1 . T h e S i gn a l t o N o i s e o f F m a t m o d u l a t i on i n d e x = 5 i s f a c t or of S /N of A M ( a) 8 1 ( b ) 7 5 ( c ) 5 7 ( d ) 7 0
2 . N o i s e p e r f or m a n c e o f A M - D S B - S C s i gn a l i s s a m e a s t h a t of A M - S S B - S C s y s t e m d u e t o ( a) M o r e b a n d w i d t h ( b ) M o r e i / p s i g n al p owe r ( c ) L e s s i /p s i g n al p owe r ( d ) L e s s N oi s e p owe r
3 . Fo r a m o d u l at i o n i n d e x β > 0 . 5 th e n oi s e p e rf or m a n c e o f F M w h e n c o m p ar e d t o A M i s ( a) C a n ’ t b e c om p a r e d ( b ) S a m e ( c ) wo rs t ( d ) B e tt e r
4 . P r e - e m p h as i s i n F M i s u s e d a t ( a) B e f or e D e m o d u l a t i on ( b ) R e c e i v i n g e n d ( c ) Tra n s m i t t i n g e n d ( d ) I n th e C h a n n e l
5 . L on g wave s t r an s m i t t e r wo r k s i n th e f r e q u e n c y r a n ge ( a) 1 M H z ( b ) 2 0 M H Z ( c ) 6 0 M H z ( d ) 3 00 K H z
6 . M i c r owave t r an s m i t t e r s h ave t h e i r wo r ki n g f re qu e nc i e s a t a r e a b o u t ( a) 8 0 M H z ( b ) 1 00 0M H z ( c ) 1 00 M H z ( d ) 1 0M H z
7 . A d e vi c e t h a t re d u c e s th e g ai n of A . F . a m p l i fi e r w h e n t h e i n p u t e x c e e d s p re d e t e r m i n e d va l u e i s c a l l e d ( a) Pe a k c l i p p e r ( b ) e ch o s u p p r e s s or ( c ) D e t e c t o r ( d ) D i s c r i m i n a to r
8 . I n A M m o d u l a to r c i r c u i t s , th e c a r ri e r an d th e m o d u l at i n g s i g n al ar e ( a) S u b t r ac t e d ( b ) A d d e d ( c ) M u l t i p l i e d ( d ) M i x e d
9 . T h e r an g e o f F . M . t r an s m i t t e r wo r ki n g i n t h e U H F ra n g e i s ( a) l a rg e ( b ) ve r y l ar g e ( c ) S m a l l ( d ) l i n e of s i g ht d i s ta n c e
1 0. T h e m ax i mu m d e v i a t i on us e d i n p ol i c e F M r ad i o i s ( a) 2 0K H z ( b ) 1 5K H z ( c ) 3 K H z ( d ) 5 K H z
1 1. T h e ab i l i ty o f a r e c e i ve r to d i s t i n g u i s h t h e want e d a n d u nwa nt e d s i g n al s i s ( a) s e l e c t i vi ty ( b ) S e n s i t i v i ty ( c ) S / N r at i o ( d ) e ffi c i e n c y
1 2. T h e ou t p u t f r o m r a d i o re c e i ve r va r i e s a b r u p tl y m any t i m e s w i t h o u t n ot i c e . T h i s i s c a l l e d ( a) M o t or b oa t i ng ( b ) n o i s e ( c ) H u m ( d ) f a d i n g
1 3. I n a s u p e r h e t e r o d yn e r e c e i ve r f re q u e n c y c o nve r s i o n t ake s p l ac e a t ( a) d o e s n o t ( b ) 2 p l a c e s ( c ) 4 p l a c e s ( d ) 3 p l a c e s
1 4. T h e f o l l ow i n g i s n ot o n e of th e c o m m on s t ag e f or A M & F M re c e i ve r s ( a) m i x e ( b ) I F am p l i fi e r ( c ) r at i o d e t e c t o r ( d ) l i m i t e r
1 5. I n a s u p e r h e te ro d y n e r e c e i ve r ( a) L o c al os c i l l at o r f r e q u e n c y i s g re at e r t h a n i n c o m i n g s i gn a l f re qu e n c y ( b ) T h e ou t p u t c i r c u i t of m i xe r i s t u n e d t o s i gn a l f r e q u e n c y ( c ) R F wo rk s at 45 5 K H z ( d ) L o c al Os c i l l at o r f r e q u e n c y i s d o ub l e I F
1 6. W h i ch o f th e s t a te m e nt s ab ou t t h e am p l i t u d e l i m i te r i s u nt r u e ( a) T h e c i r c u i t i s al ways b i a s e d i n c l as s C , by v i rt u e of t h e l e a k ty p e b i a s ( b ) T h e ou t p u t mu s t b e t u n e d ( c ) L e a k ty p e b i as mu s t b e u s e d ( d ) W h e n i n p u t i n c r e as e s f as t th e t h r e s h o l d of l i m i t i n g, t h e g ai n d e c r e a s e s to ke e p th e o u tp u t c on s ta nt
1 7. Fr o m t h e p oi nt o f v i e w , t h e m a i n d i ff e re n c e b e twe e n t u b e a n d t r a n s i s t or re c e i ve rs i s th a t t h e l at t e r ( a) mu s t h ave I F s ta g e s e ve n m or e s t ab i l i z e d t h an th e y ar e n or m a l l y ( b ) r e q u i r e AG C p owe r r at h e r t h a n t h e vol t a ge ( c ) d o n o t r e al l y n e e d AG C b e c a u s e ove r l oa d i n g c a u s e s l i m i ti n g ( d ) h ave tr o u b l e s b e c a u s e AG C i s n ot ve r y e ff e c t i ve i n t h e m
1 8. A ty p i c a l s q u e l ch c i rc u i t ( a) c u t s off t h e I F am p l i fi e r w h e n t h e AG C i s m a xi mu m ( b ) c u t s off t h e a u d i o am p l i fi e r w h e n t h e c ar r i e r i s b l o ck ( c ) c u t s off t h e I F am p l i fi e r w h e n t h e AG C i s m i n i mu m ( d ) e l i m i n a t e s t h e RF i nt e r f e re n c e w h e n t h e s i gn a l i s we ak
1 9. AG C fi l te r u s e s n or m a l l y t h e val u e s o f R = 5 00 K a nd C e qu a l t o ( a) 2 µ F ( b ) 1 0 µ F ( c ) 1 µ F ( d ) 2 0 µ F
2 0. F M c ap t u r e e ff e c t i s d u e to t h e f ol l ow i n g c i r c u i t ( a) D e e m p h a s i s ( b ) AG C ( c ) L i m i t e r ( d ) D i s c r i m i n a to r
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