Trends in NASA Communication Satellites

8/7/2019 Trends in NASA Communication Satellites

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NASA TECH N ICALMEMORANDUM

N A S A TM X-68141

00NOIX


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ABSTRACTSatellite telecommunications can help to satisfy several national

needs such as education, health care, cultural opportunities, and datatransfer. There are current experiments being conducted with NASA-s p a c e c r a f t ATS 1, 3 , and 5 in an attempt to satisfy these national needs.Future experiments are planned f o r t h e A T S F /G a n d C T S spacecrafts.T he next generation of communicationssatellites must provide multipleregion coverage, multichannel capability, high quality T V pictures, andm u s t allow low cost ground receivers to be used. T he proposed NASA

^ spacecrafts, ATSH/I, will satisfy these requirements. Other countriest- of the world can benefit f r om A T S H /I technology.w


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1T R E N D S IN NASA C O M M UN I C AT I O N S A T E L L I T E S

b y Joseph N . Sivo, W il l iam H . Robbins ,and D . Michael S tr e tchber r yL e w i s R e s e a r c h C e n t e r

S U M M A R YTelecommunica t ions has the potential fo r p r ovid ing s ignif icant

assistance in the d r i v e to satisfy a var ie ty of national needs in the U SAin the 1980's. T hese needs inclu de edu cation, health care, cul tur a l op-portunit ies and the efficient t r ansmiss ion of data over large d is tances .These fu tu re t e l e c o m m u n i c a t i o n s systems will include both satelliteand terrestrial segments and will have the capability of d ir ect b r oad cas t ,networking and in ter act ive c o m m u n i c a t i o n . B e f o r e th e r e q u i r e m e n t s ofsuch operational telecommunications systems can be f i r m l y established,a per iod of exper imentat ion with var ious mod es of p r o g r a m m i n g and in-format ion t r a n s f e r is necessar y . C ur r ent ly , such exper imentat ion isbeing d one us ing the ATS 1, 3, and 5 s p a c e c r a f t s . In 1974 and 1975 the


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I N T R O D U C T I O NT h i s p a p e r discusses s o m e of the nat ional need s of the United States

and indicates how c o m m u n i c a t i o n s satellites can help solve some of theseneeds. High p o w e r satellites that al low a s ignif icant expansion in com-munica t ions capabilities as well as l o w e r costs are a good way to satisfyth e national needs. N A S A ' s p r o p o s e d c o m m u n i c a t i o n s satellites A T S H /Ihas been designed to m e e t these needs.Satellite t e l e c o m m u n i c a t i o n s has received considerable attention andis cer tainly not ne w . H ow eve r , the ap p lication of satellite t e l e c o m m u n i -cations capability in an effort to p r o v i d e for national needs other thanthose associated w ith the business activity of a country is new.

Many of the m a j o r p r o b l e m s facing t he U SA and cer ta inly many na-t ions throughout the w o r ld s tem f r o m the inadequacy of education, healthcare services and cultural opportunit ies due to uneven popula t ion distri-bution. As a national goal, therefore, the USA is striving to p r o v i d eadequate educational and health care op p ortunities for all. But, toprovide adequate services for al l the population regardless of w her e thepeople reside can p lace an enor m ous and p er haps imp oss ib le bur d en onavailable resources. It is imperative that innovations in service delivery


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t imely and cost effective solution to the c o m m u n i c a ti o n s n e e d . I t wouldappear that th e same conclusions could b e d r a w n on an internationalscale for m any underdeveloped nations.T h e r e are many c o m m e r c i a l satellite system options available toco m m u n icat io n s users throughout th e w o r l d . T h e internationalI N T E L S A T system is p e r h a p s th e best known. Ho w e v e r , ma n y countriesare seriously conside ring dom estic satellites to serve the s pec i f ic needsof their country. Seven separate prop os a ls have been m ade by p r iva teindus t ry to p rovide domes t ic satellite service in the US A . C anada wi llb e launching a d o m e s t i c c o m m u n i c a t i o n s satellite this fa l l . NASA h asprovided m u c h of the technology upon which thes e s ys tems were bas ed.Most of this effort has been docum ented e lsewhere and this paper wi l lnot address itself to this t y p e of service. T he paper wi l l discussN A S A ' s t rends in advanced exper imenta l com m unica t ions satellites andindicate how their capabilities will b e dictated by the needs to be ful-f i l led.

N A T I ON A L N E E D SSome of the more impor tant na t ional needs of the USA are:


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O ur modern society seems bent on the generation of paper and datain all forms along with a desire to send this proliferation of w o r k overlong distances so that data transfer requires a m a j o r investment inlabor and resources. The us e of electronic mail handling and similarlythe remote printing of newspapers m ay offer significant cost savings.

A n area of concern in this world where new technology is beingdeveloped at an ever increasing rate is the gap between the time whennew technology is available and when it is effectively applied. In theU SA over 95 percent of the new technology is generated at the federallevels of government with th e remainder at state and local levels. How-ever, solutions to most of the problems discussed here are the respon-sibility of state and local governments and hence th e urgent need totransfer the ad v an cem en t in technology to those w ho need it most. Asimilar situation exists between the highly developed nations and thedeveloping nations.

C U R R E N T ROLE OF SATELLITE TELECOMMUNICATIONSIn general, a satellite system consists of a ground transmitterw h e r e a message originates, a satellite w h ic h acts as a repeater and


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T E L E C O M M U N I C A T I O N E X P E R I M E N T SNASA has three experimental communications satellites in s ynchro-nous orbit at this t ime. They are called Applicat ions Technology Satel-

lites or A T S . A T S - 1 is positioned over the P a c i fi c O c e a n . A T S - 3 andA T S - 5 are in orbit over the A tlantic O cean . A picture o f t he A T S - 3satellite, which is typical of 1 and 5 also, is shown in f igure 4. It is arelatively small satellite weighing 75 0 p o u n d s and has an earth coverageantenna system on board .

Several satellite com m unica t ion exper iments are being conductedusing these satellites, s ome of which are listed in table I. In Alaskamedical ins truction an d emergency medica l services are being providedus ing two -way voice com mu nica t ions v ia A TS -1. E xp er im ents in voicebroadcast fo r education an d p ublic broadcast ing are also being conducted.In Haw aii two -w ay voice co m m unications are used to link H awaiian uni-versities also via A T S-1. This exper iment has been extended to includeother universities in the Pacific area. Other experiments for theNational Bureau of Standards, Federal Aviation Adminis trat ion and theFederal M ari t ime C ommis s ion are being conducted using ATS-3 andA T S - 5 .


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T he type of communications experiments planned for these newsatellites is shown in table II. For ATS F an educational televisione x p e r i m e n t will b e conducted in the Rocky Mountain region. Directsatellite broadcasting will be used to provide educational televisionp r o g r a m m i n g to 300 to 5 00 remote receive terminals. This will per-mit the evaluation of E T V as an educational aid for rural communities.

A f t er the Rocky Mountain experiment, the satellite will b e movedfrom 94 W longitude to 35 E longitude so that th e India instructionaltelevision experiment can be conducted. This experiment will provideinstructional television to 5000 villages throughout India. About 3000direct receive units will b e used along with 2000 conventional T V sets.T he important element of this test is the use of low cost direct receiveterminals which allows widespread coverage at a manageable cost.

T he Canadian/USA satellite will extend th e experimentation inCanada and the U SA in both education and health care. Again, th e goalis to evaluate the use of satellites in conjunction with lo w cost receiveterminals for use in remote regions.

It should be noted that the experiments are limited in scope andcoverage. In the future, more extensive telecommunications capabilityis required for experimentation. NASA and the users are currently in


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receiving direct broadcasting f r o m th e satellite. This is necessary fo ran economical ly viable system .(d) M ultichann el Cap ability - Future needs will l ikely expand suchthat diverse p rogram m ing will b e required. For example, educationaland ins t ruc t ional p rogramming as well as health services will requiremany information channels.

(e ) High Quality T V Pictures - There wil l b e a need for a high qualityreliable signal.T he kinds of coverage patterns contemplated are shown in f igure 10.These footprints are concentrated for the most part in the mountainousareas of the continental U SA plus Alaska and Hawaii. T he satellite canbe moved to cover other areas if required. Sim ultaneous transm issionto all four areas with two to three television channels is p lanned.T o a large extent th e success of these future telecommunicationssatellites will depend on the ability of people to receive th e signal.This will require large n u m b e r s of low cost ground terminals. T hekind of ground terminal that is envisioned is shown in f igure 11. Itconsists of a 7' antenna connected to a small box which processes th esignal such that it can be received on a conventional T V set. T he costof this rece iver in quantities of 1000 is estimated to be $3000- $4000.


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8A spacecraft that will meet the requirements outlined above is the

A T S H/I. It is shown in f igure 13. It also has the capabilities of:(1 ) Generating large electrical power.(2) Remaining stationary over a single point on the earth.(3) T he ability to be moved f r o m one position to another to cover

various segments of the earth.(4) The spacecraft is approximately 100 feet long - antenna diam-

eter 8 feet.

I N T E R N A T I O N A L APPLICATIONSThere are also international applications for these advanced satel-

lites. Typical possibilities for coverage of South America are shownin figure 14. Precise area coverage of any country can be provided asshown with separate programming on a noninterference basis. Withproper positioning of the satellite, any continent can be covered. An-other example is Africa (fig. 15).

C O N C L U S I O N S


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p o w e r satellite ( a m p l i f i e r p o w e r of 1 kW or m o r e ) w i th an advancedantenna is needed to m e e t the r equir ements . The pr oposed ATS H/Isatellites m e e t these r equir ements . T h e technology developed fo rA T S H/I can also be uti l ized by other countr ies of the earth to satisfytheir communicat ions need s .

REFERENCES

1. M o r g a n , R. P.; and Singh, J. P.: P r o g r a m on A p p l i c a t i o n ofCo m m u n icat io n s Satellites to Ed ucat ional D evelopment . W ashingtonU ni v. (NASA CR-124724), N o v . 16, 1971.

2 . D ysinger , J. H.; Foster, D. E.; and H a v i l a n d , R. P.: An Investi-gation of N etw ork Television Distr ibution Satellite Systems. Vol.1 - S u m m a r y R e p o rt. Prepared for Public Broadcasting Serviceb y General E lectr ic C o . , Sp ace D iv . , Sp ace Sys tems O r ganizat ion,Feb. 1971.

3. Dei Rossi, J. A.; Reiser, R. S.; and K i n g , N. S. : A Cost Analysisof Minimum Distance T V N e t w o r k i n g fo r Broadcasting Medical In-f o r m a t i o n . R e p . R M - 6 2 0 4 - N L M , T h e Rand C orp . , Feb. 1970.

NASA


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CS-64270

A LA S K AMEDICAL INSTRUCTION & EMERGENCY COMMUNICATIONS2-WAY VOICE BY SATELLITEATS-1EDUCATION & NATIONAL PUBLIC RADIODIRECT B R O A D C A S T OF VOICEATS-1

HAWAI IEDUCATION - COMMUNICATIONS B E T W E E N UNIVERSITIES2-WAY VOICE BY SATELLITEP E A C E S A T - EXPANSION TO INCLUDE PACIFIC UNIVERSITIESATS-1

NATIONAL BUREAU OF S T A N D A R D SR E L A Y OF PR ECISION,TIMING TO U . S . A .DIRECT B R O A D C A S T BY SATELLITEATS-3

FEDERAL AVIATION AGENCYPOSITION LOCATION OF A I R C R A F T VIA SATELLITEA T S - 5FEDERAL MARITIME COMMISSION

POSITION LOCATION & DA TA TRA NSFE R FOR SHIPSATS-5 C S - 6 4 2 7 0

T a b l e I. - Ongo ing Te lecom mu nica t ions Exp er ime nts .I L I

NASA


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CS-64271

ROCKY MOUNTAIN STATESEDUCATIONAL TELEVISIONSATELLITE B R O A D C A S T TO 300-500 REMOTE TERMINALSA T S - F SATELLITE (MID-1974 LAUNCH)

