BSTJ 40: 6. November 1961: Engineering Aspects of the TH Microwave Radio Relay System. (Kinzer, J.P.; Laidig, J.F.)

17.9 MB·English

THE BELLSYSTEM
TECHNICAL JOURNAL

Vouene xt Novrware 1881 ene

Engineering Aspects of the TIT Microwave
Radio Relay System

By J.P KINZER awl J LAIDIG

Toe myer ine a genera dsoripinn af he TH eaten, whieh dln
at oyto operating ss the SD2S-B525 ne had, Lesa t conser
finns goernang the meso Hexigh deienas, keh Kod to. a FL yee
if age cence ech deetiay she working aud te poottion, Br
‘hel hos yok ore width. The paper cates wit
Aiacanon 1 wri sowideratnen,posarily from the vient of ile
ioe Wonsninon. Fiebaion note ant mation nose are ths pie
ip! eo, oth nkerforore Inte rack chowels a wsinor Str.

“The TL oi relay system is the owt regent in the mecesson of
uli Tacites Gevelee Tor nse in the Bel System eommistion
Cewove, \ pois-topaint ha sscnm was sw ns path of the com
rece telephony tion deel ae 18292 This wd wabeeenent pi
[Repair instllat ions ere peal es sing singeshop, are
fan sycent te camry ne or a fe eleplane eoaverctione wee
tents ver salon of wot este impactienb, The 58 ok
fin relay aed sera purpose fay The Bell Spey wore was
Snuggtatel wit the nstlainn of He expermercal TD-X.ayatem
Tidween New Verk ssid Bret 197. From hos ital 220k
rete, he vain networks bal espa by the ent of 1950 over 44,000
Fonte ales carrying ne tensive alin telepbow cit anes
ind 70,00 ele channol males

“fhe mje portion of thie uetwors provided bythe Tang-aul
baal TD syetonn owrising an ve 40N0ane comunon exer
1500 nem rte evens mivwetest oct, SOFNAMER Ht

‘hand. relatively small moun is provided by short-haul feeder aye
feat Many of the 'TD-2 routes ate now folly ened and ao more
sudo chansels ean be added within the assigned frequeney band. The
congestion is parteuiarly acne where tea o more rater er oF
Fontan eis, Aiiioral veins thes arene can be met
tnly by the we of dillrenFrequenry fund

‘The TH rosio aeey sytem has Ion developed to provide the wl
ional sinus. 102 Ineadnnd pan essen oper in
He momen easier Dani Tse S096 18 wn PH ane? The ace
exign cojective is to provice 1000 mie elephone andl telviion ie
foie wit Tremsaissien enshty and rebiabit eommersmace with the
Drveent eystem objeetors, Ab sr sane fine, maxi tation of
the avaiable froquouey spectrum i mperstive and the uso of as mae,
1s posible ofthe esstng TD? plant sid ergincvingoflort is ceonemi-
cally desirable. Along wth these quirement isthe nood te provide
Aitilty to et hag end of sng, bot in et of rou
saps of sgl oe eure. Thie pager give be esr on
HT the syste and desert overall cnnotring eevee whih Ted
tothe a ayate, Sie pps dbs bn yr dal the
sig of he sons cmon po ne PH syn

‘The TH system i how i Mock digs ing, 1, Bah brosdbnee!
sdeeit coats of an FMC tistnter, a szanenitting entrance Ea,
‘ote ot more audio wpeater sections, a reocing entesuen ink and az
{WaT mewiver. The FAT Frmattenpondoees a PLC signal whieh ie
Teer saleby te Heung eters gal. Thi nee
sedated gu i fod 19 endo eaeamitter or a onan et
tne Ti "he alin transhien Ione the TT goal co the
rain nietowaet troquene'y ave apie fae eaatnn to the we
Savion The taco rveiver atthe next station heavens the miro
ftequevay task to the FLLme intermedia fequeney for aplication
and rquatzssien. ‘The atpnt of tbe radio mseiver may thes be cn
beewd to anocher ratio temaatter for trasemzson farther down the
onte or may Le connoeeed shrenah a areiving entrance link co sn FM
teriver. The FM revive deme the signal snd divers fh base
al eignal tothe temaiting expe

Bighr ewo-mery, bread aio channels and eo ton, aro
bad radio casinele (alle he sir ehaumels) se provided nthe
ssvigved bus as show iv Fig 2 hrvach sation, ll (be rab ran
tiene am cpl none Tlf of the sige ba ela the mle
teceivere ute ater bf of the Ban. Six of he reac chine
ne ea suki cow ee the wlio to te we pote
Meee i i
due Toute in the guna syueey Seton Hie bocudbsd nna ent
And terivers anda the comes of he baad. Taose are ur to provice
‘Seesite dor voiwe order wires, for the estamatie provetion xitebing
fevton, su for tnmieson of alms From matted atin Te
“ev ary eal in wren en ae cue to prove sng
stuns creat wi frequesey diver

