Three satellite communication projects now in progress in Japan are described. The first is a project to establish a telecommunication network for tele-education, TV conference, and tele-medicine in the Asia-Pacific region by using the Japan's Engineering Test Satellite-5 (ETS-5). The second is a project of the ETS-6 satellite, to be launched in 1993, for inter-satellite communication, mobile and fixed communication, and millimeter wave personal communication experiments. The third is a project of the Communications and Broadcasting Engineering Test Satellite (COMETS), to be launched in 1997, for advanced mobile satellite communication, inter-satellite link, and advanced broadcasting experiments at higher frequencies

Iida, Takashi

Obara, Noriaki

Wakana, Hiromitsu

English

NASA Technical Reports Server

--tNAPE,¥ XVI, Houston, Texas, May 29, 1992
[,_ ,fie
N 93-26470
ETS-V, ETS-VI and COMETS Projects
in Japan
I
Takashi Iida, Hiromitsu Wakana and Noriaki Obara
C:)mmunications Research Laboratory,
Ministry of Posts and Telecommunications
Koganei, Tokyo, Japan 184
Abstract
This paper describes three satellite communication projects now in progress in
Japan. The first is a project to establish a telecommunication network for tele-
education, TV conference and tele-medicine in the Asia-Pacific region by using
the Japan's Engineering Test Sateilite-V (ETS-V). The second is a project of the
ETS-VI satellite, to be launched in 1993, for inter-satellite communication, mobile
and fixed communication and millimeter wave personal communication experi-
ments. The third is a project of the Communications and Broadcasting
Engineering Test Satellile (COMETS), to be launched in 1997, for advanced mobile
satellite communicatior_, inter-satellite link and advanced broadcasting experi-
ments at higher frequencies.
1. Introduction
In the 21st centur), satellite com-
munications systems will become more
advanced forms and be extended to the
personal level by using higher frequen-
cies than those in existing satellite sys-
tems. In the fields of direct satellite
broadcasting or inter-satellite communi-
cation systems, the use of higher fre-
quencies is expected for high quality and
high data rate transmissions.
The Communications Research
Laboratory (CRL) has been carrying out
mobile satellite communications experi-
ments for ships, aircraft and land-vehi-
cles by using the ETS-V satellite(l) . As a
part of the International Space Year's
(ISY's) projects, we ale planning to
establish a telecommunication network
using ETS-V in the Asia-Pacific region.
As a challenge to future advanced
satellite communication systems such as
Ka-band and millimeter wave mo-
bile/personal satellite ,-ommunications,
the ETS-VI and COMETS satellites will be
launched by Japan's H-II rockets. This
paper presents an overview of these cur-
rent satellite projects.
2. ETS-V and PARTNERS
Project
The ETS-V satellite is now being
used in mobile satellite communications
experiments for ships, aircraft and land-
vehicles. L-band of 1.6/1.5 GHz is used
between mobiles and the satellite, and C-
band of 6/5 GHz is used between the
satellite and the coast/aeronautical earth
station. The L-band antenna beams con-
sist of two beams: the North-beam cover-
ing the Northern Pacific Ocean and the
South-beam covering the South-Western
Pacific Ocean. Fundamental communica-
tion links are C-to-L and L-to-C links be-
tween the coast/aeronautical station, at
Kashima in Japan, and mobile earth sta-
tions.
The Space Agency Forum oll the
ISY (SAFISY) in the United Nations has
assigned this year, 1992, to the ISY, and
has proposed to utilize space technologies
to deliver educational programs, medical
treatment, space science and technology
for developing countries via satellites. At
SAFISY #4, held in Moscow May 1991, the
Government of Japan has proposed a
project of tele-education systems in the
Asia-Pacific region by using the Japan's
ETS-V, in cooperation with the University
of Hawaii. This project is named "Pan-
Pacific Regional Tclecommunications
Network Experiment and Research Satel-
lite (PARTNERS)", and it is planning to be
64
https://ntrs.nasa.gov/search.jsp?R=19930017281 2020-03-17T05:40:31+00:00Z
ETS-V
User Terminals _ _"_"';:,m;r;,""m;;;op,';;;_;"
(_ : monitor/ speaker I
"_"_'i 4L_ Ir_ HubStation i _J _
L I C link : 3 Ml-lz
/
T : ....3.:..k..:...............
..................... . J
_ 4.8 kbps x 2
L/LIInk :300kHz I i _ er 9"6 kbpsxl:
I--i-q I 300bpl
16 kbps x 2
L.J 1,_
.:..,yo,;,;.,,.o.ly?...............
