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Study material for UPSC


IES interview is a technical interview and most of the questions

will be technical in nature .They will ask very less questions

form ur bio-data most of the questions will be related to ur

subject, job exp and latest technology in case of

Electronics&Commnictaion engineering.

This material contains following items:

1. General guide lines for UPSC interview


Questions based upon your bio-data


Type of technical questions asked from subject in UPSC in

Electronics&Communication Engineering in last 5



Study -material for latest technology(ECE&EE)

1.General guidelines for UPSC interview:

Before actual interview there will be your certificate verification. There are generally 5-6 candidates in one session (There are 2 session 10-1&2-5) so generally time allotted is 30 minute for every candidate but it is liable to vary. There are 4 members in interview panel one will be UPSC member and other 3 will be senior professors/scientists/higher rank officers like DRM/GM/CST from railway/director from research institute etcs.

Basic rules (Do’s and Do not’s) for UPSC Interview:

1. Just after entering in board room greet every one and if lady member is there then greet her first and then rest of members. No need of greeting one by one say good-morning/evening all of you sirs (by making eye contact to everybody)


2. If lady member is there then say good morning/evening mam and then say good morning/evening to all of you sirs. (never use madam).

3. When they offer chair then say thank you mam/sir to chairman of your board.

4. Distance between chairman and you will be large so speak loudly. 5. Never interrupt them, 1 let them complete their

6. If you don’t know answer of any question then with more confidence say sorry sir I don’t know or say i studied earlier but this time i m not able to recall.

7. Try to avoid giving wrong answers and some time if you are not sure about answer you simply say sir I m not sure but i think answer is this. If he tells you correct answer say him/her thank you very much sir/mam.

8. If they offer Tea/water to you then avoid it if possible but don’t forget to say thank-you sir/mam.

9. Try to answer in a simple language so that chairman can also understand it. Chairman of board is decision maker for your marks and he is generally a non technical person.

10.Don’t contradict yourself in questions related to your bio-data.

If you have written any thing related to your hobby, sports, extra activities etc. then you can n’t say sorry sir i don’t know. In interview never get tensed, if u r then hide it. Always give answer with light smiling face.

11.Never give negative answer to anything. Never blame system for anything. Never blame anybody for anything during your interview process. You can’t say our whole system is corrupt .our system is responsible for that etcs.

12. There are 4 members during interview and they ask questions one by one. So maintain eye contact to person who is asking questions and


for short while u can see other members also but main focus must be on that person only.

13. Answers must be given in very simple language and upto the points .try to avoid formulas give logical explanation.

14. Be more cautious in questions related to your bio-data and non technical questions. In these questions you can’t say I don’t know. eg. If they ask why do you want to join IES you can’t say sorry sir I don’t know. If you have written some thing in your bio-data then you are supposed to know it.

15. Wear proper dress and if possible don’t use perfume etc. Your cloths must be neat and clean and shoes must be polished.

16. Never use words like social status, social-value, job security& cool job etcs.

17.Try to use words with which you are familiar. For Example if you are answering about routers and not good in packet switching then try to avoid packet switching word, while explaining about router.But at the same time if you are good in packet switching then use word packet switching intentionally.

18. Before leaving room don’t forget wishing every one and saying thank you to all of you sirs.

2.Questions based upon your bio-data:

There will not be many questions from this portion but we are giving all possible questions?

Q. some question from your name and what is meaning of your name? Q. some question can be asked form your place any thing famous from ur place and if anything famous that can also be asked, if any current issue is arising there then plz go through that issue.

Q. profession of your parent and why did you not chose that or correlation with present job etc.


Q. If any addition degrees like M.Tech then why don’t u want to continue that?

Q. If you have any academic break after 12 and B.Tech then explain it. Q. If you got any scholarship and medal then question can be asked? Q. If your university and college has some historical importance then Question can be asked upon this?

Q. Many Non technical and non technical questions can be asked related


to ur job?

(i) why do u want to leave ur previous job

(ii) how will u utilise ur previous job exp in IES job? (iii) are you satisfied with ur previous job

(iv) what was ur responsibility there?

(v) If your previous organisation has some collaboration or done some thing latest then they can ask question on it

(vi) why do u want to join IES by leaving ur previous job? (vii) Don’t you think your previous job is better than this job? (viii) How did u continue ur preparation in previous job?

Q. many questions can be arises with ur hobbies and sports etc. Q. They can ask some technical questions from ur hobby

Q. They can also ask some technical question from ur favourite sport Q. questions can be asked on Job preference in your bio-data.

Q. why have u given railway as ur 1 option.

Q. Many questions asked based upon ur hobby and fav sport? Q. they can ask some technical question related to ur hobby? Q. they can also asked many questions related to ur fav sport?


Q. They can also some technical question based upon ur fav sport?

Q They can also some questions if u held any position in college school etc.

Q. why did you not join private sector?

Q. Are you preparing for civil service exam?

Q. Why have you given railway signal as 1 option? Q. Why have you given railway store as 1 option? Q. How will you improve railway telecom system?

Q. what can be done to avoid accidents in Indian Railway? Q. what can be done to handle fog situations?

Q. how your previous job experience can be utilised for railway?

st st

3.Type of questions asked in UPSC in last 5

years (Memory based collected from

students who appeared for Interview)

Subject: Electronics&Communication Engineering

we can divide our whole syllabus into following parts from interview point of view.

