171. FM broadcast band lies in—

1. 1. VHF band

   
   
   

   2. UHF band

   
   
   

   3. SHF band

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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172. An increase in the modulation index leads increase in bandwidth in case of—

1. 1. AM

   
   
   

   2. FM

   
   
   

   3. PM

   
   
   

   4. None

   
   
   

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1. View Hint View Answer Discuss in Forum

   Refer synopsis

   Correct Option: B

   Refer synopsis

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173. Which of the following process is a linear modulation process?

1. 1. NBFM

   
   
   

   2. WBFM

   
   
   

   3. NBPM

   
   
   

   4. None

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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174. Assuming other parameters unchanged if the modulating frequency is halved in a modulating systems, the modulation index is doubled. The modulation system is—

1. 1. A M
      
      

   
   
   

   2. FM
      

   
   
   

   3. Phase modulation
      

   
   
   

   4. Angle modulation

   
   
   

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1. View Hint View Answer Discuss in Forum

   Since modulation index is given by
   

   β =	KfAm
   	ωm

   
   given,
   

   ω'm =	ωm
   	2

   
   Now,
   

   β' =	KfAm	= 2β
   	ωm/2

   
   Hence alternative (B) is the correct choice.
   Since here,
   

   β ∝	1
   	ωm

   Correct Option: B

   Since modulation index is given by
   

   β =	KfAm
   	ωm

   
   given,
   

   ω'm =	ωm
   	2

   
   Now,
   

   β' =	KfAm	= 2β
   	ωm/2

   
   Hence alternative (B) is the correct choice.
   Since here,
   

   β ∝	1
   	ωm

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175. In a single-tone FM discriminator (S₀/N₀) is—
     

1. 1. proportional to deviation
      

   
   
   

   2. proportional to cube of deviation
      

   
   
   

   3. inversely proportional to deviation
      

   
   
   

   4. proportional to square of deviation

   
   
   

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1. View Hint View Answer Discuss in Forum

   SNR in single tone FM is given by
   

   	δ0		=	3	β2
   	N0			2

   
   

   	δ0		=	3		Δf		2
   	N0			2		fm

   
   or
   

   	δ0			∝ Δf2
   	N0

   
   i.e. square of frequency deviation

   Correct Option: D

   SNR in single tone FM is given by
   

   	δ0		=	3	β2
   	N0			2

   
   

   	δ0		=	3		Δf		2
   	N0			2		fm

   
   or
   

   	δ0			∝ Δf2
   	N0

   
   i.e. square of frequency deviation

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