1953 a Decimal Code for Analog-To- Digital Conversion
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1 5 8 I R E TRANSACTIONS-ELECTRONIC COMPUTERS December T h e foregoing exampleshows that t h e Williams mem- BIBLIOGRAPHY ory, when operated i n th e manner described, i s more [ 1 ] Williams, F . C . , a n d Kilburn, T. , A Storage System f o r U s e with Binary Digital Computing Machines. Proceedings o f t h e IEE, flexible than a magnetic drum. It i s also possible to Vol. 96 , Part I I I (1949), p . 81 . eliminate some o f t h e access timenormally unavoidable [ 2 ] Eckert, Jr., J . P . , Lukoff, H . , a n d Smoliar, G . , A Dynamically Regenerated Electrostatic System. PROCEEDINGS OF T H E IRE, o n t h e drum, unless serious coding requirements a r e Vol. 3 8 (1950), p p . 498-510. [ 3 ] H . Pomerene, J . a n d Smith, C . V . L ., Progress imposed. Report, Electronic Computer Project. Corresp ondence This section i s devoted t o brief reports o n n e w ideas in t h e computer field, comments o f timely interest t o PGEC members, o r comments o n recent papers i n t h e TRANSACTIONS O N ELECTRONIC COMPUTERS. Communications should ordinarily b e limited to 1,000 words i n length. T h e delay between submission o f t h e communication a n d i t s publication will be held t o a minimum. Authors ar e invited t o send t w o copies o f appropriate material t o t h e Editor. A Decimal Code f o r Analog-to- lying o n three different suitably displaced number. Fortunately, boundary effects, a s Digital Conversion brushes t o generate A, B , a n d C . well as t h e effects o f inexact machining o f Variants o f t h e code P (for example, t h e commutators a n d brushes, canbe minimized Consider t h e following binary-coded rep- right-hand code P ) which a r e derived by with a logical detenting scheme which e n - resentations f o r the ten decimal digits: interchanging t h e vertical columns, and/or ables th e D brush alone t o decide between uncertain readings i n t h e vicinity o f quan- t um boundaries. P = A B C P = A B C D P = A B C D Logical detenting f o r t h e described b i - 0 = 0 0 0 0 0 = 0 0 0 = 0 1 1 nary-decimal codes c a n b e accomplished b y 1 = 0 0 0 1 1 = 0 0 1 1 = 0 1 1 1 making t h e conductive segment provided t o 2 0 1 0 2 = 0 0 1 0 2 = 0 1 0 0 generate A , B , a n d C somewhat smaller than 3 = 1 1 3 = 0 1 1 3 = 1 0 1 five times the size o f t h e associated D seg- 4 = 1 1 0 4 = 1 1 0 4 = 0 0 0 ments a s shown i n Fig. 1 . Two brushes a r e 5 =1 1 1 1 5= 1 0 0 0 5 = 1 0 0 1 6 =1 1 1 0 6= 1 0 0 1 6 = 1 0 0 0 7 = 1 1 7 = 1 1 7 = 1 1 BLCL D 8 = 1 8 = 1 0 1 1 8 = 1 0 1 9= 1 1 9= 1 1 1 0 9= 1 1 1 1 2 T h e representation scheme P =AB C D interchanging O s a n d l s i n o ne o r more col- 6 (shown i n t h e center above) i s a constant umns, and/or b y cyclic reassignment of th e 7 weight type o f binary-coded decimal num- Arabic numerals corresponding to code com- 8 bering system wherein P can be evaluated binations without changing their relative se - r b y means o f th e formula quences, c a n likewise b e generated with only I t wo rows o f commutator segments. Variants 2 P = .5.4 2B ± 2 C D which omit t h e 0000 a n d 1111 combinations when O s a n d l s a r e substituted f o r t h e let- a r e sometimes desirable. 