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INTRODUCTION TO PROGRAMMING(IP)

QUESTION BANK

UNIT-1:

Short Answer Questions:

1. What are variables in C?
2. Write keywords in C.
3. What are constants in C?
4. What is meant by pseudo code?
5. Difference between machine language and assembly language.
6. Write two differences of source file, header file, object file and executable files.
7. What is the difference between compiler and linker?
8. What is an assembler?

Long Answer Questions:

1. Illustrate Basic data types in C.7M.
2. Illustrate Implicit(write about type conversion) & Explicit Type Casting (write about type casting) in ‘C’ programming.
3. Explain about Bitwise and Logical operators in C programming with necessary examples.5M.
4. Write in detail about operators in C(all the Operators).10M.
5. Explain about Operator precedence and associativity.7M.
6. Sketch Block Diagram of computer. Explain in detail about it or Explain Basic Organization of a Computer.5M.
7. Explain how Memory is categorized in a Computer(write about Memory, Primary Memory, Secondary Memory).5M.
8. Discuss the structure of C program with a neat sketch.7M.
9. Define Algorithm. Write the Algorithm to add, subtract two numbers. 5M.
10. Explain Type conversion with an example.5M.
11. Differences between RAM and ROM.5M.
12. What are the characteristics of Algorithms? 5M.
13. What are variables in C? Explain initialization of variables with some examples.5M.
14. What is a flow chart? Explain the blocks of a flow chart with necessary explanation.7M.
15. Write the advantages and disadvantages of Algorithms.6M.

UNIT-2:

Long Answer Questions:

1. Design and develop a C program to reverse of an integer number NUM and check whether it is PALINDROME or NOT.10M.
2. Write a C program to find even and odd number using if-else.7M.
3. Write a C program to find a number as prime number or not using for loop.7M.
4. Write a C program to find the Factorial of a number using for loop.7M.
5. Write a C program on Simulation of a calculator using switch case.7M.
6. Write a C program to find a vowel and consonant using switch case.7M.
7. Write a C program to compare two numbers using if-elseif-else.7M.
8. Give the syntax and flow chart(or construct) of if statement in C programming. 5M.
9. Give the syntax and flow chart(or construct) of if-else statement in C programming.5M.
10. Give the syntax and flow chart(or construct) of switch statement/case in C programming.5M.
11. Explain the usage of break and continue statements in C programming with example program.7M.
12. Write the differences between While and Do-while loops with necessary example program.7M.
13. Give the syntax and flow chart(or construct) of for loop in C programming.5M.
14. Write a short note on Nested if with an example program.7M.

UNIT-3:

Long Answer Questions:

1. What is memory model or memory representation of arrays? Explain with an example.6M.

Ans.  The Memory representation of an integer array is explained using the following example.

An array of size 15 is declared in a C program as follows and the data type takes 2 bytes of memory. It means the declared array is of type integer array.

2. What is a string?Write the syntax of string manipulation functions strlen( ),strcmp(  ),strcat(  ) and strcpy(  ) . and write an example program for each function. 10M.
3. Write a ‘C’ program to remove duplicate elements from a given array.7M.
4. Illustrate two-dimensional arrays and declaration(row and column major order is not required) of two dimensional arrays with an example program.
5. Write a program on linear search of array elements.
6. What are multidimensional arrays in C? Where are multidimensional arrays used? How does memory allocation take place for a multidimensional array in C.
7. Define array. Write a short note on access the elements of an array with an example program.
8. Write a C program to find the length of the given string without using string handling functions. 7M.
9. How to declare, initialize and access arrays in C? Give example.6M.
10. Write in detail about the following functions of strings scanf function, getchar( ), getch( ) or getche(  ),putchar(  )10M.
11. Write the differences between gets( ) and puts( ) with an example program.5M.
12. Write a C program that Implements string copy operation STRCOPY (str1, str2) that copies a string str1 to another string str2 without using library function.
13. Program on array of strings or program to access student names using strings.7M.
14. Write a short note on Array of strings.5M.
15. Program to concatenate two strings without built-in functions.7M.
16. With a neat sketch, explain the memory representation of single and multi dimensional arrays in C programming.10M.
17. An integer array of size 15 is declared in a C program. The memory location of the first byte of the array is 2000. What will be the location of the 13th element of the array? Assume int data type takes 2 bytes of memory.

Ans. An integer array of size 15 is declared in a C program as follows. And the data type takes 2 bytes of memory. It means the declared array is of type integer array.

The Memory representation of array is given in the figure, the location of the 13th element of the array is arr[12] is 13and its address is 2024.

UNIT-4:

Long Answer Questions:

1. Write a short note on pointer arithmetic. Write a C program on Pointer arithmetic. 10M.
2. Compare and contrast structures and unions.7M.
3. Explain pointer expressions. Explain different arithmetic operations that can be performed on pointers with examples.7M.
4. Why do we need to create nested structures in C programming? Explain with an example C program.10M.
5. Program to display students data using unions7M.
6. Program on Accessing the members of a structure or program to display students data using structures.10M.
7. Develop a C program to access the students data by using array of structures.10M.
8. What is a pointer? Illustrate declaration of pointers with an example.7M.
9. Explain the utility of ‘typedef’ keyword. Write a program to illustrate it.7M.
10. What is dynamic memory allocation? Write and explain the different dynamic memory allocation functions in C. 7M
11. Write a C program to find the length of the given string without using string handling functions. 7M.
12. Write about dereferencing and address operators in pointers.4M.
13. List the Rules for pointer operations.7M.
14. Explain Array manipulation using pointers. Program on array manipulation using pointers.10M.
15. Define structure. Write about declaration of a structure and declaration of structure variables, initialization and accessing members.10M.
16. Define structure. Write a C program to illustrate the declaration, initialization and accessing structure members.10M.
17. Define Union. Write about declaration of a structure and declaration of structure variables, initialization and accessing members.10M.
18. Define Union. Write a C program to illustrate the declaration, initialization and accessing of Union members.10M.
19. How to declare, initialize and access pointers in C programming? 7M
20. Explain the difference between char *S and char  S[  ] with a sample C program.7M.
21. Explain the differences between an array of characters and a character pointer. 7M
22. Give the syntax of Union in C programming? What are the constraints of using Unions? List out the merits and demerits of using Unions.10M.
23. Write about lvalue and rvalue in pointer expressions. 7M
24. What are pointers in C programming? Mention the advantages and disadvantages of using pointers.10M.

UNIT-5:

1. Illustrate arrays as parameters to functions with an example program.10M.
2. How to declare, define and call a user defined function in C language? Explain with an example.7M.
3. Develop a C program to swap two numbers using call by reference.5M.
4. Develop a C program to swap two numbers using call by value.5M.
5. What is meant by recursion? Write a C program to calculate factorial for a given integer using recursive function.
6. Illustrate different file modes in C in detail?

Ans:

Mode	Description
r	Open a text file for reading. If the stream does not exist, then an error will be reported
w	Open a text file for writing. If the stream does not exist, then it is created. If the file already exists, then its contents would be deleted
a	Append to a text file. If the file does not exist, it is created
rb	Open a binary file for reading. b indicates binary. By default this will be a sequential file in Media 4 format
wb	Open a binary file for writing
ab	Append to a binary file
r+	Open a text file for both reading and writing.
w+	Open a text file for both reading and writing.
a+	Open a text file for both reading and writing(appends stream at the end)
rb+	Open a binary file for read/write
wb+	Create a binary file for read/write
ab+	Append a binary file for read/write

7. Explain the following (i) Function prototype (ii) Actual and Formal parameters.7M
8. Write a C program to find the GCD of two numbers using recursive functions.7M.
9. Program to print Fibonacci series using recursive functions (or) Give a recursive function for computing the nth Fibonacci function.10M.
10. Write a C program to add two 2-dimensional arrays using the concept of arrays as function arguments.10M.
11. Scope and lifetime of variables.
12. What is 2D array? Write a C program to find the Addition of two matrices in 2D array?
13. Explain the ‘fprintf()’ formatted output function.6M.
14. What are various types of parameters passing techniques in ‘C’ programming? Explain with an example.7M.
15. How to declare a function and differentiate calling and called function? Explain with an example program.10M.
16. Define File. What are different types of Files in C programming? Explain. [7M].
17. Write about various standard library Input / Output functions for processing files in C. (7M)
18. Write a C program to convert a Binary File into a Text File.7M.

