DEPARTMENT OF coidtER::z LetTeT BUREAU OF STAlTDARDS C i rclJT a r

'JAS"1NGTCN L+375 -

(Replacing k 1 7 1 , October 25, 1932. 2gO and 3lQ' . )

USES Cp TRAI;SiiiISSIONS 07 STAI?DAP.D R A D I O FREQUEYCIES

This F:al._;ptiiet g i v e s nethods of frequency nea,surener_% f o r u t i l i z i n g t h e s t anda rd f r equenc ie s t r a n s m i t t e d b y r a d i o by t h e Net iona l 3ureau cf Standa,rc?s. I t i s i n " three p a r t s .

Part 1 g i v e s netho(ls of u s i n g t OCO-kc transriis t k e c a l i 5 r a t i o n of star;&zrd. g s p i l l a t jn simple ca.aes t h e f r e q u e n c i e s have such niimerical e s as -t;o 'st: r e a checked d i r e c t l y i n t e r a s o f the. t ~ a q g q i s s i o n s .

n i s s i o n s t o check with g r e a t accuracy t h e frequency standari used i n any b r o a d c a s t i n s s t a t i o n ( e . g b , t h e con i tDr r e y u i r e h by F.R.C.Rule 145). The d i s c u s s i o n i s di7rided ' i n t o thl-ee GectlORS, A , B, and C , p rog res s ing i n d i f f i c u l t y af nezsurec1ent. Sec t ion A d e a l s w i t h two f r e q u e n c i e s , 1 G G G and 1250 kc, r h i c h c0xil-d r e a d i l y be aeasu red as exp la ined i n S e c t i o r Very l i t t l e apparacus i s required. for neasureyients - a t t h e s e freqt+iencies - S e c t i o n A i n c l u d e s i n f o r n a t i o n on t h e neasu rezen t s r e q u i r e d when a s t a t i o n s t a n d a r d i s used g h i c h d i f f e r s from t h e a s s igpcd frequency by 500 or 10GO c y c l e s pe r second. S e c t i c n B g i v e s t h e nethod of neasurenent when an a u x i l i a r y g e n e r a t o r i s r e q u i r e d . The nethod desc r ibed i n t h i s Sec t ion a p p l i e s nhen t'ne f r e s x e x y i n k i l o c y c l e s i s a i ~ u l t i p l e of 50. S e c t i c n C g i v e s t h e method o f neasurenent f o r a:iy broadcas t f requency ( m u l t i p l e s of t e n )

.nethods o f f requency neas.irei:wnt cay be found, and dev ices f o r use i n frequency neasu renen t s a r e desc r ibed . The r e f e r - ecces g ive o t h e r ne thods , which r ? q e f rom t h o s e us ing ve ry s i n p l e aprmratus giving; results a c c u r a t e t o one p e r c e n t , t o $hose u s i n g c c n p l i c a t e d a.nd expensive anpaTatus g i v i n g r e m l % s accura t e t o b e t t e r t han a p a r t II? a ~ ~ i l l i o ~ . . ,

The St;,Xn@ard Trequency Tr?rLs:xissions The Burem of S t a n s t r a n sill i t s s -t and? r d f rt; que nc i e s f Bashingtcn , D . C , every 'Fiesday. The t r a n s n i s s i c n s ?,re OE 5000 k i l o c y c l e s , and &re giiven cont inuous ly fo;- tmo k m r s & z i n g t h e day and t w o hours a t n i g h t . s u l t a c u r r e n t trans: . : ission ssh u l e such aa i s gublisiiet? !:lcnthly in the Trccce?.inGs of the I r , s t i t u t e G: Fiadio E q t n e - e r s ,

S t m d P r d s . ) Th~3 t . r ansn i s s ions can be hszrd alii u t i l i z e 2 b y s t r , t l o n s equig?t,d for continuous-wave r e c e p t i o n tn~oug-hou$ the VP-lLed Szates, ei2nough no t w i t h ce r t a i r , $y i n sone p l a c e s . The acs-x"cy o f ~ 7 . e frecuenc;? i s 2"; ,111 til-,cs b z t t e r t han one ~ y c l s ii? f i v e rAilli.o>=

F a r t 2 g i v e s s p e c i f i c i n f o r n a t i o n f o r t h e use o f t h e t rans- -

P a r t 3 i s a b i b l i o q r a p k y , i n whick; r e f e r e n c e s t o o t h e r

M .its s t a t i o n iJiVV,

( T c r t h e hours ct ";aans:iiSsian con-

and r.0 4aT, C T ~ ? i i ~ ? i iJ2,y be obta ined OR re;ueEt; f ~ o : ~ the S U T ~ P ~ E Df

. _

~ " I . . . . .. , . . . . . s ;

. . .\ . . . , . , '

. ..

The t r a n s a i s s i o n s c o n s i s t r-iainly -.-. of - .-.--- cog$* - U A k y c r $ c a r r i e r f requexcy, giving ' a-'%XitTnuous w h i s t l e i n the phones crhen r ece ived v i t h an osc . i l i s . t o sy - r c c c i v i n g sot.. - tl f i r s t f i v e n i n u t e s t h e g,eneral ca l l . , (GQ de a e n t of t h c frequency a r c t rans . : i i t ted. Th ncy and t h e c ~ l l l e t t e r s o f t h e s t a t i o n (*WV) arc g iven every tGn t n s r e a f t e r . - ,

. . . . . , .. . .

. . - .

A . Llethod of Muawrement r ,

ii'h i~l s t anda rd f recpency t r a n s n i s s i o n . nay be used for nany s t a n d a r d i z a t f o n p u r p o s c s , t h e riost cor".n use i s t o de t e r - u i n e a c c u r a t e l y t equency of a p i ezo o s c i l l a t o r . The ap- p a r a t u s ne c e9 s ary 1,) t h e F i e z o o s c i l l a t o r , ( 2 ) a cont in- uous ly v a r i a b l e r frequency- g e n e r a t o r which i s approxir ia te ly c a l i b r a t e d , (3) a v a r i a b l e audio-frequency g e n e r a t o r , and ( 4 ) a r a d i o r e c e i v i n g set. A f requency r ie te r of resonaiice type i s a l s o usefG1.b i s not eoaeDtia1,

