Abirami Subramanian: 2013

ISRO 2011 EC SET A

1. In an amplitude modulated system if the total power is 600 W and the power in the carrier is 400W, the modulation index is
a. 0.5
b. 0.75
c. 0.9
d. 1
Solution:

P_{Side band}= P_Total – P_carrier

P_{Side
band = 600 - 400 = 200 W}

P_S / P_{T = 200/600 = 1/3}

Solving we get µ = 1

Answer: Option d

2. The channel capacity under the Gaussian noise environment for a discrete memoryless channel with a bandwidth of 4 MHz and SNR 31 is
a. 20 Mbps
b. 4 Mbps
c. 8 Kbps
d. 4 Kbps

Solution:

Channel capacity = C=B log₂(1+ SNR)

= 4 M log₂(1+31)

= 4 M x 5 = 20 Mbps

Answer: Option: a

3. In satellite communication, frequency modulation is used because satellite channel has
a. High Modulation index
b. Small bandwith and negligible noise
c. Large bandwidth and severe noise
d. Maximum Bandwidth and Minimum noise
Answer: Option d
4. For a 3-µm diameter optical fiber with core and cladding indexes of refraction of 1.545 and 1.510 respectively. The cut off wavelength is
a. 2.3 µm
b. 1.29 µm
c. 1.5 µm
d. 3.24 µm
Solution:

= 1.2808 µm

Answer: option b

5. A 12 bit ADC is operating with a 1 µs clock period and total conversion time is seen to be 14 µs always. The ADC must be of the type

a) Flash

b) Counting type

c) Integrating type

d) Successive Approximation type

Answer: option d

Solution:

Answer: Option b

A Process contains only sequential statements.
Answer : option b

2¹² = 4096 bytes = 4Kbytes

Answer: option d

A resistance in parallel with an indeal current source.

Answer: Option b

The dominant mode has lowest cutoff frequency and hence highest cutoff wavelength.
Answer: Option d

The reverse recovery time involves a diode switching from FB to RB. Reverse recovery time will be of several microseconds. Therefore at t=0, the diode would not have recovered from forward bias condition. Hence current will be same as 100 mA.
Answer: Option d

Aswer: option d

Thread: the primitive that can execute code. It contains an Instruction pointer and sometimes has its own stack.
Process: An environment in which one or several threads run.
Kernel: Run time OS- takes care of thread scheduling.
Answer: Option d