..... ; Option
Fig. 1 Concept of PARTNERS Network.
started in August, 1992. CRL, Ministry of
Posts and Telecommunications, the
National Space Development Agency of
Japan (NASDA) and the Science and Tech-
nology Agency are carrying forward this
project in cooperation with educational
institutions, government agencies, or-
ganizations in Japan and in Asia-Pacific
countries.
Main purpose:; of this project are
to support the peoples in various areas
including education, health, marine re-
source managements, and environment
and communications, and to promote in-
ternational collaboration for space ac-
tivities in the Pan-Pacific region
through a low-cost satellite communica-
tions network, as shown in Fig. 1. Con-
tents of this project are summarized as
follows.
(l)Transfer of Space Technology
-Cooperative researches on radio-wave
propagation characteristics in satellite
paths with researchers in the Asia-
Pacific countries.
-Education programs on space tech-
nologics for the people in developing
countries.
-Cooperative research on the optimum
satellite communications systems for
remote rural areas.
-Cooperative research on satellite tele-
education systems for rural areas.
(2)Exchange of Informatio.
-F, arlh envir(_nme,t.
-Space deveh_pmen! related activities.
-l_ducation programs, medical Ireatment
and researches: demonstrations of a
lele-educalion syslem, a tele-medicine
syslem.
(3)Interchange between Organizations
-Various events, for example, an open
forum on space science for young
generations.
-TV conference via satellites.
-Cooperative events with another ISY
projects.
Now, we are now constructing a TV
conference network using ETS-V with
simple and lo,._-cost earth stations at
65
about six places in the Asia-Pacific re-
gion.
3. Advanced Communications
Satellite Projects
Early in the 21st c zntury, needs for
personal communications will rapidly in-
crease in fixed and mobile satellite com-
munications services. A mobile satellite
system will provide communications
services for not only airplanes, ships and
land-mobiles but also t_and-held termi-
nals and portable VSATs. Furthermore,
demands for various high quality satellite
broadcasting services such as HDTV and
high quality sound broadcasting will also
increase. Therefore, development of ele-
mentary technologies for a hand-held
terminal, a large satellite antenna and
beam interconnecting is required to real-
ize low-cost and user-friendly terminals.
In Japan, to develop these ad-
vanced technologies, two engineering
test satellite projects are in progress. One
of the satellites is ETS-VI and another is
COMETS.
3.1 ETS-VI Project (2)(3)
ETS-VI is a two-_:on class, three-
axis-stabilized geostationary satellite as
shown in Fig. 2, and is scheduled to be
launched in 1993 by _. Japanese H-II
rocket. One of main missions is to develop
fundamental technologies for advanced
inter-satellite communication systems.
  GHzl2GHz
Gimbal Platform \ I
Fig. 2 Conceptual Sketch of ETS-VI.
Table 1 Features of ETS-VI.
Bus System
Shape Rectangular body with
deployable solar paddles
Weight Approx. 2 tons
(beginning of life)
Payload capacity 660 kg
Attitude Control 3-axis-stabilization
Life 10 years for satellite bus
Electric Power 4100 W (end of life
at summer solstice)
Launch Vehicle H-II rocket
Launch Date Summer, 1993
Orbit 153.8 degrees East
Communication Experiment Mission
-Ka-band Multibeam Fixed Satellite Communications
-S-band Mobile Satellite Communications
-S-band Inter-satellite Communications
-Ka-band Inter-satellite Communications
-Millimeter-wave Satellite Communications
-Optical Satellite Communications
The major characteristics of ETS-VI and
experimental communication payloads
are summarized in Table 1. ETS-VI is
equipped with two large antennas for
fixed (Ka and C band) and mobile (S band)
satellite communications, a S-band
phased array antenna, a Ka-band and a
millimeter wave band gimbaled antennas
and an optical telescope for inter-satellite
communications.
CRL is planning to start the follow-
ing experiments in late 1993 after the
initial check-out of the satellite and con-
tinue experiments about three years. The
concept of the experiments is shown in
Fig. 3.
(1)S-band Inter-Satellite Communications
The S-band (2.3/2.1 GHz) Inter-
Satellite Communication payload (SIC) has
a multibeam phased array antenna in co-
operation with NASDA to establish the
future Japanese Data Relay and Tracking
Satellite System (DRTSS).
The specification of the SIC is
shown in Table 2. The SIC is compatible