Part-1: Material science, Electronics device circuit, Power electronics, Analog electronics, digital electronics and microprocessor

Part-2: Communication system, Electromagnetic theory and Microwave. Part-3: Signal&system, Network, Control &Instrumentation

Material science/EDC&Power electronics:

Q. why silicon is preferred material for semiconductor? why not others?

Q. why Carbon can’t be used as Semiconductor it is also from 4 group?



Q. what is concept of hole and did they exist?

Q. does hole physically exist?

Q. How will u define mobility?

Q. why electron mobility is always higher than holes?

Q. what is concept of effective mass?

Q. At what factor effective mass depends?

Q. what are the disadvantages of Ge as a semiconductor material

Q. How silicon helps in fabrication?

Q. what is use of SiO in case of fabrication?

Q. what is use of Al in case of fabrication?

Q. what are basic steps of fabricaton?

Q. If we want a high speed diode will be prefer Si only?

Q. what is value of intrinsic concentration (n ) in case of silicon and Ge at room



temperature? And how they changes with temperature?

Q. How conductivity varies with temp for semiconductor and metal and why?

Q. why in a SC conductivity increases with temp and not in metal?

Q. How extrinsic semiconductor are more conductive than intrinsic S.C


Q. what is effect of temperature on extrinsic SC

Q. what are super conductors?

Q. what is ideal behaviour of a super conductor?

Q. why their conductivity is very high?


Q. Give some example of super conductors?

Q. what is BCS theory for super conductor?

Q. How N-type SC and P type SC forms?

Q. what is effect on doping if temp is increased in case of N type and Ptype?

Q. what are direct and indirect band gap SC and their application?

Q. Plz explain direct band gap and indirect band gap SC

Q. what are applications of direct and indirect band gap SC?

Q. what are degenerate semiconductor? And where they are used?

Q. what is advantage of degenerate SC in tunnel diode

Q. what is the position of Fermi level in degenerate SC

Q. what happens on position of Fermi level if doping is increased)

Q. How will you define Fermi level?

Q. Fermi level is probability of what?

Q. where is Fermi level in case of N-type &P –type?

Q. what is Fermi level at absolute temperature?

Q. where is Fermi level for metals?

Q. what are laws other than Fermi-Dirac distribution?

Q. What is Hall effect? and its application?

Q. Discuss Hall effect for metal, SC&Insulator?

Q. For Intrinsic SC Hall coeff is –ve why?

Q. For extrinsic hall coeff will be?


Q. which current plays a major role in current of diode and how?

Q. what is ohms law for semiconductor?

Q. what is concept of drift current? And how it can be increased?

Q. Can u explain reverse current in diode and how it varies with reverse


Q. explain concept of photo diode and how it is different form solar cell?

Q. Explain working of solar cell?

Q. what are photo detector and give some example of it?

Q. what is LED and how it works? How it different form LASER?

Q. where LED is used? How it is used in Optical fiber?

Q. Can u explain concept Of Optical fiber?

Q. what are opto-isolator in case of OFC?

Q. which light is used in case of OFC?

Q. what is Total Internal reflection in OFC?

Q. what is difference between Pin diode and APD? Which one is used where?

Q. what is working of APD?

Q. what is working of PIN diode?

Q. What is break down in zener diode?

Q. what is avalanche multiplication in zener diode? And what is tunnelling?

Q. what is basic difference between 2 mechanism?

Q. which one is used for high doping and which one is used for low doping?

Q. what is effect of temp in case of avalanche breakdown in zener diode?


Q. why voltage increases if temp is increased in avalanche breakdown in zener


Q. Can u explain Zener as a constant voltage regulator?

Q. how zener diode can be used in DC power supply?

Q. what are the basic blocks of Power supply?

Q. what is the ripple used in a filter?

Q. Can u compare HWR and FWR on basis of ripple frequency? And which one

is better?

Q. which type of transformer is used in power supply and why?

Q. what is use of bleeder resistor in case of power supply?

Q. what is Form Factor and what is its significance?

Q. what is voltage regulation for a power supply?

Q. can u differentiate b/w clipper and clamper?

Q. Is clipper same as Rectifier followed by clamper?

Q. what is voltage doubler /Tripler etc?

Q. How forward voltage in a diode changes with temp?

Q. Is it same for both Ge and Si?

Q. why this value is negative?

Q. what is ideality factor in case of diode why this 1 for Ge and 2 for Si?

Q. why reverse current change with voltage in case of Si but not in case of Ge.

Q. How will u define rectifier and what is its use?

Q. what is reverse recovery diode in case of diode used as a switch?

Q. How transistor work as an amplifier?


Q. why there is 180 degree phase shift in case of CE mode and not in case of

CB and CC?

Q. what is physical meaning of Beta in case of transistor?

Q. why base width is narrow and doping light in case of transistor?

Q. For high speed transistor what will u do with base doping?

Q. what is transit time in case of transistor?

Q. what are use of CE CC and CB mode?

Q. why CE as an amplifier?

Q. why CC for impedance matching? And how it is used there?

Q. how CB is used as constant current source?

Q. what is early effect in case of transistor?

Q. what is punch through?

Q. How breakdown occurs before punch through in a transistor?

Q. what are advantage of FET over BJT?

Q. what are disadvantage of FET over BJT?

Q. why FET is more temp stable than BJT?

Q. why FET is less noisy than BJT?

Q. why FET has high impedance than BJT?

Q. Is fabrication easy in case of FET?

Q. compare gain bandwidth product b/w FET&BJT?

Q. Why BJT as a switch has higher speed than FET?


Q. How FET is used as an amplifier in saturation region?

Q. Can u explain saturation and active region in FET?

Q. what is difference between FET&MOSFET?

Q. why MOSFET has high impedance than FET? And what is its order?

Q. Can u draw ac model of a transistor?

Q. How can u draw h-parameter model with the help of ac model?

Q. why h-parameter is called hybrid parameter?

Q. Explain variation of different h parameters with respect to temperature?

Q. Compare Input impedance, output impedance, voltage gain and current gain

for CE CC and CB mode.

