Are you going for interview then this article may useful for you. Because here we are giving some important technical question and answers for C language. As we know C language is most important language. When ever you go for interview the first question would C language. C language is basic programming language for computer science and engineering. Here i will share some most frequently question that may be asked in interview. We always thought that we know everything but before going to interview we should recall all topics than only we can reply to them. When you prepared each and everything you may get more confidence. That’s why here i am providing some important questions and answers for c language.  

C  Programming Interview Question and Answers for Placement

1. What are the C tokens?

Ans. There are Six Classes of tokens: Identifier, Keywords, Constants, Strings, Literals, Operators and separator.

2. What is C Identifier?

Ans. These are names given to various programming elements such as variables, functions, arrays. It is a combination of letter. Back space is not allowed.

3. What is the difference between syntax error and Logical error?

Ans.  Syntax error: –  These involves Validation of syntax of language compliers prints diagnostic message.

Logical Error:- Logical error are caused by an incorrect algorithm by a statement mis- typed  in a such a way that difference.

4. What are the facilities provided by pre processor?

Ans. File inclusion, substitution facilities, conditional compilation.

5. What do the functions like atoi(), itoa(), gevt() ?

Ans.  Atoi() is a macro that converts integer to character.

Itoa() is converts integer to string

Gevt() it converts a floating point number to string.

6. What is a file?

Ans. A file is a region of storage in hard disks or in auxiliary storage devices. It contains bytes of information it is not a data type.

7. What is a function?

Ans.  A large program is subdivided into a number of smaller programs or subprograms. Each sub programs specifies one or more actions to be performed for the larger programs. Such sub programs are called functions.

8. Difference b/w formal arguments and actual arguments?

Ans. Formal arguments are the arguments available in the function definition. They are preceded by their own data types. Actual arguments are available in the function call. These arguments are given as constants or variables or expressions to pass the values to the functions.

9. What are the uses of a pointer?

• It is used to access array elements
• It is used for dynamic memory allocation
• It is used in data structures like trees, graph, linked list ect.
• It is used in call by reference.

10. What is storage class? What are the different storage classes in C?

Ans. Storage class is an attribute that changes the behavior of a variable. It controls the lifetime, scope and linkages. The storage classes in c are auto, register, and external static, type def.

11. Differentiate b/w a for loop and a while loop?

Ans. For Executing a set of statements fixed number of times we use for loop while when the number of iterations to be. Performed is not known in advance we use while loop.

12. What is enumeration?

Ans. They are list of named integer- valued constants. Example:- enum color{black, orange=4,y,g, b, v}, the difference b/w an enumeration and a macro is that the enum actually declares a type and therefore can be type checked.

13. What are static memory allocations?

Ans. Compiler allocates memory space for a declared variable. By using the address of operator, the reserved address is obtained and this address is a signed to a pointer variable. This way of assigning pointer value to a pointer variable at compilation time is known as static memory allocations.

14. What is dynamic memory allocation?

Ans.   A dynamic memory allocation uses functions such as malloc() or calloc() to get memory dynamically. If these functions are used to get memory dynamically and the values returned by these functions are assigned to pointer variables, such a way of allocation memory at run time is known as dynamic memory allocations.

15. Difference b/w pass by reference and pass by value?

Ans. pass by reference passes a pointer to the value. This allows the calloc to modify the variable directly pass by value gives a copy of the value to the calloc. This allows the calloc to modify the value without modifying the variable.

16. What are library functions?

Ans. Library functions are predefined functions and stored in .lib files

17. What is structure?

Ans. Structure is a collection of heterogeneous held together to a single unit. The data items enclosed within A Structure are called it’s members which may be of data type int, float, char, array ect.

18. What is the difference between arrays and linked list?

Ans. Major Difference between arrays and linked lists are in array consecutive elements are stored in consecutive memory locations where as in linked list it not so. In array address of next element is consecutive and where as in linked list it is specified in the address part of each mode. Linked list makes better use of memory in array. Insertion or deletion of an element in array is difficult than insertion or deletion in liked list.