with the S-band Multiple Access (MA)
system of the NASA's Tracking and Data
Relay Satellite System (TDRSS). CRL and
NASDA are planning to conduct funda-
mental tracking and data relay experi-
ments between ETS-VI and low orbit
66
ETS-VI (_)
[__ Table 3 Major Specifications of
/___ -_......_._._._._ ETS-VI
_ [_llllr Millimeter-Wave Transponder.
LEOsatelliteFrequency 38 GHz 30 MHz for forward
IS-Band) 43 GHz 30 MHz for return
Amp. Type SSPA (GaAs FET)
Output Power 0.8 W (SSPA1), 0.5 W (SSPA2)
_ _ d _ _ _ _ Noise Figure 5.2dB(HEMT)Freq. Stability, 1.7 10-7
TT&C mmW mmW Feeder Link !;.Band S-Band Ground
(NASDA) USSIP'I" PT Station USS MT Optical System tion systems.
USS : User Satellite Simulator F'[ : Personal Telrmina!
mmW : millimeler Wave HT :Mobile TermmaJ
Fig. 3 Concept of ETS-VI
Experimental System.
satellites. Candidates of user satellites are
the ADvanced Earth Observing Satellite
(ADEOS) to be launched in 1996, and the
Japanese Experiment Module (JEM) of the
International Space Station.
(2)Millimeter Wave Satellite Communica-
tions
The millimeter wave transponder
has the frequency of 43/38 GHz. These
frequencies have been selected,
considering the atmospheric attenuation
allowable in personal satellite communi-
cations and the achievable technology
level of millimeter wave devices. The
major specifications of the millimeter
wave transponder arc summarized in
Table 3. Two high power GaAs FET am-
plifiers are equipped in the ETS-VI
satellite: One has the oatput power of 0.8
Watts and another has 0,5 Watts. The noise
figure of a low-noise arr_plifier of HEMT is
5.2 dB. The objectives of this mission are
to develop high data rate inter-satellite
communication technology and to study
the feasibility of personal communica-
(3)Optical Inter-Satellite Communications
The onboard optical communica-
tion payload (Laser Communication
Equipment, LCE) has fundamental optical
communication functions with a tele-
scope of 75 mm in diameter, which has a
beam pointing, acquisition and tracking
mechanism with a gimbal mirror, an
aluminium-gallium-arsenide laser diode
transmitter at a wavelength of 0.83 mi-
crons, a silicon avalanche photo diode re-
ceiver at a wavelength of 0.51 microns,
modulator/demodulator for 1.024 Mb/s
pulse modulation. These features are
summarized in Table 4. This optical
communications system is expected to be
much smaller, to consume less power and
to be able to carry more information than
the radio frequency inter-satellite sys-
tems.
3.2 COMETS Project(4)
In 1990, the Government of Japan
has authorized the COMETS project.
COMETS is a three-axis-stabilized geosta-
tionary satellite with three deployable
antennas for Ka- and S-band inter-
satellite links, millimeter wave and Ka-
band mobile communication links, and
Ka-band broadcasting links, as shown in
Fig. 4. COMETS will be launched by a H-II
rocket at the beginning of 1997 to de-
Table 2 System Performance of SIC. velop key technologies of advanced
Frequency
Antenna
No. of Beams
2106.4 MHz =3 MHz for forward
2287.5 MHz :t2.5 MHz for return
Onboard bear:l forming multi-
beam phased array antenna
1 for forward
2 for return
Tracking Range 10 conical (covering LEO
satellites below 1000 km in altitude)
GFF > -4.4 dB/K
EIRP > 34.1 dBW
Table 4 Major Specification of LCE.
Wave Length 0.83 nun for down link
0.51 mm for up link
Telescope 75 mmf (Magnification: 15)
Laser Source AIGaAs LD
Output Power 13.8 mW
Detector Si-APD
Data Rate 1.024 Mb/s
Weight 22.4 k_
67
satellite communications and broadcast-
ing. Table 5 shows feature_ of COMETS.
Three mission payloads are shown below.
(1)Advanced Mobile Satellite Communi-
cations
Advanced mobile satellite commu-
nications payloads using Ka-band and
millimeter wave is being developed by
CRL to develop key technologies for fu-
ture advanced satellite communications
systems at higher frequencies. Figure 5
shows a service concept of the advanced
satellite communications system.
The two-meter Ka-band antenna
for mobile communications links has one
spot beam for millimeter wave links and
two spot beams for Ka-band links. These
beams are interconnected onboard with
an IF filter ban method or baseband pro-
cessing of a regenerative transponder.
The specification of this payload is shown
in Table 6. In the filtel bank method,
signals from an up-link beam are divided
by the IF filter bank and sent to its desti-
nation beam. In the basel_and processing,
SCPC signals in up-links ;ire demodulated
to baseband signals and ale switched and