Q. why CC is used as impedance matching?

Q. what is cascade and cascade combination?

Q. what are the advantage of cascode?

Q. How SCR works?

Q. compare power diode and power BJT?

Q. explain latching and holding current in SCR?

Q. what is the application of SCR?

Q. what is dv/dt and di/dt effect in case of SCR?

Q. How dv/dt and di/dt can be avoided?

Analog electronics/Digital electronics:

Q. why analog is called analog?


Q. How will u calculate voltage amplification of BJT?

Q. Can u draw frequency response of BJT?

Q. Can u explain every part of frequency response?

Q. what are low frequency region mid band frequency region and high

frequency region?

Q. why gain decreases in low frequency and high frequency?

Q. why gain remains constant in mid band frequency region?

Q. what are the role of coupling capacitor by pass capacitor and blocking

capacitor in BJT amplifier?

Q. which one of the following capacitor determines lower cut-off?

Q. why gain decreases in high frequency region?

Q. what is parasitic capacitance in BJT amplifier?

Q. what are the capacitance available in parasitic capacitance?

Q. what happens to lower cut-off and higher-cut off in case of multistage


Q. Please draw RC high pass filter?

Q. what happens when a step is given as input to it?

Q. when it works like a differentiator?

Q. Do values of R&C decide is it differentiator or not?

Q. what is the condition for RC high pass as a differentiator circuit?

Q. what is the output of RC differentiator if square wave is given as input?

Q. Same questions can be asked for RC low pass which is an integrator?

Q. what is tilt in case of High pass filter?


Q. How will u define rise time in case of RC LPF?

Q. Can u draw π model of a transistor?

Q. what new changes occurs when a transistor is operated at high frequency?

Q. what is base spreading resistance?

Q. why base spreading resistance occurs?

Q. why junction capacitance occurs at high frequency in case of BJT?

Q. what are various junction/parasitic capacitance in case of BJT?

Q. which capacitance is dominated for calculation of higher cut-off?

Q. why h-parameter can’t be used for power amplifier?

Q. Can u explain concept of oscillator?

Q. is it same for sinusoidal &triangular wave generator?

Q. what concept is used for sinusoidal generator

Q. what concept is used for triangular wave generator?

Q. how RC phase shift oscillators used for sinusoidal wave generator?

Q. what are the ranges of RC phase shift oscillator?

Q. what is concept of offset nonlinearity in case of RC phase shift?

Q. can it be made by FET only or BJT also is used?

Q. what is difference between RC phase shift by use of BJT&FET.

Q. why RC BJT oscillator uses voltage shunt feed back while RC phase shift

FET uses voltage series explain?

Q. what factors change frequency of oscillation in both cases?

Q. what is concept of wein bridge oscillator and where it is used?


Q. what are audio frequency and radio frequency oscillator?

Q. do both have same concept?

Q. what is basic concept of radio frequency oscillator?

Q. what elements are used for radio frequency oscillator?

Q. is Radio frequency oscillator and Crystal oscillator same?

Q. How relaxation oscillators are used for triangular wave generator?

Q. what is basic concept of relaxation oscillator?

Q. what are Bistable, Monostable &Astable multi-vibrator?

Q. how will u decide which one is bistable, monostable&astable.

Q. what is stable stable&which is quasi stable state?

Q. what is difference between stable state& quasi stable state?

Q. How will u use Bistable as a Flipflop?

Q. How will u use mono stable as Pulse width modulator?

Q. how astable is used as voltage to frequency convertor?

Q. how astable works as it has 2 quasi stable states?

Q. what is Schmitt trigger?

Q. How it is different from astable muti-vibrator?

Q. Can u draw input and output for Schmitt trigger

Q. show UTP&LTP in terms of input and output?

Q. which mutivibrator is used for clock generation?

Q. what are the advantages of negative feedback?


Q. why negative feed-back are stabilised while positive feedback are unstable?

Q. how negative feedback improves stability?

Q. when one uses negative feedback and when positive feedback?

Q. what are DC amplifiers? And what are their applications?

Q. what is the problem with DC amplifers?

Q. what is the drift problem in case of DC amplifier?

Q. How Differential amplifier can remove this problem?

Q. explain working of differential amplifers?

Q. what are different modes in differential amplifier

Q. what are differential mode and common mode in case of differential amplifer

Q. what is CMRR and what is physical significance of it?

Q. Is CMRR link with noise rejection? What is meaning of infinite value of


Q. where differential amplifiers are used and what is its use in case of OPAMP?

Q. how will u define digital?

Q. Is digital& binary are same?

Q. what is difference between digital&discrete or both are same?

Q. Are analog &continuous same?

Q. how will u define continuous&analog?

Q. what is difference between both continuous and analog?

Q. what is meaning of universal gate?


Q. for (n) variable function implementation what shd be size of MUX

Q. what is difference between MUX and encoder?

Q. what are encoder?

Q. Can u tell one application of encoder?

Q. what is decoder and how it is different from encoder?

Q. what is priority encoder?

Q. where this priority encoder can be used?

Q. how will u implement higher order decoder/Mux by lower order?

Q . How will u implement 8x1Mux by use of 4X1 MUX?

