BSTJ 20: 2. April 1941: Engineering Requirements for Program Transmission Circuits. (Cowan, F.A.; McCurdy, R.G.; Lattimer, I.E.)

9 MB·English

Engineering Requiremonts for Progeam Transmission
Cizeuitat

Sy FA, COWAN, RG. MCURDY ua 1B. LATTIOR

Precn-lay program eas are feone a he stalin of
reprcing deen, aot ueearan ae ersloed to aoe a ets of
he renee" Intrswingcenaeraton ithe Forth
dewpraat of jegram aotwrke = hip of rebar noe ae
seeds. “The pretation of the gee ie supolemerice by
‘kcsurstaton of she uly abate by ance vee vache

NIE roach of via Luauleantiyg eo the magnitude sor setiozal
ilscry wich the lat twenty yesre hae bee amine bythe
erlopment f¢ rao ile pater ef wiedice neevacksinersonct ng
Frondnecs of Lroaica'ng sito | Pipers tave Dok pocenve. before
‘thi aasicefeom vine so time! seri, Ue (ses 9) pleat wae for
these nerks vl disingirportan! feature ther design 2 apc
Hise, With chee snooty yeate uf ta nrinnas ne a buku fash
si bof erent evi How the var rogue uf rating
hive infuencet the deseepran: of We never sve to onal ate
le Gsstors wea heve deterked the yuint Ws whieh taearasion 1
operat featune: have son bon cation
Simpy sla seven a means Ey Wah souls iginted et ne
place ate epeeduse sera tonesnaly toleage waar Tae ers distibute!
ver wie 1eas. ‘Te snplest possible midi bracdesing epee ‘soul

Goat of = mith 4 radio brsadsses nailer and some nadia
csiving ste Sash a tyeers oul srve ly sb Uaceners wethia the
Cormparatvey aia serve ana of ho teanater, Tu serve the whole
futioa many easter rs! eecavianed aoa the wwut'y. Freer

‘more the ost dese seueces progam a m0 uly fn In weigh oe
Tel the transmis nll rt we listenr sea Lane, snc tle
tend to be corcetsutl ix ceca n fue the county, aul sect sorts
of interes may eccusanynlace. ‘The 3 tebe eountiyewile serve $0
Thar every listener ear hear the propre he enjoys mesever they may
[BELA SYSTRAC TECHNICAL JOUN AE
rignate, a supplementary cninemiion system smest be provided, ince
fomuwcling he eany stadiosand brocsatingeations, ‘Ihe wire networks
that peform sis iin compre tebe matte of thi apes

"The esent exten of the wireline lacie whch are sociated with the
‘major postion of ice uciworks i inlcted in Fig she with of the
Ties on this cart bas ben made popueionl tothe numberof crate
theverisussectirs.Tactolal lei: lo! dae cet ne eves 11000
tiles, and tis not urusal for x prograry originating et same peint ap
botrk to averse mote chan 7000 wile et elon bing broadest
Ty the saat ete slat.

"Te eguzeeal whic the prograse networks must meet zen he Sal
sali determined lngely by the ess lta boacasters The objective
Gf progam networs sevice is to meet tise news in as eomplete and
prompt a ranner ae posible cosicent wil eamaable ci, With is
‘bfesive in ming cf necessary In plasig the pant to conser rot ony
theeay-so-ay news, bu: the posse future acesas wel. The ingertanct
of thie ney be appreciated whe iis eared Unt pnt provided today
For prowtaz transmission service wll eal Io healt 0 the eevice
‘urements ten or iwenty years hens, Ax a eel of such plansing,
fale and equpmneat itll’ fv, te, andl tees years ago met pres.
they veguzenents, aud, th some veartangees, wil tke os of tho
Tiel to develop tomomow

ve dead planting of Progra
tio a

1. The numer of ciel likely be ruined, section by section, over

4. The provisions for rihlty, fest, operation, ané supervision

saison ciesite recs considera-

‘ecenialtow highs nebo rice
4. The transnsionrecrements, or elasrical characteris, neeeery
wv achieve a atcal reproduction of he progean,
‘hese thee geneal classes of requirements Wl be cnsiderel inane

Nowere oF Ciscvies Requi

The cecil which have been etaihed un a fl-tie basis or comin
ing motor the hucKisn ofthe geen atorks, ve for thee eels,
nerve, permanente f relative sine frequent extensions and reactangee
spents ave made to meet changing requirements the boueastes. Asie
‘om this fle recite fete ate intermittent requirements esasioned
by spel events snd ether shore pesod need of the boadeeatei, same of
which invalve networks almost as extensive a the fallie netwocks,
Th adi elllty of service regutesjmvvsen for remuing the nts
‘roe i the event of nie, Fate 2 avnes the year by gene goth in
28 nous SrSTEM TSCHNICAE JOURNAE

the ere aleage of program eile for the pied 1926 to 194
(Of Le mors chan HIG ah- leaf erevits sown La 1040, oct 48600
the have been prised “or the shore-perod services and as stand ly
cles for preteen, Tn kia va these, there ae ll ner eis,
worl sig to otter sevice, hich ste mrp oe ceadily ada
ae to rograr eric to spleen ce reserve frie maintained om &
live basis

"Tae Line inceval nesessy assompeaping any esteasive constrestian
onoject maxes neces cnincer plot corsierabiy in advance &
teal serie eq ements br net at tae expected growth, bu
the ehanuos in netnork siting. Figure ¥ shui ee twa eypiel sets

a 7
xe — ite —

lag maar routes che vskations ia soqainervats for fulltire network

oulg foo sont tl seavrangements guise by the Breede
asters ‘Wale, in pliwing to aeeet ther rap vazatios ia eet
yavescens.aevan-age san Le laben of sre aiile which exe the
Fiicof toate or osashnal ves ar prta'ion Eats, he ask
Salane'ng the snwises of cits eget requ eles '5 ap eate ining
anfactes éifeat one fo de zen engine.

Dpmamne Requnesus

Considering for 8 manent the varity! prams ovainting at many
Aiferent points has can behest ar ary bow rn self che course o an
veng without nce unging the tng wil ke apparent that minute
teminite tearangeinenis uf an etal interconnecting network mse
he posible, For example, studie have to be chunged fom reeving #0
foviginating, setins ofthe etwork have Loe vate to mot fst in

[NEW YORK. ALBANY SECTION

6
TTT I

CCOLUMBUS-DAYTON SECTION.

BI Oy we
vor

cae lcetinn ane then in the other, and brches have co be combed ant
asoarece. "Thee charars inthe network Eve te be mae ithe Se
Setar sing between the lee of one pregats a i etl ue ne
fu theecepl ol were words orsounds, Even durig the course of.
single progam, evtches or reversls may kave tobe rae tw charge the
trignatng ink temporal. Te evi for tes epi changes pec
pezation std special stching and evesing equipment re repel at
thang points long the nezverks Mud this equipment is ver nemae
ontol fr, sete pints

the greet portion othe switching of program cnr tee at shout
25 pine nveghout the county om the major rer. On he wverage
note ths 25000 stenng sets pot ont ace peforme at these
ZB points, Daring the bury hours any fypirt veting te may be
etl ver S00 meso tty a al ofthe ofices ba he et work

i pwns waste svishirg.enisienss are simpe, the stein equp-
reeut consiesmenea feng, At starr fais bere esnitchine
Feduitements ame couple, the sviehing easymens coasts a! claborate
Fela and contr! acrangeient, “These ase 20 designed thet ci pasibie
(hosel up iv abaiee the cor oombiatione equiv for the ensuine
Droge pert sithoat disturbing he arog in poeares. "The recusl
rithing oration takes pe atthe Ssetant the omer alent
ign the the ossipt theta of slesee cone, al wt Before then. This
“ype artaugetren- aos etn of aroocion ast error 2
ome ovelcck the prosetting fr he gost site ete ast nue
hange if rasesiry snp He bea de sviten hasbeen de

igure 4 shows ¢ kane of sch © evitehing arranger 3: uke a
‘sha Nebaash for le broadeaatng eompary= AU hs uns 18 deeits
Shed in vars trunks branch settione of tr selworks a connected
Tbchesvitchingcgiauent. Zee are grespel is vaeuscombientios to
lake case afte teany ee fe sivaliaweam peace, A nema hve
ce might havo, be sive in sie at this pot

"The operon ail abanterance of the nciwoake are carve out by a
sesiel enesrizaton ade certs auld cad trae he applica
{Hor of wil meds and pronolires found by experience ta he peu
tive of bes soll, Cranes 5s esitned continuously nt erate
Sointsabout se retworta In ones to fcitace she acceso group

orig thocaads of mer of fy seamsasiceng telephone ard toes,
‘Grossate provides fall ie ur ei ue.
I pitor o wit posion inthe progam caneisson ofr a

Wastinzen, DC. shawn in ig. 8 Lei be note atthe ronitoring
tendancy india eedeet Thine of special nigh Hi ily
{ype and ison to avo the cousin that oll tau fom ater pti
fovnoniar a mili of difereat programe si ancously with loud
feeiers Lo spare ace ayailable, boseer, or sepsementary ches
‘of quality whenever requir.

Accurate tenendevon messing equipment is wees at the varies
operating points about the netwnrks tn insure satsactory tvensmision
‘ainteaance reuls

—

he era trarsmision t2quiemen: fora

de peezrme materis be enamel i &
Although the exact determination of theta
‘would sotomplish thi involves many consideration i wil be assumed in
{hn ciwnsian chat on ideal transalon system ie in which the sound
“reves ime on the listener eran the home area exact epic ofthe
ound waves striking the strophone inthe stant audio, Linitaions
jnteren in che human ea, the program material to be created and
in she ural listen-ng conditions, however, make 20ch “el trenton
lunneceesry. In tres te rouirerents ler atactory transmission,

Frequency fange, sttenatin dscordoa, dey Histrtian, sonnei and
oie nee usta indies of ually

ig, Moving psn at Wasingtn, D.C

“Before taking up the tananstonrequremens ofa progr cri is
lunporant to conser futer Ube fanatmentl acsors tht are involved
fig the chaacivsicecousiderst dere forthe entire system. Ac
oneing tn Harvey Fletcher the we of audbiity of the average nora
finan vr for paseo single frequerey sounds ise zea within she enrre
GE Lig. 6. Thu abaciees reproeert frequency’ ace chr unlinaes show be
anges ety copays ad betvcen the lnm Tinit or tesa
of avai nl Use upper dit where the sensason of pain is ft. Tes
er tnt she etree frequeney ange shown onthe chart ens aot 20
-PaaGhAM TRANSMISSION crnCuLTS es

0 29000 cycles per second, ‘This range fs for youre people, It ie conde
‘ecably ess for middle-age! and eel people, and vanes wth inven,
‘In addition tothe Limitation ofthe car theres he ars thst thei ite
energy present in most program erateral inthe extetes of ths range,
DarLealiey fn Lie apr equeaces, Ie enetsy vere requeyss ee
ff muse aa other farms of program asve been plished eewben?
igure 7 shows ha iequency ra whith vat be tanamitted fra nutner
sf tastrmonts, spece, an rin ness, 39 thae crapaei levers
fennel celect any arpuinnent.) For ble archeste, experinent hes

sO TW
120] eT =|
Peeeaiiiil y
Bahk
% | !
5 off H
ne i | T
2 IM _ tu
i
é |
z bad | TTT 77]
7° i
YC ill |
Jay Soe ates

Fraqueney in cys per Second

som thatthe elimination of requecies Uo 40s! above
feereumnd is tedetetible# Te the upper at of te tral freuen
"Se sloered rom 15,00 eels, the pret i fa erey detectable
bot increases at an accelerating race. When de init js maceclly sce
‘han 00 eels, che los relly appa bv wan yong

Another iaperant consieratin i vlan rage that i the ference
hetmeen she marin and minum lovee the progr. "eonnates
1 Figs ao ha tor par of she rene sng, che ean esp va

tangeot intent! more than 10cetbele, with perbape 100 dees a 8
meen. However, the following eansilertans shoe that the velune rage
“aki the tenamison yee to secommedse i onsileably nar
ower tra the fteneay nest alah Cae ea" ccm mes

‘the fst lac, she range! prea wolures to which che ear can
seapond such es than the rg ose rogues fein sown EY
hecurve Drogas waves age F gu sen sexy ineglorin sksp wed exe
ft consian luioe estan loge ed anal peaks cPerng in arate y
Shany dec, The range heewen ihe volume at whieh Te hiyhst peas
fact he anim insta ane leads wai te rare Feral a

mene | Mii i

the volume at which the amoilest yaks are ju above the threshold of su
bili ib ctetue lee by» numberof deiels thom the nensiy rig of
theear ss rented by svg fresancie,

Tn the second ptr, tne velune tenge of the wus progson material
hus tiie limits, Mesaurecente have shown that a lalge sympbery
tcker preines rraliute suum range of al TO desiels* Ube
‘volume ange of sos ther is of prozam is considers te isn hi
Sar example, bing ony aboot 251 30 deciles fr dance musi sad Title
rebut 15 dsipel fo ruta he calgue factors a dra,