16. If the carrier of a 100 per cent modulated AM wave is suppressed, the percentage power saving will be—
    

1. 1. 50
      

   
   
   

   2. 150
      

   
   
   

   3. 100
      

   
   
   

   4. 66.66

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given, modulation index, μ = 100% = 1
   

   % Power saving =	Power saved	× 100
   	Total power

   
   

   =	Pc	=	Pc	× 100
   	Pt		Pc( 1+ μ2/2)

   
   

   =	2	× 100 =	2	× 100
   	2 + μ2		2 + 1

   
   

   =	2	× 100
   	3

   
   = 66.67%
   

   Correct Option: D

   Given, modulation index, μ = 100% = 1
   

   % Power saving =	Power saved	× 100
   	Total power

   
   

   =	Pc	=	Pc	× 100
   	Pt		Pc( 1+ μ2/2)

   
   

   =	2	× 100 =	2	× 100
   	2 + μ2		2 + 1

   
   

   =	2	× 100
   	3

   
   = 66.67%
   

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17. An AM receiver uses a diode detector for demodulation. This enables it satisfactorily to receive—
    

1. 1. Single-sideband, suppressed-carrier
      

   
   
   

   2. Single-sideband, reduced carrier
      

   
   
   

   3. ISB
      

   
   
   

   4. Single-sideband, full carrier

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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18. To permit the selection of 1 out of 16 equiprobable events, the number of bits required is—
    

1. 1. 2
      

   
   
   

   2. log₁₀ 16
      

   
   
   

   3. 8
      

   
   
   

   4. 4

   
   
   

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1. View Hint View Answer Discuss in Forum

   No. of bits required = log₂ 16 = log₂ 2⁴ = 4

   Correct Option: D

   No. of bits required = log₂ 16 = log₂ 2⁴ = 4

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19. A signalling system in which each letter of the alphabet is represented by a different symbol is not used because—
    

1. 1. It would be too difficult for an operator to memorize
      

   
   
   

   2. It is redundant
      

   
   
   

   3. Noise would introduce too many errors
      

   
   
   

   4. Too many pulses per letter are required

   
   
   

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1. View Hint View Answer Discuss in Forum

   A signalling system in which each letter of the alphabet is represented by a different symbol is not used because noise would introduce too many errors.

   Correct Option: C

   A signalling system in which each letter of the alphabet is represented by a different symbol is not used because noise would introduce too many errors.

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20. The Hartley law states that—
    

1. 1. The maximum rate of information transmission depends on the channel bandwidth
      

   
   
   

   2. The maximum rate of information transmission depends on the depth of modulation
      

   
   
   

   3. Redundancy is essential
      

   
   
   

   4. Only binary codes may be used

   
   
   

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1. View Hint View Answer Discuss in Forum

   Hartley law states that the maximum rate of information transmission depends on the channel bandwidth.

   Correct Option: A

   Hartley law states that the maximum rate of information transmission depends on the channel bandwidth.

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