IAF Placement Papers - Electronics and Communication Engineering Questions
Indian Air Force Placement Papers - Electronics and Communication Engineering Questions
1. If in a system the modulation frequency is made 2 times, modulation voltage is kept constant and modulation index is halved then the system is?
A. Angle Modulation
B. Frequency Modulation
C. Phase Modulation
D. Amplitude Modulation
2. In a dedicated communication system, noise is most likely to get inside the system:
A. At the destination
B. Inside the channel
C. At the transmitter
D. In the source of information
3. Which of these is a characteristic of a HIGH frequency system?
A. They are affected by solar cycle
B. They are reflected by D layer
C. They are observed by F2 layer
D. They find application in long distance communication made to moon
4. The concept of Impedance inversion is most likely to be observed with?
A. ½ wave line
B. ¼ wave line
C. Short circuit stub
D. Open circuit stub
5. Why is a duplexer used?
A. To couple 2 differing antennae without mutual inductance to a transmitter
B. For increasing the speed of pulses inside a pulse radar
C. For preventing interference caused b/w two antennae when the connection is made to receiver
D. For allowing one antenna to be used for reception purposes or for transmission purposes without making the use of mutual interference
6. Which of these terms do not find application in a Yagi-uda array?
A. High Gain
B. Folded dipole
C. Good Band Width
D. Parasitic elements
7. In a system if you apply forward error correcting code if will only correct errors which:
A. Require retransmission (partial) of the signal
B. Require retransmission (full) of the signal
C. Use parity to make connection to errors in all the cases
D. Require no part of signal for transmission
8. Determine the order of the signal strength received from a geosynchronous communication signal
B. Pico Watts
C. Milli Watts
D. Kilo Watts
9. How is telephone traffic measured?
A. In terms of grade of service
B. In erlangs
C. By making use of echo cancellers
D. By the means of relative congestion
10. Which of these is digital?
A. Pulse Frequency modulation
B. Pulse Width modulation
C. Pulse Code modulation
D. Pulse Position modulation
11. In a colored Television which are the three primary colors?
A. Red Blue Green
B. Red Orange Green
C. Red Orange Blue
D. Red Green Yellow
12. A probable solution to “blind speed” problem that arises in any radar system is:
A. Changing Doppler Frequency
B. Using mono pulse
C. Varying PRF
D. Changing Doppler Frequency
13. On what characteristic of a television does the number of active picture elements depend on?
A. FB Ratio of receiver Antenna
B. Received band width
C. Fly back time
D. CRT Screen Size
14. A class B amplifier is biased:
A. Nearly twice cut off
B. Just at cut off
C. So that IB equals IC
D. At the mid point of the load line
15. If the maximum power transmitted inside a radar system is multiplied by 16 then calculate the factor by which maximum range will increase:
16. What is the main use of a common base emitter?
A. As a voltage amplifier (Common Emitter)
B. As a current amplifier(Common Base for HF applications)
C. For the rectification of AC signal (Any configuration but Common Emitter)
D. For matching a high source impedance to low load impedance (Common Collector)
17. Which of these sentences does not indicate high PRF condition:
A. Increase with maximum range
B. Having no effect of range resolution
C. Making target tracking easier with conical scanning
D. Making returned echoes easier to distinguish from noise ratio
18. Which of the following devices represents characteristics which are very close to an ideal current source?
B. Zener Diode
C. Field Effect Transistor
D. Transistor in the common base mode
19. How can a half adder be created?
A. Through an AND gate and XOR gate
B. AND gate and OR gate
C. NOT gate and OR gate
D. Two NAND gates
20. In a logic circuit what is positive logic:
A. Logic 0 and 1 are represented by 0 and a positive voltage respectively
B. Logic 0 voltage is lower than logic 1 voltage
C. Logic 0 voltage is higher than logic 1 voltage
D. Logic 0 and 1 are represented by positive and negative voltage