DRDO Interview on 24th August, at Allahabad.This is Dharm here. 24th August 2009, it was one of the most memorable days of my life. DRDO Came in my College for campus interview. Well there was only a technical interview for toppers of class (9 students).After taking interview of several colleges, they made all India merit. The result is announced on 17th March 2010. I got selected in DRDO. I have appeared in DRDO interview for scientist-B at Allahabad on 24th August 2009. First all candidates have to sit in waiting room at venue center and give signature for presence.
This is Dharm here. 24th August 2009, it was one of the most memorable days of my life. DRDO Came in my College for campus interview. Well there was only a technical interview for toppers of class (9 students).
After taking interview of several colleges, they made all India merit. The result is announced on 17th March 2010. I got selected in DRDO. I have appeared in DRDO interview for scientist-B at Allahabad on 24th August 2009. First all candidates have to sit in waiting room at venue center and give signature for presence.
After that we go for documents verification and submission of their required bio data from one by one in administrative office according to list of candidates. Please never forget to bring at least one photocopy of each document. At the interview was started in sequence (UR-OBC-SC). Average time for interview is
half an hour. In interview room there was six members. One from BHU, 2nd HOD of JK Institu, 3rd HOD of MNIT and other from DRDO. I was 5th candidate to go into the interview room.
When you inside interview room you have to sit in front of board members. One will first demand for your project report and about your interesting subjects of your discipline. Then different board member ask question about your interesting subjects. I am highlighting question below which I have faced in
Me: Good afternoon to all of you sir.
Int: Good afternoon, please sit.
Me: Thanks (after sitting).
Board Member 1st (main)
Int: (seeing my mark sheets),you have read basic electronics three year in B.Sc. and then three year in B.TECH. I thing this is your strong subject.
Me: Yes sir.
Int: Tell me your three area of interest (favorite subjects).
Me: 1. Basic electronics
2. Digital communication
Int: Are you ready to start with basic electronics?
Me: No sir. Start with digital communication.
The Int: kya baat hai pahle hi bhagne lage (hindi).
(Then he invites to HOD of MNIT to ask questions in digital
Member 2nd (HOD of MNIT)
Int: What do you understand by FSK?
Me: FSK means frequency shift keying. Here we use frequency as a key. That is why it is called frequency shift keying.
Int: What do you mean that frequency use as a key in FSK?
Me: means by frequency we can distinguish symbols. e.g. in digital for 1 we take high frequency and for 0 take low frequency.
Int: How will you generate FSK?
Me: I started telling modulator circuit but.
Int: I want to know the IC name which is used in your lab.
Me: 555 timers
Int: No, do you about VCO?
Me: YES SIR, it is voltage controlled oscillator whose frequency changes with modulating signal. But by VCO we process analog signal and here modulating signal –Digital, carrier- analog and modulated signal –analog. Then how possible to generate FSK by VCO?
Int: Take digital signal as analog signal with two values only, ok.
Me: Yes sir.
Int: What is coding?
Me: To generate code word according to signal.
Int: Why required?
Me: Suppose you have a signal with 8 levels and you are transmitting it without coding, then in receiver side, receiver compares 8 levels for required output. But if you use coding then there will be only two levels 1 and 0, so in 2nd case there is less probability of error.
Int: Define Hoffman coding?
Me: Sorry sir, I can not give the definition of Hoffman coding .But I can do Hoffman coding. I know that it gives codes of optimum length.
Int: How will you receive FSK signal?
Me: I told receiver circuit in which there are multiplier, integrator and decision device.
Int: What is decision device?
Me: This is a device, which gives decision on the basis of threshold level. e.g. Above threshold level-1 & below threshold -0.
Int: Will there a summer after decision device?
Me: Yes sir.
HOD of JK: jitani device paye laga dejiye. Are hammer right direction me mariye. (In Hindi)
Int: Are you sure?
Me: Yes sir.
Int: Where is the use of FSK?
Me: In low speed modem.
Int: Do you know PSK?
Me: Phase shift keying, in this scheme phase of carrier changes according to the value of modulating signal.
Int: Which one is better FSK or PSK?
Me: Bandwidth requirement is smaller than FSK.
Int: and power?
Me: No answer.
Int: Bandwidth and power are very important factors for any scheme.
Me: No answer.
Int: what is SNR?
Me: signal to noise ratio and SNR requirement in PSK is lower than FSK.
Int: what is difference between DB and DBm?
Me: S = 10 logs1/s2
When s2 in watt, S in DB
When s2 in mill watt, S in DBm.
Int: not good.
Another member (external): Base?
Me: (This is a clue for me) yes sir in DB base is watt and in DBm base is mill watt.
Int: Change -10 db into watt?
Me: I solved on the paper and gave answer.
Int: Ok Dharmendra (Now he invites to an external member from DRDO to ask microprocessor)
Int: What is the difference between microprocessor and microcontroller?
Me: Microcontroller has ROM, RAM, Timmer and I/O port on the chip but microprocessor does not.
Int: what is meaning by 8 bit microprocessor?
Me: ALU size is 8 bit.
Int: It means we can not process 16 bit data?
Me: We can, but first 8 bit then remaining 8 bit.
Int: Generate sine wave from microprocessor?
Me: No answer.
Int: Only make the block diagram?
Me: I made block diagram on the paper containing microprocessor, buffer and latch etc.
Me: latch for data hold and buffer for impedance matching.
Int: there is no need of power supply?
Me: no sir, it requires 5v power supply and a crystal oscillator.
Int: then why did you not make it?
Me: Because I feel this is understood.
Int: ok Dharmendra, please give me that paper.
Me: I gave the paper. Member 5th & member 6th
Int: What is full form of GSM?
Me: Sorry Sir, but I know the full form of CDMA.
HOD of MNIT: why?
Me: Because this is in my 5th semester and presently I am studying in 5th semester which is started just now.
Int: But this question is of high school level.
Member 1st (main): you do not have mobile set?
Me: no sir. HOD of MNIT: Tell me full form of CDMA?
Me: code division multiple access.
Int: Multiple or multiplex?
Member 1st (main): ok Dharmendra, you may go now.
Me: Thank you sir. (I left the interview room)
DRDO is waiting for you all guys so go and rock them with your knowledge.
“Best of Luck “to every aspirant.
Mobile No: 09900184937