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NASA TM-77672

DISCUSSION ON THE PROGRESS AND FUTURE OF SATELLITECOWUNICATION (JAPAN)

M. Ogata, H. Mizusawa, and K. Irie

Translation of "Eisei Tsushin no Ayumi to Kongo no Kadai,"Mitsubishi Gunki, Giho (Mitsubishi Journal of Military Hardware),Vol. 59, No. 6, 1985, pp. 408-412.

(NASA-TM-77672) DISCUSSION ON THE PROGRESS N86-10378AND FUTURE OF SATELLITE COMMUNICATION(JAPAN) (National Aeronautics and SpaceAdministration) 20 p HC A02/MF A01 CSCL 17B Unclas

G3/32 27456

NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONWASHINGTON, DC 20546 SEPTEMBER 1985

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STANDARD TITLE PAGE

1. Report No. 2. Government Accession No, 3. Recipient's Catalog No,TM-77672

4. Title and SubtitleDiscussion on the Progress-and Future of

5, Report Datesnptnmber 19A

6. Performing Organization CodeSatellite Communication (Japan)

7. Author(s) 8, Performing organization Report No.M. Ogata, H. Mizusawa, K. Irie

10. Work Unit No.

11+,Cp^Iroet o ► Grant No.RAW-40A9. Performing Organization Name and Addzoss

13. Type of Report and Period CoveredTranslation

The Corporate Word1102 Arrott Bldg. Pittsburgh, PA 15222

12. Sponsoring Agency Name and Address

National Aeronautics and Space Administration 14. Sponsoring Agency CodeWashington, DC 20546

15. Supplementary Notes

Translation of "Eise i Tsuhin'no Ayumi to Kongo no Kadaii" MitsubishiGunki Giho (Mitsubishi Journal of Military Hardware), Vol. 59,No. 6, 1985, pp: 40$-412.

16. Abstract

The current status of communications satellite development inJapan is presented. It is shown that beginning with research onsatellite communications in the late 1950's, progress has been madecontinually in. the areas of communications, remote sensing, andtechnology experimentation. The current status of communicationssatellites under development is presented, stressing development-inthe areas of CFRP construction elements, the use of LSI . and MICcircuits, advanced multi beam antenna systems, Ku and Ka. bandtransmission systems, and the shift to small-scale earth stations.Methods for reducing costs and increasing transmission efficiencyare shown. The.technical specifications of all satelliteprojects currently being developed are given. Users of Japanese-communications satellite are presented, including INTELSAT, ARABSAT,Japan Public Telegraph and Telephone'Co., ITT.:and AUSSAT.

17. Key Words (561ected by Author(s)) 18. Distribution Statement

Unclassified - Unlimited

19. Security Clussif. (of this report) 20. Security Clossif. (of this page) 21. No. of Pages 22.' Priei "

unclassified unclassified 20

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i PRECEDING PAGE BLANK NOT FILMED' NASA•H6i

DISCUSSION ON THE PROGRESS AND FUTUREOF SATELLITE COMMUNCIATION (,JAPAN)

M. Ogata (Main Branch)H. Mizusawa (Kamakura Manufacturing Plant - PhD)K. Irie (Communication Manufacturing Plant - PhD)

1. Introduction. /408*

Satellite communication has steadily progressed, and now the

number of communication and transmission satellites in

stationary orbit exceeds 400 [1). Since CS was launched in

1978, our country's satellite communications have shown a great

increase as a system which bears the burden of one wing of

advanced information communication. In this special edition:, we

shall emphasize not only the results of communications

satellites and recent technological results in ground station

development, but also prospects for future technological

developments, developing technologies which will be the key to

satellite development, and, further, diversified ground systems.

2. Developments in Satellite Communication within our Company

Our company began to develop artificial satellites in the

late 1950 1 s, and up to the present we have developed many

axtificia,l satellites and loading devices in such fields as

observation, communicatior,, and technology testing. In

particular, with respect to our country's series of

communication satellites, as a maker of communication satellites

we were consistently in charge of development and worked to

advance independent technology in accordance with national

policy. The Number-3 communications satellites which we /409

are presently developing, and for which we have design

*Numbers in the margin indicate pagination in the foreign text.