Q. How will u define select lines in case of MUX?

Q. Can u design a Full adder with half adder only?

Q. what is difference between combination circuit and sequential circuit?

Q. what are the advantages of sequential circuits in digital?

Q. Is feedback digital circuits same as sequential?

Q. what are the basic applications of sequential circuits?

Q. how sequential circuits used as a memory elements?

Q. Are sequential same as Latch?

Q. what is difference between latch and flip-flop?

Q. what is basic use of latch?

Q. what are transparent latch?

Q. can we differentiate latch and flip flop based upon triggering of clock?

Q. In microprocessor how a latch is used?


Q. what is difference between level triggering and edge triggering?

Q. what is basic problem with level triggering?

Q. How above problem can be removed by use of edge triggering?

Q. what are set up time and hold up time? And wht are their values and their


Q. what is their significance in case of level triggering and edge triggering?

Q. what is meta stability problem in case of flip-flop?

Q. Is it linked with setup time and hold up time?

Q. How meta stability can be removed?

Q. what is race around condition?

Q. why does it occur?

Q. does it occur in case of both level and edge triggering?

Q. How one can remove race around condition?

Q. what is master slave flip-flop?

Q. How does it remove race around condition?

Q. can u explain working of Master slave FF?

Q. can u design MOD-10 counter by use of 4 FFs and NOR gate?

Q. In place of NOR gate can we use AND gate?

Q. why we will use only NAND and OR gate in above case?

Q. For ripple counter can we use D FF or S FFs

Q. why only T&JK FFs are used?


Q. Does triggering affects MOD of ripple counter?

Q. what is basic problem with ripple counter?

Q. can u explain glitch problem in ripple counter?

Q. How this glitch problem can be removed in ripple counter?

Q. what are the advantages and disadvantages of synchronous over ripple?

Q. How will u design a synchronous binary counter?

Q. what components are required for design of MOD-16 synchronous counter?

4.Study material for Latest technology:

Generation of Mobile: 1G:

2G: 2.5G:

Purely analog

It i mainly for voice and slow transmission

So the cellular services combined with GPRS became' 2.5G.'

GPRS could provide data rates from 56 kbit/s up to 114 kbit/s. It can be used for services such as Wireless Application Protocol (WAP) access, Multimedia Messaging Service (MMS), and for Internet communication services such as email and World Wide Web access.

2.75G: GPRS networks evolved to EDGE networks with the introduction of 8PSK encoding. Enhanced Data rates for GSM Evolution (EDGE),

Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC) is a backward-compatible digital mobile phone technology that allows improved data transmission rates, as an extension on top of standard GSM. EDGE can be considered a 3G radio technology and is part of ITU's 3G definition, but is most frequently referred to as 2.75G. EDGE was deployed on GSM

networks beginning in 2003—initially by Cingular (now AT&T) in the United States.


International Mobile Telecommunications-2000 IMT-2000( ), better known as or , is a family of standards for wireless

communications defined by the International Telecommunication Union, which includes EDGE, CDMA2000, the UMTS family as well as DECT and WiMAX. Services include wide-area wireless voice telephone, video calls, and wireless data, all in a mobile environment. Compared to 2G and 2.5G services, 3G allows simultaneous use of speech and data services and


higher data rates (up to 14.4 Mbit/s on the downlink and 5.8 Mbit/s on the uplink with HSPA+). Thus, 3G networks enable network operators to offer users a wider range of more advanced services while achieving greater network capacity through improved spectral efficiency.

GPRS (General Packet Radio Service):

It offers high speed data services in GSM network. It uses Packet Mode Technique to transfer data and provides connectivity to Internet. Users will be able to browse Internet using handsets supporting Internet

browsing. They will also be able use their e-mail accounts as is being done through landline Internet access. Also browsing of Internet from Laptops and Desktop computers is possible by connecting the computer with the GPRS enabled mobile handset through a data cable or Infrared connectivity.

Using GPRS you can download in your mobile the following: • Polyphonic ring tones

• MP3 tones • Colour logos • Wallpapers • Videos

GSM: Global system for Mobile Communication CDMA: Code Division Multiple Access.

GSM networks operate in a number of different frequency ranges

(separated into GSM frequency ranges for 2G and UMTS frequency bands for 3G). Most 2G GSM networks operate in the 900 MHz or 1800 MHz bands. Some countries in the Americas (including Canada and the United States) use the 850 MHz and 1900 MHz bands because the 900 and 1800 MHz frequency bands were already allocated. Most 3G GSM networks in Europe operate in the 2100 MHz frequency band.

GSM-900 uses 890–915 MHz to send information from the mobile station to the base station (uplink) and 935–960 MHz for the other direction

(downlink), providing 125 RF channels (channel numbers 0 to 124) spaced at 200 kHz. Duplex spacing of 45 MHz is used.

In some countries the GSM-900 band has been extended to cover a larger frequency range. This 'extended GSM', E-GSM, uses 880–915 MHz

(uplink) and 925–960 MHz (downlink), adding 50 channels (channel

numbers 975 to 1023 and 0) to the original GSM-900 band. Time division multiplexing is used to allow eight full-rate or sixteen half-rate speech channels per radio frequency channel. There are eight radio timeslots (giving eight burst periods) grouped into what is called a TDMA frame.


Half rate channels use alternate frames in the same timeslot. The channel data rate for all 8 channels is 270.833 kbit/s, and the frame duration is 4.615 ms.

