ESI VideoBridge 2150, Service Manual

Page: 127 / 332

Gene rator Reve rsa l
( be l ow 2 0 0H z ) i s t h e s i new a v e g e n e ra t o r r e v e r s i ng
p o l a r i ty a f te r t h e f ou r t h s a mp l e t i me w i t h s e t t l i n g t i me a n d l i n e lock
t i me a dd e d b e f o r e the f i rs t a n d f i f t h s a mp l e t i mes . I t i s e n a b l e d by
prog r a mm i n g 25 CODE- - t he V i de o B r i dg e w i l l pe r f orm g e ne r a t o r re v e r sa l
b e l ow 2 0 0 H z a n d sw i t c h t o d e t e c t o r r e v e r s a l a t o r a b o v e 2 0 0 H z .
C a n c e l l a t i on o f op a mp o f f s e t s i s t h e same a s f o r de t e c t o r r e v e rsa l .
FAST Mea surement Mode
i s e n a b l e d by pre s s i ng t h e < b l u e > a nd < FAST >
k e y s . T h i s p u t s t he V i de oB r i dg e i n i t s f a s t e s t p r e s e t me a su re m e n t mode
by p e r f o r m i n g a n a l t o g e t h e r d i f f e r e n t s a mp l e r o u t i n e . T h e n o r ma l
V i d e o B r i d g e r e v e r s a l r o u t i n e c om p a r e s t h e f i r s t f o u r i n t e g r a t i o n
m e a s u r e me n t s o f
o f
t h e u n known a n d s ta n d a r d aga i n s t oppo s i t e p o l a r i ty
FAST mode , t h e
m e a s u r e me n t s
t h e u n k n own a n d s ta n d a r d . I n
V i de o B r i dg e compa r e s t h e f i r s t f o u r mea s u r e m e n t s o f t he u nk n ow n a nd
s t a n d a r d
a g a i n s t a z e r o re f e r e n ce mea s u r e me n t ( t o g r ound ) .
M e a s u r e me n t s a r e s u b t r a c t e d f r o m t h i s r e f e r e n c e i n s t e a d o f f r o m
opp o s i t e po l a r i ty mea suremen ts . T h i s r e q u i re s l e s s t i me ( f i v e samp l e
mea s u r e me n t s a re t a k e n i n s t e a d o f e i g h t
s e e F i g u r e 2 - 1 6 ) , w h i l e
s t i l l p r o v i d i ng a de q u a te o f f s e t c a n ce l la t i on .
N O T E :
F i v e m e a s u r e m e n t s a r e t a k e n o n l y w h e n t h e t e s t
f r e q u e n cy i s a t or be l ow 1 0 kH z . A bove 1 0k H z , e i g h t
mea surements are taken t o i mprove the s igna l - to-n o i se ra t i o .
L i ne l ock Time
( g e n e ra t or re v e r sa l on l y ) i s t h e a v e rage t i me f o r the
l i n e f re q u e n cy to rea c h the z e r o c r o s s i n g p o i n t w i t h a po s i t i v e - g o i n g
s l ope . L i n e l oc k t i me i s a dded t o se t t l i n g t i me f o r t e s t f re q ue n c i e s
be twe e n 2 0 H z a n d 2 0 0 H z . L i ne l o c k t i me c a n vary , depe n d i ng on t he p ha se
re l a t i o n s h i p a t a ny g i v e n t ime o f g e n e ra tor
re v e r s a l t o l i n e
f re q ue n c y . Wo r s t c a s e i s t he p er i od r e q u i re d f o r two c o mp l e t e l i ne
vol t a g e c y c l e s ( on e pe r ha 1 f m e a s u r e me n t s e q u e n c e , or 3 3 m s t o t a l a t
6 0 H z ) . F o r t e s t f re q u e n c i e s a bove 2 00 H z , l i n e l o c k t i me i s z e r o .
NOTE :
L i n e l oc k t i me f o r 5 0 H z l i ne f re q u e n c y i s 2 0 m s p e r h a l f
me a s u reme n t ( 4 0 m s f o r o n e f u l l mea su r e me n t sequ e n ce ) .
2 - 8 9
e
l
s
l
i 2 1 5 0 / 2 1 6 0 9 /8 5