5 t e r symbols. A problem which always crops up i n t h e 6 T h e left-hand code, P =AB CD , i s identi- design o f reading-type coders i s that o f pos- 7 c a l with P i n t h e A digit. Fo r t h e remainin sible transition errors at values o f t h e analog a X binary digits, however, B =-B, C -C, a nd fo r which changes occur i n t h e numerical 9 D =D when A = 0 , b u t B =B, C , a n d representation i.e., a t quantum bounda- ~ ~ C~~~ ries).21 Some transition errors with t h e codes D = D when A = 1. (X = X means that when of th e type P are smaller than with many Fig. 1.-Brush a n d commutator arrangement. X i s 0 , X i s 1 , a n d when X i s 1 , X i s 0. ) other codes because t h e maximum number T h e latter code i s o f special interest b e - o f b i t changes which occur when decimal cause t h e A , B , a n d C columns each contain digit changes i s two; o n t h e other hand, t h e then provided f o r each o f t h e digits A , B , a n d five l s in sequence. I t i s easily seen that, i n necessity f o r t h e A, B , a n d C brushes t o b e C . O n e se t o f brushes, A . etc., i s t o o small in a digitizer of t h e reading type (which e n - positioned accurately, a n d i n a special man- size t o compensate f o r t h e fact that t h e c o - codes a n analog quantity by means o f ner, introduces a possibility o f a n e w type O f operating commutator segment i s under- commutator segments a n d brushes or the transition error, especially hard to control i n s e . AL , BL~, a n d C L , however, a r e large functional equivalents), this 4-bit code c a n t h e case o f t h e fine digits of a many-place enough t o over-compensate f or this reduc- be generated with only t wo rows o r zones o f tion. Note now, that, a s w e scan t h e sequence commutator segments p e r decimal digit, r e - 2 us R.de. Seasu, beaym deflectioJn tube f o r o f y miatiompnsind d b e P , chanhges i n A a r e 2 7 , p p . 49-57; January, 1948. b ut changes i n B a n d C a r e always accom- 1 G . S ; White, Co,depd deciImal nuymberin sysem n 0 Lippel. A high-precision analog-to-digital panied by converse changes i n D . We there- 1452; October, 1953. ruary, 1952. * * foecmietesvnlcrcaoups
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Transcript of 1953 a Decimal Code for Analog-To- Digital Conversion
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1 9 5 5 C o n t r i b u t o r s 1 5 9
s h o w ni nF i g .t i nc i r c u i t sw h i c hp e r f o r mt h e d e c i m a l n u m b e r , r e g a r d l e s so f t h e d i g i t s b r u s h i so f f s e ti n t h ed i r e c t i o no fd e c r e a s i n gf o l l o w i n gl o g i c a lo p e r a t i o n st o g e tu n a m b i g - s t a n d i n gi no t h e r d e c i m a lp l a c e s .W i t ht h e s e n u m b e r sa n d i s u t i l i z e dw h e nt h e p r e v i o u su o u s 4 - b i tr e p r e s e n t a t i o n so f t h e d e c i m a l c o d e s ,t h e r e f o r e ,a s i m p l es w i t c h i n gm a t r i x d e c a d e sA d i g i ti sa 1 ;t h e o t h e r b r u s h i so f f -d i g i t s : a l o n ec a n s er ia l l y t r a n s l a t ee a c h b i n a r y s e t e q u a l l y i n t he d i r e c t i o no f i n c r e a s i n g
A=A ALD i . e . A is t h e log icag roup i n t od e c i m a lt e r m s , o rt h eb i n a r yc o d e n u m b e r sa n d i s b r o u g h ti n t op l a y w h e nt h eA = A . + A L D ;i . e . , A i St h el o g i c a lc o m b i n a -g r o u p sc a n o p e r a t e t y p e w r i t e r sd i r e c t l yt o p r e v i o u sA i s 0 .
t i o no fA . o r ( A La nd D ) p r i n tA r a b i cn u m e r a l sw i t h o u tt he u s eo fa L o g i c a ld e t e n t i n g o f b i t sa n d d e c a d e sB = B 8 , + B L D t r a n s l a t o r .C y c l i cc o d e s a l w a y s r e q u i r e g r e a t l yr e d uc e s t he a m o u n to f a c c u r a t e
C = B C . ± B C L D )t r a n s l a t o r so p e r a t i v eo n a l l d i g i t sc o l l e c - w o r k m a n s h i pr e q u i r e d i n r e a d i n g - t y p ed i g i -
C =C 8 J + C L D t i v e l y . t i z e r sb e ca u s e o n l yt h ec o m m u t a t o rs e g m e n t sD=D R e f e r r i n gt oc o d eP o rc o d eP a se x t e n d - i n t h eu n i t sd e c a d em u s tb e a c c u r a t e ± 1 / 2
I f we u e t e c d v a i n P ( b e dt o t w oo rm o r ed e c a d e s ,w en o t e t h a t t h e q u a n t u m .S u c c e e d i n gd e c a d e sm ay b e c o n -P b y i n t e r c h a n g i n g sa n dI si nb o t hB a n d r e l a t i o n s h i pb e t w e e nt h eA d i g i to fo n e d e c - s t r u c t e dw i t h t o l e r a n c e sp r o p o r t i o n a lt o t h eC c o l u m n s )t h el o g i cr e q u i r e df o rd e t e n t i n ga d e t o t h e d i g i to ft h e n e x t h i g h e rd e c a d e w e i g h t i n gf a c t o r sf o rt h e g e ne ra t e d d e c i m a l sc o l u n s m p l e ri c o i ss i m i l a rt ot h a tb e t w e e ns u c c e s s i v ed i g i t si n p l a c e s .
i s e ve n s im pl er , v i z: t h en a t u r a lb i n a r yn u m b e r i n gs e q u e n c e ,v i z : T h e a b o v ep r i n c i p l e sc a n a l s ob e p u t t oA = A, ALD Al i sa l t e r n a t e l y0 a n d 1 ( o v e r5 - q u a n t u mi n - u s e f o rd e c i m a l r e v o l u t i o n sc o u n t e r s ,c o n -
t e r v a l s ) ,a n dD 1 oi s l i k e w i s ea l t e r n a t e l y0 a n d s t r u c t e dw i t hi d e n t i c a ls t a g e s ,a n dg e a r e dup( o v e r1 0 - q u a n t u mi n t e r v a l s ) ;w h e n e v e rA l w i t h g e a r i n go f i n d i f fe r en ta c c u r a c y. 5 6T h eC = C . CL D g o e sf r o m1 t o0 a st h en u m b e ri n c r e a s e s ,D i o e a s ew i t hw h i c ht he g e n e r a t e dc o d e sa r ec o n -D = D c h a n g e ss i m u l t a n e o u s l y ;w h e nA l c h a n g e si n v e r t e d t o c o n s t a n t - w e i g h tc o d e s s i m p l i f i e s
t h er e v e r s ed i r e c t i o n a st h en u m b e ri n c r e a s e sd e c o d i n gt or e a l i z ea n a n a l o gp r o p o r t i o n a lt oC o d eP a l s oh a s s o m ea d v a n t a g ei n m o r e t h e r ei s n e v e r a c ha ng ei n D 1 o .L o g i c a ld e - t h e c o u n t ; t h i sm a k e st h e s y s t e mp a r t i c u -u n i f o r ms p a c i n go fA , B ,a n d C b r u s h e s .I n a t e n t i n go v e r a n u m b e ro f e n c o d e dd e c i m a l l a r l ya t t r a c t i v ef o rs e l f - b a l a n c i n gp o t e n t i o m -c o d e r w h i c h u s e s t r u e c o n t a c t s w i t c h i n g ,p l a c e si s t h e r e f o r ea c c o m p l i s h e db y c o m b i n - e t e r sw i t hd i g i t a lo u t p u ts o m eo ft h el o g i cc a n b e p e r f o r m e db y m e a n s
i n gt h ea b o v ed e t e n t i n g
p r i n c i p l e sw i t h t h e
B E R N A R DL I P P E Lo f d u p l i c a t eA , B a n d C c o m m u t a t o rs e g - V- s c a nt e c h n i q u eu s e d f o rt r u eb i n a r y c o d - S i g .C o r p s .E ng rg . L a b.m e n t s , s e r v i n g l a r g ea n d s m a l lb r u s h e s i n g . 4 F t .M o n m o u t h ,N . J .i n d i v i d u a l l y ,a n d s e r i e s - c o n n e c t e dc o n t a c t s . Two b r u s h e sa r ee m p l o y e dt og e n e r a t e