The transmission power in the handset is limited to a maximum of 2 watts in GSM850/900 and 1 watt in GSM1800/1900.


One of the key features of GSM is the Subscriber Identity Module, commonly known as a . The SIM is a detachable smart card containing the user's subscription information and phone book. This

allows the user to retain his or her information after switching handsets. Alternatively, the user can also change operators while retaining the handset simply by changing the SIM. Some operators will block this by allowing the phone to use only a single SIM, or only a SIM issued by them; this practice is known as SIM locking, and is illegal in some countries.

SIM card

WAP (Wireless Application Protocol):

It provides a standardized way of linking the Internet to mobile phones. WAP is an application communication protocol. WAP is used to access services and information. It is inherited from Internet standards. It is used for handheld devices such as mobile phones and PDAs. It is a protocol designed for micro browsers. It enables the creating of web-applications for mobile devices

WAP uses the mark-up language called WML instead of regular HTML. The WAP facility is available over CSD & GPRS for the CellOne customers. MMS ( Multimedia Messaging Service ):

Mobile Messaging is evolving beyond SMS text messaging with the

introduction of MMS (Multimedia Messaging Service). MMS delivers a total communication experience, allowing personalized multimedia content

such as images, audio, text, video and combinations of these.

Multimedia Messaging Service (MMS) is a store and forward messaging service that allows mobile subscribers to exchange multimedia messages with other mobile subscribers. As such it can be seen as an evolution of SMS, with MMS supporting the transmission of additional media types: MMS is an important emerging service, which allows the sending of multiple media in a single message, and the ability to send a message to multiple recipients. The originator can easily create a Multimedia

Message, either using a built-in or accessory camera, or can use images and sounds stored previously in the phone (and possibly downloaded from a web site).Even if the recipient phone is not switched on, the Multimedia


Message will be stored and sent to the recipient as soon as they switch on their phone. If the recipient has not subscribed to the MMS service, still he/she can view the MMS through internet based on the SMS notification he/she gets.

A number of Multimedia Messages can be stored in the users handset and reviewed or forwarded at a later date.


(AsynchronousTransferMode&PermanentVirtual circuit):

ISDN:(integrated circuit Digital Network):

ISDN Has emerged as a powerful tool worldwide for provisioning of different services like voice, data and image transmission over the telephone line through the telephone network. ISDN is being viewed as the logical extension of the digitalization of telecommunication network and most developed countries are in different stages of implementing ISDN.

An ISDN subscriber can establish two simultaneous independent calls (except when the terminal equipment is such that it occupies two 'B' channels for one call itself like in video conferencing etc.) on existing pair of wires of the telephone line (Basic rate ISDN) where as only one call is possible at present on the analog line /telephone

connection. The two simultaneous calls in ISDN can be of any type like speech, data, image etc.

Services Offered By ISDN Normal Telephone & Fax (G3)

Digital Telephone -with a facility to identify the calling subscriber number and other facilities.

G4 Fax

Data Transmission at 64 Kbps with ISDN controller card Video Conferencing at 128 Kbps

Video Conferencing at 384 Kbps (Possible with 3 ISDN lines) Broadband service:

BSNL is in the process of commissioning of a world class, multi-gigabit, multi-protocol, convergent IP infrastructure through National Internet Backbone-II (NIB-II), that will provide convergent services through the


same backbone and broadband access network. The Broadband service will be available on DSL technology (on the same copper cable that is used for connecting telephone), on a countrywide basis spanning 198 cities. In terms of infrastructure for broadband services NIB-II would put India at par with more advanced nations. The services that would be

supported includes always-on broadband access to the Internet for residential and business customers, Content based services, Video

multicasting, Video-on-demand and Interactive gaming, Audio and Video conferencing, IP Telephony, Distance learning, Messaging: plain and feature rich, Multi-site MPLS VPNs with Quality of Service (QoS) guarantees. The subscribe will be able to access the above services through Subscriber Service Selection System (SSSS) portal.

Important Terms in modern communication: Wi-Fi: Wireless fidelity

1. Wi-Fi allows local area networks (LANs) to be deployed without

wires for client devices, typically reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.

2. Wireless network adapters are now built into most laptops. The

price of chipsets for Wi-Fi continues to drop, making it an

economical networking option included in even more devices. Wi-Fi has become widespread in corporate infrastructures.

3. Different competitive brands of access points and client network

interfaces are inter-operable at a basic level of service. Products designated as "Wi-Fi Certified" by the Wi-Fi Alliance are backwards compatible. Wi-Fi is a global set of standards. Unlike mobile

telephones, any standard Wi-Fi device will work anywhere in the world.

4. Wi-Fi is widely available in more than 220,000 public hotspots and

tens of millions of homes and corporate and university campuses worldwide. The current version of Wi-Fi Protected Access

encryption (WPA2) is not easily defeated, provided strong

passwords are used. New protocols for Quality of Service (WMM) make Wi-Fi more suitable for latency-sensitive applications.



WiMAX, meaning Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides wireless transmission of

data using a variety of transmission modes, from point-to-multipoint links to portable and fully mobile internet access. The technology provides up to 3 Mbit/sec broadband speed without the need for cables. The

technology is based on the IEEE 802.16 standard (also called Broadband Wireless Access). The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and

interoperability of the standard. The forum describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL

What is electronics?

Electronics is flow of electrons or other electrically charged particles in semiconductor in a controlled manner but electrical is study of presence or movement of electric charge.

Microwave oven:

It uses Magnetron microwave and generates microwave at frequency of 2.45 GHz for purpose of cooking of food. This is based on molecule of water and other components and other compounds which rotate or

vibrate and due to this vibration heat is generated. Every organic matter is generally made up of matter.