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Introduction to Python (IP)

Quiz

Unit-1:-

1. Python was created by (    )

1. Dennis Ritche
2. James Gosling
3. Guido van Rossum
4. Bjarne Stroustrup.

 

2. Find the output of the following python program (      )

x = 5

print (type(x))

 

1. <class int>
2. <class float>
3. <class str>
4. None of the above.

 

 

3. What is the output of the following python program ( )

Str = “HelloWorld!”

Print(len(Str))

1. 10
2. 12
3. 15
4. 11

 

4. When the break statement is executed, the python interpreter ( )

1. None of the above
2. Continues the loop
3. Both b and d.
4. Jumps out of the loop.

 

5. List the sequence data types ( )

1. int, float, complex
2. set, frozenset
3. list, tuple ,range
4. bool

 

6. What is the output of the following python program is ( )

 

1. python is portable, python is easy to use.
2. Python is easy to use, python is portable.
3. python is portable.
4. None of the above.

 

7. Find the output of the following python program ( )

x = [“apple”, “banana”]

print(“banana” in x)

1. 0
2. 1
3. True
4. False

 

8. Find the output of the following python program ( )

print (10 & 3) (      ) 1M.

1. 2
2. 4
3. -1
4. None of the above.

9. Evaluate the following expression ( )

print(4/2*4+3+2**3-2)

1. 22
2. 17
3. 625
4. None of the above.

 

10. Find the output of the following python program ( )

1. 0
2. Zaheer khan
3. Saurav Ganguly
4. 10

1. What is the output of the following program(   )

1. John
2. Jack
3. Black
4. displays an error message

12.What is the output of the following program(    )

 

1. orange,banana,cherry
2. orange,cherry,banana
3. banana,cherry,orange
4. displays an error message

13.What is the output of the following program(    )

1. orange,banana,cherry
2. apple,cherry,banana
3. apple,banana,cherry
4. displays an error message

14.What is the output of the following program(     )

1. python is language
2. python is programming language
3. C is programming language
4. Java is programming language

1. What is the output of the following program(     )

1. python is language
2. python is high level language
3. C is programming language
4. python is portable

16.What is the output of the following program(      )

1. python is language
2. python is high level language
3. C is programming language
4. python is portable

17.What is the output of the following program(     )

1. python
2. Java
3. None of the above
4. python

Python

python

18.What is the output of the following program(      )

1. Java
2. python
3. c
4. Java

Java

19.A variable inside a function can be converted into global variable by using the keyword—–

1. Local
2. Constant
3. global
4. int

20.The data types of the following variables are(        )

1. Complex,string,list,set
2. List,set,string,complex
3. List,string,complex,set
4. Set,list,string,complex.

21.What is the output of the following program(      )\

1. Python,True,False,Java
2. python,True,False,Java
3. True,False,python,Java
4. False,True,Java,python.

1. What is the output of the following program(     )

1. 10,20,0,15,40
2. 10,20,0,20,40
3. 10,20,0,40,15
4. 20,15,10,0,40.

1. Fill up the blanks, The difference is that bytes array ————-be modified but the bytearray type array ———-modified.

1. can be, can be
2. can be, cannot be
3. cannot be, can be
4. cannot be, cannot be

1. The difference between a list and an array is that a list can store ——————of elements but an array can store only —————-of elements.

1. different types, one type
2. one type, different types
3. different types, different types
4. one type, one type.

 

25. What is the output of the following program(    )

1. 20,20,55.5
2. 10,20,55.5
3. 10,20,55.5,mango
4. 20,55.5,mango

26.What is the output of the following program(     )

1. 30 32  36  38
2. 30 32 36  38  40
3. 32 36  38  40
4. 32 36 38

27.What is the output of the following program(     )

1. larger is:5
2. larger is:10
3. larger is:0
4. larger is:50

28.What is the output of the following program(     )

1. 1,2,3,4,5,
2. 2,3,4,5,6,
3. 1,2,3,4,5,6,
4. 1,2,3,4,

29.What is the output of the following program(      )

1. m,a,n,g,o
2. t,a,n,g,o
3. a,n,g,o,m
4. a,n,g,o

1. The syntaxes of return and assert statements are(      )

1. return expression, assert expression
2. return expression, assert message
3. return expression, assert expression,message
4. return message, assert message

31.When ‘break’ is executed, the python interpreter ————-and When ‘continue’ is executed, the —————will start.

1. Next repetition, jumps out of loop
2. jumps out of loop, Next repetition
3. jumps out of loop, jumps out of loop
4. Next repetition, Next repetition

32.What is the output of the following program(      )

1. mango,life
2. apple,life
3. life,mango
4. life,apple

33.What is the output of the following program(     )

1. 10,9,8,7,
2. 10 9 8 7
3. 10*9*8*7*
4. 10$9$8$7$

34.What is the output of the following program(     )

1. X,i,o,a,m,i,
2. X.i.o.a.m.i.
3. X$i$o$a$m$i$
4. X*i*o*a*m*i*

35.State True or False ,The syntax of while loop is:

1. True
2. False

 

 

 

 

 

 

 

Numbers and Math functions: – There are three numeric types in Python int, float, complex. Variables of numeric types are created when you assign a value to them. example: -complex=1j To verify the type of any object in Python, use the type() function as print(type(variable)). example: – a=5 print(type(a)) You can convert from one type to another with the int(), float(), and complex() methods. example: – a=2 x=float(a) Mathematical functions: – Operators are used to perform operations on variables and values. Arithmetic operations are addition, subtraction, multiplication, division, modulus, exponential and floor division. addition: – The operator ‘+’ is used to add two numbers. subtraction: – The operator ‘-‘ is used to subtract two numbers. Multiplication: – The operator ‘*’ is used to multiply two numbers. division: – The operator ‘/’ is used to divide two numbers. Modulus: – The operator ‘%’ is used to find the remainder in division operation. Exponential operation: – (a**b) is used to find a to the power of b value. floor division:-(a//b) is dividing one number by another and then rounding the result to the closest integer that is smaller.

In a standard broadcast receiver, generally local oscillator frequency (f_o) is chosen greater than the signal frequency (f_s).

i.e,   

 

This is a well known phenomenon which manifests itself by the picking up of the same short wave station at two nearby points on the receiver dial.

• It is causal because of poor front end selectivity that is inadequate image frequency rejection.
• Intermediate frequency(IF) stage takes care of eliminating different adjacent signals.
• If there is no RF Amplifier in a receiver then it suffers badly from double spotting.
• Suppose if a receiver having an Intermediate frequency of 455 KHz. There is a strong station 14.7 MHz and a weak station 13.79 MHz. If a receiver is turned to 14.7 MHz (strong station) then receiver picks up same station. But if Receiver is tuned to a weak station 13.79 MHz then also receiver picks up near by strong station 14.7 MHz.
• Double spotting is harmful because a weak station may be marked by the reception of nearby strong station.
• An improvement in image frequency rejection will reduce Double spotting.
• One advantage of Double spotting is , it is used to calculate intermediate frequency of an unknown receiver.

The probability of error can be obtained as similar to integrate & dump receiver. Here we will consider generalized Gaussian noise.

The output at the sampler is 

index 85

file:///Users/pras/iCloud%20Drive%20(Archive)/Desktop/plugins/my%20web/ece4uplp.com/relation-between-laplace-and-fourier-transform/index.html

Introduction:-

Communications refer to sending, receiving and processing of information by electrical means, that is it means exchanging information between transmitter and receiver.

In early 1840’s the type of communication used was Wire telegraphy later on the forms are as telephony, Radio communication (possible with the invention of triode tube, Satellite communications and fibre optics(with the invention of transistors and IC’s and semi-conductor devices), that means communications become more advanced with increasing emphasis on computer and other data communications.

A modern communication system is concerned with

before transmission:- 

• sorting:- sorting for the right message.
• Processing:- processing is to make that message more suitable for transmission.
• storing:- storing that message before transmission.

then the actual transmission of that message takes place (processing and filtering  noise)

at the receiver:-

• decoding:-decoding the original message.
• storage:-storing a copy of that message.
• interpretation:-and analyzing for the correctness of that message.

the different forms of modern communication systems includes Mobile communications,Computer communications, Radio telemetry etc.

to become familiar with communication systems one needs to know about amplifiers and oscillators that means fundamentals of electronic circuits must be known, with these concepts as a background the every day communication concepts like noise, modulation and information theory as well as various types of systems may be studied.