19. Where are the auto variables stored?

Ans. Auto variables are stored in main memory and their default value is a garbage value.

20. What is the use of typedef?

Ans. It increase the portability. It simplify the complex declaration and improve readability of the program.

21. Why n++ executes faster than n+1 ?

Ans. The expression n++ requires a single machine instruction such as INR to carry out the increment operation whereas, n+1 requires more instructions to carry out this operation.

22. What is dangling pointer in c?

Ans.  If any pointer is pointing the memory address of any variable but after some variable has deleted from that memory location while pointer is still pointing such memory location. Such pointer is known as dangling pointer and this problem is known as dangling pointer and this problem is known as dangling pointer and this problem is known as dangling pointer problem.

23.  What is a pointer?

Ans. Pointer is a variable that contains address of another variable in the memory. Pointers are quite useful in creation of linked data structures (such as linked list, trees, graphs), managing object allocated memory dynamically, optimize the program to execute faster and use less memory.

24. What are the techniques you use for debugging?

Ans. Using compiler’s features , read the fine module, printf() debugging. Code grinding, assertion.

25. What are macros? What are its advantages and disadvantages?

Ans. Macro is a pre-processor. A major advantage of using the macro is to increase the speed of the execution of the program. Disadvantage of the macros are no type checking is performed in macro. A macro call may cause unexpected results.

26. What are segment and offset addresses?

Ans. When paging technique is performed, the page will break into segments and it’s sequence is said to be segments and its  width can be said to be said as offset, in short segment is physical addresses and offset is logical address.

27.  How many types of scope in c ?

Ans. There are totally four scopes are block scope, function scope, file scope, program scope.

28. what is the difference between calloc () and malloc ()?

Ans. Calloc () allocates a block of memory for an array of elements of certain size. by default the block is initialized too. the tatal number of memory allocated will be number of elements*size.

Malloc () takes in only a single arguments which is the memory required in bytes, malloc allocated bytes of memory and not blocks of memory like calloc ().

Now do not even bother about any topic. We have covered all topics for c language. These questions and answers are most frequently asked in interview. Just prepared well and crack the interview. Do not think about anything just be confident.

Hi, friends How have you been, i hope everything fine. If you are searching like final year projects for ECE students then this post may useful for you because here i am giving best projects for electronics and communication final year students. I can understand your intension that how to choose best project topic. Now you do not need to take any tension because here i am giving best project topics for final year students. even i have covered all topics. Would like to know more about project topics just have a look here i will give you full list of best projects for ECE final year students

1000 Best Electronics and Communication Engineering projects

Here you will get full information about best projects for ECE students. As we know final year project is very import for one and all. We need to take serious about this matter. Just follow here you will get some idea about final year projects.