3

TABLE I

COMMUNICATION SATELLITES AND EXPERIMENTAL TEST

SATELLITES WITHIN OUR COMPANY

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4

authorization, have captured 80% of the domestic market. Inaddition, we are exporting loading equipment for organizations

such as INTELSAT. The communications and experimental test

satellites for which our company was responsible are shown in

Table 1.

The experimental CS medium-capacity stationary.

communications satellite, our country's first communications

satellite, was begun in 1974 and was developed by the Space

Development Group. This satellite was a genuine 350-kg

communications satellite in a stationary orbit and, without any

precedent in the world, used the standard millimeter wave band

(the Ka band). It was a developmental prodv t of Japan PublicTelegraph and Telephone. In addition to reaching the expected

objectives of standard millimeter wave experiments and

establishing techniq?les for practically applying satellite

communication systems, the satellite continued its normal

functions even after its designed lifespan and collected a great

quantity of data for a long period of time.

The communications satellites CS-2a and CS2b (2) now in use

were of about the same capability as the CS and were launched

from the Tanegashima Space Center. At present they are being

used not only by the Japan Public Telegraph and Telephone

Corporation '(Ltd.) and municipal agencies, but also in planned

pilot experiments by the Ministry of Postal Services.

More than just being able to continue the service of the

CS-2 and deal with increased and diversified communication

demands, the No. 3 communications satellites CS-3a and CS-3b are

able to further present development. These satellites weigh 550

kg and occupy a stationary orbit. Their communication

capabilities and capacities have been increased on a large scale

based on the CS-2. They have the greatest capacity of their

class for carrying communications equipment. They use new

5

technology such as galium arsenate solar cells [3] and CFRP

(carbon fiber reinforced plastic) lightweight construction.

As the main contractor we were responsible For the

development of ETS-II, Japan's first stationary satellite, and

FTS-IV ? Japan's domestic large-scale satellite, each of which

collected important data. Further, we are now promoting, as the

main contractor, the development of ETS-V, the first domestic

stationary triaxial satellite. The ETS-V will be developed byindependent technology using such important technology as thehigh-stability triaxial position control. system [41, lightweightCFRP st ,lar paddles, lightweight CFRP body construction, and

large-capacity heat control systems. It also anticipates things

that will facilitate development of the next generation of

high-effi,clenoy, 'large-scale satellites.

We began developing communications satellites for export in

the late 1960's, though we were already supplying loading

equipment to IN"TELSAT III. Further, our company, along with allthe European countries, pa.tici.pated in INTELSAT V, the latest

large-scale triaxial satellite ordered by America's Ford

Aerospace Co., and we were in charge of the antenna, electrical

power control devices, telemetry units, and command unit. This

led to ARAL'SAT's order for loading equipment.

For future communications satellites, we envision things

which will promote capacity growth in response to

communication's demands for growth., diversification, and

economizing. There is a multi-beam satellite communication

system which will efficiently advance the growth in satellite

capacity. A.s for technical problems related to tnis system's

communications, there are small multi-beam antennas, SS-TDMA

technology, and technology for reducing size and weight such as

equipment "LSI-izing" and "MIC-izing". Also, in the satellite

housing, lightweight large-body construction, lightweight

high-powered solar cell paddles, lightweight long-life

6

batteries, and high-capacity, high-efficiency heat control

Systems are important.

3. Satellite Communication Earth. Stations in our Company

Since our firm delivered its first antenna for InternationalTelegraph and Telephone's (Ltd.) Ibaraki Satellite Communication

Station in 19 74, we have delivered equipment relating to many

earth stations all over the world. If these are generallyclassified according to use, there are those for international

communication, those for domestic and regional communication,

and our country's domestic communication (CS and BS response),

and satellite tracking and control. Including equipment that

will. be delivered in 1985, the total number of deliveries comes

to 150. The main deliveries are outlined below.

