The optimum threshold to achieve minimum bit error rate (BER) is

1.   ½

2.   4/5

3.  1

4.  3/2

View Answer  
4
Correct Answer :

4/5


Explanation :
No Explanation available for this question

Suppose that the modulating signal is m(t)=2 cos(2πfmt) and the carrier signal is xc(t)=Ac cos (2πfc t). Which one of the following is a conventional AM signal without over-modulation

1.   x(t)-Ac m(t)cos(2πfct)

2.  x(t)=Ac[1+m9t)] cos(2πfct)

3.  x(t)=Accos(2πfct)+(Ac/4) m(t)cos(2πfct)

4.  x(t)= Accos(2πfct) cos(2πfct)+ Acsin(2πfct) sin(2πfct)

View Answer  
4
Correct Answer :

x(t)=Accos(2πfct)+(Ac/4) m(t)cos(2πfct)


Explanation :
No Explanation available for this question

Consider an angle modulated signal x(t)=6cos[2π X 106t + 2 sin(8000πt)+4 cos (8000πt)]v The average power of x(t) is  

1.   10 W        

2.  18 W

3.  20 W

4.  28 W

View Answer  
4
Correct Answer :

18 W


Explanation :
No Explanation available for this question

A message signal m(t)=cos 2000πt+4cos4000πt modulates the carrier c(t)=cos 2πfct where fc= 1 MHz to produce an AM signal For demodulating the generated AM signal using an generated AM signal using an envelope detector, the time constant envelope detector, the time constant RC of the doctor circuit should satisfy  

1.   0.5 ms

2.   0.5 μs

3.  RC

4.  RC >> 0.5 ms

View Answer  
4
Correct Answer :

 0.5 μs <RC <0.5 ms


Explanation :
No Explanation available for this question

The signal m(t) as shown is applied both to a phase modulator (with kp as the phase constant) and a frequency modulator (with kr as the frequency constant) having the same carrier frequency. The ratio kp/kf (in rad/Hz) frequency. The ratio kp/kf (in rad/Hz) for the same maximum phase deviation is

1.   8π

2.  4π

3.  2π

4.  π

View Answer  
4
Correct Answer :

4π


Explanation :
No Explanation available for this question

An analog signal is band –limited to 4 KHz. Sampled at the Nyquist rate and the samples are quantified levels Are assumed to be independent and equally probale

1.   1 bit/sec

2.  2 bits/sec

3.  3 bits/sec

4.  4 bits/sec

View Answer  
4
Correct Answer :

2 bits/sec


Explanation :
No Explanation available for this question

A source alphabet consists of N symbols with the probality of the first two symbols being the same. A source encoder increases the probality of the first symbol by a small amount ε and decreases that of the second by ε. After encoding, the entropy of the source

1.   Increases

2.   Remains the same

3.  Increases only if N=2

4.  Decreases

View Answer  
4
Correct Answer :

Remains the same


Explanation :
No Explanation available for this question

In a base band communication link, frequencies up to 3500 Hz. are used for signaling . Using a raised cosine pulse with 75% excess bandwidth and for no inter-symbol interference, the maximum possible signaling rate in symbols per second is

1.   1750

2.  2625

3.  4000

4.  5250

View Answer  
4
Correct Answer :

4000


Explanation :
No Explanation available for this question

An image uses 512 x 512 picture elements. Each of the picture elements can take any of the 8 distinguishable entropy in the above image will be

1.  2097152 bits

2.  786432 bits

3.  648 bits

4.  144 bits

View Answer  
4
Correct Answer :

786432 bits


Explanation :
No Explanation available for this question

A binary source has symbol probabilities 0.8 and 0.2. If extension coding (blocks of 4 symbols) is used, the lower and upper bounds on the average code word length are

1.   Lower___

2.  Higher___

View Answer  
2
Correct Answer :

Lower___



Explanation :
No Explanation available for this question
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