Final year Electronics and Communication Engineering Projects Topics

• Auto Intensity Control of Street Lights
• Automatic Irrigation System on Sensing Soil Moisture Content
• Programmable Switching Control for Industrial Automation in Repetitive Nature of Work
• Automatic Wireless Health Monitoring System in Hospitals for Patients
• Precise Digital Temperature Control
• Optimum Energy Management System
• Security System Using Smartcard Technology
• PC Based Electrical Load Control
• Secret Code Enabled Secure Communication Using RF Technology
• Density Based Traffic Signal System
• Line Following Robotic Vehicle
• TV Remote Operated Domestic Appliances Control
• Password Based Circuit Breaker
• Programmable Load Shedding Time Management for Utility Department
• Object Detection by Ultrasonic Means
• Street Light that Glows on Detecting Vehicle Movement
• Tampered Energy Meter Information Conveyed to Concerned Authority by Wireless Communication
• Distance Measurement by Ultrasonic Sensor
• Portable Programmable Medication Reminder
• Programmable Energy Meter for Electrical Load Survey
• Security System With User Changeable Password
• Networking of Multiple Microcontrollers
• Solar Powered LED Street Light with Auto Intensity Controllers
• SCADA (Supervisory Control & Data Acquisition) for Remote Industrial Plant
• Parallel Telephone Lines with Security System
• Using TV Remote as a Cordless Mouse for the Computer
• Movement Sensed Automatic Door Opening System
• Railway Level Crossing Gate Control through SMS by the Station Master or the Driver
• GSM Based Monthly Energy Meter Billing via SMS
• DTMF Based Load Control System
• Synchronized Traffic Signals
• Pick N Place with Soft Catching Gripper
• Fire Fighting Robotic Vehicle
• War Field Spying Robot with Night Vision Wireless Camera
• Theft Intimation of the Vehicle Over SMS to Owner Who Can Stop the Engine Remotely
• Closed Loop Control for a Brushless DC Motor to Run at the Exactly Entered Speed
• Automatic Surveillance Camera Panning System from PC
• Flash Flood Intimation Over GSM Network
• RFID security access control system
• Integrated Energy Management System Based on GSM Protocol with Acknowledgement Feature
• Cell Phone Based DTMF Controlled Garage Door Opening System
• Display of Dialed Telephone Numbers on Seven Segment Displays
• Non Contact Tachometer
• RFID based attendance system
• Line Following Robotic Vehicle Using Microcontroller
• Automatic Dialing to Any Telephone Using I2C Protocol on Detecting Burglary
• Life Cycle Testing of Electrical Loads by Down Counter
• GSM Based Energy Meter Reading with Load Control
• BLDC Motor Speed Control with RPM Display
• Predefined Speed Control of BLDC Motor
• Stamp Value Calculator for Postage Needs
• Dish Positioning Control by IR Remote
• Hidden Active Cell Phone Detector
• Long Range FM Transmitter with Audio Modulation
• Railway Track Security System
• Sun Tracking Solar Panel
• Remote Jamming Device
• Wireless Electronic Notice Board Using GSM
• IR Obstacle Detection to Actuate Load
• Automatic Dusk to Dawn (Evening on to Morning Off)
• Rhythm Following Flashing Lights
• Thermistor Based Temperature Control
• Object Counter with 7 Segment Display
• Incoming Phone Ring Light Flasher
• Solar Power Charge Controller
• Wire Loop Breaking Alarm Signal
• Video Activated Relay to Control the Load
• Touch Controlled Load Switch
• Time Delay Based Relay Operated Load
• Electronic Eye Controlled Security System
• Fastest Finger Press Quiz Buzzer
• Pre-programmed Digital Scrolling Message System
• Speed Checker to Detect Rash Driving on Highways
• Home Automation Using Digital Control
• Four Quadrant DC Motor Speed Control with Microcontroller
• Intelligent Overhead Tank Water Level Indicator
• Speed Synchronization of Multiple Motors in Industries
• Pre Stampede Monitoring and Alarm System
• Unique Office Communication System Using RF
• PC Controlled Scrolling Message Display for Notice Board
• Touch Screen Based Industrial Load Switching
• Touch Screen Based Home Automation System
• Speed Checker to Detect Rash Driving on Highways
• RF Based Home Automation System
• Wireless message Communication Between Two Computers
• Obstacle Avoidance Robotic Vehicle
• Solar Powered Auto Irrigation System
• Auto Metro Train to Shuttle Between Stations
• Touch Screen Based Remote Controlled Robotic Vehicle for Stores Management
• Metal Detector Robotic Vehicle
• RFID Based Passport Details
• Beacon Flasher Using Microcontroller
• Discotheque Light Stroboscopic Flasher
• IR Controlled Robotic Vehicle
• Automatic Bell System for Institutions
• Cell Phone Controlled Robotic Vehicle
• RFID Based Device Control and Authentication Using PIC Microcontroller
• Theft Intimation of Vehicle Over SMS to Owner Who Can Stop the Engine Remotely
• Street Light that Glows on Detecting Vehicle Movement
• Density Based Traffic Signal System Using PIC Microcontroller
• Solar Energy Measurement System

I hope you have selected best topic for your final year project. If you want to know more about particular topic you can find out very easily because there are so many website where you can get free projects for ECE, Free Mini projects, Free final year projects etc.

Bill Gates Quotes

There are so many things that we want to do in our life. Every one has own role models in their life. My role model is Mr. Bill Gates. I always admire the way he work hard to achieve his dreams. At starting stage we face so many struggles but really thing is how much we learn from them. There is so much of dedication towards his work.  You know what once upon a time he was very poor man. He was hardly having any money on his pocket. He was obviously not success at that time, but now he is one who started Microsoft Company.  Now he is one of the most popular and richest people in the world. Today here I am giving bill gates quotes about life, success, failures and technology ideas ect. When you read these quotes you feel like there is so much of inner meaning of his words. Even you get to know about his beyond feelings.

Top Best Bill Gates Quotes

Bill Gates Quotes about Life

• Life is not fair, get over it.
• If you cannot make it good at least make it look good.
• Before you were born, your parents weren’t as boring as they are now. They got that way from paying your bills, cleaning your clothes and listening to you talk about how cool you thought you were. So before you save the rain forest from the parasites of your parent’s generation, try delousing the closet in your own room.
• Most people overestimate what they can do in one year and underestimate what they can do in ten years.
• I really had a lot of dreams when I was a kid, and I think a great deal of that grew out of the fact that I had a chance to read a lot.

Bill Gates Quotes about Success

• Its fine to celebrate success but it is more important to heed the lessons of failure.
• As we look ahead into the next century, leaders will be those who empower others.
• if you are born poor its not your mistake, But if you die poor its your mistake.
•  Our success has really been based on partnerships from the very beginning.
• Success is a lousy teacher. It seduces smart people into thinking they can’t lose.
•  When you have money in hand,only you forget who are you .But when you do not have any money in your hand,the whole world forget who you are.It’s life.

Bill Gates Quotes about Failures

• I failed in some subjects in exam, but my friend passed in all. Now he is an engineer in Microsoft and i am the owner of Microsoft.
• The vision is really about empowering workers giving them all the information about what’s going on so they can do a lot more than they’ve done in the past.
• I have been struck again and again by how important measurement is to improving the human condition

Bill Gates Quotes about Technology

• The first rule of any technology used in a business is that automation applied to an efficient operation will magnify the efficiency. The second is that automation applied to an inefficient operation will magnify the inefficiency.
• Technology is just a tool. In terms of getting the kids working together and motivating them, the teacher is the most important.
• Success is a lousy teacher. It seduces smart people into thinking they can’t lose.
• The Internet is becoming the town square for the global village of tomorrow.
• Software is a great combination between artistry and engineering.

Bill Gates Inspirational Quotes

• Don’t compare yourself with anyone in this world…if you do so, you are insulting yourself.
• I choose a lazy person to do a hard job. Because a lazy person will find an easy way to do it.
• Your most unhappy customers are your greatest source of learning.
• I studied everything but never topped…. But today the toppers of the best universities are my employees
• Success is a lousy teacher. It seduces smart people into thinking they can’t lose

Bill Gates Quotes in Hindi

• चाहे आपमें कितनी भी योग्यता क्यों न हो, केवल एकाग्रचित्त होकर ही आप महान कार्य कर सकते हैं।
• आपके सबसे असंतुष्ट ग्राहक आपके सीखने का सबसे बड़ा स्त्रोत हैं।
• सफलता एक घटिया शिक्षक है। यह लोगों में यह सोच विकसित कर देता है कि वो असफल नहीं हो सकते।
• अपने आप की तुलना किसी से मत करो, यदि आप ऐसा कर रहे है तो आप स्वयं अपनी बेइज़्ज़ती कर रहे है।
• जब आपके हाथ में पैसा होता है तो केवल आप भूलते है की आप कौन है लेकिन जब आपके हाथ खाली होते है तो सम्पूर्ण संसार भूल जाता है की आप कौन है।
• सफलता की खुशियां मनाना ठीक है लेकिन असफलताओं से सबक सीखना अधिक महत्वपूर्ण है।
• हमें अपने पैर पर खड़े रहने के लिए गूगल बिंग जैसे ब्रांड से प्रेरणा लेते हैं।
• यदि आप गरीब जन्मे है तो यह आपकी गलती नहीं है लेकिन यदि आप गरीब मरते है तो यह आपकी गलती है।
• यह सही हैं की सफलता का जश्न आप मनाये पर अपने पुराने बुरे समय को याद रखते हुए।
• जीवन न्याययुक्त नहीं है, इसकी आदत डाल लीजिये।
• मैं एक कठिन काम को करने के लिए एक आलसी इंसान को चुनुंगा क्योकि आलसी इंसान उस काम को करने का एक आसान तरीका खोज लेगा।
• अगर मैं पहले से कोई अंतिम लक्ष्य बना के चलता तो क्या आपको नहीं लगता है कि मैं उसे सालों पहले पूरा कर चुका होता।
• बेवकूफ बनकरखुश रहिये और इसकी पूरी उम्मीद हैं की आप अंत में सफलता प्राप्त करेंगे।
• निसंदेह मेरे बच्चों के पास कम्प्यूटर होगा लेकिन पहली चीज़ जो वो प्राप्त करेंगे वो बुक्स (पुस्तकें) होगी।
• जीवन सेमेस्टर में विभाजित नहीं है। आपको गर्मियों में छुट्टी नहीं मिलती है और कुछ नियोक्ता आपको अपने आप को खोजने में मदद करने में रुचि रखते हैं।

• यदि   जनरल मोटर्स कम्प्यूटर  इंडस्ट्री  के  हिसाब  से  अपनी  टेक्नोलॉजी  का  विकास  करता  तो  आज  हम  $25 की  कार  चला  रहे  होते  जो  1000 माईल्स पर गैलन के  हिसाब  से  चलती।
• अगर आप अच्छा नहीं बना सकते तो कम- से- कम ऐसा तो कीजिए कि वह अच्छा दिखे।
• अगर हम अगली सदी की तरफ देखें तो लीडर वो होंगे जो दूसरों को शशक्त बना सकें।
• एक अच्छा पेशेवर इंजीनियर बनने के लिए आपको अपनी परीक्षा की तैयारी हमेशा देर से शुरू करनी चाहिए क्योंकि यह आपको समय को मैनेज करना और इमरजेंसी को हैंडल करना सिखाएगा।
• मेरा विश्वास है की यदि आप लोगो को समस्याएं दिखाओंगे और उनका हल सुझाओगे तो लोग उसको अपनाने के लिए आकर्षित होंगे।
• टीवी वास्तविकता से परे है। वास्तविक जीवन में लोगों को नौकरी पर जाना पड़ता है बजाए कैफे में बैठने के।
• उम्मीदे प्रथम श्रेणी के सत्य का एक रूप है : यदि लोग ऐसा विश्वास करते है तो यह सच है।
• रोकथाम के बिना उपचार अस्थायी है।
• हम सभी को ऐसे लोगों की जरूरत है जो हमे फीडबैक (प्रतिक्रिया) दे सके। क्योंकि इन्ही के कारण हम सुधार करते है।
• ऐसे लोग हैं जिन्हें पूँजीवाद पसंद नहीं है, और ऐसे लोग भी हैं जिन्हें पर्सनल कम्प्यूटर्स पसंद नहीं है। पर ऐसा कोई भी नहीं है जिसे पी सी पसंद हो और वो माइक्रोसोफ्ट को पसंद ना करता हो।
• चाहे वो गूगल हो या एप्पल या फ्री सौफ्टवेयर, हमारे कुछ शानदार प्रतिस्पर्धी हैं जो हमें चौकन्ना रखते हैं।
• जलवायु परिवर्तन एक भयानक समस्या है, और इसे पूरी तरह से हल किया जाना चाहिए।यह एक बड़ी प्राथमिकता होनी चाहिए।
• अक्सर आपको अपने अंतर्ज्ञान पर ही भरोसा करना होगा।
• व्यापार, कुछ नियमो आर बहुत सारे जोखिम के साथ एक पैसों का खेल (मनी गेम) है।
• मैं परीक्षा में कुछ विषयो में फ़ैल हो गया। और मेरे सभी दोस्त पास हो गये !अब वे माइक्रोसॉफ्ट कम्पनी में इंजीनियर है और मै माइक्रोसॉफ्ट कम्पनी का मालिक हूँ।
• हर व्यक्ति को एक कोच की जरुरत होती है।  इससे कोई फर्क नहीं पड़ता की आप एक बास्केटबाल, एक टेनिस खिलाडी, एक पहलवान या एक ब्रिज प्लेयर है।
• टेक्नोलॉजी केवल मात्र एक औजार है जो बच्चों को एक साथ काम करने के लिए पास लाते है पर जहां तक बात बच्चों को प्रेरित करने की है तो शिक्षक सबसे महत्तवपूर्ण है।
• हालाँकि मुझे दूसरों को क्या करना चाहिए, के बारे में बात करने का कोई अधिकार नहीं है, मुझे लगता है कि मैं बहुत भाग्यशाली रहा हूँ और एक बहुत ही महत्वपूर्ण तरीके से समाज को वापस देने के लिए एक जिम्मेदारी महसूस कर रहा हु।
• बोधिक  सम्पदा किसी केले की बाहरी खोल की तरह होती हैं।

Your worst Mistakes can help you make the best decisions in the future. if you are wise through to learn from them. There are two important  key aspect that every one should remember one is never feel to reject anything and never give up to anyone. These are best bill gates quotes for life, success and failure. i hope you enjoy the above article.

SO these are some of the famous quotes of Bill Gates. Here i have posted bill gates quotes in English and Hindi about Life, Success and motivation. Hope you like these Bill gates quotes.

Hey guys here we brought some Electronics Engineering (ECE) Interview Questions and Answers. It’s a very difficult to study all topics that’s why  here we covered all subjects. These questions are asking most frequently during interview time.  You can covered all subjects at very short period of time. We all know during interview time what’s the situation so be prepare in advance. There is a solution to every problem. Do not take tension just be prepare your self and make it more strong than you. If you do not have any idea about technical questions just take a look here i will share with you some technical interview questions and answers for freshers.

Electronics and Communication Engineering (ECE) Interview Questions and Answers

1.What is analog-to-digital conversion of signals?

A discrete-time signal is defined by specifying its value only at discrete times, called sampling instants. When the sampled values are quantized and encoded, a digital signal is obtained. A digital signal is obtained from the analog signal by using an analog-to-digital converter. This entire process is referred to as the conversion of signals from analog to digital form.

2.What are the properties of ROC for z-Transform?

Properties of the ROC for the z-Transform:

X(z) converges uniformly if and only if the ROC of the z-transform X(z) of the sequence includes the unit circle. The ROC of X(z) consists of a ring in the z-plane centered about the origin. That is, the ROC of the z-transform of x(n) has values of z for which x(n) r-n is absolutely assumable.

• The ROC does not contain any poles.
• When x(n) is of finite duration then the ROC is the entire z-plane, except possibly z=0 and/or z=infinity.
• If x (n) is a right sided sequence, the ROC will not include infinity.
• If x (n) is a left sided sequence, the ROC will not include z=0. However if x(n)=0 for all n>0, the ROC will include z=0.
• If x (n) is two sided and if the circle |z| = r0 is in the ROC, then the ROC will consist of a ring in the z-plane that includes the circle |z|=r0.
• If X (z) is rational, then the ROC extends to infinity, i.e. the ROC is bounded by poles.
• If x (n) is causal, then the ROC includes z=infinity.
• If x (n) is anti- causal, then the ROC includes z=0.

3.What are the functions of Base Station System (BSS)?

Functions of BSS are as follows:

• Radio path control.
• BTS and TC control.
• Connection establishment with MS-NSS.
• Mobility management, speech transcending.
• Connection of statistical data.

4.What are the parts of Network Management System (NMS)?

Following are the parts of network management system:

• OMC: Operation and maintenance center – Computerized monitoring center.
• NMC: Network Management Center – Centralized control of a network is done here.
• OSS: Operation and support system – Used for supporting activities performed in an OMC and/or NMC.

5.What are applications of DSP?

Some selected applications or digital signal processing that are often encountered in daily life are listed as follows:

• Telecommunication: Echo cancellation in telephone networks.
• Military Radar signal processing
• Consumer electronics Digital Audio/TV
• Instrumentation and control
• Image processing image representation, image compression
• Speech processing speech analysis methods are used in automatic speech recognition
• Medicine Medical diagnostic instrumentation such as computerized tomography (CT)
• Seismology DSP techniques are employed in geophysical exploration for oil and gas.
• Signal Filtering Removal of unwanted background noise.

6.What are the drawbacks of Walsh codes?

Walsh codes have the following drawbacks:

• The codes do not have a single, narrow auto correlation peak.
• The spreading is not over the whole bandwidth; instead the energy is spread over a number of discrete frequency components.
• Although the full sequence cross correlation is identically zero, this does not hold for a partial sequence cross correlation function. Thus advantage of using orthogonal codes is lost.
• Orthogonality is also affected by channel properties like multi path.

7. Explain radio environment in building.

• Building penetration: Building penetration depends on the material used for construction and architecture used. This varies building to building and is based on building construction.
• Building Height Effect: The signal strength is always higher at top floor and generally floor gain height is about 2.7dB/floor which is not dependent on building construction.
• Building Floor Reception: The signal isolation between floors in a multi floor building is on the average about 20dB. Within a floor of 150 * 150 feet, the propagation loss due to interior walls, depending on the wall materials is about 20 dB between the strong and the weak areas.

8. List some advantages of GSM.

Here are some advantages of GSM:

• GSM is mature; this maturity means a more stable network with robust features.
• Less signal deterioration inside buildings.
• Ability to use repeaters.
• Talk time is generally higher in GSM phones due to pulse nature of transmission.
• The availability of Subscriber Identity Modules allows users to switch networks and handset at will.
• GSM covers virtually all parts of world so international roaming is not a problem.

9. What are the various types of numbers for network identity?

Various types of number for network identity are as follows:

• MSISDN (Mobile station ISDN) Number: It is international mobile subscriber number which is normally called mobile number. It is unique worldwide.
• MSRN (Mobile Subscriber Routing Number) : MSRN is used during mobile terminate trunk call to provide location of mobile subscriber.
• HON (Hand Over Number) : HON is used for providing information required to transfer call from one B?SC to another BSC or to another MSC.
• ISMI (International Mobile Subscriber Identity Number) : Purpose of ISMI is for location update and authentication.
• TMSI (Temporary Mobile Subscriber Identity) : TMSI is used instead of IMSI to improve security efficiency of network.
• IMEI : International Mobile Equipment Identity.

10.What are GPRS services?

GPRS services are defined to fall in one of the two categories:

• PTP (Point to point)
• PTM (Point to Multi point)

Some of the GPRS services are not likely to be provided by network operators during early deployment of GPRS due in part to the phased development of standard. Market demand is another factor affecting the decision of operators regarding which services to offer first.

11.What are the advantages of CDMA?

Advantages of CDMA are as follows:

• Frequency diversity: Transmission is spread out over a large bandwidth due to that less affected by noise. If bandwidth is increased S/N ratio increases, which means noise will be reduced.
• Multiplication Resistance: Chipping codes used for CDMA not only exhibit low correlation but also low auto correlation. Hence a version of the signal that is delayed by more than one chip interval does not interfere with dominant signal as in other multi path environments.
• Privacy: Due to spread spectrum is obtained by the use of noise like signals, where each user has a unique code, so privacy is inherent.
• Graceful Degradation. In CDMA, more users access the system simultaneously as compared to FDMa, TDMA.