The most general form of Communication system ( one or two blocks may differ) is shown in the figure basic terminology used in Communication systems is message signal /information/data,channel,noise,modulation, encoding and decoding. Communication system is meant for communicating messages between Transmitter and Receiver (or) source & destination.

source:-

source or information source is the primary block in communication system which generates original message / actual message. 

i.e, selecting one message (actual message) from a group of messages itself is called as sorting data (or) information. Source generates message which may be in any form like words, code , symbols, sound signal, images, videos etc.among these the desired message has been selected and conveyed.

A transducer is one which converts one form of energy into electrical energy because the message from information source may not be always in electrical form, a transducer is used in between source and transmitter as a separate block sometimes (or) may be a part of Tx ^r.

Transmitter:-

Tx^r is meant for the following tasks

• restriction of range of audio frequencies (i.e, limiting the bandwidth of the message signal).
• Amplification.
• Modulation. 

In general modulation is said to be the main function of the transmitter.

Channel:-

The medium that exists between transmitter and receiver is called as channel. The function of channel is to provide connection between transmitter  and receiver, two types of channels are  there wired/point to point  and wireless/broadcasting channels.

Point to point channels are generally wired channels(i.e, a physical medium exists) like Microwave links, optical fibre links etc. 

Microwave links:- these links are used in telephone transmission.In these type of links guided EM waves are used to transmit from Tx^r to Rx^r.

optical fibre links:- used in low-loss high speed data transmission and uses optical fibers as the medium .

Broadcast channels:- the medium or channel is wireless here, in broadcasting a single transmitter can send information to many receivers simultaneously, satellite broadcasting system is one such system.

during the process of transmission and reception, the signal gets distorted due to noise in the channel, noise may interfere with the signal at any point but noise in the channel has greatest effect on the signal.

Receiver:-

The main function of the receiver is to reproduce the message signal in electrical form from the distorted received signal. This reproduction process is called demodulation (or) detection , in general this demodulation may be assumed as the reverse process of modulation carried out in transmission. 

there are a great variety of receivers in communication systems, the type of receiver chosen depends on type of modulation, operating frequency ,its range  and type of destination required. Most common receiver is superheterodyne receiver .

so many types of receivers are available from a very simple crystal receiver with headphones to radar receiver etc.

Destination:- It is the final stage of any communication system. it would be a loud speaker / a display device/simply a load etc depending up on the requirement of the system.

Reconstruction filter (Low Pass Filter) Procedure to reconstruct actual signal from sampled signal:-

Low Pass Filter is used to recover original signal from it’s samples. This is also known as interpolation filter.

An LPF is that type of filter which passes only low frequencies up to cut-off frequency and rejects all other frequencies above cut-off frequency.

For an ideal LPF, there is a sharp change in the response at cut-off frequency as shown in the figure.

i.e, Amplitude response becomes suddenly zero at cut-off frequency which is not possible practically that means an ideal LPF is not physically realizable.

i.e, in place of an  ideal LPF a practical filter is used.

In case of a practical filter, the amplitude response decreases slowly to zero (this is one of the reason why we choose  )

This means that there exists a transition band in case of practical Low Pass Filter in the reconstruction of original signal from its samples.

Signal Reconstruction (Interpolation function):-

The process of reconstructing a Continuous Time signal x(t) from it’s samples is known as interpolation.

Interpolation gives either approximate (or) exact reconstruction (or) recovery of CT signal.

One of the simplest interpolation procedures is known as zero-order hold.

Another procedure is linear interpolation. In linear interpolation the adjacent samples (or) sample points are connected by straight lines.

We may also use higher order interpolation formula for reconstructing the CT signal from its sample values.

If we use the above process (Higher order interpolation) the sample points are connected by higher order polynomials (or) other mathematical functions.

For a Band limited signal, if the sampling instants are sufficiently large then the signal may be reconstructed exactly by using a LPF.

In this case an exact interpolation can be carried out between sample points.

Mathematical analysis:-

A Band limited signal x(t) can be reconstructed completely from its samples, which has higher frequency component f_m Hz.

If we pass the sampled signal through a LPF having cut-off frequency of  f_m  Hz.

From sampling theorem  

.

.

g(t)     has a multiplication factor  . To reconstruct  x(t)  (or)  X(f) , the sampled signal must be passed through an ideal LPF of Band Width of    Hz and gain   .

.

.

.

If sampling is done at Nyquist rate , then Nyquist interval is  .

 therefore  .

h(t) = 0.      at all Nyquist instants    , when    g(t)    is applied at the input to this filter the output will be  x(t)  .

Each sample in g(t)  results a sinc pulse having amplitude equal to the strength of sample. If we add all these sinc pulses that gives the original signal  x(t) .

.

 .

.

 .

This is known as interpolation formula

It is assumed that the signal  x(t) is strictly band limited but in general an information signal may contain a wide range of frequencies and can not be strictly band limited this means that the maximum frequency in the signal can not be predictable.

then it is not possible to select suitable sampling frequency  f_s  .

UNIT 1-QUIZ1

1. Find the modulation index if the amplitude of message signal is Two thirds of the amplitude of carrier signal ———————.
2. The diagonal clipping in Amplitude Demodulation (using envelope detector) can be avoided if RC time-constant of the envelope detector satisfies the following condition, (here W is message bandwidth and ω is carrier frequency both in rad/sec) ( )
   a. RC<1/W             b. RC>1/W                  c. None of the above         d. RC>1/ω.
3. Given AM signal is  XAM(t)= 10 (1+0.25 sin 2πfmt) cos 2πfct , then The average side band power given for the above AM signal is ( )
   a. 25W                    b. 12.5W               c.1.5625W                    d.3.125W.
4. Given AM signal is XAM(t) = 100 (1+0.85 cos 2πfmt) ,then The total power required for the above AM signal is ( )
   a. 25W                   b. 12.5W               c.6.806KW                       d. None of the above.
5. Consider the AM signal A_c cos W_ct + 2 cos W_ct cos W_mt   for the demodulation of the signal using envelope detector the minimum value of Ac should be ( ).
   a. 2                          b. 1                         c. 0.5                                    d. 0.
6. Given AM signal is SAM(t) = 100 (1+0.3 cos 2πfmt +0.4 sin 2πfmt) cos 2πfct i. i.The total power required for the above AM signal is ( )
   a. 5.625W              b. 5.625KW             c.6.806KW                  d. None of the above.
   ii.Modulation index is ( )
   a. 0.53                     b. 0.5                         c. 0.2                               d. None of the above.
   iii.The carrier power is ( )
   a. 5KW                    b.6KW                       c. 7KW                           d.100KW.
   iv. Total current flowing through the transmitter if carrier current is 5A ( ).
   a. 5mA                      b.5.303A                 c. none of these          d. 25A.
7. If the band width of message signal is 5KHz and the carrier frequency is 200KHz then upper sideband frequencies are( )
   a. 205KHz,190KHz                                                b.205KHz,-205KHz
   c. 205 KHz,-195 KHz                                           d. None of the above.
8. If the highest frequency of message signal is 5KHz and the carrier frequency is 200KHz then lower sideband frequencies are( )
   a. 205KHz,190KHz                                                b.205KHz,-205KHz
   c. 195 KHz,-195 KHz                                            d. None of the above.
9. If the bandwidth of message signal is 500Hz then the bandwidth of Amplitude Modulated signal is ( )
   a. 500Hz                    b. 1000Hz                    c.2KHz                     d. None of the above.
10. If the message m(t)= 10cos⁡2000πt and carrier signal is                                      C(t) = 25 cos 200000 πt then draw the amplitude spectrum of AM signal————— .