Different microwave frequency band:

L, S, C, X, Ku, K, Ka(1-40GHz) and other higher frequency bands are as follows: 1. Q-band(30-50) 2. U-Band(40-60) 3. V-band(50-75) 4. E-band(60-90) 5. W-band(75-110)


6. F-Band(90-140) 7. D-band(110-170)

Cable TV: CATV (Community Antenna TV)

CATV is a system of providing TV FM radio programming and other services to consumer via radio frequency signals transmitted directly to people’s TV through optical fiber and Co axial cable. In case of radio broad casting use of different frequency allow many channels to be distributed through same cable without separates wires for each. Here tuner of TV-VCR (Video-Cassette-Recorder). Since here a point is

operating like an antenna from where many house holds are taking cables so it is known as community antenna TV.

Plasma TV:

It is an emissive flat panel display. It is lighter and much thinner than traditional TV and video display .In Plasma TV light is emitted by phosphorous which is excited by plasma discharge between two flat panels of glass. Thickness of plasma is less than 10 cm. There is Neon and Xenon gas in plasma TV which is contained between hundred of tiny cells. Phosphorus in a plasma display give-off coloured light when they are excited. Contrast ratio of plasma TV is 5000:1. Main advantage of plasma TV is that a very wide screen can be produced using extremely thin materials. In plasma each pixel is lit individually so image is very bright and looks good from almost every angle.

Plasma state: It is an ionised gas and considered to be a distinct phase of matter, here ionised means at least one electron has been

disassociated from a significant fraction of molecule. Plasma are most common phase of matter and entire visible universe out side solar system is plasma.


It is a thin flat display device made of any number of colour or

monochrome pixels arrayed in front of a light source or reflector. It uses a very small amount of power and ie. Why suitable for use in battery

powered electronic devices. LCD works on concept of optical polariser. For colour LCD 3sub pixels are used which are coloured as red, green and


blue. Main advantage of LCD is less power consumption and its disadvantages are lower contrast ratio and larger response time. Analog&Digital TV:

Analog TV encodes television picture information as an analog signal ie. By varying the voltage or frequency of signal. Common Analog TV system are NTSC (National Television system Committee) and PAL(Phase

Alternating Line).

Digital TV uses digital modulation and compression to broad cast video audio and data signals. It can be used to carry more channels in some amount of bandwidth than analog TV and it receive high definition

programming. This digital signal eliminates common analog broad casting defects such as ghosting, static noise etcs.

Aspect ratio in case of digital TV is 16:9 while in analog it is 4:3. High-Definition-TV(HDTV):

It has higher resolution than traditional formats like NTSC, PAL etcs. HDTV is broadcasted generally and therefore coincides with introduction of digital TV. High definition means TV or display is able to accept video over a HDMI connection using a new connector known as HDMI. HDTV has aspect ratio of 16:9 and thus effective resolution is increased.

High Definition Multimedia Interface (HDMI):

It provides an interface between any compatible digital audio video/audio source such as set-top-box, DVD player and digital TV. HDMI supports standard, enhanced or high definition video plus multichannel audio on a single cable.

Direct to Home (DTH):

It is a term that describes satellite television service which is delivered via communication satellite.


It is a portion of electromagnetic spectrum in which electromagnetic waves can be generated by AC fed to an antenna. Generally RF range is between 3Hz-300GHz.

Sub-marine cable:

This is cable laid beneath the sea to carry telecommunication between countries. Normal radio communication can’t travel through thick conductors such as salt water. VLF(3-30 KHz) can penetrate sea water down to a depth of roughly 20 meter hence a submarine staying at shallow depth can use these frequencies.


It is an analog device that amplifies an input signal which may be either digital or analog. Repeaters are used in both copper wire cables and

optical fiber carrying light. Repeaters are used in broadcasting where they are known as booster.

FCC- Rules :( Federal Communication Commission)

These are certain rules and which governed all radio spectrums in world wide.

Short wave: (3MHz-30MHz)

Short wave frequencies are capable of reaching other side of planet because they can be reflected by ionosphere. SW are used for domestic broad casting in countries with a widely dispersed population and also for international broad casting.

Medium wave (300 KHz-3MHz)

It is standard AM broad cast band. These waves have property of

following curvature of earth i.e ground wave at all times and also reflect ionosphere. Medium wave is ideal for both local and continent worldwide. Long wave (<500KHz)

Frequency below 500 KHz in these wave follow curvature of earth unlike SW they don’t reflect or refract from ionosphere.


Different broad cast frequency: 1. AM radio :535-1605 KHZ(LF) 2. TV band-I :54MHz-88MHZ(VHF) 3. FM radio band-II: 88MHz-108MHz(VHF) 4. TV band-III: 174MHz-216MHz 5. TV band-IV&V:512MHz-806MHz(UHF) Audio frequency:

It has range between 20-20KHz. These range are audible to human ear. It contains bands ELF, SLF, ULF&VLF.

Nano technology:

This technology is based upon fact that properties of material becomes totally different when their size approaches that of a few hundred or tens of atoms. By control of matter at dimension of roughly 1-100nm property will change. 2 phenomenonas occur by going at that level.

1. Quantum confinement 2. Gibbs-Thomson effect.

So nano technology means there is plenty of room at bottom Wi-Fi:( Wireless-fidelity)

By this technique a computer/laptop/PDA will connect to internet. There is a hot spot which is radiating internet signals in air. Wi-Fi uses

IEEE802.11 standard. For access to internet person’s laptop must be wi-fi enabled. In this case hot-spot will broadcasts its SSID(Service Set

Identifier Network) via packets.