12.What are the advantages of spread spectrum?

Spread spectrum has the following advantages:

•  No cross talk interference.
• Better voice quality/data integrity and less static noise.
• Lowered susceptibility to multi path fading.
• Inherent security.
• Co-existence.
• Longer operating distances.
• Hard to detect.
• Hard to intercept or demodulate.
• Harder to jam than narrow bands.
• Use of ranging and radar.

13. Explain the steps involved in demodulating a signal.

Once the signal is coded, modulated and then sent, the receiver must demodulate the signal. This is usually done in two steps: Spectrum spreading (e.g., direct sequence or frequency hopping) modulation is removed.The remaining information bearing signal is demodulated by multiplying with a local reference identical in structure and synchronized with received signal.

14. How can a Pseudo Random Noise Code be usable?

To be usable for direct sequence spreading, a PN code must meet the following conditions:

• Sequence must be built from 2 leveled numbers.
• The codes must have sharp auto correlation peak to enable code synchronization.
• Codes must have a low cross-correlation value, the lower it is, more are the number of users which can be allowed in the system.
• The codes should be “balanced” i.e. the difference between ones and zeros in code may only be one.

15.What are different categories of antenna and give an example of each?

Different categories of antenna are as follows:

• Wire Antennas – Short Dipole Antenna
• Micro strip Antennas – Rectangular Micro strip (Patch) Antennas
• Reflector Antennas – Corner Reflector
• Travelling Wave Antennas – Helical Antennas
• Aperture Antennas – Slot Antenna
• Other Antennas – NFC Antennas

16.What is handover and what are its types?

Handover in mobile communication refers to the process of transferring a call from one network cell to another without breaking the call. There are two types of handover which are as follows:

•     Hard Handoff: hard handoff is the process in which the cell connection is disconnected from the previous cell before it is made with the new one.
• Soft Handoff: It is the process in which a new connection is established first before disconnecting the old one. It is thus more efficient and smart.

17. What is ionospheric bending?

When a radio wave travels into the ionospheric layer it experiences refraction due to difference in density. The density of ionospheric layer is rarer than the layer below which causes the radio wave to be bent away from the normal. Also the radio wave experiences a force from the ions in the ionospheric layer. If incident at the correct angle the radio wave is completely reflected back to the inner atmosphere due to total internal reflection. This phenomenon is called ionospheric reflection and is used in mobile communication for radio wave propagation also known as ionospheric bending of radio waves.

18.What is CDMA?

CDMA stands for Code Division Multiple Access which uses digital format. In CDMA systems several transmissions via the radio interface take place simultaneously on the same frequency bandwidth. User data is combined at the transmitter’s side with a code, then transmitted. On air, all transmission get mixed. At the receiver’s side the same code is used as in the transmitter’s side. The code helps the receiver to filter the user information of the transmitter from incoming mixture of all transmissions on the same frequency band and same time.

19.Explain the concept of frequency re-use.

The whole of the geographical area is divided into hexagonal shape geometrical area called cell and each cell having its own transceiver. Each BTS (cell site) allocated different band of frequency or different channel. Each BTS antenna is designed in such a way that i cover cell area in which it is placed with frequency allotted without interfering other sell signal.

20.Explain Bluetooth.

Bluetooth is designed to be a personal area network, where participating entities are mobile and require sporadic communication with others. It is Omni directional i.e. it does not have line of sight limitation like infra red does. Ericsson started the work on Bluetooth and named it after the Danish king Harold Bluetooth. Bluetooth operates in the 2.4 GHz area of spectrum and provides a range of 10 meters. It offers transfer speeds of around 720 Kbps.

These are the questions and answers for Electronics and communication engineering. I have covered all important topics. you can easily crack the interview. Now be prepared with these question and answer in interview.