UNIT 2- QUIZ 2

1. Angle modulation is a technique in which the ————— of the is varied with respect to instantaneous values of ————————— by keeping as constant. 2M.
2. Write the expression for Angle Modulated signal –. 1M.
3. An Angle Modulated signal is given as 𝑥(𝑡) = 100 cos(2𝜋𝑓𝑐 𝑡 + 4 sin(1000𝜋𝑡)) where 𝑓𝑐 = 10 𝑀𝐻𝑧. 6M.
   i. The Peak frequency deviation is ( )
   a. 2K                           b. 4000                   c. 4π                      d. 8π.
   ii. The Peak- phase deviation is ( ).
   a. 4                              b. 6                           c. 0                        d. None of the above.
   iii. The power of the Modulated signal is ( ).
   a. 10KW.                   b. 5 W                       c. 5 KW                d. 50W.
4. The amount of change in carrier frequency produced by modulating signal is known as ( ). 1M.
   a. phase deviation                                                            b. amplitude deviation
   c. Frequency deviation                                                  d. none of the above.
5. The total Transmitted power in FM is equal to the power of ( ) 1M.
   a. An AM signal.                                                            b. an unmodulated carrier
   c. Message signal                                                         d. all of the above.
6. A 20 MHz carrier is frequency modulated by a sinusoidal signal with frequency 1KHz such that peak frequency deviation is 100KHz what will be the modulation index ( ) 2M.
   a. 100                           b.101                                c. 99                         d.200.
7. The bandwidth for above FM system will be ( ) 2M.
   a. 101 KHz                 b. 202 KHz                     c. 99 KHz              d. 100 KHz.
8. Which one of the following is an indirect method of generating FM ( ) 1M.
   a. Armstrong method                                                   b. Varactor diode modulator
   c. Reactance BJT modulator.                                     d. Reactance FET Modulator.
9. In which of the Modulation system when the modulating frequency is doubled the modulation index reduces to half while modulating voltage remains constant ( ) 2M.                                                                                                        a. Phase                   b. Amplitude                   c. Frequency       d. None of the above.
10. In FM, the frequency deviation is ( ) 2M.                                                                         a. Proportional to modulating frequency.                                                                         b. Proportional to amplitude of modulating signal.                                                     c. Constant.                                                                                                                                   d. Zero.
11. In indirect method of FM generation FM is obtained from ( ) 1M.                         a. AM                    b. PM                 c. DSB                              d. FM
12. Write Carson’s rule –. 1M.
13. The Bandwidth of NBFM is given as –. 1M.
14. A 25 MHz carrier is modulated by a 400Hz audio sine wave. The carrier voltage is 4V and the maximum deviation is 10 KHz. The modulation index will be( ) 2M.                                                                                                                                  a. 2.5                  b. 5                     c. 15                        d. 25
15. For the above problem write the expression of FM wave will be———————————————————————————————–.1M.
16. For the problem in 14 write the expression of PM wave———————————————————————————————————.1M.
17. Standard FM broadcast stations uses a maximum bandwidth of ( ) 1M.              a. 150 KHz                   b.75KHz.            c. 200KHz         d. 15KHz.
18. Which type of oscillators are preferred for carrier generation because of their good frequency stability ( ) 1M.                                                                                 a. LR               b.LC                       c. Crystal                         d. RC.
19. The oscillator whose frequency is varied by an input voltage is called as ————————————————. 1M.
20. Maximum deviation results at what point on modulating signal if the system is FM( ) 1M.                                                                                                                      a. Zero crossing of m(t)                                                                                                              b. Peak negative amplitude and peak positive amplitude of m (t).                        c. None of the above.                                                                                                                d. Both a and b.

UNIT3-QUIZ3
(Radio receivers and Transmitters)

1. Radio receivers are classified into how many types ( ). 2M.
   a. Three                   b. two                      c. four                             d. none of the above.
2. The ability of a radio receiver to amplify weak signals is called as ( ). 2M.
   a. Fidelity             b. Selectivity            c. sensitivity                  d. all of the above.
3. The phenomenon of Picking up of same short wave station at two nearby points on the receiver dial is known as ( ). 2M.
   a. Fidelity            b. sensitivity               c. Double spotting               d. selectivity.
4. The ability of a receiver to reject unwanted signals is called ( ). 2M.
   a. Selectivity           b. Fidelity                  c. sensitivity                  d. Double spotting
5. Standard broadcast AM receivers tuned in the frequency range of 540 KHz to 1640 KHz has an intermediate frequency of ( ). 2M.
   a. 455 KHz                 b.1MHz                      c. 20Hz                      d. 200Hz.
6. Standard broadcast FM receivers tuned in the frequency range of 88MHz -108 MHz has an intermediate frequency of ( ). 2M.
   a. 455 KHz                    b.1MHz                   c. 20Hz                      d. 10.7MHz.
7. Television receivers in the VHF band(54MHz-223MHz) and in the UHF band(470MHz-940MHz) use an IF between 26MHz and 46MHz with the two most popular values ( ). 3M.
   a. 36 MHz and 46 MHz                                                b. 455 KHz and 46 kHz.
   c. 36 KHz and 46 KHz.                                                 d. none of the above.
8. In a broadcast FM receiver if the local oscillator is tuned to 98.7 MHz then the image frequency is ( ). 3M.
   a. 88MHz              b. 109.4MHz                   c. 96 MHz                d. none of the above.
9. In a broadcast AM receiver if the signal is tuned to 530 KHz then Intermediate frequency, local oscillator frequency and image frequency are( ). 3M.
   a. 200 kHz, 730 KHz and 1000 kHz.
   b. 10.7MHz, 15.37MHz and 1000 KHz.
   c. 455 KHz, 985 KHz and 1440 KHz.
   d. None of the above.
10. In communications, Audio frequency range is —————-. 2M.
11. In communications, Radio frequency range is—————–. 2M.
12. Draw the radio frequency spectrum with detailed values starting from Very Low Frequencies (VLF) to Extreme High Frequencies (EHF). 5M.
13. Draw the block diagram of TRF receiver (only diagram). 5M.

UNIT5-Quiz5
Pulse Modulation Techniques

1. In Pulse Position Modulation, the drawbacks are ( ) 2M.                 a.Synchronization is required between transmitter and receiver                       b. Large bandwidth is required as compared to PAM                                                 c. None of the above                                                                                                                 d. Both a and b.
2. In PWM signal reception, the Schmitt trigger circuit is used ( ) 2M.                    a. To remove noise                                                                                                                    b. To produce ramp signal                                                                                                      c. For synchronization                                                                                                            d. None of the above.
3. In pulse width modulation, ( ) 2M.                                                                                    a. Synchronization is not required between transmitter and receiver              b. Amplitude of the carrier pulse is varied                                                                      c. Instantaneous power at the transmitter is constant                                              d. None of the above.
4. In different types of Pulse Width Modulation, ( ) 2M.                                                a. Leading edge of the pulse is kept constant                                                                b. Trailing edge of the pulse is kept constant                                                                c. Centre of the pulse is kept constant                                                                              d. All of the above.
5. In Pulse time modulation (PTM), ( ) 2M.                                                                         a. Amplitude of the carrier is constant                                                                             b. Position or width of the carrier varies with modulating signal                           c. Pulse width modulation and pulse position modulation are the types of PTM                                                                                                                                                 d. All of the above.
6. Drawback of using PAM method is ( ) 2M.                                                                      a. Bandwidth is very large as compared to modulating signal                                  b. Varying amplitude of carrier varies the peak power required for transmission                                                                                                                                  c. Due to varying amplitude of carrier, it is difficult to remove noise at receiver                                                                                                                                          d. All of the above.
7. Pulse time modulation (PTM) includes ( ) 2M                                                              a. Pulse width modulation                                                                                                        b. Pulse position modulation                                                                                                  c. Pulse amplitude modulation                                                                                              d. Both a and b.
8. Calculate the Nyquist rate for sampling when a continuous time signal is given by  x(t) = 5 cos 100πt +10 cos 200πt – 15 cos 300πt ( ) 3M.                            a. 300Hz                                                                                                                                            b. 600Hz                                                                                                                                            c. 150Hz                                                                                                                                          d. 200Hz.
9. Calculate the minimum sampling rate to avoid aliasing when a continuous time signal is given by x(t) = 5 cos 400πt ( ) 3M.                                                              a. 100 Hz                                                                                                                                            b. 200 Hz                                                                                                                                          c. 400 Hz                                                                                                                                          d. 250 Hz.
10. A distorted signal of frequency fm is recovered from a sampled signal if the sampling frequency fs is ( ) 2M.                                                                                          a. fs > 2fm                                                                                                                                        b. fs < 2fm                                                                                                                                      c. fs = 2fm                                                                                                                                        d. fs ≥ 2fm.
11. The desired signal of maximum frequency wm centered at frequency w=0 may be recovered if ( ) 2M.                                                                                                    a. The sampled signal is passed through low pass filter                                              b. Filter has the cut off frequency wm                                                                              c. Both a and b                                                                                                                              d. None of the above.
12. The frequency spectrum of x(t) is X(f) is given as follows 6M.

