is divided into 3
not limited to manual configuration and storage of the RF
primary systems as CTS system, PCTS system and
switch setup, graphical representation of the active RF
PODS. The overall EGSE S/W configuration is shown in
path, access to the system calibration files for graphical
Fig.5.
viewing and printing, and the ability to upload correction
CTS system performs all RF data collection. It has the
factors to the RF instruments.
responsibility of controlling all RF data collection, EGSE
The test scheduler is responsible for launching the
RF switch matrix, and calibration. It makes all of the
specific battery of tests required for the selected
required RF test measurements.
operational mode. It will provide the core ABORT
PCTS system is responsible for DC stimulus, command
control for the individual test routine, or the entire
and telemetry functions for the EGSE test system.
battery of tests to be terminated. The test scheduler also
PODS(Paper On Demand System) is responsible for
allows the operator to programmatically retile, and bring
supplying all hardcopy data as well as a means of data
the current test windows to the foreground at any time
archival and storage. Data is able to be viewed, analyzed
during the testing process.
immediately after the data collection has been performed
The calibration routine is invoked from the Test
without interfering with the RF data collection process.
Executive program. It allows the user to independently
Fig.5 EGSE Software Configuration
calibrate the EGSE RF paths. This routine contain built
in self checks to reduce calibration errors by insuring that
the selected paths are physically connected. The system
PCTS System
Data
Acquisition
Data
Transmitter/
Receiver
stores the calibration files in standard ASCII format.
CMD & TLM
Subroutine
System calibration values can be viewed in the utilities
CTS System
menu. In addition the center frequency calibration values
PODS System
Test Executive
User Interface
Abort
TCP/IP
RF Test Data Files
Print Manager
User Interface
Data
control all of the EGSE switching for the selected paths.
Summary File
Update
Test Scheduler
Data
EGSE configuration program supply the user with a
Print?
Automated Test
Martix
EGSE
Configuration
will be printed on the data hardcopy. This routine can
EGSE
Utilities
Calibration
Routine
RF Test
Routines
means of interactively updating the operation of the
Yse
No
Print Data
Store Data
EGSE through a GUI. It
Data Reprint
allow the user to change the
active test level, EGSE operational mode, and load the
Printer
ASCII.INI files to the binary encoded system files for
4.1 CTS System
program use. The user also able to define EGSE RF
The CTS system software is running on the Microsoft
switch paths, calibration files, define payload switch
Window 98 operating system. It was written in the
configuration
graphical programming language and developed with
information.
and
review
configuration
control
National Instrument LabView.
Test executive is a small low overhead routine that
4.2 PCTS System
launches at system that is responsible for enabling user
PCTS System is the PC-based system with MIL-STD-
access to automated EGSE functions. When testing is
1553B I/F card for the telemetry data transfer, which are
selected to run, the test executive will prompt the
all COTS (Commercial off-the-shelf) products. The
operator for the required information to begin testing.
application software on Windows-NT is coded in C++
Based on the operator’s input, only the test modules that
language, and consists of two tasks as shown in Fig.6.
have been selected will be loaded into system memory.
For the GPIB interface, GPIB command is formatted in
At the conclusion of testing, utilities, or calibration, the
GPIB interface function, and sent to Power Supply for
system will return to the test executive main screen, and
+70V power on, and the GPIB telemetry is collected and
remain there until another function has been selected.
displayed on the telemetry window of GUI.
The Utility software bundle provide the operator with the
ability to access EGSE functions that are normally
Fig.6 Task Diagram of PCTS System
DC Power
Supply
PIU
hardcopy results when desired. The system can be
CMD
TLM
configured as that the user can view the data, on the
1553B I/F
GPIB
I/F
WrapArround
RD
CMD
DISC
CMD
Heater
CMD
Bi.
Serial
CMD
TLM
(PA/AA/DG/Heater/Serial
/CMD Status)
PODS monitor, in its final form prior to printout. In this
way the user can decide which data is generated into
hardcopy.
CMD
TLM
CMD
DB
TLM Display
GUI
TLM
DB
Each data file contains a data page revision that is allow
archived data to be viewed in it’s original form if the data
CMD GUI
page format is incompatible with the current version.
HDD
Event Log
CMD/TLM Data
Batch printing can be accomplished by creating a .LST
Event/Error
Display GUI
Error/Event Data
file in a standard ASCII editor with the filenames of the
data to be printed out. This file can then be copied into
The 1553B command function is quite simple. Each
the print directory of the PODS minimizes the amount of
command to be transferred is selected on the command
‘non-essential’ hardcopy test results due to system aborts,
window of GUI, and frame formatted in 1553B interface
incorrect setup, special testing, etc.
function for 1553B command. And then, this formatted
The test computer will create all archive data files in
command is sent to the transponder through the PIU for
standard ASCII delimited format. This feature of the
the command execution. For the 1553B telemetry
system is allowed viewing on multiple platforms for
monitoring
future retrieval/off line post processing in database
function,
PCTS
system
operation
is
performed as follows:
programs such as Excel, Dbase, Lotus etc. This process
At first, the PCTS controller sends a kind of telemetry
will update a test summary data file that can be used to
request to the PIU such that the PIU can send the
easily identify completed/remaining tests. This is done
telemetry raw data in response to it. And then, when the
when the PODS write the data file to the archive data
raw telemetry data frame comes, it is parsed into each
storage directory.
mnemonic in accordance with the telemetry database.