Wi-Max(Worldwide Interoperability of Microwave Access):

It is similar to wi-fi concept but it is used for long distance access. Wi-MAX is a wireless MAN. It is a network that connects IEEE 802.11(hot spot) with each other and to other parts of internet and provides a


of linear service area range and allows connectivity between users without a direct LOS.

ISDN: (Integrated service Digital Network)

It is a type of circuit switched telephone network which is designed to allow digital transmission of voice and data over ordinary telephone copper wires which result in better quality and higher speed than available with analog system. It provides simultaneous voice-data and text transmission between individual desktop ,video conferencing and group video conferencing systems.

Channels in ISDN:

B-channel are used for data and D-channels are intended for signalling and control but can be used for data also.

Access in ISDN:

There are two types of access to ISDN.

1. Basic Rate Interface (BRI): Here BRI consists of 2B channels with a B.W of 64Kbps and one D channel with a B.W of 16 Kbps. So BRI contains 2B+D

2. Primary Rate Interface (PRI): here PRI consists of large no of B channels and one D channel. PRI consists of 23B+D

Digital Subscriber-Line (DSL):

DSL is replacement of ordinary modem over same copper cable. So it is a family of technologies that provides digital data transmission over local telephone network. Down load speed ranges from 128 kbps to

24000kbps. It is a very high speed connection that uses same wire as regular telephone network.

Advantages of DSL Modem:

1. In this case one can leave interconnection open and can still use phone line for voice call.


2. Speed of DSL is higher than that of normal modem

3. DSL modem does not require new wiring and can use same phone line for internet connection.

Disadvantage of DSL modem:

1. DSL connection is better when you are closer to provider’s central office

2. Connection is faster for receiving data than for sending it over the internet

3. Service is not available every where ADSL-(Asymmetric Digital Subscriber Line):

Here data flow in 1direction is higher than data flow in other direction .Here down load speed is higher than upload speed. ADSL uses two frequency band

1. 25.875KHz-138KHz is used for upstream

2. 138KHz-1104KHz is used for down load speed.

VDSL-Very high bit rate DSL: It is used for high bit rate DSL

SDSL- Symmetric DSL: It is used mainly by business man. Receiving and sending data rate is same for both down load speed.

RADSL- Rate Adaptive DSL:

Variation of ADSL modem can adjust speed of connection depending upon length and quality of line.


It is combination of mechanical-engineering,

electronics-engineering& software- engineering. Mechatronics is related with self operating machine eg.robot.


Internet is a collection of interconnected computer networks linked by copper wires&fiber optics cables. While web is a collection of

interconnected documents linked by hyper links and URL and is accessible using internet. It is publically accessible worldwide system of

interconnected computer network which transmits data by packet

switching using a standardized Internet protocol (IP). Internet is based upon packet switching.

Internet was started as ARPANET in 1965 by DARPA (Defence Advance Research project Agency) which later grew as internet. ARPANET is Advanced Research Project Agency Network.

Internet protocol (IP):

These are certain rules which govern communication of data across a packet switched network.


It is a unique number that devices use in order to identify and

communicate with each other on a network utilizing internet protocol standard. Number currently used in IP address ranges from to Internet protocol knows each logical host interface by a number, the IP address on any given network.


It is a wireless internet service which is very popular in Japan. It was inspired by WAP developed in USA. I-mode was developed as an

expensive method of packet switched high speed communicaton. WAP :( Wireless Application Protocol)

It is an open international standard for application that uses wireless communication eg. internet access from a mobile phone. It is known protocol used for majority of world’s mobile internet sites.

POTS service: (Post office Telephone service )

ACARS :( Aircraft Communication Addressing and Reporting system):


It is a digital data link system for transmission of small message between aircraft and ground station via radio or satellite. It was protocol defined in 1970 and used telex format.

Mobiles phone are not allowed in aircraft because mobile phone could interfere with sensitive equipment on aircraft. Level of interference

depends upon phone system used and phone components in plane. Older analog phones transmit more power and so more interference.

Blue tooth:

It is a way to connect and exchange information between two devices like mobiles Mobile jammer:

,PC’s, laptops, printers and digital camera etc.It is available every where and i.e why called as globally available short range network. Both devices in this network must be blue tooth enabled.

General application of blue tooth:

It transfers file between 2 mobiles, laptop to laptop, 2 LANS can also be constructed keyboard to PC and between desk top and mice.

Mobile Jammer:

By use of mobile jammer mobile can’t transmit and receive signal from/to BTS. It is basically used for avoiding disturbances at temple, church etc. It works on very simple concept that is interference. This mobile jammer sends same frequency which mobile phone uses and this causes enough interference for mobile signal which make mobile signal very weak and finally not able to communicate with respective BTS.


For sending e-mail from one place to another important protocols used are SMTP and POP-3.

Working of E-mail:

Step-1: sender writes e-mail and his MUA(Mail-User-Agent)formats the message in internet e-mail format and a protocol SMTP sends it to local MTA(Mail-Transfer-Agent). Mail-Transfer-Agent is a computer program


that transfer e-mail message from one place to another place MTA is same as Mail-Exchange-Server.

Step-2: MTA looks up this domain name in DNS to find another MTA accepting message for that domain this another MTA is nothing but another Mail-Exchange-Server.