Draw the frequency spectrum of sampled signal by assuming suitable values for sampling frequency under the following conditions
i. Over sampling                      ii. Under sampling                         iii. fs = 2fm.

EXPERIMENT WISE VIVA QUESTIONS ANALOG COMMUNICATION LAB

Amplitude Modulation:

1. What is meant by Modulation? What is the need for modulation?
2. What are different types of analog modulation techniques?
3. What are the other names of message signal? What are the other names of carrier signal?
4. Write the equation of AM signal and explain each parameter in that equation?
5. Define Amplitude Modulation? Define modulation depth or modulation index?
6. What is the range of Audio frequency signals? What is the range of Radio frequency signal?
7. What are the applications of Amplitude modulation?
8. How many generation methods are there to generate an AM wave? What are the methods of demodulation of an AM wave?
9. Explain the operation of diode detector circuit?
10. Write the formula for modulation index? Differentiate under, over and perfect modulation in AM?
11. As the amplitude of message signal increases, modulation index increases or decreases?
12. Define single tone modulation? In laboratory type of AM is single tone modulation or not?
13. Draw the frequency spectrum of AM wave?
14. If modulation index is 100%, calculate the ratio of total power to carrier power of an AM wave?
15. If µ=1 in an AM wave what is the amount of power saving in an AM wave? What is the band width of an AM wave?
16. Explain the operation of AM modulator? Explain the operation of 8038 circuit in AM modulator?
17. Explain the procedure of Amplitude modulation? What is the significance of E_max and E_min points in AM wave?
18. Plot message, carrier and AM signals?
19. What is meant by envelope detector?
20. The frequency of AM wave follows — (message signal frequency or carrier frequency)?
21. The amplitude of AM wave at f_c +f_m is— and The amplitude of AM wave at f_c -f_m is—–
22. In amplitude modulation the amplitude of ——— is changing with respect to ——
23. Envelope of AM signal follows————– (message signal/ carrier signal)?
24. What are the advantages and disadvantages of AM?
25. How demodulated signal differs from original signal in AM?
26. The two important distortions that can appear in the demodulated output of an envelope detector are————– and—————————- –.
27. Differentiate high-level and low-level modulations in AM?
28. What is trapezoidal rule?

Balanced Modulator:

1. What are the disadvantages of AM?
2. Most of the power in AM spectrum is carried by ————
3. Define DSBSC modulation?
4. How DSBSC is more efficient than AM in terms power saving, explain?
5. What is meant by frequency response?
6. Draw the magnitude response or amplitude spectrum of DSBSC signal?
7. The signal generated by balanced modulator is———–
8. Draw the wave form of DSBSC wave and AM wave, and differentiate those two waveforms?
9. Give the equation of DSBSC signal?
10. What are the generation methods of DSBSC?
11. What are the demodulation methods of DSBSC?
12. What is the bandwidth of DSBSC signal?
13. Define Costas loop and it’s operation?
14. Amount of power saving in DSBSC signal is————
15. Coherent detection means?
16. Give the practical applications of balanced modulator?
17. Explain the operation of product modulator?
18. Why the circuit is called balanced modulator?
19. If the circuit is operating in balanced state, the modulation index value is——- –.
20. Explain the working procedure of 1496 IC for the generation of DSBSC wave?
21. As message signal amplitude increases, carrier suppression in dB’s ———
22. Plot message, carrier and DSBSC waves and explain each wave clearly.
23. How do you differentiate modulation by demodulation?
24. Explain the significance of local oscillator frequency in modulators and in
25. Differentiate synchronous and non synchronous detection techniques in analog modulators?
26. The phase shift at zero crossings in DSBSC wave is——- –.
27. What is Quadrature carrier multiplexing?
28. How DSBSC is different from SSB?

Frequency Modulation:

1. Define Frequency modulation? How it is different from phase modulation?
2. Write equation of FM wave, explain each parameter in it?
3. Draw the amplitude spectrum of FM wave?
4. Give the Carson’s rule in FM?
5. Define modulation index β, frequency deviation?
6. Differentiate Narrow band FM with Wide band FM?
7. Explain the FM operation using 8308IC?
8. Draw message, carrier and FM waves and explain each wave clearly?
9. Explain the methods for generation of FM and its demodulation?
10. How FM wave is different from PM wave?
11. Give the practical applications of FM?
12. State advantages and disadvantages of FM?
13. The range of speech signals is——— –.
14. Type of Modulation used in radios is——- –.
15. Type of modulation used for voice signals in T.V — and for video signals in V is—- –.
16. Noise immunity is more in which analog modulation technique———– –.
17. FM is more robust to noise compared to AM, why?
18. Carson’s rule is for———- –.
19. In commercial FM broadcasting, the audio frequency range handled is only up to—- –.
20. The transmission band width required for commercial FM broadcasting is——– –.
21. Define Hilbert transform?
22. Explain capture effect in FM broadcasting?

Pre-emphasis and De-emphasis:

1. Define pre-emphasis and De-emphasis processes in
2. Why Pre-emphasis is used at Transmitter of FM and de-emphasis at FM receiver?
3. Draw the pre-emphasis circuit and explain its working in detail?
4. Draw de-emphasis circuit and explain its working in detail?
5. Draw the frequency response characteristics of pre-emphasis and de-emphasis explain each one in detail?
6. Calculate the cut-off frequencies of pre-emphasis and de-emphasis circuits practically
7. Pre-emphasis circuit operation is similar to——— –.
8. De-emphasis circuit operation is similar to——— –.
9. What is the necessity of boosting up high frequencies in frequency modulation communication system?
10. Define 3dB frequencies?

Sampling and reconstruction:

1. Define sampling theorem? What is the need for sampling?
2. What are the necessary and sufficient condition for sampling and reconstruction of a signal?
3. Define Nyquist rate and Nyquist interval in sampling theorem?
4. If message frequency is 2 KHz and sampling frequency is 2 KHz,4 KHz, 8 KHz and 16 KHz in each case the number of samples are—————————– –.
5. What are different types of sampling techniques?
6. What was the effect on sampled signal if f_s < 2 f_m ?
7. Draw the amplitude spectrum of sampled signal if f_s < 2 f_m, f_s =2 f_m, f_s > 2 f_m.
8. What is aliasing effect in sampling? How to avoid it?
9. Why do we use pre-filtering in sampling?
10. What do you mean by reconstruction of sampling theorem?
11. What are the types of filters used in reconstruction?
12. Define sample and hold process?
13. Differentiate second order, fourth order and sixth order low pass filters in reconstruction process.
14. Explain the sampling and reconstruction process in detail by using the trainer
15. Define band pass sampling?
16. How sampling is different from PAM?
17. Define a continuous time signal or an analog signal. Give some examples of analog signals.
18. Define a discrete time signal. Give some examples of discrete
19. What is the difference between discrete and a digital signal?
20. Define a digital signal? Give some
21. What is the need for converting a continuous signal into a discrete
22. Explain about zero-order hold circuit.
23. How to convert an analog signal into digital signals?

Digital signal processors operates———— as inputs.As the number of samples increases, the reconstruction of original signal becomes?

Pulse Amplitude Modulation:

1. What is the basic principle of PAM?
2. Name some Pulse Modulation techniques?
3. Define PAM?
4. How PAM is different from AM?
5. Can we produce a PAM signal using a sampling circuit?
6. Differentiate PAM output with sampling output?
7. Does PAM come under Analog modulation technique or Digital Modulation technique?
8. What is the Bandwidth of PAM?
9. Compare BW of PAM and AM?
10. Draw waveforms of PAM. explain each one briefly.
11. What are the advantages of PAM over AM?
12. What are the advantages and Disadvantages of PAM?
13. Explain the working procedure PAM kit?
14. Can we use PAM technique in TDM?
15. Differentiate uni-polar and bi-polar PAM.
16. What do you mean by zero order holding? And draw the circuit diagram of zero-order hold circuits?
17. What are the drawbacks of PAM?
18. Explain the working of PAM demodulation circuit?
19. Define Flat-Top sampling?
20. Draw the circuit diagram of Flat-Top Sampled circuit?
21. What was the roll off characteristics of sinc pulse?
    

    Pulse Width Modulation (PWM):

    1. Define PWM?
    2. Differentiate PWM, PAM and PPM?
    3. Name the applications of Mono-stable multivibrator?
    4. What is a Multivibrator?
    5. Differentiate Monostable, Bi stable and Astable Multivibrators?
    6. How a Monostable Multivibrator produces a PWM signal?
    7. What are the other names of PWM?
    8. Define Pulse Duration Modulation?
    9. What is Pulse Time Modulation?
    10. Draw PAM and PWM signals and each one in detail.
    11. Draw PWM signal with respect to message signal?
    12. In PWM —————- of Pulse carrier signal is changing with respect to message signal.
    13. Explain the operation of PWM circuit.
    14. 555 timer in Monostable mode produces————.
    15. 555 timer in Astable mode produces——————.
    16. What are the advantages of PWM over PAM?
    17. What is the difference between PWM and FM?
    18. Which type of noise is affecting the amplitude of PWM signal?
    19. Which system is more immune to noise (PWM or PAM)?
    20. What are the disadvantages of PWM?
    21. What are the applications of PWM?
    22. Band Width of PWM is—————-.
    23. Band width of PAM is—————-.
        

        Pulse Position Modulation (PPM):

        1. Define PPM?
        2. The information is conveyed by ————- of Pulses in PPM.
        3. In PWM information is conveyed by————— of pulses.
        4. In PAM information is conveyed by————— of pulses.
        5. What are the advantages and disadvantages of PPM?
        6. Compare PPM with Phase Modulation.
        7. PAM is similar to————————–.
        8. PWM is similar to————————–.
        9. PPM is similar to————————–.
        10. Differentiate Analog Modulation Techniques with Pulse Modulation Techniques.
        11. What are the applications of PPM?
        12. Draw PPM signal with respect to message signal.
        13. Draw PPM signal with respect to PWM signal.
        14. Explain the operation of PPM Modulator?
            

            Phase Locked Loop (PLL):

            1. What are the applications of PLL?
            2. Why this circuit is called Phase Locked Loop?
            3. What are the three components of PLL circuitry?
            4. Explain the operation of PLL by using a Block Diagram?
            5. Define free-running frequency?
            6. Define Lock range and Capture range of a PLL?
            7. What is meant by Frequency synthesizer?
            8. Why PLL is used in FM Receivers/
            9. How PLL is used in FSK demodulation circuits?
            10. What do you mean by Lock state in a PLL?
            11. What is meant by Pull in time in PLL?
            12. Phase Detector or Phase Comparator is used for ——————.
            13. Why VCO is used in feedback loop of PLL?
            14. What are the input and Output signals of a VCO in a PLL?
            15. What are the advantages and Disadvantages of PLL?
            16. Why Lock range is greater than Capture range in a PLL?
                

                Time Division Multiplexing (TDM):

                1. Define the concept of Time Division Multiplexing?
                2. Differentiate Multiplexing and Sampling?
                3. What are the different types of Multiplexing Techniques?
                4. Does TDM come under analog Multiplexing or Digital Multiplexing?
                5. Define a frame in a TDM?
                6. Why synchronization is required in TDM?
                7. Why multiplexing is required?
                8. What do you mean by inter-leaving gaps in TDM frame?
                9. If two signals of frequencies 2KHz and 4 KHz are multiplexed in time –domain then draw TDM signal
                   1. Without inter-leaving gap.
                   2. with inter-leaving gap of 10 ms.
                10. What are the advantages and Disadvantages of TDM?
                11. Differentiate TDM with FDM?
                12. What are the advantages of TDM over FDM?
                13. Explain the operation of TDM using trainer kit used.
                14. Synchronous TDM means?
                    

                    Additional Questions:

                    1. What is a filter?
                    2. Differentiate Active and Passive Filters?
                    3. Why LPF is used in Demodulation Circuits?
                    4. Why pre-filtering is required in sampling?
                    5. Anti-aliasing is achieved by using———– in Sampling Circuits?
                    6. Define Single-tone modulation in AM and FM?
                    7. Why FM receivers are more immune to AM receivers?
                    8. BW of Narrow band FM is ——————.
                    9. BW of AM is ———————————-.
                    10. How to calculate Image frequency of a Radio Receiver?
                    11. Define Power Spectral Density.
                    12. Define AWGN noise.
                    13. Define SNR.
                    14. Where do we use Hilbert Transform?
                    15. Over modulation in AM means….
                    16. What is µ value when AM wave is similar to DSBSC wave?

Slip test-1

1. In a PCM system, if the Quantization levels are increased from 2 to 8,                 i. Find the change in Signal to Quantization Noise ratio.                                ii.Find the change in Transmission Bandwidth.
2.  i. Convert the following signal x(t) = 10 cos (200πt) to a discrete signal x[n] if sampling rate is 1000Hz.                                                                                       ii. Write the advantages of Digital Communication system over Analog Communication system.

PART-B

1. Draw the Basic Block Diagram of Digital Communication System and explain each block in detail.                                                                                                                             
2. Deduce the expression for Signal to Quantization noise ratio in PCM system.                                                                  Slip test-2

1. A PCM source transmits four samples (messages) with a rate 2B samples /second. The probabilities of occurrence of these 4 samples (messages) are equally likely Find out the information rate of the source.                                                           
2. A source produces 26 symbols with equal probability what is the average information produced by this source?     

PART-B

1. State Mutual information. Prove any three properties of Mutual information.                 
2. A source alphabet has 10 symbols with the given probabilities 0.02, 0.04, 0.17, 0.02, 0.16, 0.06, 0.03, 0.27, 0.20, 0.03 construct Shannon-Fano coding and calculate the efficiency.                                                                                                                             

UNIT-1

QUIZ

1. The band width  needed to transmit Television video plus audio signals of bandwidth 4.2 MHz using Binary PCM  quantization level of 512 is (  c     )         a. 2 MHz            b. 25.6MHz                        c.37.8MHz                    d.75.6MHz
2. A signal m(t)has a bandwidth of 1.0 KHz and exhibits a maximum rate of change of 2.0 volts/sec. The signal is sampled at a sampling frequency of 20 KHz and quantized using delta modulator. The minimum step size to avoid slope overload is (  b    )                                                                                                                      a. 1.0mV        b. 0.1mV                c.10.0mV                      d.0.01mV
3. For a 10 bit PCM system, the signal to Quantization noise ratio is 62 dB. If the number of bits are increased by 2, then the signal to Quantization noise ratio will be (  c      )                                                                                                                    a. Increased by 6 dB                                   b.  Decrease by 6 dB                                       c. Increased by 12 dB                                  d. Decrease by 12 dB
4. Write the condition to eliminate slope overload error in a Delta modulation system—————————
5. Write the condition to eliminate slope overload error in a Delta modulation system if the input is a single-tone signal—————————
6. For which value of A , A-law has linear transfer characteristics——————–.
7. For which value of µ , µ-law has linear transfer characteristics——————–.
8. In a PCM system if the step size is 5V , then the Quantization noise in dB is   (  d    )                                                                                                                                             a. -5 dB.          b. -3.18dB       c. -10dB                      d. 3.18dB.
9. Draw the characteristics of Mid-rise and Mid-tread type Quantizers ————–
10. The maximum slope of the signal ———————-
11. The sampling rate of the signal ————————–
12. The step size in a 8- bit pcm system if the input signal to PCM is oscillating between [+4V,-4V] is—————————–

UNIT-2

QUIZ 2

1. Entropy is a measure of ——————————– 3M.  
2. The capacity of a band – limited AWGN channel in terms of kbps if the average received signal power to noise power spectral density is 1000 and the bandwidth is approximately infinite is (  a    )   [Hint: Shannon’s bound C_infinity =  S/N_o]                                                                                                                        a.  1.44        b. 1.08                                c. 0.72                           d. 0.36
3. If Y= g(X) where g denotes a deterministic function, then the conditional entropy H(Y/X) is (  b ) 3M.                                                                                                           a. ≠ 1         b.  = 0                           c. = 1                           d. ≠ 0
4. A Source generates three symbols with probability of 0.25, 0.25, and 0.50 at a rate of 3000 symbols per second. Assuming the symbols are generated independently from the source, the most efficient source encoder would have average bit rate of ( b ) 4M.                                                                                             a. 6000 bits/sec                                                         b. 4500 bits/sec                                 c. 3000 bits/sec                                                         d. 1500 bit/sec.
5. A source generates four equi-probable symbols. If the source coding is adopted, the average length of the code for 100% efficiency is ( c )                       a. 6 bits / symbol                                                          b.   3 bits / symbol                           c.  2 bits / symbol                                                        d.  4 bits / symbol
6. Draw the channel diagram of Binary Erasure channel and write its channel matrix ………………………..
7. For a Binary Symmetric Channel the entropies of X & Y are if the conditional probability p=0.5, where X & Y are input & output random variables of BSC  (   d     )3M                                                                                                                          a. 1,0           b. 0,0               c. 0,1                           d. 1,1
8. Match the following   (  d    )                                                                                                       a. Lossless channel                                           1.  only one non-zero element in each row                                                                                                                                        b. Deterministic channel                                2. Only one non-zero element in each row and each column.                                                                                                   c. Noiseless channel                                           3. Only one Non-zero element in each column.                                                                                                                                d. for a noiseless channel                                  4. H(Y/X)=0 and H(X/Y)= 0. a. none of these                                                  b.   b-3,c-4,a-1,d-2                                    c. c-4,d-3,a-1,b-2                                             d.  b-1,c-2,a-3,d-4.
9. Given a Binary Symmetric Channel, the expression for Entropy is (pis conditional probability of error   ——————- 3M.  

Digital Communications Unit-3 Quiz with Solutions

UNIT3

QUIZ3[CO3]

1. The number of Parity check bits in an (n, k) Linear Block codes are (    b      )      a.n                b. (n-k)                       c.  (n+k)                       d. k
2. The Hamming Weight of the following code words 10011101 & 00111100 is      (   c   ) 2M.                                                                                                                                       a. None of these      b. 4, 5              c.5, 4                           d.3,4
3. A cyclic code can be generated using———————— and A block can be generated using——————-.(   c   )                                  a.Generator matrix & Generator polynomial.                                                          b.Generator matrix & Generator matrix.                                                            c.Generator polynomial & Generator matrix.                                                            d.None of the above.
4. The rate of a Block code is the ratio of(    c     )                                                                a.Message length to Block length.                 b.Block length to message length.  c.Message weight to Block length.                 d.None of the mentioned.
5. The syndrome in LBC is calculated using , where Y represents received code word   (     a       ) 2M                                                                                                                      a. S= Y H^T          b. S = YH                    c. S= Y^T H                  d. S= Y^T H^T
6.  A non-Zero value of Syndrome in a Block code represents ( b    ) 2M.                  a.No error during transmission.     b.An error occurred during transmission.   c.Both a and  b                                         d.None of the above.
7. The transmitted code word(X) in an LBC can be obtained from received code word( Y) by using the equation (  a   ), where E represents error vector.              a. X= E + Y           b.  X = X.Y                  c. X= E.Y                    d. X= X/Y
8. The parity check matrix of a (6,3) block code if Generator matrix is G  3M.             ——————-.
9. In the above question find the Code words corresponding to message vectors [110] and [111]——————-. Ans: [110110], [111000].
10. For the Q.8. Find the syndrome value when the received code word is 001111—-4M. Ans: syndrome value [0 0 1]
11. For a (7,4) cyclic code , the generator polynomial is given as find the codeword  for the data 1100       Non systematic codeword is—————- .Ans:  1011100              Systematic codeword is——————–.Ans: 1011100.

    UNIT-4

    QUIZ-4

    1. The modulation technique that provides minimum probability of error is (  b   ). a. ASK                  b. PSK                   c. DPSK                        d.FSK
    2. At a given probability of error, binary coherent FSK is inferior to binary coherent PSK by (  c  )                                                                                                         a. 6 dB                b. 2 dB           c.  3 dB           d.  0 dB             e. None of these.
    3. If E_b, the energy per bit of a binary digital signal, is 10^-5watt-sec and the one-sided power spectral density of the white noise, N_o= 10^-6 W/Hz, then the output SNR of the matched filter is  (   d    )                                               a. 26 dB         b.  20 dB          c. 10 dB          d. 13 dB          e. None of these
    4. In which system, bit stream is portioned into even and odd stream (   c   )  a. BPSK                  b.  MSK            c. QPSK                     d.  FSK
    5. Optimum filter can be called as———when the input noise is white noise (  a   ) 2M.                                                                                                                        a. Matched filter   b.  High pass filter        c. Low pass filter      d. None of these
    6. The probability of error of ASK is ————————————.
    7. The probability of error of FSK is ————————————.
    8. Write the expression for QPSK modulation —————————————-2M.
    9. Draw the block diagram of DPSK system————————————.
    10. A pulse g(t) = A cos(πt/2T) for 0 ≤ t ≤ T is transmitted over an AWGN channel with two sided noise power spectral density N_o/2 Watts/Hz. The impulse response of the matched filter is (  a     )                                                           a. A sin (πt/2T)                                                            b.   A rec (πt/2T)                           c. A rec (π(T-t)/2T)                                                    d. A sin (π(T-t)/2T)           
    11. If the probability of error function of a modulation scheme is P_e = (½) erfc(x) thenthe same P_e interms of Q-function is ( b   )                                             a. Q ( 3^1/2 * x)                    b. Q (2^1/2 * x)                c. Q(x)             d. none of these.
    12. 

 

 

UNIT 2:

Short answer questions:

1. What is meant by Carson’s rule? Problem on calculation of Bandwidth of FM signal using Carson’s rule.(imp)
2. Distinguish between NBFM and WBFM.(imp)
3. Problems on instantaneous phase and frequency.
4. What is the basic principle involved in Phase discriminator?
5. Define capture range and lock range of a PLL.
6. Problem on Armstrong method of generation of a WBFM signal?(imp)
7. Capture effect and threshold effects in FM (very very imp).
8. Problems on carrier swing, frequency deviation, BW, modulation index etc.
9. Phasor diagrams of NBFM and AM.
10. What is the need for limiter in FM receivers? (Very very imp).
11. Find the maximum Frequency deviation of Frequency Modulated signal given by  S(t) = 10 cos(1000000 *pi*t + 5 sin(2000*pi*t)).
12. A carrier signal 10 cos(8x 10⁶πt) is modulated by a modulating signal               5 cos(30x 10³πt)  then i. Find the Band width of Frequency Modulated signal assuming  k_f  =15KHz.   ^ii.     Calculate Highest Frequency and lowest Frequency of FM signal.  iii. Find  Modulation index of FM signal.
13. Compare Frequency Modulation with Phase Modulation.

Long answer questions:

1. Explain the operation of balanced slope detector in detail.
2. Explain in detail about frequency spectrum of WBFM signal using Bessel functions.
3. write in detail about generation methods of FM signal
4. Direct method of generation
5. Indirect method of generation (Armstrong method).(very very imp)
6. What is ratio detector? Explain its working in detail with neat circuit diagram. Explain how ratio detector provides amplitude limiting?
7. What is amplitude limiter? Draw its circuit diagram explain its working. Why amplitude limiter is needed in FM receivers justify.(very very imp)
8. Compare and contrast foster seeley discriminator with ratio detector.
9. What is PLL? What are the applications of PLL? Explain the working of PLL with neat block diagram.(imp)
10. How audio frequency signal is demodulated by using PLL? Explain in detail.
11. Write about pre-emphasis and de-emphasis circuits in detail. Give the significance of pre-emphasis and de-emphasis.(imp)
12. In an FM system if the AF is 500 Hz and its amplitude is 2.4V with a frequency deviation of 4.8 KHz. If the AF voltage is increased to 7.2V then find the modified frequency deviation calculate BW in above two cases.
13. Design Armstrong FM generator for the generation of WBFM signal with frequency deviation=75 KHz and using the NB carrier as 100 KHz and second carrier as 10 MHz Find the suitable multiplying factors. Assume the message signal is defined in the range 100Hz-15 KHz.
14. Draw the block diagram of single-tone NBFM signal if message signal is.
15. Derive an expression for an FM signal with carrier frequency fc and a modulating signal Obtain an expression for its spectrum.
16. Why an FM system is preferred over an AM system?

Unit 2

Assignment 2

1. Explain the generation techniques of FM signal using Direct and Indirect methods in detail.
2. Explain the working of the following demodulator circuits of FM                        i. Balanced slope Detector for FM modulation.                                                            ii. Foster-Seeley discriminator.                                                                                         iii. Ratio-detector.
3. Explain the detection of FM signal using PLL.
4. Explain in detail about pre-emphasis and De-emphasis circuits in FM.