T h e c o d e sc i t ed a r ep r e f e r r e do v e r c y c l i c i nt he t e n sp l a c ea n d h i g h e rp l a c e s .O n ec o d es e q u e n c e s( i nw h i c he x a c t l yo n e b i n a r y SA . D . S c a r b r o u g h , A n a n a l o g - t o - d i g i t a lc o n -
v e r t e r ,T R A N S .I R E , v o l .E C - 2 ,p p . 5 - 7 ; S e p t e m b e r ,d i g i tc h a n g e s a t e a c h t r a n s i t i o n )b e c a u s e 4 R .H .B a r k e r , M e a s u r e m en to fa n gl e u s i n gt h e 1 9 5 3 .e a c h g r o u p o f f o u r b i n a r y d i g i t ss t a n d s f o r b i n a r y d i g i t a ls c a l e( S e eA .T u s t i n , A u t o m a t i ca n d 6 W . H . L i b a wa n d L . J . C r a i g , A P h o t o e l e c t r i cM a n u a lC o n t r o l ,A c a d e m i cP r e s s ,I n c . ,Ne w Yo r k , d e c i m a l - c o d e ds h a f t d i g i t i z e r ,T R A NS . I RE ,v o l .one p a r t i c u l a rd e c i m a ld i g i ti n a m a n y - p l a c e p p .5 6 1 - 5 6 6 ;1 9 5 2 . ) E C - 2 ,p p .1 - 4 ;S e p t e m b e r,1 9 5 3 .
H erman B l a s b a l g( A 4 8 )r e c e i ve d t h et e r e s ti s i n t h eu s e o fh i g h - s p e e dc o m p u t i n g F r o m1 9 5 3t o 1 9 5 4 ,h e w o r k e da sa p r o j -
B . E . E .d e g r e ef r o mt h eC o l l e g eo ft h eC i t y m a c h i n e si nd y n a m i c a lm e t e o r o l o g y . e c te n g i n e e ri n t h eC o s m i cR a y s G ro u po fo fNe w Yo r ki n 1 9 4 8a n d t h e M . S . E . E .d e - H e i s a m e m b e ro f t h e A m e r i c a nM e t e - t h eU n i v e r s i t yo fC a l i f o r n i aB e r k e l e yp h y s -g r e ef r o m t h eU n i v e r s i t yo f M a r y l a n di n o r o l o g i c a lS o c i e t ya n d o ft h eA s s o c i a t i o nf o r i c sd e p a r t m e n t .I n 1 9 5 4h e j o i n e dt h e r e -1 9 5 2a n d i s c o m p l e t i n gt h er e q u i r e m e n t sf o r C o m p u t i n gM a c h i n e r y. s e a r c ha n d d e v e l o p m e n tf a c i l i t i e so f t h et h e D o c t o ro f E n g i n e e r i n gd e g r e ea t J o h n s N o rt h A me ri c a nAv i a t i o nC o . ,w h e r eh e a s -H o p k i n sU n i v e r s i t y . s i s t e di n t h ef l i g h tt e s t i n go fa d i g i t a lc o m -
Fro m 1 9 4 8t o 1951 h e w a se m p l o y e db y E d m u n dG l a s e r ( S 4 9 - A 5 0 - M 5 5 )r e - p u t e r . I n 1 9 5 5 h e j o i n e dt h et e c h n i c a ls t a f ft h e M e l p a rC o . ,A l e x a n d r i a ,Va . ,w h e r eh e c e i v e dt h eB o E n E gd e g r e ef r o m t h e C o o p e r o f t h e R a m o - Wo o l d r i d g eC o r p . ,i n L o s A n -w o r k e di n t h e f i e l d so fm u l t i p l e xp u l s ec o m - U n i o nS c h o o lo fE n g i n e e r i n gi n 1 9 4 9a n d t h e g e l e s .m u n i c a t i o na n d a p p l i e di n f o r m a t i o nt h e o r y . M . S v E . E .d e g r e ef r o mJ o h n s H o p k i n sU n i - M r . M a c I n t y r ei sa m e m b e ro fE t a K a p -S i n c e1 9 5 1 h e h a sb e e n w it h t heR a d i a t i o n v e r s i t yi n1 9 5 4 .H e w a s e l e c t r o m e c h a n i c a l p a N u .L a b o r a t o r yo fJ o h n sH o p k i n sU n i v e r s i t y .A s e n g i n e e rw i t h t h e G l e n n L . M a r t i n Co .