Step-3: Now message goes to User’s inbox from this MTA by use of SMTP protocol. So mail is reached in Modem and Codec:

Modem: For long distance transmission data should be in analog form because digital data can’t be sent for long distance. In case of digital

reprater, transformer can’t be used efficiently. But in general modulation used is Digital so to avoid this problem one will use Modem which will convert digital to analog on T side and analog to digital on R side. So by use of modem transmission is made easier over transmission channel. So Modem means modulation and demodulation both.

X x

Codec: It means coding/decoding or compression/decompression. Communication/Telecommunication: Exchanging information

between 2entities is known as communication if it is at long distance then it is known as telecommunication. If receiver is listening and understands every thing effectively then it is inbox from MTA by use of SMTP.

Step-4: Now user gets this e-mail by use of Post-Office-Protocol(POP-3) Difference between

called as effective communication. Various channel Access method:

FDMA: Frequency Division Multiplexing TDMA: Time Division Multiplexing

SSMA: Spread Spectrum Multiplexing SDMA: Space Division Multiplexing


CSMA: Carrier Sense Multiplexing

FDMA: In this case total bandwidth is divided into many bands of frequency and each subdivision/band has its own carrier frequency.

TDMA: In this case same frequency is divided into different time slots. This is generally used in mobile telephony.

GSM uses FDMA to prevent interference between outward and inward signals while TDMA is used to allow multiple handsets to work on a single cells.

SSMA: In this case energy generated at a single frequency is deliberately spread over a wide band of frequency. This concept is generally used in

mobile jammers.

SDMA: Here power is distributed in a particular direction which has more number of users. So directivity of antenna will be high in a

particular direction and low in another direction.So space division is according to situation or availability of users.

WDMA: when multiple optical carrier signals are multiplexed on a single optical fiber by use of different wavelengths of LASER light to carry

different signals.

Note: WDM is applied to optical carrier while FDM is applied to radio carrier. Both Radio and light are both forms of electromagnetic radiation.

CSMA: Transmitter listens for carrier wave before trying to send it, it tries to detect the presence of an encoded signal from another station before

attempting to transmit. Multiple access means multiple nodes send and receive on one medium.

Line code: it is a code chosen for use within a communication system for transmission purposes. This line code must not contain DC component

because transmission of DC component is not possible for long distance so line code is preferred for long distance communication. Example of line code are Uni-polar, Polar, Bi-polar and Manchester.


Manchester coding is one in which each bit of data is signified by at-least on transition. It is known as self clocking i.e accurate synchronisation of data stream is possible.

Pulse Code Modulation (PCM): It is a standard form of digital audio &video and is used in Compact Disc(CD). PCM is a digital representation of an analog signal where magnitude of signal is sampled regularly at uniform intervals and then quantized to a series of symbols in digital code.

MP-3 player: MPEG-1 audio layer-3 is a lossy compression format and it provides representation of PCM audio data in much smaller size by

compressing redundant terms. So MP-3 player is nothing but compressed form of PCM based digital audio.

Dolby sound: It is a trade mark for audio noise reduction system and other systems that improves performance and fidelity of audio recording. FM&PM: Frequency modulation and Phase modulation are two modulation techniques. FM is generally used at VHF radio frequency for high fidelity broadcasts of music and speech. Advantage of FM is that it is more robust against noise and interference and i.e why it is a high fidelity radio transmission. PM is not preferred because it requires more complex receiving hardware and there can be ambiguity problem of phase.

TV/Car remote control:

IR(Infra-red) transmission is used for this type of remote control. IR transmission is used for short range communication. Remote control

contains LED which transmits IR light and TV/car contains Si-Photo-diode. IR light from remote control falls on the photo diode of TV and this photo diode responds to IR light. Generally this photo diode responds only to rapidly pulsing signal created by transmitter.

IR radiations are useful for indoor use in areas of high population density and it cannot penetrate walls &so does not interfere with other devices in adjoining room.

I-MAX: It is a film projection system created by company called I MAX of Canada. It is 22 meter wide and 16 meter high.


Global-Positioning System (GPS): it is a satellite navigation system which is used to determine position of a target by use of a satellite

constellation of 24 satellite in intermediate circular orbit 20200Km. It is used for locating a target, vehicle and also used for surveying.

Vehicle tracking by GPS/GPS tracking:

Every vehicle will contain GPS receiver and calculates current position using process of trilateration after measuring distance to at least 4 satellite by comparing satellite coded time signal transmission. Here receiver calculates the orbit of each satellite based on information

encoded in their radio signals and measures distance to each satellite. So this data is recorded in this unit,this recorded data can be stored within tracking unit or it may be transmitted to a central location form where info can be send back to user after making it in user friendly form. Attenuation&distortion:

Attenuation means loss of signal and generally repeaters are used for compensating attenuation or loss. But repeaters amplify the noise along with the signal resulting in a poor signal to noise ratio.

Distortion means inaccurate reproduction of a signal caused by changes in signal’s waveform,either amplitude or frequency. To avoid distortion

equalizers are used and one type of equaliser used in analog environment is the load coil. By use of load coils frequency response is flatten.

Performance parameters in digital transmission:

In digital transmission system the quality of communication is mainly assessed by two factors:

1. Bit-Error-Rate 2. Jitter

BER :The BER is the measure of error bits with respect to total number of bits transmitted in a given time. The total number of bits transmitted can

be known from the bit rate of digital signal. For quality communication the requirement is not more than one error bit in one million bits.


Short term variation of the significant instances of digital signal from their corresponding reference positions is referred to as jitter.




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Outline : Microwave oven: