BSTJ 50: 1. January 1971: Model for Computation of Interference to Radio-Relay Systems From Geostationary Satellites. (May, A.S.; Pagones, M.J.)

8.7 MB·English

Model for Computation of
Interference to Radio-Relay Systems
From Geostationary Satellites

By A.S MAY and M, 1, PAGONES

(Munn macrod Jone

A satan! model i suet for tn vompattion ofénerforence into
tere radirelay systems from geostationary en

"The mol i oneal T incorporates taney charactrie, ails
erangemens, and allowable eatlide power ue desis. A program
Uimlator can be used fo ealolae Hm mato power flux density caren
‘ponding ta partoular radioely interference objet.

Tetrferones dition ave compl or ATT and COTR raio-reiay
‘odode wing the power fae dey Cha mee suggested for stuly atthe
199 CCTR Foti Matiog e¢ Gena, Suiteerlant.

‘Terrestin!redio-relny systems opernting ia the 4GIv and 6-H
hands ehare these frequencies wish eommminiention stelive psn,
find adkitionel bunds may be desigaled for shared uray. Tn the
future, os the promationary orbit oceapancy ineenses,ooeistence of
these cyetrs will be possible only 'f tonzole are imposel on both
‘Prenat, the Internationa! Radio Consulleive Committee (COTE)
recermenct’ thar radlo-elgy enters, eudisting froeuences ore
sol ly saelites, mantein a pected anger wpanatinn

{o the genstainnary orbit a. where Us ie nol praetia,
‘he apploation of power inition to Ue erste] tranamiane. They
Turuher teonmmend? thet sutellive power fe density be limited as «
ction uf Ue angle of ursinotion wb bs earth's surface. The point-
Jing restretion intended to pole) sateen from terrestrial systems
MMeihode Inve Inen device for euleulaing bearorbit separation
‘fiction of neimuch dilaoenent ofthe untennm from interop wl
82 cane maa evening seunacaa socAGAD, SAMAR EAL

‘the rerommeadaion is being cerspiod with by te Boll Systm, The
stelle po lnitetion Ese seen eblerged ta Geog too resiesire
and, in the intrest of satelite asster economy, em izerease ct the
Tieher angles of arvival has been props

ho sviation ofthe prsentsacellive power ux-densty limitation
vesasaes ene riowelay station in a -Rop sytema will have a direct
fsnomute to @ geostationsy satelite, and the rineinng ststione ml
Inne nfieiens antenna discrimination that the eddiions! inerteence
‘snot simitcane. On this premise the tix-denscy Tint ara tangeria?
ray was esablisied, A Tver weation Tor higher ang of arial
fzea:nes arly for ¢ éiinntia ir tetnersinion ose aed atelita ame
fezna gain beusecr he Tori ai she subsatellite poi & prapesal
to erect ineroave Ue ths dlvsly Tait at all engl bor hae ae
Aogsoesreouice a nem evetuatio

AY present the number af rwnmunication steliieg by soll aul
the elistive seat power in Hels existing its, Chmsesenty,
fexpetitnent with existing sels tnerering into the terrestrial net
‘work wll nat generate fia! rls in delersining adequate proteee
tion for bath syatemie_A Inboratory expesiment is sore tractable but
iis very difieteto smilnge actu sae hevnuse the entrferote i
2 Towler of Se spatial arm uganen of the oo tema, aed 39 Be
ete should be appliable iveraationaty, ‘Pa pee an experience
elite the genmeaonary orbit forthe picpase of mensuting inte:
femmes nly rns apie is Iabierons tor ib would yield ne more
information thon « Inboracory experiment and woald be wiineratle
nthe some imitations
Anew attompr to evaluate the satellite power fx densay tinita-
Lion nrginated In the SLA. in peepazstion for the 1959 CCTR wets
ing in Gave, Seitaesland, Ib wae concluded ‘hab au analyte ape
‘ach i the ast promiing,

Ta subsequent sceticcs wa precent a desesiotion of the sylea model
ovlepl bythe gathers for etudsing ectlite interference ine ve
testa? systems, along with tbe sratyele,corsputer simulation, al

“The satllce system ie sesumed deterministic wich all satelite in
th yrowtationery orbit, ‘The spacing between satellites‘ nssusned
‘Gaede coch. satelite trmamitting the aaaze elective ruditee
Iwas: Moneever, it fewer (ve etn orbit i fed
‘tae aesamption that all sstelites are in the goostabianany oobit i
realimie because the number of sihunmonhic systems ie snl, and
Ihe ditional ilesferenee from anedium orbit satellites eam be #o-
sonal Jor by desaring the interferenes allocation ofthe eationnry
fvelites, Of oouree, she short-term slevfereace contibution from
titi oobi seelies shoul oot be jane, ut thi is nt the au
ot of this cieewedn, rte, tie saramed chat it slit
visible to a saiioselay eat, 3: wil Mlomiate sho urea uf che
tlierlay alalion wath the fux ety pecmittad by the ane of
rival Astunly isi ot lst the eae, A satelite may be veble
Tha it may ase ® Highly sete antexte Ghat oes not iliaminate
all swlioseay ebtione wth Ue maximum. permissible Cus senwty
Sein, the effect vt sue sesumpsion ie not eeions because the pot
ini batts ale redsge the iaterinenee tnd Toes eff con be
celsguitely akon “a eeeount by izenasiog che elorlise sale le

"The redv-elny system Is assumed to be compose of « nuber 0
hops. The number of hops depends ax the syst hops for w
‘CCTR system and MU hope for a» AAT system, Figure 1 ineroduece
the svetem model coop

ro axioath of sh Isdio-ety syste, eer to as a tending
fs aoutnad ge a zandom vivian. The disibution that wee need for
the rnule even in Section V i air betcoon and 2x, Towaver

= persue
8 oe mn svarEw weMTOM, somMNAT, TETANY

‘he simulation is eapable of using any distribution, For the AT@T
‘emestial network, © uniform distribution ie wasonsble; however, for
‘thor eouatrise the distributions will be bitoed (Canada's network it
howey east-west). Sineo the direction of esch etstion isnot the ee ws
(he trandize (intrweyatem intesfeenee ane gegrepEy dietste a nig-x8g
route}; the destion of each atation is asromod as a random variable
‘within sume rage about the direction ofthe treline, Again the rents
in Setion V wor ealoulaad Zor «uniform distsbution witha =£25° of
the treline dation

The ratio-relay unianna patiers ean bo wy aporoprinve patorn
erating on the neta yet, Llomever, che angalar weparation be
fiveen Ure bean of the nadio-cly tabioa und the eatelile does not
arreepand to the of-becn angle uf moet magne ankenna patiams
Teezine the pallens ere usully meeeured je either the horioatel or
{he vente dicestion, Te teus ungulnesepeertion is nother, bu either
peter mn be ut eeu mvs 08 the intarereneereaite when the
Separation wngle is emnell, and the pattern is nearly symmetrical in
All places for emall of-beam anlee.

TT aussie, tho mode ineorporstas « axtlite apueing, radio
Pelny anienne peter, number of bope, tendline, ditrbation, and
ution pointing ditribation. ‘hese parumcon ure tbe inpute for a
fompulte sregeur wT ek enrulnoe Gr distibucom ofthe tora mam
Felay inference

‘The ication of the redio-relay eyatem need only be identifiod in
Inside, Sine the stationary evi 'ssecumed fled with a constant
2etelie spacing, he longde need not be a parameter of tho inte
faveneo, Tho starting azumption ‘3 wade thatthe Brat eudiowcag ste-
tion ie on the sara longitude 2s one of the saalites. Moreover, the
Inciude ofthe eartarof the rain-rlay eysvem is nee as & peremotar
ta deserie the geogeaphicel lneation of the radio-elay ayetem and
‘this parameter i definitely one ofthe veriables ofthe aysamn Inter
fevasee. ‘The tending dierton ies esndom variable thal was d=
‘arod earlier, Tie variable wil not appese in the Snel answer be-
favs aikibution witb aad and Te willbe averaged oat TE
tymmmotrion dissnion jenni abou zen degre, There are ene
‘bow pointe of emmy tho: ehouid be considered én oer to save
ompulaton tine, Assuming chat Ue ladle draiion ie meseured
im sho south, there i no nial tu consider negative trendline cai-
saouoeneiay rrnrEREe 85

the beenuse duplionie results wil be generated. Furthermore,
spective of the nssumml disebution, only che dizcetion of trans
tnission having soulierly poizine reeivere need bo runsidered bee
fuse that tation wil feveive he sgrifieant interferer. Consa-
{uy the saith dsetions that nil be considered ue hetmeen
‘Oand / rudinnsftcus seth for the wart Inituces,

"Tho compte program brgine by welling a latitude forthe center
of the radio-relay sysier, Rests are provid in Uhie memorandum,
for libre betireen 20° said 70° in 10” izeroment for 50-hop ays-
teane and 40" fer ¢ al-opspxiem, Some exze is rogue in selen=
ing the Tattudse ased in the compiler progears. hove hut are an
sina nay cae te sudo-ily eles Go ecom Ube equator requiring
ome of tee loge of the pmunsnm to be chenged to sevount for the
Porsuver of th equaturin, sbi. All Ul desived geometry, howeve,
je. veld, For asividos beyuad stout 863°, Ube entire geostationary
Cis ia eow the horizon. Cinseueay, sarin Beyond tie Inte
sll eee np inuerference.*

‘After a lecuae hae hoe selected, a troedlise diroeton, ris eores
Troma random number generstor of sumbere be:weun 0 and 1,

C0) ”
Eoin, °

shore TT is she gral-f'sla angulsr apar of the nadio.seley selon
‘Tae average angular spas for a CCL ey en [50 Ips) is mear 22°
nd for no ATET store 1140 Eepe! aoat 61”
"With le kris abel ansene iete

lotion is the total izvervone ins Tie Mea sation fhe al vate
ental, Th iit of tha vsile sal ionary abi a eden
fd tie wil, intra, ceterace the mati of vibe ayia. Fes,
the achat dizpucument, (oH ron of le psn onary
frbit wl Un Dorgan de ealeulti} nad Chen Ue rlaivg “orgidi
fisplacer sub, a, fone the soto is determined soe Fig. 2). Tao wie
tnt displaemene” (aegaarc fr she nowt) 3

TReaiae re
Sipeely iain
86TH me sverige eHeAL JouRSeR, raNaRO An)
aoinergaat va eee 8

‘The ale equation getunes sew die elevation for the raion
lay akon ond nore remeron. The peoblem eauld have Inn ear
Fist on with s naa-xyeleatun and with sn appropriate disemtion,
Humever, most exist system Have » mean of near zero degrees.

eo, taking tetaeien fro necoune wend ave no elgniBeance in
Sia eal rise, Consequently. any’ ule sumption Wau not hase
bec nih one walsh

"The rletve ‘ongiadnal eeyxauton of se icereat ie
in Iain AL = CIE ®
Sines Ure spin of Uke stationny orbit Se symmetseal about he vm
ler saith fie, the toe lotwenal span of the orbit i 2A,
Comouentls, the murher of wise satellites iy Une toi of tae one
fn the same niertiar se ce fet eadioclg”tesm aa all otter
telizee elude by ieverentig “he aver autaite sepurion
the erties! Ionita 4, i+ ol, cre Alka fo negative eaizambe
the aatllito sposing scp gato inorements enti the og
tive erie! longline i veadhed.

"The problem then reduces the ealeulation of the angular sepnni=
tio fon the heats of he radio-elay station to exch vile tlt
find conversion zo se mypeyiace inceferenes suppres,

"The asim, eto vac vse sabe hs

Ay = oot” Joot Seg ®

wvhege Avis the relative luis tothe neat satelite, ‘Phe elevation
ngle to tho seit, nssumiing aero-degoe elevation ofthe naioseay

s-S-wr a. ©
os

Winaiy, che seperation angle, a2 abomm In Fig. 3, evo a

os eo @ on w
‘where 8 ie the random direction of tke winery wots mane
88 ay wna sven AUEMLOML JOURNAL, vasUARY I

froma the sth and i
B= (+259) — SO-RND @.

{9m naodom number ae a3 deonibed eater sn. th
‘yay £25* about the chcemn trendline.

Tho enule, y is one ef the Sanctions of tho interference, However,
ofore eumguing the interference, neooemary do determine Ue
Jeti far the next station besa He aw diferente wl
jt is iprebuble that i onthe eame meridian us exe ofthe sult,
‘The proeriee sto exleante th new Iaitde nl Longtnteof exe
steading statlon and start esleusting the intarfrenee from the
stelite that wus need ot the dest radioreey mation, Natarally new
eimntlnl huis ofthe orbit, UA), aod lovgitudinal Hit, 4, wit be
calculated, Farthersore, since tke starting catlite is the acme cx
‘thas of the fst sation, the aumber of visbleeaalitas an ee ile
‘of tho wartingantliza wi, not be emetic

“The latitude sift of the net tation i

38 = sin“ [ind cos p — cos cin poss}, (LHD
where 9 ie sho arcat-crel: axeuler gpa “o the new. tation. Aine the
(otal aageler epen wee prov.ourly given as 32° far Bop ater,
ie approximately 038°,

"Tho lone shift of the next eatin ie
‘The eometry of the latitude and louse shits ix shown in Fig, 4
From ules vals she animatha! Emi of Ue orbit and the reletive
Ingitade to ench tele ern be eee’. Capeceueny, he beam
feperstion ale from exch rence slaion te cath vise satelite
fem be caleulaed,

"To etsumarize briedy, (he progam stars ab a giver Taitude ani
éooges a trendline disetion, Then i sista the latizade of the fret
Stalin in one to make the senzer ofthe urenline le nowt the middle
of the ehoeon Iattde, ane i picks Ue beam diretion of the fist
Sadioseiy sation, Te elouiee the Jnana Tits of the visible
lelionary orbit snd eslealatas th interference om each visible
fatelite taking into account the [nim separation angle. The eoorle
hes of the Beat etation ere calealad and the new ect of visile
Callie detained, Tho interference i ouce again eeleuete starting
te the came aavelite we the one ool fr the Be etstion and proveating
in poshive and negative satllve spacing inewmeste unl 0) visible
satallves re exhuisies. Th interference (o ell radioxeiny stations
‘of o sytem i stllasly esloulsod, The praypam proesece with other
Sacple Luniline diredions and hues x slfirien nomber of dreo-

Fig, 4 Geumalay dering te ses and ead
20 tee wets onan nec. dorsi, SANE AMY LOL

tions to sevurately amive at az interference cietebution, The results
in Section ¥ mere cerivr fo a sanple 60 tndlinee ab ech [atic
lie, Furhsrmere, the provesune is sepected wel ese “aticade

‘The size of che stviie appeneee eelequste Zor ealesntion of the
seen; hosever, 1 was tag tral tfo- eelenlecion of the tals, Couse=
Aqueely, sore smonthing wae aopbed to the rez, aud sume onset
tier geran wit lager sales 2b cesue thot she suggested ‘eel of
Ue SO-satole neste war atanraln, Inewasing tbe sample size oo
sreater than. 80 Wat not od Tacningful Because tho uscertainty af
Ihe ruio-rclay and satellite sharecterstion wae lange ezoush #0 that
snore acetate computation with higher rmplea would net eve bees
snore enlightening

‘The exnot ealeutation af the Fntercrenre between the suite an
radisteay eystem involves the earvoition of tho to revel per
tral densities, with the enpeession of the Satsfering spesra density
being efanetion ofthe beam senertion ane, y. However, a approx
imate eolouletion ie posible hgewee tle satelite gyal ix ote of
relative bigs index. Consecuers, ube simplilsig aswimp'on ean 3
rade chat the iaterferine epwctiun: ie subelerially Mas over Le

Tn, The yore Cnt 12x asain way sole

‘alae hecho ies i a uli! high, az when he tye

is math emaller eh thx? of the

jerlay sym, Feeney, rn for thw eases an upper bound

Cnlelation can be msde by easing 8 At apelram with the see

nent ws the pes of Ue clas! epectrun, Also the asssuption ie
‘act thal eareer dispersal is ured ding pies of Hilo

‘The actu convolution vould have been masily eave ou but the
reason the comptatins were siaplied ie Lisl the pesk ofthe baso=
and inieriernee ist funtion af speeteal denies, from
separation of the tw eigrals, ni! the deemphasis of the radio.
stent, Hones, i med have intsdavad ationn! dimensions i i
‘bumber ef variate. Monaver, the fen i dhe rosula would have
brea owgionn, Tis ako “net ht a salt signe without ceriey
lopersel and Tow-itdex of oculatan may geuertce more inter:
iron, Te any event se Mat sper apron’ nll 8 aed in ard
torah the -ralle mote atan'

‘The bean’ intas‘erenew ea Ie ort oo the thermal raise af
the eyatem be