The f u n d m e n t a l f-reqalency of a p iezo a s c i l . l a t o r i s f i x e d by t h e dinens t h e ' qya r t z plat e used. Thi.; vacuul-1-tube c i r c u i t a r ra r i II which the q u a r t z p b t e i s connected g i v e s n - ~ m r o u i c s f o r each fun(iaaenta1 frequency. The r a d i o - f r e q u e ~ c y e r a t o r , which i s cont inuous ly v a r i a b l e , can be a d j u s t e d t o any f requency , and l i k e w i s e g i v e s a s e r i e s o f han ion ic s for each fundaczn ta l freq1;ency t o mhich i t i s ,

a d j u s t e d , If the frequcncy of t h e rpdio-frequcncy g e n e r a t o r is v?,Tied over E. wide range , b e a t n o t e s are produced at a nuziber cf s e t t i n g s of' t h e gcnerLtor by t h e i n t e r a c t i o n of v a r i o u s ha rcon ics of t h e ' fundamental frequency of t h e p i ezo o s c i l l a t o r w i t h a harzionic of t h e f u n d m e n t a l f requency of t h e g e n e r a t o r The b e a t n o t e s c a y be heard i n a p a i r o f telephone-s s u i t a b l y c o m e c t e d t o t h e g e n e r a t c r or t o the g i e z o o s c i l l a t o r . A p y . f rcqucncy p r e s e n t i n t h e piozo o s - s i l - l a t o r can be? nding frequency p r e s e n t i n t h e rad io- f requen i c h !1:akes i t p o s s i b l e t o se't t h e ger_er;ltor a t encies which have i? s i r ip lc r e l a - t i o r , t o t h c f t a l f r q u c n c y of t h a p i ezo o s c i l l i t o r ; Frovid ing t h e i c r e l a t i o n s h i p i s known, a e a s u r e n e n t s can be nzde a t nuriber of f r equenc ie s i n t e r s i n p l e s t znda

a1 frequer,cy of t h e p i e z o osc i lLla t s r t h e fundaL3eTtaJ f requency of t h e

s z e r o b e z t , t h e n

2.f = bF

mhere a and b a re i n t e g e r s (1, 2 , 3 , 4, e t c . )

-7 E. Axariples of L(easTire.-.jent Lethod

Suppose i t i; r e q u i r e d t o r>czsure t h t f recuency o f a p iezo o s c i l l a t o r , t h e c?pnroxi- lnte f reauency of which i s 700 kc, i n t e r n s of t h e 50OG-!lc s t anda rd frequency siF:yials

53th har;ionir, (5900 kc) m i l l b e2 t v i t h t h c 5000-kc t r a n s n i s s i o n , and t h e 7 t h h a r n o l ~ i c (TOO ko) w i l l b e a t with tCe’fuRdanenta1 of ’

If t h e radio-frewldncy g e n e r a t o r i s c t t a t 109 kc, t h e

I , t h e p i ezo o s c i l l a t o r .

The 5C00-k~ ctar.dard frcqGency signal. i s r c c e i u e d f i r s t and i d e n t i f i e d pilith the r e c e i v i n g s e t i n thi: gene d i t i o n . The radio-frequency ,cener%tor i s t n e n ’ t u a d j u s t e d t o ne2.r lOG kc. This ‘should g ivc a bea t t h e frequency g e n s r a t e d by t h e r e c e i v i n g s e t . Th t i o n of t h e r e c e i v i n g s e t i s t h e n reduced usti l’ t s t o p s g e n e r a t i n g . A bi.,?“t no te should then be h i.n gen5ra l be of l e s s i n t e n s i t y t’ian. - t ’ ~ a t ‘p rcv i This i s ;;he b e a t between t h e 50th h s m o h i r ; -of t h e radio- f requency g e n e r a t o r and t h e frequency of t h e illconlng wave. This Sea t n o t e should be reduced t o zero frequency b y adjust- ixg t h e radio-freq-lepcy g e n s r a t b r . t h i s adjust:yent should be r.:ade by -us i rLg c2 b e a t f requency i n d i c a t o r o r o t h e r neans of i n d i c a t i R g exac t z e r o b e a t . A s i r i p l e r and e q u a l l y a c c u r a t e s u b s % i t u t e i s t o b r i n g i n a tun ing f o r k as desc r ibed below. cussionsof t h e s t e p s involved i n t h e neasurenefit , it w i l l be assunzd t h ? t en accu ra t e zero-beat s e t t i n g i s obta ined .

For n o s t g r e c i s e work

Howeyer, for a s i n p l e d is -

The radio-frequencjf g e r e r a t o r i E : t h j u s x e d s o t n a t it has a frequer-cy oz. l a 0 i t s adjust:-.ient, couple . t h e p i ezo o s c i l l a t o r to i t 3oosely. b e a t note should be h e a r d i n t h e telephones i n t h e o u t p t o f t5e p iezo o s c i l l a t o r unless t h e freaustl?_cy en by t h e Fie20 o j c i l l a t o r i s an exact rnu l t ip le o f 1510 k c . UPPOSe, f o r exacp le , i t i s 700.529 k c . p e r second w i l l b e heard . n o t e , t h e audio-frt.quency g e n e r a t o r c L s t be .;.scde

€?fore precisel:. Fd-

A * Without ch=%ing

I n t h i s case a beat o f K20 c y c l e s To d e t e r n i n e t h e value of t h i s

es a d i a g r a c x i t i c r e p r e s e n t a t i o n o f t h e f r e -

i ghe r o r l o a G r t h a 9 700 kc. frequency of t h e r s d i o - f r c

~f i n c r e a s i n q tha frequency C I ~ t h i s gener dzc reas ing the bent rAc:t3, t h e n t h z Diezo h i g h e r t h a n t h e referc-Qce fT&quency, t h n t is, t h e audio frequency i s t o be a d c - e d _ $ o 700 kc.

I t ~ i's"-ne-cess.s,rg -ta de-terninc kke the r t h e p i e This can bs done

?'?CY ? w e r a t o r * G r re:'.;Llts in ciila1Ior is

If t h e r eve r se i s t r u e , " t h z n tni: aud io f rcquensy i s t o bz s u b t r a c t e d .

2 0

C . Use of Audi o-Frequency Note i n L:sasurenent.

A change i n t h e r;ethod d e s c r i b e d abcve which does n o t r e q u i r e a b e a t i n d i c a t o r , i s t o adjust t h e radio-frequency g e n e r a t o r t o have a ki:cwn frequency d i f f e r e n c e w i t h t h e in- coyding vave by m a n s of watching w i t h t h a t of a t u n i n g fork of known frequency sur';. as 1000 c y c l e s pe r second. : This rilzthod i s n o r e c o n p l i c a t e d i n c a l c u l 8 t i o n because u u s t be nade of f o u r f a c t o r s , (1) as t o f h e f h e r t h e radio- f requency gsnerat ,or was ad j -Js ted h i g h e r o r lower tlmn z e r o b e a t , ( 2 ) the f requenc;~ d i f f e r e n c e , .(j) t he harnonic rela- t i o n between t h e s t a n c a r d s i g n a l and the r&dio-frequency g e n e r a t o r , and ( 4 ) th:: haruonic r e l a t i o n between t h e radio- frequency generator aild t h k p i e z o oscillator. The ha raon ic r s l a t i o n s , however, cone i n t o any nethocl af rieasur-e t h i s kind. -The acasurenen$s invc-lving the use of t h fork for adjusting t h e g e n e r a t o r io g?vc 8 b e a t no te c y c l e s p e r .second be1o-a t h e 5000-kc sic.na,l would be nade as f o l l - o w s , an a r e s h o m diagrnnnat ica , l l -y i n Fig. 2 . S e t g e n e r a t o r f r o n approximate z ~ y o ' b e a t at 100 kc t o 99.9g kc. The -50th herrinnic i s 99.9s x 50 = 49y5.0 kc ( b e a t s wi th 50OO-k~ i,n r e c e i v e r a k i c h i s no% o s c i l l ? t i n g and g i v e s a 1000-cyslie -note)'. The 7 t h h a r m n i c o f t h e g e n e r a t o r ('J9.gg x 7 = 629.86 kc) a a y now be hea rd b e a t i n g i n . t h e . t e l e p h o n e s sf t h e p i ezo o s c i l l a , t o r which i s known t o S z ' a p D r o x i a a t e l y 700 k c . 700,000 - 699.a60 kc or 140 c y c l e s w o i ~ l d be h e a r d . t h e b e a t no te produced i s n a t c h e d ' w i t h a .cor reEpcndin5 n o t e f r o m t h e audio-frequency g e n e r a t o r :