A fall equipped repeater sat emla tery ein

ret lls or tig" liar chal

eecivers and
went ral trailers, ech meaing riernenve bal ilar
sigoal, Rashor than providing for inlvidal oars, omen
torrie sup i used for all the roevene. and teanemiters i a statin,
Zong fw highly tsquenes-tcilzed eyed asellator operating
0 HS! me, the sommon eerie suppl generates the Zod, th, ast
sul 25th mnie cw provide wo WH sao ot A085 gm 3
ral or ener gle 4 BOI ge tl Dae Te ap
brite oFe of tke ton Sect ailator frequencies basen Figs 2 i

vk by cither The CORbne or AGU am sul is goat it
Te motives Umamaniter ie erin enw ef Us trou ign
find ove of the VHT sal, Since The Talos of the commen eetiee
She oa sation otk escalate, i ie auld duplicate
‘ih asus nailing to standliy wi whew neoewaty

he haces eign bo evi

sr the UL apeamn ae shows i
142 us nth eve mecnstest OER, NOUEMDENE ot

Fig. 8. "the telephone vue ure dived by singlo-sidehand ini
‘echipient of tae type nied it the LB conxial eae system The
telephone sul for PH cilfers fn thr standard 1 telephone signal
‘only in the amount of pe-eupbsls, Highton theater tloeeon
‘ectpying Ue nine 10m been my sf Unset

‘The TIL estem a vod above i basically sila to Une exist
Ing ‘D-2 aystem ar eta many mires Tis fe aeeompliened
through feu o neal develope eeziponents al through appleing
the eaperieuce gone Fv he TD-2 ester, Te esx: dept rom
thas of the vider system wacever nw impraverent ie indened. and
svn seruens or ua siento 8s

{allows that of the older system only if rview of the vasous posse
bliin showed that approach coe bet.

ns Anta Sto

A lenge portion of the expen of ny rio rela route e the eet of
repeater low, sree tds tad lowers tn anon The atom Any
ferrin sins eed To design yale hs weer ie tl
oom of cee cyst aval posb'a Furthermore, th wae ante?
hotles for us mans ssrems on any tose a penile, The est
Denalty for using separate unter for each system involves provision
(OF heawier, mone_cxponsire towers val aligonal rere se
‘well ae tho ation smtennte thomas, Tr neipeten of he a
ff TD2 (1 fh, THE kane) sd pesly TY (21 kane) sym othe
face route, He fane-eftae antenna was developed Thi ane,
Wil is orale waveguide bed, em teas eas polar gua
{So these lade Platestion is ed Hell epatattwegoala be
er tess ragesher ia foe” be spare eopletel ay pti
fale fees The env polation dssinsnation of spate sets,
cluding the gntenras, round waveguieee gue aveiom ambi net
‘works expect tot st ee 25 Rr he TL ystems, The perform:
nee of the antennas i one of she factors permitting the elas sping
tf adjacent chins ws shown in Ti 2

‘The harvensetor waters i droid 1 ave appre‘ ely ie
nein the ke luna te delay’ ae gall Wor
weth TD. Thi in rn sets the angen gen st hace a4 lb "Ths
verge species of TD-2 exporters 3 ubout 80 miles. The Gk pats
lece betwren szotcpieeadatrs spaced 0 ms apart = Hz db Thus
ing TD2 plant e-
rescrstins aSPRe A MH HST we

yo metenar ravagubis for ena égaeney ar ov amine
them nto sense late snl in che aoxad waegeie, The indica
"nme of the TU system se enabined sn che tandem once ehan-
hol sprain net,

The tof the site anon fr tmstmitens an reseivers perl
insproved elie aguint fares man antean oF ie round wave
se on & hewvily sleveloped mil, sme lure of ng one anton
thas wot shut sown all rain elses ‘heist ati TH
hora eons of one Woeng nd one prtectnn hesaband channel
Ty th sandal rowth plan, thie ate ehanols and 8 {channel 4
sgt he alennate resin chanele Hand 24 rq a ake
‘wpa continu anatiion path, se). Awsdirineal broad ci
tvs are ruins, serene pie is added ro prvi seeond working
til second ptetien enn, Uhnse tag he either the her to
{vow nuhered ehanaels or a pat of ot-nezbazed ebuanele (sora
{Fad 7). Irthe fit dour are sl evensaombered chm, they one
on &. single pei of antennas as shows ithe sppes pecs of Pi yom

the ies of thesia par etaeone ny hn deena ni a
twhlsnberel elit qsine. Wl he else aaa
is silently. a ehes "TH isabel vn TD2 soe ald
eippes th Tio eioton aslonvas, ceblnanned rhatals are
te Tir sl evi pir ize the ders lai! the ext

tirevata. Acie) shacicl as then added se mee ut alsa
te ans eine a saw: Fig.

Noval, ehanne:s Laud § ate equipped ket to leave to slats in
etal wei tage hued yp near ight esnmense ws lo

as poste,

22 Fesgnoney Atecoton

‘The frequency allocation pla of TH provides masimom utilization
of the argued hot emestent nit the tamanaon ohjeeives ter
ferenee bets tations ail gowivers an eat satin
ried gremping wl she rae gels none Bal of he Ea
fn all he receivers together inthe fhe half, ge sown in Fig 2 Thi
together wich dhe as of ees poimin, mis Hae g hnds
bers to one at the enter a ae dl Delve th eaten
an! the eeveives, snd gue at each ee of the hand Retest. the THE
Sipyals nd an’ servers ia adecont bands, Decese of the escellest
Tevktocbaes dissvimication of the borwtstzetor apteans, che same
feequeney muy be ser! tna inbetween
tl el my be ut ices
1406 cw wee erst muesien

‘Ae shows ix Hig, 2, vats real 9 ated sour fo Trad
Tey Bnd ne ait pes eg empeater =taton, Heeger ggg i
oesauty to grovea fre fem the tepenter omc Ube Sop
In TIL, #4 tvaniterand a orver are eperled a th sane feequeney
in the sme satin, te Joe between she taster aid the recive
Ti tn le yeeies than 1:8 db to keep itefeenys a2 a talerabe love
(Oly had aati with tal toon pri’ no nearby eective
tf eas be sade to moet srk a roquPeeat

‘Minium ehennel sporinge ste decermined by adjacent channel
interfere considerations, With low es Trequeney modulation, the
intefennc inereens sharply shen th cbannelepring smd tothe
‘int that the secusdsrier senda of ene channel overap the Bret
‘der sidebende of the ote: "Thae the minimum chanel pacing ese
St three times the Hop Iwedhend frequen. For the 1Osne nominal top
Ihcband frequency MTT, the ebetel pucings rant he about 3D ne
"Thoveeoniratione determine the gener freieneyallorstion pl of
‘TH. "Thr exaet che of Srayuorviss sessed in renneetion with the
cco rae spp ater Su this poe

sua Spe of Modatation

"The tyne of soda ty be wed ia apstem ie ehoscn vo pi the
Ino wommise beeen sete ad distotion gerformnse on the ont
Thane and peaceable sign Tanaris on tie offer Hur example
pike medule:ion sxstern an be ade to eve evron, ine ce dice
Fovtinn eviormasice chivagh diane refers ch ander, but hey
fhe ok aval foe as fa ths TH aysien weanee of te lege bud
tres they namin. High index zeuerey mvaatien i unsuitable for
the sume reusn since st soo trace ardidth for noise petormne
At the eller creme, single sited suppressed carson tras
tnakee the wnat eliient a of lio sperteura and of fansmiier powe,
bres eyuies igh degre of onplide linearity in the apie to
duce distortion. Ar he pmsl sate of te sr, kine power amplifiers
Of the require eogrse of linearity would be prohibitively age ain
expensive, they nd he be all ‘The soprorase chosen for TH
ielow deviation inejueucy anodalition, Ths eins a eatvely narrow
hand approximately thee Hine the top baseband Frequency) an wl
toleaie wompersion in the semper

‘The opliman fregiesey devotion to Tw oied ie elated to. many
Saciors name whieh the more important are the transmitter power,
the noun figute of the sip ron, the system delay distortions, an
the Wesebane signal to be deanaartled. Av the tine ‘TH wus being
TNCINUBRISD AAPM UF ta SH 87

pluored,« traveling tube in neasonahe siz with 5 watts ont
Fret me i pried poses, This ws chngen ae tho output wage fo
Hi, wl thr ibe was developed ws the Weetetn Kletse Type S4447*
[New muvhilalor eystals and the ke of an klucori the rdulator
ing combine to give reir re Fine of 10 db, Al exmprnents
Gf TH ate designed for low delay distortion by using the cet stable
‘Senwnis vailable in eirit-eonbgurstione heving minim delay
‘storton, The trveling-wase tle ampli is desi tober ntally
fiat overthrentze S00 ne 7 loot wth oly ior ing aluston's
tevin foreach channel The IF ampitior wwe farlory adjusted, fe
nc interstage ii dsighed one eles of ehanges tube
pnsmieters, The aio. rypater room 3 temperate controlled to
Ininimige fomperture ert oa sesveguile Ars When these parae=
fer are cone dens iy tere of te 1840 (pine channel lewd the
dprincunsfrecuerey vlevis on it found to be EL ane peck, which is
stout the seme a that wed in D2,

a Ta af Reuter

Thre geeal type of rolls epratee ght ie weed. These ane he
vm C

boushend repecter vic ye ial ie dpnsblatind tn Dasebard al
Srmeulsced on se ru fescowery at eueh repeater the HF repeeter,
tr obish tie mesila-ed tadio Pecnnnty signal it sovrelyws? Gs an
‘ernie fequeney fe aeaptien ion ae eguasecen ed hem

Ieceralynel ik bs adn fneueney mit! demodation; and the
IRE raptor, whisk te signet oplifed and rorolisted ith only
Ue fovmieney if rege 2 tngging. AP royce may bo
tile a single radi easel rewire the rutin chasnele ro

‘hiwaed and ample idividna, anmphiers, rw malicbuonel re
Frater in which afl rake wbatiels su one Sine ary aamplied in w
‘ingle ample

The mrksndtepesterproiles he hxhest: drape of ote Pesiiity
boy imag te basta igual la tal rageator nts wig the
roue, Homever, in longa system seh ae TT, the ge nmaber of
Froition and demosulcors merle tae wo suite each
fron va nee extremely eringent dition requirement The
thule RY repeat vol stable oe appliratins wht polis
Thon it nee co aparate Us spots of adjoent rain eaunels, "This
Tres the single vd RF nate a the TP repeat £2 possible
hice for TIL ‘The latter ua cio Brune of He greater oe of
fepuiating nl eqoalsing chusnels sed of suitcing betwoor wucking
Se prtertin eanels ab AF
3488 ue wee caenr maeMteaL JovISAL, Sova WML

‘The ws of TFype mpouters fuss 10 the yew af the intermediate

‘the ate. Ths ola uf he PME Louie sad the pa of the
TEM roesver re tle to porate with Se ra TP igual a wed in
the rao rpeater. rane liv, when maple tar emesh widely
separteal ilo equipment aul lighter, ace ala operate

Ae TR, Good route flebity reas, rine all auto meignments
Auditions ve made Yy TF intneonscetins
Tne iiverfeenoe chr te kakage of the beet fmaqueney aeilacors
Into the radio chimes est be minnie by she proper eho of the
inteediato regen It the TI is make eal Uo a kt sol pe
f Fall the chanc! soeingy the Ikage tones fll mie beeen two
‘Goan aml re fest agp both, Pt experien wil oher
rere evstens hei ed has as Tf bat 70 «ol
‘ompromise in the TH amplifier design neen eleesnor tebe input
fctdtaver nd Drnladl ewuplng tenes di This Yad to the
ft hate sig 7. na} ft the TL erode
fequenes."Thia LF ol eampattle wh the Wace LP of TD. ox
ret sel te of cirwet TI Sorervectons of te oo lis we
Feextrencly unlikely, size the use of the Were bondideh uf TH to
tery she tem tn ee sal of TD2 real be eeeomlly wate
fad ens sho use of set Deke bay he eer aig Ti
incpeeehe, Yor ensengney rest uf eervies che wiles Ts bard
UTIL yal permet traminsiow af the ct TTD nel wl ot
the expense af pore ive tunel i eserves of te ty dst
nora oat ites

we ol 2h

2 Comman Mforonnve Corie Somply

orty miomnre ent oeilaer sigue req a lly equipped
nls repeater tation. The use nf eosin enrier sly ent than
inva supple nals the vatice esi) maquina, moc
maintenance effort ease abi reyuitomenia, abd peemite Detter
oni of tone interferes

‘The Freqiency staliily ohietive af the “TL eyatem (rive fom
inverierenoe and eistortion cnsidestions) is chit sto pon i «AUD
nal ett soll the tsssaitte frequency be i ror by more tha 280
lee fone por esut of che transmit? bandwith), OF this tokniner,
Toa he allen ted he FM tems with My resting Ne
tvwlable for errors iv the carer supple of ¥B% tame tay me
pater. If nv supplies were we Me 180 fs would nse to be
vide wag 368 apes Ness mans linn