h e a do f t h e S i g n a lA n a l y s i sG r o u p ,h e h a s w h e r eh e d i dd e s i g nw o r ko n g u i d e dm i s s i l e- w o r k e do n p r o b l e m si n s i g n a ld e t e c t i o n ,s i g - c o n t r o ls y s t e m s .H e h a s b e e n w i t h t h e R a -n a l w a n a l y s i s ,a n a l y z e rs y s t e m s ,a n d i n f o r m a -d i a t i o nL a b o r a t o r yo f t h e J o h n s H o p k i n sn t h e o r y . Mr . B l a s b a l g i s p r e s e n t l y a s t a f f U n i v e r s i t y s i n c e1 9 5 2 w h e r e he h as been R . S . Mackay w a s b or n o n J anua ry 3 ,t i o n s t t h e o r y .M r . B l a s b a l gi s p r e s e n t l ya s t a f f w o rk i n g o nd e s i g no f e l e c t r o n i cs y s t e m sf o r 1 9 2 4 .H e r e c e i v e dt h e A . B . d e g r e e a n d , i nc o n s u l t a n t . s ig na l a n a l ys i sa n d s y s t e m ss t u d i e si n t h e 1 9 4 4 ,t he P h . D . d e g r e e ,f r o mt h eU n i v e r s i t yHe i sa m e m b e ro fS i g m aX i a n d t h eI n - f i e l do fe l e c t r o n i cc o u n t e r m e a s u r e s .H i sp r e s - o fC a l i f o r n i a .I n 1 9 4 6 ,w h i l eh ew a sa t e a c h -
H e i s a m e m b e ro f T a u B e t a P ia n d a n c h a rg eo ft h e U n i ve rs i t yo fC a l i f o r n i a se l e c -a s s o c i a t em e m b e ro fS i g m aX i . t r o n m i cr os co p e. H i ss p e c i a l i t i e sa r en o n l i n -
B r u c eG i l c h r i s t( A 5 5 )w a sb o r n i n P o n - e a re l e c t r o n i cc i r c u i t s ,b i o p h y s i c s ,p u l s et e c h -- t e f r a c t ,E n g l a n do n A u g u s t4 , 1 9 3 0 .H e r e - n i q u e s a n d m e d i c a le l e c t r o n i c s .c e i v e d t h eB . S c .d e g r e ei n m a t he ma t i c s f r o m R . M. M a c I n t y r e( S 5 0 - A 5 1 )w a s b o r n H e i s n o wa t t h eU n i v e r s i t yo fC a l i f o r n i at h e U ni v er si t yo f L o n d o ni n 1 9 5 0 a n d t h e i nJ e r s e yC i t y ,N . J . o n Ma y 2 3 ,1 9 2 7 .H e r e - a s d i r e c t o ro ft h eR e s e a r c ha n d D e v e l o p m e n tP h . D . d e g r e ei n m e t e o r o l o g yf r o mt h es a m e c e i v e dt h eB . S .d e g r e ei n e l e c t r i c a le n g i n e e r -L a b o r a t o r y,a s s o c i a t er e s e a r c hb i o p h y s i c i s t ,u n i v e r s i t yi n 1 9 5 2 .S i n c e1 9 5 2 D r .G i l c h r i s t i n gi n 1 9 5 0f r o mU . C . L . A .a n d t h eM . S .d e - a n d l e c t u r e ri n b i o p h y s i c sa t t h e M e d i c a lh a s b e e n a s t a f fm e t e o r o l o g i s ta t t h eI n s t i - g r e ei n 1 9 5 4 f r o m t he U n i v e r s i t y o f C a l i - C e n t e rc a m p u si n S a nF r a n c i s c o ,a n d a s s i s t -- t u t ef o rA d v a n c e dS t u d y . H i s p r i n c i p a li n - f o r n i a . a n t p r o f e s s o ro f e l e ct r ic a le n g i n e e r i n g .