I f t h i s v a l u e werz e x a c t l y 703 k c , a-note of

If t k e p i ezo o s c i l l a t o r . I

~ c 3 j g .-- 7/11/32. 5.

had t he freqilericy of 700,520 kc 8 s assuned previously, t he audio- freqiJZ:x::y x o t e n-eLsurGd-bould have bc.:n 7OO.520 - 699.860 = 06660 kc or 600 cycles p e r second.

.Phekher to add o r subtract tihe audio-frequency note o f 660 c y c l e s tG the known frequency of 695.860 Rc-wauld be decided as f c i l o w s mr ie r , t h e radio-frequercy generator mas s e t lower t han t h e stzndar .2 f requency s i g m l , If 10vb:eri;lg~ t h e radlo-fTequencjr gener= , tor i n c r e a s e s t k e c y c l e s i n L n i s c ~ s e ) ~ add. t h e beat n o t e f r e q n c y , o r if in- creasing the f requency of -chz rad ic- f requensy g e n e r a t o r d-e- crea6es t k c beat n o t e , add the b e a t note frequency.

... ... . -. 1 I -.-- _"_,_

.-- _- .- *--- .- . .- . "

. . . . . . . . .

.... - . ,-.. .. .. , . .

. . - . . . . . . . . .

....... . . . . . . . . . . . I,-r.. .- . - .

. . 1 - . . . . . . . . . . . . . . . . . \

. :.. ..? . . . . -

. _ . . . . - . .

. .

Fig . 1 '>a = f requency

I d i f f ekence ne a su r e d

gcOG kc standard f rcquenc a t r e c e i v i n g s e t

r e c e i v i n g s e t

-- - ,

F i g . 2 a = f r equency

~ ~ e d wi th a . f . 699.860 kc d i f f e r e n c e ceas-

& 5000 kc s t anda rd f requency s igm-1 a t r e c e i v i n g s e t

1000-cycle no te Deter::ined by tmi ing f o r k ) ,~,

50 th harnor_ ic I I

I 'i

g ene ra t ST. Fre- quency of p i ezo oscillator i s 699.g6 -i- a kc.

P i e z o o s c i 1 l a t or t o be neasured

F ig . 3.

1000-cycle no te 7 .1' Deter:-lined by tun ing f o r k j

5000-kc s t enda rd fre- f quency signal at-'- '

- "f

il- - i I I Genera tor s e t

h igh from 1 . . ]3h>a , r !:I on 1 i c 1

. a, = f requency d i f f e r m c e meas- ured with a . f , gene ra t o r Fre- quency of p i e z o o s c i l l a t o r i s 7C0.14 +- z kc.

?i i .zo o s c i l l a t o r t o be r.iea.sured

~ ~ 3 3 5 -- 7/11/32. 7.

The neasurenent could e l s o be nede by a d j u s t i n g t h e

The 50th harnonic i s 103.020 x 50 = 5 O C l kc geEera to r t o 3.OC.020 kc usi-cg t h e thoussnd-cycle t l x i n g f o r k , a s i n rig. 3. which b e a t s w i t h t h e s t a n d a r d frequency s i g n a l o f 5000 ks and produces a 1000-cycle Rote. produced i n t h e t e l egkones of t he p i e z o o s c i l l p t o r , which i s na tched w i t h c2 sini lcar no te fro:: t h e audio-frequency o s c i l - l a t o r P S b e f o r e , If lotrrering the f requency of t h e radio- f requency g e n e r a t o r reduces t h c audio-frequency n o t e h e a r d , s u b t r a c t i t f r o n t h e knonn frequency o f 700.140 k c , o r i f i n c r e a s i n g t h e frt3auency cf t h e ' r3dio-freqvency g e n e r a t e r i n c r e a s e s t h e audio n o t e , s u b t r a c t i t . The ?,udio-frcquency no te hea rd wi th a p iezo o s c i ? _ l a t o r kavirrg t h e 8ssiined fre- qdency would bc 3gO c y c l e s , hence 700.140 + 0.j80 = 700.520 k c .

The liethods d e s c r i b e d above are capKble of g i v i n g very a c c u r z t c v a l u e s of f requency i f p r o p e r l y c a r r i e d o u t . iruch s i x p l e r procedure by vhich less accura t e v a l u e s :Tay be ob ta ined i s t o c a l i b r a t e a frequency n e t e s i n t e r i l s of t h e s t a n d a r d f requency s i g n a l s and t h e n c i c u u r e t h e p i e z o o s c i l - l e t o r by r;ean0 o f t h e f r cqcency w t e k .

A c e r t a i n audio-frequency no te i s

.

A

P a r t 2, ChcckinG Erozdcast Freauency Standards .

The f r equenc ic s which Zrc: i c t e g r a l sub-imlt i p l e s of

c a s t f r e q u e n c i c s , 1000 elid. 1250 k c , which b e a r t h i s r e l z t i o n . The f i f t h harnonic of 1060 kc i s 5000 k c . If a 1000-kc o s c i l l a t o r ) wkether a t r a c s a i t t i n g set or f rcqucncy s t a n d a r d , i s coupled t o 2, TEtBio receivcr t u n e d . t o 5000 kc a t a t i x when t h e stand2r.d si 21 i s 3eiRg receivec?, a heterodyne note w i l l be produc which 1s equal t o t h e fr<quencY d i f - f e rence bettvzcn t h e 5 t h hFLrl.ioi:ic of t h e LOOO-kc o s c i l l a t o r and t h e s t a , n d u d signa.1. t h e 1000-kc o s c i l l a t o r i s krlown, all t h a t reviains i n order t o :2easure t h z f rzquency a c c u r a t e l y , i s t o detcr!:1irie t h e frequerlcy of t h e b e a t n o t e and r h e t h e r thc, frequeficy i s h i s h e r or loner t h a n t h e s t anda rd s i g n a l . . T h i s i s done mhen thz radio r e c e i v e r i s no t i n t h e gcnsra t i r ig c o n d i t i o n . The i:lost convenient ne thod , i f th,a b e a t n o t e i s i n t h e aud ib le r ange , i s t o :latch i t v i t h a k n o x audio frequency p r o d ~ c e d by a d a l i b r a t c d audio-frequency c s c i l l a t o r . direct ic l i i of t he d e v i a t i o n i s riost e a s i l y deterlJinec? 'cy nak- ic& a s l i g h t ckanqe of knova d i r e c t i o n i n the u ~ l c - _ ' C T ~ f r e - qucncy. If an i n c r e a s e ir, t h e unknown frequency i n c r e a s e s t h e audio-frequency b e a t no te t h e freqiJc:ncy i s hiqh.

, i n c r e a s e i n t h e unkno-fi;n frequency decrecices t h e audio-freq b e a t n o t e , t h c frequency i s low. Converscly, i f a decrease i n

. 59CO kc a r e .Joet e3isily : x ~ ~ s i ~ r ~ d , Thepe are only t;i-o b r o a d -

Assu!ling t h a t t h e non ina l va lue o f

Thc

If an

LC335 -- 7/11/32 8.

t h e unknowh frequency i n c r e a s e s t h e audio-frequency b e a t nott: t h e f requency i s l o w , ani?, i f a d e c r e a s e . < i n t h e u’nknown frequency de- c r e a s e s t h e audio-frequency b e a t n o t e , t h e f requency i s h igh . If t h e audio frequency t o be neasu red iG between 5 and 260 c y c l e s p e r second, t h e audio-frt : u2ncy ar rangenent d e s c r i b e d i n a p rev ious Burzau p u b l i c a t i o n ? by W.P.Case can be used w i t h a ve ry high degree of accuracy. I f t h e audio f requency i s s t i l l lower and goes below t h e range of t h e audio-frequency m p l i f i e r , i t i s necegsary t o provide a carrier for t h i s audio-frequency n o t e . This i s dons by m k i n g the r a d i o r e c e i v e r gene ra t e and a d j u s t i n g t h e r e s u l t i n g b e a t n o t e s o t h a t i t i s approx ina te ly 1000 c y c l e s pe r second. A f l w t u a t i o n i n t h e a a p l i t u d e of t h i s 1300-cycle n o t e , which hasca, f requency e q u a l t o t h e f requency d i f f e r e n c e be tmem t h e tmo rad io f r e q u e n c i e s , w i l l t h e n bc heard . I f i t i s only d e s i r e d t o r e a d j u s t t h e unknonn f requency t o agreenent w i t h t h e s t s n d a r d s i g n s l , i t i s a s imple m t t e r t o a d j u s t t o z e r o bea t . The sayle ne thod can be u s e d for a f requency o f 1250 kc. P r c c a u t i o n n u s t be taken t o nake i t p o s s i b l e t o cor-ibine t h e s i g n a l s w i th approxir ia tc ly e q u a l i n t e n s i t y . So-e d i f f i c u - l t y i n t h i s r e s p e c t nay be I

expec ted i f ncasu renen t s a r e nadc when t h e t r a n s m i t t e r i s o p e r a t i n g u n l e s s t h e ha rnon ics a r e ve ry co;ripletely supprcssed .

A s t a t i o n frequency n o n i t o r which u t i l i z e s a p i ezo o s c i l - l a t o r having -q nf~ggu’e’noy .of 1000 .-o 25G kc can be nee.sured o r a d j u s t c d t o f requency i n a s i n i l a r r.:anncr, If t h e r a d i o t r a n s n i t t e r i s o p e r a t i n g , t h e neasurenent ean be na,de i n d i r e c t l y i n terns of t h e t r a n s n i t t e r i n the‘ fo l lowing m n n e r . LIeasure the frequency of t h e rad io t r e n s x i t t e r i n terns of t h e 50OQ-k~ s igna l and s i w l t a n e o u s l y rzed t h e fl-equency as i n d i c a t e d by the frequency d e v i a t i o n m t e r on t h e n o n i t o r . Tne two frequen- c i e s should agree. I f t h e y do n o t , 8 t j u s t t h e frequency cioni- t o r u n t i l t h e d e v i a t i o n n e t e r i n d i c a t e s t h e c o r r e c t f requency d e v i a t i o n . I t nay be d e s i r a b l e t o neasu re t h e frequency m n i - t o r d i r e c t l y a g a i n s t t h e s t anda rd signal a t a t i n e when t h e radio t r a n s n i t t e r i s not ope ra t ing . I f t h e S requemy u o n i t o r i s of t h e t y p e which is a d j u s t e d t o e x a c t l y 1000 o r 1250 kc, t h e Lieasurenent can be m d e t h e sane as i n t h e case o f t h e r a d i o t r a n s n i t t e r . H o v ~ v c r , i f t h e n o n i t o r i s s e t h igh o r lor^ bj. 500 or 1000 c y c l e s , i t w i l l be necessa ry t o caEe use of an audio-frequcncy o s c i l l a t o r t o detcr}-iine thi: v a l u e of t h e audio b e a t frequent;:. Ir t h e case o f a :-ionitor which h a s a frequency of 999.500 or lOSO.5OO k c , t h e b e a t no te t o be neasured would be 2500 c y c l e s pe r second. A s f ’ v e c y c l e s

frequency o s c i l l a t o r which would be cons t an t t o 5 c r 10 c y c l e s p e r second would be adcau-ate. I n t h e case of a x ioni tor ‘which h a s a Erequency of 999.000 o r 1031.590 kc a 5000-cycle no te would be produced. Si i i i i lar ly f o r 1250 k c , ?>udio-freauGncy bea t 1

Yas ia t ion i n t h e bea t n o t e i s only 1 p a r t i n 10 6 , pny audio-

See r e fe rence (69), P a r t 3.

i iotes of 2000 and 4009 cycle.; per s c c o n d have t o 'ce acesu red . The g e n e r a l r e l a t i o n i h a t t h e audio-frequeccy n o t e produced by heteroZynTlig3hC n i t o r f reauency and t h e 5000-kc s t a x d a r d s i g n a l i s equal r0c;ttlct of t h e nu!nb;:r af c y c l e s t h e ~ a n f T c f - S s s e t h igh o r a~&--the- n t i o of 5000 t o t h e no+: ina l va lue of t h e :- lonitor.

E?. Xe=surerJents x i t h Aux i l i a ry Genera tor f o r Prequency ldu l t ip l e s o f 53.

2t:asurc:':ents of any of t h e s e f r e q u e n c i e s r e q u i r e the u ~ e o f an auxi1i ; ) ry qene razo r i n a d d i t i o n t o t h e h igs- f requrncy r e c e i v e r . The a u x i l i a r y g e n e r a t o r r!ay be a p i e z o o s c i l l a t o r o r i t !:lay be P izanually c o n t r o l l e d o s c i l l a t o r . If a p i ezo o s c i l l e t o r of t h e d e s i r e d frequency i s a.va,il;?ble, i t i s d e c i r a b l e t o u s e one. I n t h i s case a d i s t 9 r t i n T a x p l i f i e r i s n e c e s s a r y i n o r d e r t o b r i n g out t i le hw':-;onics s o th?,t t he b e a t

a i n s t t h e 5OOO-kc s t a n d a r d s i g n a l can be easily hea rd . T h i s e z o o c c i 3 l a t o r should be provided wi th a v 2 r n i e r f requency

aG2justxat s o t h a t i t car_ be r e a d i l y adjuste? t o egreerr3enz with the 5L?Ov-kc s t a n d a r d i n t h e xanner p r e - r i o u s l y desc r iPed . A f t e r t h i s i s done t h e n o n i t o r or r a d i o t r a n s n i t t c r can be ':it=asured i n t e r r i s of he rn6n ics of t h e a u x i l i a r y g e n e r a t o r . If a r a n u e l l y con t ro l l ed . g e n e r a t o r i s used , t h e & r a , t i o ~ 1 1 ~ s t

be low s o tket t h e f rcquQncy can be e a s i l y a d j u s t e d t o zero beat wi th t b e s t a n d a r d frecpcricy, and r e a d i l y h e l d on t h a t f requency.

C

Tinere a r e txo n a i f a c t o r s which detE:r;:iine t h e -frequency t o which t h e a u x i l i a r y e.nerc?tor shoulc? be a d j u s t e d . The f i r s t i s t n a t i t s f r e ncy u u s t have an i n t e g r a l r e l a t i o n s h i p n l t h t h e s t a n ? a r d f requency and t b e frequency t o be ne8,sured. The second i s t h a t t h harr--ionic which i s heterodyned w i t h the s t a n d a r d f r equency nu .bc of s u f f i c i e n t i n t e n s i t y to -p roduce a b e a t cot,: nh ich i s e a s i l y rccognized . Taking; both. f a c t o r s i n t o account t h e b e s t r e s u l t i s a t t e i n e d i f t h e f r e q u e n c y - o f t k e aTuxiliary g e n e f a t o r 5 s t h e h i g h e s t c o x o n . f a c t o r of t h e s t a n d a r d f requency and t h e f quency t o .be ; icqsured. There i s one o t h e r c o n s i d e r a t i o n i t h e case af a nanua l ly c o n t r o l l e d a u x i l i a r y generau+or and that i s , . t he l o n e r i t s frequency,- t l ie less t r o u b l e is. exper iqnced i n h 0 l d i n r i t a t zem b e a t a g a i n s t t h e s t anda r f.req'uency. The f owing t a b l e i n d i c a t e s t h e b roadcas t f quenc ie s 'which ea e . iieasured i n tefi-:S of t h e 5000-kc s t a n d a r d f r equsncy . t r a i s s i o x b y x a n s of a bish-

r a d i o ' r e c e i v e r and an a u x i l i a r y g c n e r a t o r . I t m l i i

Ehich a r e :XI p l e s of 5 0 , 'cut doe9 no t inrlicp,tc ;:ore t h a n one g e n e r a t o r f.r ency f o r t h e s e f r e q u e n c i e s except f o r 1060 and

tood t h a t t h e t a b l e gives a l l b roadcas t f r e q u e n c i e s

10.

600 1000

1500 800

1000

.. .

I .

,1100 750 1.300 g50 1200

1400 9 50- ._ 1059

1.150

1500

1250

1350

X.; an e x a ~ p l e o f t h i s ne thod o f ;xasurei:!ent , assuae t h e f requency of t h e r a d i o t r a n m i t t e r t o S e 1150 .kce The s e d i o r e c e i v e r , i n e p n e r ( ? , t i n g c w d i t i o n , i s tuned u n t i l t h c 5OOG-kc s t a n 61 f requcncy s i g n a l i s hsard. Th gc i i e ra to r , s6t on approxi a t e l y 50 kc, i s t h e n t u r n e d on and t h e f requency v a r i e d u n t i l a second audio f reqmrlcy i s he2rd on t h e output of t h e high-frequency r e c e i v e r . -If tlie r p d i o r e c e i v c r i s t h e n a d j u s t e d So t h a t i t does not g e n e r a t e , t h e a u x i l i a r y g e n e r a t o r cay be s z t t o ze 'ro bea t with ' t h e s t a n d a r d f requency s i g n a l . If t h e r a d i o reccsiver i s a g a i n nade t o g e n e r a t e , t h e a u x i l i a r y g e n e r a t o r can be e a s i l y s e t t o agree- nen t w i th t h e s t a n d a r d f requency s i g n a l as p r e v i o u s l y exp la ined . The rough adjus e n t t o zero b e a t r iust be nade i h e n t h e r a d i e r e c e i v e r i s i n t h e non-genera t ins c o n d i t i o n , o the r i i i s e t h e r e i s danger of s e t t i n g t o zero S s a t between t h e t w o aud io frequen- c i e s o r ha rnon ics or" t h e a u d i s f2equencies . If a p i c z o o s c i l l a - t o r i s used , t h i s p r f c a u t i o n i s u h e c e s s a r y , A ? e t z c t o r - - a n p l i f i e r i s s e t u? s o as t o r e c e i v e p o r t i o n s of $he o u t p u t s of t h e auxi- l i a r y g e n e r a t o r am? t h e I l 5 O - k ~ r s d i o t r a n s r i t t e r , Fig.4, The ou tpu t of t h e a,r-iDlifier w i l l g i v e tht: audio beat f reauency be- $ween t h e 23d harxionic o f t k c & m i l i a r y ,geneTator m d t he 1150 kc of t k e rac-?io t rans! : i i t t e r . If t h i s audio-frequency i s reduced t o z e r o a s i n d i c a t e d on a . r i sua l b e a t i n d i c a t o r t p e t r a n s b i t t e r f requency w i l l be i n e x a c t egreeiient ijlrith t h e s t a n d a r d f requency s i g n a l , One person can ~ a k e t h i s a d j u s t c e n t , as an a u r a l i n d i - c a t i o n nay be used for t k c m x i l i a r y g e n e r a t o r an:!. a v i s u a l one f o r t h e t r a n s n i t t e r a d j u s t x e n t

~ ~ 3 3 5 -- 7/11/32. 11.

Pick-up f r o n t r a n s m i t t e r o r nori i tor

" I

. ._..

I f a p i a z o o s c i l l a t o r i s used a5 t h e a u x i l i a r y g e n e r a t o r , i t need only be checked a g a i n s t t h e s t anda rd frequency s i g n a l a t i n t e r v a L s .

C. &&asurknent o f Any Broadcast FreauenGp

The ne thods o f aeasurcment g iven i n t h e preceding para- graphs are a 9 p l i c a P l e t o tvjenty of t h ? f r equenc ie s i n t h e broad- cast band. The h i g h e s t coY;won f a c t o r of 5000 kc and t h e remain-

l i & r y g e n e r a t o r must t h e r z f o r e be 10 kc if t h e o t h e r broadcas t f r e q u e n c i e s a r e t o be checked r c a d i l y i n terms o f t h e 5O0O-k~ t r a n s m i s s i o n s e The b e a t n o t e ,between t h e 500th harmonic of t h 2 10-kc g e n e r a t o r -2.nd t he 5300-kc t r ansmiss ion would not be Ioud enough t o bc h z a , r d . d i s t i n c t l y . The s i ; - iplest s o l u t i o n , t h e r e f c r e , i s t o s e t thi: a ~ x i l i z r y ger ,erator 011 100 kc and l e t t c o n t r o l a, 10-kc m u l t i v i b r a t o r . The bea t a g a i n s t t k c s tan- a-d f r eqceccy s i g n a l cocld thcii br: heard c a s i l y and t h e har-

rrofiics of t h e 10 k c would heterodyne e q u a l l y well w i t h frequen- cics i n t h e b roadcas t band. I t i s evi4cnz t h a t wi th th i f i equipment all aEsigned f r equend ies i n t h e b roadcas t band can be checked agoainst t h e 5000-kc s t anda rd f r equency s i g n a l , F igure 5.

. i n g b'roadcast f r e q u e n c i e s i s 10 kc. The frequcncy of t h e ai lxi-

LC335 -- 7/11/32*

I ’ x O /

r e c e i v i n g i s e t

. .

PicBup f r o m t r a n s m i t t e r o r moni tor .

0 ,Y

I Beat I

of a,ux.gen. of cu l - t ivibr8- t o r \ I Audib- 1

Tkkre a e . %,-o:-ie- cas<o “in which a frcquency cen be measured by nor$, .than one of t k c method:; indicatc .d . Tht3 ques t ion a r i s e s as t o t h e ZdvailtaTes and d isadvantages of t h e v a r i o u s p o s s i b i l i - t i G S o r a:: t o hor; e x i s t i f i g eqliipnent n i g h t be brought i n t o use. The f i r s t nethod i s a , p ~ l i c e ’ c ; l a t o only tivo f r e q u e n c i e s . I t pro- v i d e s t h e i - ~ o s t a c c u r a t e chcck f o r f r ?quenc ie s t ~ h i c n a r e ve ry near t h e harnonic ve,lue. F o r izoni tors , hotioevcr, wnich are s e t h igh o r l o w b y 5G.3 o r 1000 cycles per sccond, t h c audio frequency which n u s t be Iiaasurcci i s s o n i g h t h a t i t i s Very d i f f i c u l t t o

itsfvalue. Tnis r:ctk.,oc? is f - i r t hc r handicapped by t h e f a c t that , i f the t-i2Z;U.TeigtntS a r e riade i n t h e transixi. t t ing sta- t i o n whdn the power arzpl i f i e i i o opt?ra,ting, t h e harnonic which i s p i cked up on t h e r e c e i v e r nay be s o s t r o n g t h a t I t w i l l block, t h e r ece iv , c r . If that : -s t h e case i t mould be necdssary t o r o c a t e t h e r e c e i v e r a t sone d i s t a a c z f r o z i t h e t r a n s m i t t e r and use a 1inG bc-tween t r a n s n i t t e r and r e c e i v e r .

The second i::cthod r e q u i r e s a n a u x i l i P r y g e n e r a t o r and d e t e c t o r - a n c l i f i e r i n a d d i t i o n t o t h e cquipncnt used i n t h e

LC335 -- 7/11/32. 13

(N0tc.- These pcb lhca t ions a,re no t issued. by , n o r ?,re .%>ey a-fail-

( * ) i n d i e a t s r?, I3h -ex p u b l i c a t i o n , a n d if R p r i c e i s added, a, copy m y e ob ta ined fro!? tk;e Superintendent o$ Docunents, Go-Terncant Printin;; O f f i c e , Xnskinqton, D.C. The&? pub l i caa

?'ole f T O 2 , i?c Burzp,u of < S t n n j a r d c , exct33t xhere noted. i\: star

c a n S=r: consu l t cd i n ,public 1 i b r F r i e s v:hich n a i n t a i n : .

Pie 7 o-e l cc t r i c 1 t y

, df p e r i o d i c a l s ) " . . . _ . I

(2) ~~, , t iy . , V . G . , - T ~ E p i e z o e l e c t r i c resonator, Procee$i-ngs of t h e I n s t i t u t e of Ra:Zio Z r l g i ~ L g r s , (Xcn ' iork, B.Y.'), vole 10,

( 3 ) 'F i e rce , G.;J., P i c z o e l e c c r i d c r y s t z l r e s o n a t o r s and 1 o s c i l l a t o r . p p l i c d t q t n c p r e c i s i o n c a l i b r a t i o n of t e r s , Proc. 6ricFi-: Aca'&:-ly A r t : ; .ScicEbes, (VJasYi- ; D.C.), v o i 9, P A T , 11'923.

( 4 ) Capy, d . G . , PiL:zoelectr ic star,da.rdc of h i g h f r e q u m c y , P S a c i e t y of A:-e+ica, ' ( I t h a c a , N.Y.)", vol, IC,

. .

L C 3 3 5 -- 7/11/32. - 14,

(5) Hun<, A . , Uses m d p o s s i b i l i t i e s of p i e z o c l e c t r i c o s c i l - l a t o r s , Procesdings of t h e I n s t i t u t e o f Radio Engineers , ( ~ e w Y'ork, N.Y.), vo l . 14, p.447, 1926.

e l e c t r i c c i r c u i t , London Thysica.1 S o c i e t y Proceedings, (bondon, Enqland) , v o l . 38, p.399, 1.926.. (7) Cross l ey , A . , Quartz c r y s t e l c a l i b r a t o r s , QST, (Har t fo rd ,

Conn.), V O ~ . 11, p.23, 1927.

(8) Hitchcock, R . C . , Radio-frequency s tanf ia rds , E l e c t r i c

(6 ) Dye,' D . W j p . , P i c z o e l e c t r i c a u a r t z r e s o r a t o r a n d equ iva len t

Journc21, ( i lenasha, 'Vis.) , ~ 0 1 . 2 4 , p.430, 1927.

(9) Hitchcock, R . C . , Uounting q u a r t z o s c i l l a t o r c r y s t a l s , Proceedings of the I n , z t i t u t e of Radio Engineers, (New York, K.Y.), V O ~ , 15 , p.902, 1927.

(10) Barron, J.H. , Jr., 4- Je thod o f u i i n g f r a c t i o n a l harr;onics o f q u a r t z c r y s t a l s , Re.clio Se rv ice B u l l e t i n , (Government P r i n t i n g O f f i c e , vrlashingtpn, D t p .7 , Dee. 31, 1927. - - --.- - , >*- . * . . . - -

(11) Cady, N.G.

( 1 2 ) Lack, F .R . , Observa t ions on uo&s o f v ib ra t io l ? and tenpera-

Bib l iography on piczcr e ' l z c t r i c i t y , Proceedings of th'e I n s t i t u t e of Radio Engineers , v o l . 3.6, p.521, l92g,

t u r e ooe f f i c i e r i t c o f q u a r t z c r y s t a l p l a t e s , Proceedings of t h e I n s t i t u t 8 ' o f Radio Engineers , (New York , K.Ye), v o l . 1 7 , p.1123, 1929; Bell Systei-n Technica l JoLirnal, ( N e w York, N.P.), v o l . 8 , P.515, 1929.