For an earth station for international communication, there

are, for example, 6/4 G.Hz large-model, stations (standard

A-model), 6/4 GHz small-model stations (standard B-model), and

14/12 GHz large-model bureaus (standard C-model). Including the

7 delivered to International Telegraph and Telephone (Ltd.), we

have delivered 34 standard A model stations (21 of which

included antenna equipment). Among those, however, some such as

the following deserve special mention.

(1) The Ibaraki number 3 antenna delivered to International.

Telegraph and Telephone (Ltd.) in 1972 established a

four-reflector beam transmitting system and standards for

wheel-drive, large-scale earth station antennas.

(2) Delivery of a direct bipolarization joint-use antenna

for use in the INTELSAT V satellite to British Electronic Mail

public Corporation in 1977

7f,

gib. _

(B) Delivery of a C-band (6/4 GHz) TT&CM/IOT 32m antenna to

International Telegraph and Telephone's (Ltd.) Yamaguchi

satellite communication station in 1980 [6].

(4) The Yamaguchi number 2 antenna which was delivered to

International Telegraph and Telephone's Yamaguchi satellite

communication station in 1981 delivered a) correction in the

properties of the wide angle-side lobe that took into account

reflection from the auxiliary reflector support mirror and b) a

device that compensates for the deterioration of cross

polarization characteristics due to rainfall.

(5) Delivery of a common-use C-band antenna to British

Telecommunications International in 1984.

(6) Delivery of an entire TDMA/DSI system for use with

INTELSAT to International Telegragh and Telephone's (Ltd.)

Yamaguchi satellite communication station.

(7) Delivery of 2 complete TDMA/DSI systems to Sweden's

Tanama Station and one complete system to Australia's Sedeuna

Station [7]

The standard B-station is a SCPS-PCM/PSY,system with a

13-11-m antenna and is used in countries with relatively little

traffic and in developing countries. Our company has delivered

4 of these [8].

As for domestic and regional satellite communication systems

placed in other countries, in 1975 we delivered 4 SCPC-supplied

2 standards and inspection stations for the TDMA and a

8

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station for joint use by all Nordic countries. In the case of

Australia's domestic satellite communication system, AUSSAT, our

company received orders for twelve main line stations that are

currently being built by the eight states and capital

territories. They have now entered the final stages of

construction aimed at inaugurating television broadcasting in

October 1985.. These stations adjust antennas to 18 m in areas

of heavy rainfall and 13 m in areas of light rainfall tocompensate for decreases in rainfall. EUTELSAT's Nordic station

is the same, but the earth stations of advanced countries are

set up as computer-controlled, unmanned operations, capable of

remote control. In the AUSSAT system the other 11 stations are

controlled by the Sydney station. Also, the small station (2.4-

and 3.7-m antennas) which can be used by established

communications lines of small towns and villages scattered

throughout Australia have begun in-use testing due to

competition from three other domestic and foreign companies.

In the field of Japan's domestic satellite communications,

we have delivered various earth station-related devices to such

groups as Japan Telegraph and Telephone Public Corporation, the

Space Development Group, the Communication and Broadcasting

Satellite Organization, and the Japan Broadcasting Association,

but recently we have delivered small-scale Ka-band (30/20 GHz)

earth stations to many private users as a link with the CS-2

association and satellite-use pilot plan.

we have delivered a great deal of experimental equipment to

the Japan Telegraph and Telephone Public Corporation's Yokosuka

Electrical Communications Research Facility since the early days

of satellite communication, including a multi-frequency

common-use antenna already completed in 1973, the first in the

world. After that came the CS, Cs-2 period when many Ka- and

C-band antennas for use as part of public circuit satellite

/410

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TABLE 2

REPRESENTATIVE SATELLITE COMMUNICATIONS EARTH STATIONS

x

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n

"+lava Antenna CosuaulticUticnfrequency diameter G/T(dA/K) RIRP (M)

systemUs*

band (Cllr.) (m)

