1 . W h i ch o f th e f o l l ow i n g d e m o d u l a ti o n m e th o d s e x h i b i t t h re s h ol d e ff e c t ( a) B a l a n c e d d e m o d u l a t or ( b ) E nve l op e d e t e c t i o n o f A M ( c ) S q u ar e l aw d e t e c t or ( d ) S y n ch ro n o u s d e m o d u l a t i on o f A M
2 . T h e S i gn a l t o N o i s e r a t i o of V S B - S C s ch e m e i s ( a) 3 ( b ) 2 ( c ) z e r o ( d ) 1
3 . I n P M , t h e p owe r s p e c t r a l d e n s i ty o f t h e O/ P n o i s e , va r i e s w i th f r e q u e n c y a s ( a) U n i f o r m ( b ) H y p e r b o l a ( c ) Pa ra b o l a ( d ) c i r c l e
4 . I n F M , t h e p owe r s p e c t r al d e n s i ty o f t h e O / P n o i s e , va ri e s w i t h f re qu e n c y a s ( a) H y p e r b o l a ( b ) c i r c l e ( c ) Pa ra b o l a ( d ) U n i f o r m
5 . A B u ff e r a m p l i fi e r i s p l ac e d i n b e twe e n ( a) T wo A F A m p l i fi e rs ( b ) M o d u l a te d an d m o d u l at i n g am p l i fi e r ( c ) T wo R F a m p l i fi e r s ( d ) C r y s t al os c i l l at o r an d h ar m o n i c g e n e r a to r
6 . T h e on l y d i s ad vant ag e of c r ys t al o s c i l l a t or as M a s t e r o s c i l l a to r i s ( a) u n s t a b l e f r e q u e n c y ( b ) l a rg e s i z e ( c ) m o u nt i n g c a p ac i ta n c e ( d ) fi x e d f re q u e n c y
7 . A C ol l e c t o r m o d u l at e d t ra n s m i t t e r h a s s u p p l y vo l t ag e o f 1 2 Vo l t s a n d c ol l e c to r c u r r e nt o f 1 A . T h e m o d u l a te d p owe r f o r 10 0 % m o d u l at i o n i s ( a) 6 W ( b ) 1 2 W ( c ) 2 4W ( d ) 1 8W
8 . . A c l a s s C a m p l i fi e r h a s s u p p l y vo l ta ge o f 1 2 V an d c ol l e c t or c u r r e nt o f 1 A . I t s e ffi c i e n c y i s 80 % . T h e RF ou t p u t p owe r i s ( a) 9 . 6W ( b ) 1 5W ( c ) 2 4W ( d ) 1 2W
9 . A n A M t r an s m i t t e r s h al l p ro d u c e 1K W o f c a r r i e r p owe r w i t h 2 00 V s u p p ly. T h e l oa d s e e n by t h e a m p l i fi e r i s ( a) 2 0? ( b ) 4 0? ( c ) 5 ? ( d ) 1 0?
1 0. A n R F a m p l i fi e r i s avai l a b l e a t 4 0 M H z . To w h i ch o f th e f o l l ow i n g i t c an b e e m p l oye d ( a) A M B r oa d c a s t ( b ) F M b ro a d c as t ( c ) R ad a r ( d ) U H F T V b r oa d c a s t
1 1. G o o d A d j a c e nt ch a n n e l s e l e c t i v i ty c an b e o b t ai n e d by t h e u s e o f ( a) L ow I ( b ) H i g h I F ( c ) T R F a m p l i fi e r s ( d ) R F a m p l i fi e r s
1 2. I n a s u p e r h e t e r o d yn e r e c e i ve r a m p l i fi c a ti o n o f th e s i g n al af t e r c onve r te r i s d o n e at ( a) A ny f r e q u e n c y ( b ) h i g h e r t h an s i gn a l f re qu e n c y ( c ) O n l y I F ( d ) s i g n al f r e q u e n c y
1 3. T h e l o c al Os c i l l at o r of a s u p e rh e t e r o d y n e r e c e i ve r w i l l b e t u n e d t o a f r e q u e n c y ( a) l owe r t h an s i gn a l f r e q u e n c y ( b ) s i g n al f r e q u e n c y - I F ( c ) S i g n al f r e qu e n c y + I F ( d ) O f t h e s i gn a l
1 4. A d o u b l e c onve r s i on c o m mu n i c at i on r e c e i ve r i n d i c a t e t h a t i t h as ( a) I F ’ s ( b ) I F & RF ( c ) d o u b l e b a n d s ( d ) I F
1 5. T h e l o c al os c i l l at o r of a b r oa d c a s t r e c e i ve r i s t u n e d t o s f r e q u e n c y h i g h e r t h an t h e i n c o m i n g f r e q u e n c y ( a) t o p e r m i t e a s i e r t r a cki n g ( b ) t o al l ow t h e i m ag e f re qu e n c y r e j e c t i o n ( c ) o th e rw i s e i nt e r m e d i a te f r e q u e n c y c an n o t b e p ro d u c e d ( d ) t o al l ow a d e q u at e f r e q u e n c y c ove ra g e w i t h o u t s w i t ch i n g
1 6. N o i s e l i m i t e r i s a n al o go u s to ( a) R e c t i fi e r ( b ) C l i p p e r ( c ) C l a m p e r ( d ) AG C
1 7. I n a ra d i o r e c e i ve r w i t h s i m p l e AG C ( a) a n i n c r e a s e i n s i g n al s t re n gt h p r o d u c e s m or e AG C ( b ) t h e h i g h e s t AG C i s p r o d u c e d b e twe e n s t at i o n s ( c ) t h e f as t e r th e AG C ti m e c o n s t ant , t h e m or e a c c u r a t e t h e ou t p u t ( d ) t h e a u d i o s t ag e ga i n i s n or m a l l y c o nt r o l l e d by t h e AG C
1 8. f s >> 2 f m r e s u l t s i n ( a) A l i a s i n g ( b ) I n e ffi c i e nt C h an n e l u t i l i z a ti o n ( c ) At te nu a t i on ( d ) D i s t or t i o n
1 9. P W M c a n b e d e m o d u l at e d u s i n g ( a) I nt e g ra t or an d H P F ( b ) D i ff e r e nt i at o r an d L P F ( c ) I nt e g ra t or an d L P F ( d ) D i ff e r e nt i at o r an d H P F
2 0. W h i ch o f t h e f o l l ow i n g i s u s e d t o c o nve rt P P M i nt o P W M ( a) C l i p p i n g C i r c u i t ( b ) A s t a b l e M u l t i v i b r at o r ( c ) B i s ta b l e M u l t i vi b r a to r ( d ) C l a m p i n g C i r c u i t
BDACD DBBAC ACCAA BABCC
No comments:
Post a Comment