(13) Hitcncock, S.C. , The d.inensionn o f l o w frequency q u a r t z o s c i l l a t o r s , Hcvicw of S c i e n t i f i c I n s t r u c e n t s , (Menasha, Vis.) v o l . 1, p.13, 1930.

(14)*Hcaton, V.E. and E r a t t n i n , W . H . , Deqign of a p o r t a b l e t e n p e r a t u r e - c o n t r o l l e d p i czo o s c i l l a t o r , B. S. Jour.Research, v o l . 4 , p.345, 1930.. ( ~ ~ 1 5 3 , 56). Proceedings of t h e I n G t i t u t e o f Radio Engineers , (N.:w York, X.U.), v o l . lg, p.1239, 1930.

(15)*Wright,R.B. anrZ Stmxet, D. i l . So:iie e x p e r i - ? e n t a l s tud ien of t h e v i b r ion.9 -of q u a r t z plate. ; , E.S.Jour.Research, v o l , 7 , p .519, 1331 (~~356, 20b).

( 1 6 ) *Heat t enper??-ture V O ~ . 7 , p..6 t u t e of Rad

on , V, E . and Lzphazi c o n t r o l f o r p i ezo

8 3 , 1931. (RP?66, . i o Engineers , (?$&E

, E . G . , Quartz o s c i l l a . t o r r ; , lO6), Proce Y o r k , N,Y.),

' p l o t e :nount ings and B.S.Jour. Research,

edir,ks of t h e I n s t i - vol. 20, p.261, 1912.

x335 -- 7/11/32. 35-

(17) Hallnan, L.B.Jr., Bot?:; on t h e freauency o t P b i l i t y o f (Nev: York, U . Y . ) , v c l , 12,

72.15, 1932.

( l g ) Yovgaard, Q.h i ; s , Applic:ition o f qcar tz platzs t o r a d i o t r z n s i _ : i t t e r s , Proceedings 02 t b e I n F t i t u t e of RaT',io Engineers , !X;i.,w York, N.Y.), vole 20, p.767, 1932.

c u a r t z p l p t e s , Ea."iio Engineer ing ,

F r e que nc y LI t- a sur e;-? en t 9 and App ar a tu c;

(51) Wnc?ore,F.'ylJ. ax? Enqe1,B-H. , A rietlriofi of neafluring very S s h o r t r p d i o wpuve l e n p t h s and their use i n f requency s tandard i - za t i ' on , Proceedings of thc In.; t ; l tutc of Radic Engineers York, N . Y . ) , v o l . 11, p.467; 1923.

s t anda rds .of frequcncy o y t h c u s e of a harrionic a q l i f i e r , B . Sc i . 2apGrs, v o l . 2 p..179,' 1926. ( S 5 3 0 , lo#)

s i n g l e f requency s t a n d a r d , ~ o u r r a l O p t i c a l S o c i e t y of Auerica. a x d R d v i e w of S c i e n t i f i c Ins . t runsn t s , ,(i.Icnaaha, X i s - ) , v o l . 159 9 . 2 5 , 1927,

(New

( 5 2 ) * J o l l i f f e , C.3,%, 'Fnd Hazen, Grace, Es t3b l i shuen t of r p d i o S.

I -

(53) Clapp, J . K , , Un ive r sa l , f requency s tanda,rdizRtion f r o n a

i s , S., A !-;$t:ilod of c a , l i b r a t i n g a lox frequency ger ie ra tor w i th 2, one f rcquency source , Proceedings o f t h e I n s t i - ?;Ute of R a d i o Engineers , ( W t ' w Pork, N.Y.), vole 14, p . 2 1 3 , 1926.

-l (55) Fiioyden, G . T . , rrcquoncy chccking s t a t i o n at Ea rc Island, 2roceedings of the I n s t i t u t e of Eiadio Engineers , (New Pork, N.Y.),

- V o l e 15, p.313, 1927, . .

(56.) B r , a i l l a r d , R. and Divo i rc , E..? Tbe exac t and p r e c i s e ne?,surer:ent of wave lzngth i n r a d i o t r a n s c i t t i n g s t a t i o n s , Experi; l ,ental Wire less and 'firireless Eilgineer (London, England), v o i . .$; +522, p.394, 1927.

(57 ) . K a r t o n , '3-.\~. and I ( a r r i s o n , i i i l . ~ . , P r e c i s i o n f i e t e rn ina t ion 9ct;ecllngs of the I n s t i m t z of Radic Engineers , ? v o l e 26, p o l X , 1928.

. , 'ar% Clapp, J.K. $. A c o m e n l e n t nethod for r e f e r r i n g secondary f r cuuency s t a n d a r d s to a s t a n d a r d t i n e i n t e r v a l , Proceedipgs I n q t i t u t e of FWdio Engineers , ( N e m York, N.Y.), v o l . 3-7, p.252, 1929.

a s i n g l e f requency , Proceedings of t h e I n s t i t u t e of E a d i o (59) Hall, E . L . , A sys te i i for Treyucncy n e a s u r e ~ ~ e n t s based on

_ - Zngineers , (XNZW York, N.Y.), v o l . 17, p.272, 1929.

. f

LC335 -- 7/11/32. 16

. . I (60) Bogardus, E . L . ,. ana Manning, C . T . , The 0g-t i ?e’ a su r e i-ie r,t of t h e o p e r a t i n g f r zquenc ic s of b roadcas t s t a t i o n s , Pro3ecdings I n s t i t u t e of Rad io Eng inee r s , (New York, N.Y.) 1 7 , p ,1225 ,

, 1929 . I , .

(61 ) Bra i l l a rd , R. and D i ’. , ,Ke,asuqel:icnt qf mayo ,le7ngt,hs of b r o a d c z s t i n g s t a t i o n s , Experi ; - \ental IVirelesfi and Wi re l e s s Eng inee r , (London, Eng land) , ~01.6, p.412, 1929.

( 6 2 ) Pess ion , G . and Gor i0 ,T . i Uea.susenent of t h e . f requencies of d i s t a n t r a d i o t r a n m i t t i n g stations, Proceedin5;s I n s t i t u t e of R e d i o Engine’ers, (Bew York, ‘N.Y.) v o l .

(63) Xar r i son , W . A . , A h igh p r e c i s i o n Proceedings I n s t u t e of Eadio V O ~ . 17 , p.1103 N.Y.), v o l . 8 , * - s ,

neasurenent of audiO f r e q u e n k i e s , Troceedinvs I n s t i t u t e of ,RRdio Eng inee r s ;

surccient of f r equency , Proceedings I n s t i t i t e

:

(64) Fiarrie -J.’H. Omen, An e l e c t r o c a g n e t i c nonochord. € o r t h e

(new Yorkj N.Y.), vol. 17, p.1312, 1-929. (65) J iubo , S.

) N.Y.), . v o l e 9 ~9201.1,. 1929. l r

appa ra tus u8 i n t e s t i n g p i ezo b roadcas t ing s t a ons , I-3. 3. Jour . of Researc

30.’ (RP135; -10 .-. ?‘ro.ceedinas .Ins$$;tpke. ~f (>Yew kork , N . Y . ~ 0 1 . is, p.490, 1930..

(67) Mamba, Y . , The c s t a b l i s h a c n t of t h e Japanese radio- . ‘ f requency s t a n d a r d , Proccedings rnstitu.teY of Radio Enginee r s ,

Y..) , Vbl. l t3) p.1017, 1930.

J.R., I n t e r p o l a t i o n riethohs f o r , ‘ f requency s t a n s, Proceedings I n s t i t (New York, N.Y t.01. 18) p. 15725z. 1930

* f

(69)*Case , N.P., A p r e c i s 2 and zg-pid ne thod .of r jeasuring ‘fre- quenc ie s f r o ive t o tmo hundred c y c l e s p e r second, 8. S. J o u r . Research, vo 5 , p.237,’ 1 .(RP19,5,-.5b)i. p roceedings I n s t i t u t e of Rad‘ib El-gineer gew -yorK, Nay,) \role 1

_---- c ,. -_ p.1586,- 1930. . .

I , ” I , (70) J i c b o , S. ? An i n t e r n a t i o n a l conpar i son of f requency by neans of a luriinou ’resonator , ’Proceedings , I n s t . i t h t e of

(71) Koga, I s s a c , C h a r a x t e r i s t i c s of p i e z o - e l e c t r i c q u a r t z

Eia,dio Eng inee r s , ( ,’ N.Y.) 9 vola 18, p.1930,- l Y p 0 ~ I .

- *

o s c i l l a t o r s , Proceedings I n s t i t u t e o f R a d i o Eng inee r s , (New York, N . Y . ) , v o l . 18, p.1935, 1930. -

~ ~ 3 3 5 ’-- 7/ii/j2. 17 D

(727 Groszkonski,J*, Frequency d i v l s i o q , Procec(iings ai’ T;LLe Institute of R a d i o Engindt : r :q , (Yew ‘ Y o r k , N . Y . ) , v o l . lg, p . l S 6 0 , 193 ‘ (73) ‘Glcipp, S .K . , Tecpera ture control for fr2cwclency standards,,

Proceedings I n s t i t u t e o f Radio Ens inee r s , ( N G ~ J Y o r k , N.Y.) Val. 18, p.2003, 1930.

(74)*3~11,E.L. Accurate i.!athod of x e a w r i n g t r a n s i i i t t e d wave f r cquenc iec at. 5000 a n d 20,000 k i l o c y c l e s p e r .second, B.S . Jour .Resdarch, v a l . 5? ~.647,’‘1?jO. (R?22G, 5 k ) . Proceedings I n s t i t u t e of R a d i o E r i g i y e r s 9 (New York, N.Y.), v o l , 19, p.35, 1931 -‘

N.Y.), V O L 19, p.135, igji.

(75) i.i”MFce1, Y. , ~ o : - : e setho5jLs o f ncac;urinp the f requency o f s’nort waves, Proceedings I n s t i t u t e o f R a d i o En‘ineers, (New York,

(76 ) 1~Mge1, Hancs, Nonitorinr-: the operation of shor t -wive t r a n s - n i t t e r s , Proceedinns I n s t i t u t e of R F d i o Engineer? > N.Y.), vol. 19, p.214, 1931.

( N L ~ Y o r k ,

(77) Gm-rnauchel l i , 3’. and Vtcch iacch i ,B . , Di rec t - rcading f r e - quency . - ie ter , Proceddinii-s I x s t i t u t c o f Rac?io Engineers , v o l . 19, Pa6599 1931.

( 7 g ) FolkinG:horn, F.A., a n d Roetken,A,A., R device for t h e prec i r ,c :.ie?surecent o f hiL$ f r c a u e n c i ? c , Procecdings I n s t i t u t e of k d i o E y i n e e r s , (UWJ Y o r k g N.Y.), v o i . 19, p.937, 1931.

charactiristics w i t h t h e pho to -mr l io generator, Procc id ings Ins t i t u -bc of Radio Engineers , v o l . 19, p.1242, 1931. (79) S c h a f f e y ? Y, aiid ~ubazyiis;ci! , C T ~ , Zeacuring frequency

(SO) i,:cNpxirz, F . T . , A thcr::ionic type frequcncgr m t e r f o r use up t o 15 kc, Procecdings I n s t i t c t e of Radio Enginccrs, (Uev; Y o r k , N . L ) , V O ~ . 19, p . 1 3 ~ ~ 14131.

(al) * L q h a n , Z . G . , AIL i .:provcc! a,udio-freau,cl?,cy - e n e r a t o r , B . S. Jour.Research, v o l . 7, p.691, 1931. (RP367, lC$y Pro.ceedings I n s t i t u t e o f 2adio Engineers , (Netr( York, K . Y . ) , v o l . 2 0 , p.272, 1972.

( a2 ) AnCuew, V i c t o r j., The e d j z s t n e n t of n u l t i v i b r a , t o r for frequency di ; i i s ion , Froceedinps I n s t i t i l t e ~f F h d i o Engineers, (Xex York, N . Y . ) , 1-01. 19, p.1’311, 1931.

(g3) Clapp, Ja.nes K . , A p i z z o - c l e c t r i c o s c i l l a t o r of iriprovec! s t E , b i l i t y , Gcnc ra l Re.rLio Ex .pe r i r en te r , (CxYbridge, l.lc?.ss. )-, v o l . 6, p . 1 ’, 19117

LC335 -- 7/11/32. 1s.

e x p e r i n e n t e r , n ( C a z b r i d p , i i ass . )', v o l . 6 , p.5, 1932. (@-I) A f r cquency indicator for t r a n s n i t t e r s , General Rzdie

( 5 5 ) Eieploglc, .L'. fi.ecent developucnts i n p r e c i s i o n f rcquency c s f i t r o l t IiPdio Eng inee r ing , (NEK York City), vol. 12, p.29, 1932,

Revim of ' S c i d n t i f i c I n s t r u n ? n t s , (Ccnasha, Iiiis n.) v o l . 3 , . ( $ 6 ) Hale., Don, An audio o s c . i l i a t o r of t h e dynatror! t y p e ,

p.230, i y p .

(67) PcteFson, H.O. and Braattm,A,M. Tnc p r e c i s i o n f requency n e a z ~ r i n ~ 3 ; s'yetc?::? of R.C . A . Con:ziunic,ations, Inc,. Pro.cwdinqn of . th9 InE-:i",t,e of. Radi .0 *Enginears , (New Y o r k , N . Y . ) , v o l . 20,

7 941, '1532 _. .

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