Table 5 Features of COMETS.
Bus System
Platform Based on ETS-VI
Weight Approx. 2 tons (in orbit)
Mission Life 3 years
Launch Vehicle H-II rock.:t
Launch Date 1997
Communication Experiment Mission
- Advanced Mobile Satellite Communications
in Millimeter-wave and Ka-band
- Advanced Satellite Broa&_sting in Ka-band
- Inter-satellite Communication
in Ka-band and S-band
2 m_ Antenna for Feeder Link and
Advanced Mobile Satellite Communication_ ___
for Advanced Satellite Broadcasting _,_ _"
©
n$ Antenna
// lot Inter-satellite Communications
Fig. 4 Conceptual Sketch of COMETS.
Table 6 Outline of COMETS Ad-
vanced Mobile Satellite Communi-
Antenna
Diameter 2 m (Ka-band/mm-wave)
No. of Beams 3 (2 Ka-band, 1 mm-wave)
Polarization Circular
Transponder
Two Ka-band (20W/10W SSPA)
One millimeter-wave (20W TWTA)
Operating mode
- 3 3 Matrix Beam Interconnecting
by IF filter bank
- 8 ch SCPC/TDM Baseband Regeneration
multiplexed to TDM signals on its destina-
tion beam. Onboard channel assignment
is achieved by baseband switching.
(2)Advanced Satellite Broadcasting
The Ka-band advanced direct
broadcasting payload is developed by CRL
and NASDA. Major specifications are
shown in Table 7. The purpose of this
mission is to develop Ka-band HDTV
broadcasting technologies which is high-
er quality than the existing commercial
Ku-band satellite broadcasting in Japan.
Furthermore, key technologies for vari-
ous broadcasting services using Inte-
grated Services Digital Broadcasting
(ISDB) and multibeam satellite broadcast-
ing experiments for local broadcasting
services.
(3)S-band and Ka-band Inter-Satellite
Communications
As mentioned in the section of the
ETS-VI project, inter-satellite links com-
patibility at S-band frequencies will
achieve among NASA, ESA and NASDA
systems. To operate high data rate in in-
ter-satellite links, NASDA is developing
Ka-band inter-satellite systems and plan-
ning to carry out experiments in the
COMETS project. Both S-band and Ka-band
inter-satellite payloads are equipped in
COMETS to develop key technologies for
large satellite antennas, high accuracy
acquisition and tracking systems, high
data rate inter-satellite systems.
4. Concluding Remarks
In this paper, communications
satellite projects of ETS-V, ETS-VI and
68
Table 7
Advanced
Mission
Frequency
Band Width
Antenna
Diameter
No. of Beams
Polarization
Gain
,, Transponder
Outline of the COMETS
Satellite Broadcasting
Pa_'loads.
22 GHz band
120 MHz
2.3 m
2 (two areas in Japan)
RHC
> 44 dBi (field of view)
> 2(0 W (TWTA)
COMETS are briefly reported. Propagation
measurements are conducted or planned
by these satellites at many different fre-
quencies as well as satellite communica-
tions experiments. Table 8 summarizes
available frequencies for propagation
measurements, satellite,, and its missions.
The frequencies range from 1.5 GHz to
47GHz. Configuration {)f the measurement
system in the ETS-VI and COMETS experi-
ments is now under consideration. The
results of L-band propagation measure-
ments using ETS-V for mobile satellite
communications we_c presented in
NAPEX XV(1 ).
References
(1)H. Wakana, "Propagation Research in
Japan," Proc. NAPEX XV, London,
Table 8 Available Frequencies and
Satellite for Propagation Measure.
ments.
I
Frequency bands Satellite Correspondin_ Missions
1.6/1.5 GHz ETS-V Mobile satellite com.
2.2_./2.1GHz COMETS Inter-satellite com.
2.3/2.1 GHz E'I_-VI Inter-satellite com.
2.6/2.5 GHz ETS-VI Mobile satellite com.
6/5 GHz ETS-V Feeder links & sat. com.
26/23 GHz COMETS Inter-satellite com.
30/20 GHz COMETS Feeder links
28/21 GHz COMETS Satellite broadcasting
30/20 GHz ETS-VI Feeder links
30.8/21.0 GHz COMETS Mobile satellite com.
32/23 GHz ETS-VI Inter-satellite com.
43.0/38.0 GHz ETS-VI Fixed satellite com.
46.9/43.8 GHz COMETS Fixed satellite com.
510/830 nm ETS-VI Optical inter-sat, com.
(2)T. lkegami, "Plan of Advanced Satellite
Communication Experiments using
ETS-VI," Proc. NAPEX XIII, San Jose,
USA, 1989.
(3)N. Kadowaki, et al., "Advanced Satellite
Communications Experiments using
ETS-VI," in preparation.
(4)S. lsobe, et al., "Experimental Advanced
Mobile Satellite Communications Sys-
tem in mm-wave and Ka-band using
Japan's COMETS," Proc. Second Europe-
an Conference on Satellite Communi-
Ontario, Canada, 1991. cations, Liege, Belgium, October 1991.
/ I ";,%0,
........ \
TV'Conference
Fig. 5 Concept of Advanced Mobile Satellite Communications System.
69


ETS-5, ETS-6, and COMETS projects in Japan

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