INDIAINSTRUCTIONAL TElfVISION (FAMILY PLANNING, FARMING, ETC)SATELLITE DISTRIBUTION TO 5000 VILLAG E SATS-F SATELLITE

C A N A D AEDUCATION & HEALTH C A R E B Y TELEVISIONSATELLITE TRANSMIT & RECEIVE TO REMOTE TERMINALSCTS SATELLITE (MID -1975 LAUNCH)

CS-64271Table II. - F u tu r e t e le c o m m u n i c a t io n s e xp e r im e n t s.

f r .

NASA


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CS-64285

SMALL RECEIVERSFigure 1. - B r o a d c a s t m o d e .

ORIGINATING STATIONCS -64 Z8 5


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CS-64286

BROADCASTERO R C A T VRECEIVER

HOMES, SCHOOLSFigure 2 . - Dist r ibut ion mode.

ORIGINATING STATIONCS-64286

7 '.!-UIi I


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S C H O O LCS-64287


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F igu re 4. - A p p l i c a t i o n s T e c h n o l o g y S a t e l l i t e -3 .


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F i g u r e 5. - A p p l ic a t i o n s T e c h n o l o g y S a t e l l i te -F .

CS -6 4274


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BEAM WIDTH * OfATS-F LONGITUDE - 94* W

Figure 6. - An tenna b e a m c o v e r a g e of ATS F; R o c k yMounta in S t a t e s ETV. CS-64272


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LONG.BEAM CENTER: 79*E. LONG3db BW - 2.8*lOdbBW 4.4*

0 62 4 66 66 70 72 74 7 7( M 82 84 0 tt t4 98 100C S - 6 4 2 7 2

Figure 7 . - A n t e n n a b e a m c o v e ra g e o f A T S F ; India ITV.


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F igu re 8. - Com mu n ica t i ons Techno logy Sa te l li te .

NASACS-64276


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COnUCE OttMIS FW Ml UTEHU CMTOUtSsMmnc U M T S D U E 1 0 SUTIUFU E D IK M SUWUTEUITE lOICITUOC 114 OIEUSn . 15 I2!OffS1TCLUIE STUHin m . 020 Ol

PITCH 0 20 O.nw oo oifSI I ELUTE SII1W !IP1 H-S 2.00 O|.

E 020 0160 170* 00 ITO ISO 0* 9O 40* JO*

CS-64276Figure 9. - Typical antenna b e a m c o v e r a g e of CIS for North Amer i ca .

N A S ACS-64281


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FULL SIMULTANEOUS C O V E R A G ES P O T BEAMSSMALL TRAN SMITTER RE CEPTIONMULTICHANNEL CAPABILITY

CS-64281

F i gu re 10. - A T S H/I coverage capabi l i ty .

N A S AC S-S42 79


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7 FOOT ANTENNA & FEEDWITH MIXER AND IF

CONVENTIONAL HOMEV H F / U H F T V S E T - "

INDOOR UNIT:DEMODULATOR, AMPLIFIER,REMODULATOR, AND P O W E RSUPPLY^

Figure 11. - Low cost rece iv ing s y s t e m . C S - 6 4 2 7 9

NASACS-64284


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$100,000,000 J-

$1,000,000 -TERMINAL C O S T S

$10,000

$ 1 0 0

I N T E L S A T I

I N T E L S A T I V

10 20 30 40 50 60 70RECEIVED P O W E R PER C H A N N E L , dB

F i g u r e 12. - T r e n d s in r e c e i v e r c o s t s .

80

CS-64284


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NASACS-64283


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CS- 6 4 2 8 3

Figure 14. - I n te rna t iona l appl ication - independent,s imu l taneous commun i ca t i ons in Braz i l a ndArqen t i n a .

-NASA


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F igu re 15. - I n te rna t i ona l appl icat ion - i ndependent ,s imu l ta neous comm un i ca ti o n s in S u d a n andSou t h Ame r i c a .

CS-64E82

Trends in NASA Communication Satellites

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