79.2 (132Cl1) FDNI/FM, TDMA

61.$/Ctl SCPC/PCM/PSK (40 INTELSAT standard Type A stationk/4 92 40.7

67.3/Cl1 SCPC/PSK (4i) Talephonn, TV rainy

FM-TV

kl ./CIi SCPC/PCM/PSK (40)

614 11 91.7 6715/Cii SCPC; PSK (441) INTELSAT standard Typn B station

&$10 FM-TVTelephone, TV relay

Domeatic comwounication using INTELSAT

6/4 d 25 .2 37.5/Cli SCPC/AM/PSK satellite t'ranoponderTalephone, data

^- 074 120Mbps TDA(A/DSIEuropean region's satellite

commun-ication14/11 IA 99.b

5715 FM-TV Teleph one, TV relay

14111 9.9 25.0 7215 I'CM/PSK (49) 103 ( International Business Siirvice)

Australia°s domestic satellite

14/12 2.4 22,0 .i5,71Cli SCPC/CFM communications ,Small-capacity communications stations

Domostic satellite communicationsSCPC-FM

30/20 S 92,4 73.6SCPC-PCM-PSK

earth stationTelephone, fscsimiler, data,

communication conforences .

2.4x1.7 SCPC-FM Domestic satellite communications earth static90/20

(oll$ptica^l24.0 $9.0

SCPC-PCM-PSK

1Telephone, facsimile, data, photographs

communications were delivered. Among these are the first

mirror correcting offset cassegrain antennas in actual useanywhere in the world.

Table 2 shows an outline of some things representative of

what our company has delivered up to now,

Attached to this special edition are four papers on the

following subjects which form a treatise on communications

satellites: the EUTELSAT traffic station, the earth station

with the TDMA/DSI mechanism, computer-controlled unmanned system

delivered to Sweden, the Gurnhealy number 6 antenna which was a

joint-use C/Ku-band antennas delivered to British

10

Telecommunications International, the small-type Ica-band earth

station which introduced the DAMA system delivered to the

Pire-fighting Bureau, and the Mitsubishi small-scale earth

station which was an example of a trial participation earth

station.

4. Technical Problems and the Outlook for the Future

Satellite communications grew smoothly in response to the

occasional demands of both the space components, which include

the communication satellite and their launch rockets, and the

earth components, which include satellite communication earth

stations and satt,,11ito control and use stations. The new

situation is tha:: modern "communisations" has diversified

remarkably, and the role that should be attained by the field of

satellite communications has become greater and greater, Here• ^ r 4 4

we want to try to review the true technical nature of satellite

communication.

4.1 Characteristics of Wireless Communication Circuits

When we consider circuits coming down from the satellite and

about their performance, in particular their signal-to-noise

ratio, we should point out that satellite EIRP is proportional

to the area of the earth station antenna, and the system's

transmission speed is inversely proportional to the degree of

static of the earth station. Therefore, assuming a certain

transmission speed (pulse rate) required by the system, the more

you raise the satellite's EIRP, the smaller you can make the

earth station antenna and the more you canutil.ize a lessexpensive receiver. This is the most direct method of bringing

down costs and increasing earth station efficiency (generally

listed using G/T).

Because EIRP is the product of antenna size and transmission

output, increasing a satellite's EIRP requires increasing either

the satellite antenna diameter or the satellite

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transmission output. This is the primary reason why we seek the

early development of the efficient multi-beam antenna. To load

large-diameter antennas into rockets, it is essential to develop

the technology for large-scale housing construction as 44ell as

to develop lightweight components. Technological developments

that permit folding up the antenna at launch time and extending

it in orbit are also essential. Furthermore, since beam

directional accuracy must be higher as the beam becomes more

acute, the satellite posture control must also be extremely

precise.

Increasing a satellite's transmission output is another

important technical problem. Because the TWT is good at

ultrahigh frequencies and high output, in the future much effort

will be poured into developing the TWT for transmission

satellites which we want to have over loo W of power = We must

also realize that power., consumption, heat generation, and

reliability are the greatest difficulties in handling high

frequencies and high outputs. In communications satellites for

which about 20 W of output is suffic?ent, we can continue to

switch gradually from the relatively low-frequency 4 GHz band to

semiconductors. An FET amplifier for the 30/20 GHz-band has

recently been developed and, with respect to increasing

transmission ouput, this is the beginning of an era,

One cannot forget the important point that with wireless

circuits there is radio wave interference. No matter what is

said, the circuit signal coming down from a satellite, because of it'sweakness, encounters severe static from ground-based microwave

circuits. Also, because the pathway up to the orbit for

stationary satellites is getting more crowded, interference with

the circuit going up to the satellite is significant as well.

Because Lie radio beam sent out from the transmission antenna

becomes acute in proportion to the antenna diameter and wave

frequency, interference necessarily limits the reduction in

ground-based antenna diameter and accelerates the move to high

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regions of the used wave frequency bands. At present the C

band, Ku-band, and Ka-band are allotted to fixed satellite

circuits, but the overall stove from C to Ku and from Ku to Ka is

mainly for this reason. Because in Japan land is scarce and

microwave lines have grown in number, interference is a 411

special. problem. In fact, the C -band and even the Ku-band are

already overcrowded with ground lines, and as long as no

interference reduction plan is implemented, things will become

worse.

Because a given satellite's EIRP is relatively small and the

transmission speed required by a system is relatively large, it

is simply inevitable that we will create large -scale earth

stations with systems which handle large volumes of

information. Because of this kind of thing, in the early days

of satellite communications, in order to relay TV, a

30-m-diameter class, large-scale antenna with helium-cooled

receiver and a kilowatt class transmitter was used. Earth

stations with large, stable output are gradually becoming small

scale. Particularly in the case of earth stations whose systems

consist of data transmission, there is the possibility that they

can become so small that they will be just like the existing

60-cm antennas.

4.2 Properties of Coriumunications Networks

The relationship between the three factors of satellite

EIRP, earth station G/T, and transmission speed are, as stated

above, relatively simple. Since hitherto TV signals and large

bundles of public communication circuits were the main load of

transmitted information, a system's highest rate of transmission

needed to be about 100 Mbps, and earth stations' G/T was matched

to this. As wireless technology advances, EIRP and G/T plans

become relatively more free, and the information that has to be

transmitted diversifies, we will probably tend to think mainly

a

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of the transmission speed of a system and in turn of

communications networks.

Without touching on the problems relating to there being no

wires, efficient use of wave frequencies demands compress;,on of

information transmission bands. Simply digitalized TV signals

demand a high transmission speed of 64 Mbps; using recent

technology [11), however, just 768 Kbps is sufficient for TV

conference use, and also, depending on the use, one can transmit

images using just 64 KLds, the same as a telephone. Meanwhile,

regarding computer data transmission speed, we envision

high-speed data using just 48 Kbps, much less than that used by

TV and multiplex telephone. As stated previously, if the speed

of transmission is lo%,, it is all right if just that part of the

earth station is small and an increase in a satellite's EIRP

will further spur the down-scaling of earth stations.

If earth stations come to be small, many so-called compound

systems will be built from the many small-scale earth stations.

The communications network that satellites will create looks

disjointed, but actually it makes up a net-like circuit. The

fact that a perfect network is formed naturally is a satellite

communisations network's best quality. Thus, a network

constructed in this wary has the characteristic that there is

essentially no difference between international communications

which span continents and a network within a city 50 km in

diameter.

When a system's transmission rate is relatively low, there

is a drive for a computer network that can adequately manage a

satellite using small-scale earth stations. The packet exchange

system recognized by data communication is compatible with

existing communication satellite systems, and the growth of this

so-called satellite packet network is expected. Propagation

delay as a particular problem for wireless satellites is a

frequent topic of conversation. However, if one takes

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14

propagation delay into account from the start of system planning

E. which includes protocols, it is actually not a big problem.

Because satellite communication control mechanisms are able to

work with existing transmission control procedures used by

earth-bound circuits, using things that were developed from this

sort of viewpoint, they are very useful.Pi -

The TDMA system that has continued to be developed rapidly

in recent years is close to the general idea of the satellite

packet network mentioned above. Using the TDMA (Time

Multiplexing) system, one transmitting earth station can

instantly occupy one satellite relay, rather than get rid of

reciprocal. modulation which is a problem using FDM (Frequency

Dividing). Moreover, besides increasing transmission capacity,

the TDMA has extremely high flexibility in network construction.

The SS/TDMA (Satellite Switching Time Multiplexing) system

is the first switching TDMA system finally introduced from

INTELSAT IV after a long period of technical development. This

switching allows association between satellite relay devices by

microwave and, further, it advanced SS/TDMA research which^t

p ' carried out relays as an advanced system and which was based on

beam scanning. Because it is possible to do such things as

exchange signals that are on the timeg g spindle, if one comes back

to the bass band using the satellite, it is possible to build a

system which ran constitute a flexible system, which can change

allocations as needed in response to special traffic demands,

X13 and which is extremely practical.

The advance of semiconductors and the completion of software

also accelerated the creation of advanced systems. The creation

of systems like those mentioned above which used relays and

ultra-high-speed switching, at least in theory, looked quite

distant. Recently, however, high-reliability, small-sized,

lightweight "LSI-ization" has allowed advanced simulations by

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systems tests without worrying about the environment of space. {

Therefore, we can say that what should be called the ideal of

satellite communication, the creation 0.' on-board processing, is

near at hand.

If a signal is reconstituted within the satellite, it will

differ from existing transit type devices and will be able to

exclude much of the heat static and interference static involved

with transmitting up to satellites. Therefore, Including

frequency choice and circuit preparation and adding degrees of

freedom to circuit plans in turn brought about reforms i,n systemconstruction.

4.3 Cost Effectiveness

The fact that one is fully utilizing the cost effectiveness

of a satellite when one implements satellites in networks is

becoming more and more important. That is, people have decided

to build systems which make the most of the charateristics of

satellites and maximize satellite utility. As for the bottom

line in cost effectiveness, namely "a cost is a cost," it is

necessary to investigate each case on the basis of the terms

agreed upon.

The most effective way to minimize the cost of machinery,

and this is not limited to satellites, is to mass produce the

items whose development is complete. Figure 1 is extremely

rough, but it shows that costs (unit costs) decrease in response

to quantity produced (one can see this r( , ighly by date). Line 1

is the cost reduction curve for the space components

(communications satellites and launch rockets and

tracking/control). (The reduction rate from the INTELSAT

satellite is 0.6). Viewed in this way, the technical progress

of communications satellites is spectacular, and, therefore,

cost reductions are phenomenal. Line 2 is the earth part (earth

stations) cost curve; while it is not spectacular,

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. __, v - .11

t

jrr^

1

1. ^

9

M

it shows the same or greater price reduction than earthbound

wireless systems.

Meanwhile, there were many existing communications networks

combining the space and earth parts which seldom used mainly

large-scale communication satellite stations. In other words,

there were mostly stations which sent and received messages

using large-scale earth stations which used the large capacity,

long distance cables, the satellites hung in the sky. However,

in addition to recognition of the utility of satellite

communications and the diversification of their use, component

systems which use small-type earth stations continue to increase

in number. As was stated before, in order to make the earth

components simple, the space components will probably be made

even larger (curved lines l' and 2 1 ). In this way the so-called

rooftop earth stations are springing up one by one.

• However we cannot in the least ignore the future competition

for public resources. That will promote efficient use of radio

waves (wireless frequencies and bands) and stationary satellite

orbits. The development of essential interfaces to be able to

combine satellites into existing networks will, also become

important. Thus, the demand for these things will gradually

become severe. (curved line 3)

1

1 ^ f4Q ^0 lry.^^/_ s

0,1U,

(k^021.r'.^ OY

1040 W5 IR50 1955 1260 IR65

Figure 1. Cost History

Vertical scale: Relative cost;

Horizontal scale: 1961 1966

1971 1976 1981 1986;

1. Space components; 2. Earth

components; 3. Cost for

effective use of orbits and

electrical waves, for network

interfaces, etc.

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Because of facts like these, high cost effectiveness 912

will be demanded of future satellite communication systems; a)

In the field of public communications, we can probably continue

progressive development of systems entered on large-size

communications satellites and aimed at establishment of a

large-capacity wide-band region (a highway) of transmission

pathways. b) Also, for commercial use, in addition to using the

lowest cost communications satellites whose development is

already complete, feedback into the planning of communication

satellites in order to build the most efficient network will

also become a major theme. c) Further, the use of satellite

communications as the most efficient tool for radio station

networks will inevitably increase.

5. Conclusion

In the preceding, after we looked at the history of

communications satellites and satellite communications within

ou company, we explored 1) satellite communications with

wireless circuitry and 2) the technical problems involved with

communications satellites which form networks with special

features.

Satellite communications were extended from interntional

communications. This was done using primarily the matchless

characteristics of satellites, least of which is their

long-range transmitting ability. We may say that recently it

has finally been realized that satellite circuits are a unique

and indispensible tool for the construction of high-speedinformation communication networks.

Our country's communications satellites are working in a

stable way. The Ka-band, which we led the world in introducing,

has proved itself in use and opened the road to the future

efficient use of the whole spectrum c, ,f wave frequencies. There

is an extreme abundance of choices in earth stations. However,

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maximizing the efficiency of satellites will be controlled by

future systems and construction. What we need to do is solve

detailed technical problems while broadly concerning ourselves

with hardware, software, cost, and efficiency. Finally we would

like to express our gratitude to everyone involved who provided

us with continued guidance, and we hope that the use of

satellite communications continues to grow.

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REFERENCES

1. W. L. Morgan: "Satellite Locations - 1984," Proc. IEEE,Nov. 1984.

2. Kido et al.: "Communications satellite No. 2 (CS-2) and itsorbital behavioral conditions," Mitsubishi Journal ofElectrical Hardware 59, No. 6, 1985.

3. T. Miyoshi, et a1.: "An antenna despun spacecraft with GaAssolar cells," 14th IAF, No. IAF-86-63, 1984.

4. Ishikawa, et al.: "On the orbital posture of the Type Vexperimental test satellite," 28th Meeting of the JointSpace Science Technology Association, I F 16, 1985

5. Matsumoto et al.: "Equipment for the Ibaraki SatelliteCommunications Facility's number three antenna," MitsubishiJournal of Electrical Hardware, 47, No. 3, p. 252, 1974.

6. lbaraki et al.: "Eanipment for the Yamaguchi TTC&M earthstation," International Communications Research, No. 104,1980-4

7. M. Nakanishi et al.: "120 Mbps TDMA traffic terminal foruse in INTELSAT and EUTELSAT system," The InternationalJournal of Satellite Communications (to be published).

8. Irie et al.: "Small-scale international satellitecommunications supplied to Sierra Leone," Mitsubishi Journalof Electrical Hardware, 54, No. 3 p. 227, 1981.

9. Shimada et al.: "On the Yokosuka Satellite CommunicationsTest Facility's No. 3 Antenna," Mitsubishi Journal ofElectrical Hardware, 48, No. 7, p. 819, 1975.

10. T. Takagi et al.: "A 1.5-W 28-GHz band FET amplifier," 1984IEEE MTT-S Digest,, p. 227.

11. Muraue: "Dynamic multi-level vector quantization ofimages," Journal of the Electrical Communication Society, J68-b, No. 1, p. 69, 1985.

12. Shibata: "Satellite communications control devices,"Mitsubishi Journal of Electrical Hardware, 59, No. 6, 1985.

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