ANSWER KEY TO ISRO EXAM - 26th APRIL 2009

My Interview was on 30 June 2009
There are 8 interviewers - out of which one is lady. All are very cool
The chairmen of committee ask me are you employed, then i said yes followed by my company project. They are not interested in projects then they ask which subjects we touch and which subjects we do not touch. So i said i have read all subjects, you can ask from all subjects including Digital electronics and Communication. So, one of them start with communication. In between one them ask, have you done diploma, i said yes sir PGDEVD DIPLOMA form CDAC where i have read embedded systems and VLSI design, i think it gives some positive impact on them.
Questions ask by them as follows:-
1. There is one transmitter and two receiver, one is 100m away and other one is 400 m away. Which Rx receive more signal and why and also determine the ratio of signal receive at receivers antennas.
2. What is modulation index for AM and FM.
3. There are two amplifiers in cascade having bandwidth bw1 and bw2 (some values in DB). What is resultant bandwidth. (GAIN = g1*g2 or GAIN in db = G1 + G2 in db)
4. Can you draw bode plot(some figure is given).
5. Why microwave is so called.
6. Why we can not use simple RLC circuit.(Because they produce Low frequency which is not in GHZ)
7. What are resonators. what is difference between oscillator and resonator. what is difference between resonator and resonance.


SET - A
SET - B
SET - C
SET - D
1-C, 2-A, 3-D, 4-D, 5-U, 6-U, 7-D, 8-U, 9-A, 10-B,
11-C, 12-U, 13-A, 14-D, 15-A, 16-U, 17-A, 18-C, 19-U, 20-C,
21-A, 22-B, 23-U, 24-D, 25-C, 26-U, 27-U, 28-B, 29-D, 30-C,
31-U, 32-U, 33-U, 34-U, 35-U, 36-A, 37-U, 38-A, 39-U, 40-A,
41-D, 42-A, 43-A, 44-C, 45-A, 46-U, 47-U, 48-U, 49-A, 50-B,
51-C, 52-U, 53-A, 54-U, 55-B, 56-D, 57-U, 58-U, 59-D, 60-B,
61-U, 62-U, 63-C, 64-A, 65-U, 66-U, 67-U, 68-A, 69-D, 70-C,
71-A, 72-C, 73-U, 74-A, 75-D, 76-U, 77-U, 78-B, 79-U, 80-U
SET - E

DIGITAL ELECTRONICS

Represent N-Bit Number in 2's complement form.

1) RANGE : -2^(N-1) to +2^(N-1) -1
For 8-Bit Number : -2^(8-1) to +2^(8-1) -1 :: -128 to +127

LPF and HPF

1. Low Pass Filter(LPF) - "All are related to Small"
1) Select and pass the Small Signal.
2) Integrator - It collect Small quantity and make large one.
3) Lag network - Lag(Negative) is Smaller than Lead(Positive) in sign.
4) De-Emphasis Filter - D is Smaller then P in alphabetical order.



2. High Pass Filter(HPF) - "All are related to Large"
1) Select and pass the Large Signal.
2) Differentiator - It divide Large quantity into small one.
3) Lead network - Lead(Positive) is Larger than Lag(Negative) in sign.
4) Pre-Emphasis Filter - P is Larger than D in alphabetical order.