The parsed telemetry mnemonic is converted with
5. Testing
engineering unit data to represent a physical value of the
EGSE have two different kinds of modes for the
telemetry. For the analog telemetry, this engineering unit
operation, the component level testing mode and system
data is calculated from a fifth-order polynomial equation
level testing mode.
of its calibration equation curve with coefficients in
In component level testing mode, EGSE operation is
telemetry database for every mnemonic. And, for the
manual for the RF performance testing of the transponder
digital telemetry and heater status, this engineering unit
components. In this mode operation, special utility
value that is character type is decided in accordance with
software tools are allows EGSE user to configure
discrete state of “0” and “1” in telemetry database for
switches in the test system and also to plot display
each mnemonic.
contents to the system printer.
Finally, these EU values of telemetry are displayed on the
Most of EGSE testing are performed automatically by
telemetry GUI, and stored into hard disk of BC Station
RF testing sequence program S/W in system level test
simultaneously. For event log function, the system
mode. Before test, EGSE performs calibration procedure
gathers all control and status information including
for getting accurate testing results. RF testing sequence
command sent, errors, etc.. And the gathered Event log
program is consist of test sequences for the transponder
will be displayed on the GUI, and stored into the hard
RF performance testing. It performs RF stimulus
disk.
generation, switch control and data gathering and
analysis through equipment control.
4.3 PODS System
The PODS allows the EGSE to be configured to deliver
5.1 RF Performance Test
Before satellite transponder testing, EGSE performed
function to the operator and data analysis functions.
transponder
functional
The implemented EGSE was used for the CBS EQM
verification it self. The satellite transponder simulator has
level transponder testing in the laboratory. EGSE will
same structure and functions with satellite transponder
plan to be used for the FM model transponder testing.
simulator
testing
for
the
except it have only one RF channel. After EGSE
verification with simulator testing, EGSE performed
satellite transponder RF performance testing. The
parameters of the satellite transponder RF performance
testing by EGSE were as following,
 Input, output VSWR
 Noise figure
 Saturation output power
 Phase shift
 AM/PM conversion coefficient
 Channel amplifier gain control functions
 LO frequency stability
 In band frequency response & group delay
 Out of band frequency response
 Inter-modulation characteristics
Fig.7 Transfer function of Ku band transponder
 Spurious output
 Over drive conditions
References:
[1] Nicklaussen, D., “The `Abrixas' EGSE Architecture
Except VSWR measurement, all the testing on above are
performed
automatically
by
EGSE.
The
VSWR
measurements are manual.
5.2 Test Results
The RF performance testing for the Ku/Ka band CBS
transponder was performed over 3 month in Korea
facilities. The testing environmental were nominal,
thermal cycling and vibration conditions. In total 143
testing items, some of testing results were not comply
requirement specifications slightly. But these no comply
items do not affect overall system performance.
The Fig.7 shows a test result sheet of the transfer
function of the Ku band CBS transponder.
6. Conclusion
The EGSE described on above, is a self contained semimobile test station for the CBS transponder testing. It has
capability of performing several different tasks. The
EGSE can measure many RF performances of the CBS
transponder automatically. It has capability of monitor
status and control commands for transponder. It also
provides in both real time and port test mode data review
and EGSE Software Development Approach,” ESA
report to the ... COSPAR meeting, Vol. 409, 1997, pp.
37-42.
[2] Kaufeler, J.-F., “ESA Committee for Operation &
EGSE Standardization: Its Contribution to ECSS,” ESA
report to the ... COSPAR meeting, Vol.394, No.3, 1996,
pp. 1153-1160.
[3] Jones, M. Melton, B. Bandecchi, M., “TEAMSAT's
Low-Cost EGSE and Mission Control Systems,” ESA
bulletin. Bulletin ASE, No 95, 1998, pp. 152-157.
[4] Chiroli, P. Martinelli, E., “ECHO: A "Core EGSE
SW" Running on Windows-NT,” ESA report to the ...
COSPAR meeting, Vol. 457, 2000, pp. 439-446.
[5]
La
Rosa,
G. Gianotti,
F. Fazio,
G. Segreto,
A. Stephen, J. Trifoglio, M., “The EGSE Science
Software of the IBIS Instrument On-Board INTEGRAL
Satellite,” AIP conference proceedings, No. 510, 2000,
pp. 693-697.
[6] Tri T. Ha, Digital Communication System, 2nd ed.,
New York: McGraw-Hill, 1990.
[7]
T.
Pratt
and
C.
W.
Bostian,
Communications. New York: Wiley, 1986.
Satellite