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

1.   ½

2.   4/5

3.  1

4.  3/2

4

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)

4

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

4

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

4

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

4

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

4

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

4

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

4

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

4

786432 bits

Explanation :
No Explanation available for this question

1.   Lower___

2.  Higher___

2