Unit 2

Assignment 2 

1. Illustrate the working of PLL using a Block Diagram. Define capture range and Lock range in PLL.                                                                                                                 5M.
2. Sketch the circuit diagram of Ratio-detector and explain working of it in detail. 5M.
3. Sketch the frequency response curves & compare the working of pre-emphasis and De-emphasis circuits in FM communication System.

TUTORIAL TEST 2

Answer any three of the following

1. In an FM system if the AF is 500 Hz and its amplitude is 2.4V with a frequency deviation of 4.8 KHz. If the AF voltage is increased to 7.2V then find the modified frequency deviation calculate BW in above two cases.
2. Explain in detail about frequency spectrum of WBFM signal.
3. Draw the block diagram of single-tone NBFM signal if message signal is
4. Write any four differences between NBFM and WBFM.

UNIT-5

Data Acquisition systems: Study of transducer (LVDT, Strain gauge, Temperature, Force).

Photo Electric Devices and Industrial Devices: Photo diode, Photo Transistor, LED, LCD, SCR, UJT Construction and Characteristics only.

Display Systems:  Constructional details of C.R.O and Applications.

ASSIGNMENT- UNIT5

1. Explain with neat sketch, the working principle of LVDT.
2. Give the applications of CRO. Explain the Block diagram of Cathode ray tube in detail. 10M.
3. Write a short note on LED and LCD.

Short Answer questions:     

1. Distinguish between photodiode and LED.
2. Why is SCR known as negative resistance device?
3. What are the different types of transducers used for the measurement of temperature. Explain the principle of any of these.
4. Draw the symbol of a SCR and VI characteristics .explain its principle of operation.
5. What is meant by sensitivity in a CRO and explain the necessity of a saw tooth generation of a CRO.
6. What are the important characteristics of an LCD?
7. What is an LVDT? By means of a neat sketch explain how a LVDT is used in measurements.
8. Give the block diagram of a CRO, Explaining the importance of each block.
9. Explain about an instrumentation amplifier.
10. Write a note on UJT.
11. How are DIAC and TRIAC different from operational point of view.
12. What is a transducer?
13. List out the applications of a SCR.
14. Explain the principle involved in a strain gauge.
15. Draw the symbols of SCR, TRIAC, DIAC and UJT.

Long Answer questions:      

1. Explain the working of Cathode Ray Tube of CRO with neat block diagram in detail.
2. What are the applications of CRO?
3. Differentiate Photo Diode and Photo Transistor in detail in terms of operation and applications.
4. Differentiate LED and LCD in detail in terms of operation and applications.
5. Explain the working of SCR and draw the characteristics of it.
6. Explain the working of UJT and draw the characteristics of it.

 

ALL THE BEST

Prepared by         P.Lakshmi Prasanna

 

 

Unit-4:  Operational Amplifiers – Introduction to OP Amp, characteristics and applications – Inverting and Non-inverting Amplifiers, Summer, Integrator, Differentiator, Instrumentation Amplifier.

Digital System: Basic Logic Gates, Half, Full Adder and Subtractors.

ASSIGNMENT- UNIT4

1. What are the four basic building blocks of Op-Amp explain each block in detail. 10M.
2. Write in detail about Instrumentation amplifier.
3. Design and realize Full Subtractor (Give the necessary expression and Truth table and Circuit diagram)

Short Answer questions:     

1. What are the ideal characteristics of OP-AMP?
2. What is an operational amplifier? Mention some of its applications.
3. A 5mV, 1 kHz sinusoidal signal is applied to the input of an OP-amp integrator for which R=100KΩ and C=1µF.Find the output voltage.
4. What are the different parameters of an OP-amp? Sketch the circuit of a summer using OP-amp 741to get Vo= -(-V1+2V2-3V3).
5. Write a note on basic logic gates.
6. Draw the truth table of an EX-OR gate.
7. State and prove De-Morgan’s theorems. Discuss the working of half adder and full adder and give their truth tables.
8. Write a note on universal gates.
9. Realize OR gate using NAND gates.
10. What is half Subtractor? Realize full Subtractor using using NAND gate only.
11. What is an op-amp? List the four building blocks of an op-amp.
12. Draw the schematic symbol of an op-amp in detail. Write the expression for output voltage of an op-amp?
13. What are the applications of op-amp?
14. What are the advantages of op-amp?
15. Why op-amp is named as op-amp?
16. What are universal gates and why those are called as universal gates?
17. Draw EX-OR and EX-NOR gates and give the truth tables of each gate.
18. Name some basic logic gates draw their symbols and give the corresponding truth tables.
19. Draw half adder and half Subtractor.

Long Answer questions:

1. Draw and explain block diagram of op-amp in detail. Or what are the basic building blocks of an op-amp explain in detail.
2. Write in detail about
3. Half adder/ Full adder.
4. Full Subtractor/ Half Subtractor.
5. Explain the operation of inverting and non-inverting amplifier circuits using op-amp and calculate gain of each circuit in closed loop configuration.
6. Define common mode rejection ratio (CMRR).a differential amplifier has a differential mode gain of 100 and common mode gain of 0.01 then find CMRR in dB?
7. Write in detail about instrumentation amplifier.
8. Explain the operation of the following circuits of op-amp in open loop configuration.    a. Non –inverting amplifier.        b.   Inverting amplifier  c.  Differential amplifier.
9. What are the characteristics of practical op-amp?
10. Define slew rate of op amp? Problem on calculation of Slew rate.
11. Explain how op-amp is used as  Summer and difference amplifier or Subtractor.

 

Prepared by                                                                                       P.Lakshmi Prasanna

 

 

UNIT – 3

Unit-3:  Feedback concepts: Properties of negative feedback amplifiers, Classification, Parameters. Oscillators: Barkhausen’s Criterion, LC Type and RC type oscillators and crystal oscillator. (Qualitative treatment only)

ASSIGNMENT- UNIT3

1. Draw the basic block diagram of feedback amplifier and explain each block in detail. 10M.
2. What is the effect of negative feedback on input and output impedances of a voltage series feedback amplifier? Give necessary expressions.
3. Write a short note about RC Phase Shift Oscillator.

 Short Answer questions:

1. What is meant by feedback?
2. What is tank circuit? How it is used in oscillators?
3. State Barkhausen’s criterion.
4. Differentiate positive feedback with negative feedback.
5. If open loop voltage gain of feedback amplifier is 200 and feedback factor is 1/5 then find
6. Gain with negative feedback.
7. BW with negative feedback if open loop BW is 100 KHz.
8. What are the advantages of negative feedback?
9. What is the effect of negative feedback on bandwidth?
10. Explain how gain stability is improved by negative feedback?
11. Draw block diagrams of voltage- series and current- shunt feedback topologies?
12. What are four topologies of feedback amplifiers?
13. What is positive feedback .Give the advantage of positive feedback?
14. Write the definition of oscillator?
15. Differentiate oscillators with the frequency of operation?
16. Draw under damped over damped and un-damped oscillatory signals.
17. .In the forward path of an oscillator, two amplifiers of equal gain are cascaded. If the feedback path transfer function is 1/81, find the gain of each amplifier.

Long Answer questions:

1. What is the effect of negative feedback on input and output impedances in voltage-series feedback amplifier give necessary expressions?
2. Derive the general equation for LC oscillator circuits used in oscillators.
3. Distinguish between positive feedback and negative feedback in amplifiers. State the advantages of negative feedback in amplifiers.
4. Draw the circuit diagram of Hartley’s oscillator and explain its operation in detail. Derive the expression for frequency of oscillation.
5. Draw the circuit diagram of Colpitt’s oscillator and explain its operation in detail. Derive the expression for frequency of oscillation.
6. What is the effect of negative feedback on Bandwidth give explanation with necessary equations?
7. Write in detail about four topologies of feedback amplifiers and compare the topologies in terms of gain, BW, input impedance and output impedance.
8. Write the working operation of the following circuits and derive the expression of frequency of oscillation. i. RC-Phase shift oscillator. ii. Wein-bridge oscillator. iii. Crystal oscillator.
9. Draw a neat circuit diagram of an RC phase shift oscillator using BJT and explain its working principle
10. A Hartley oscillator is designed with L1=2mH, L2=20mH, and a variable capacitance. Determine the range of capacitance value, if the frequency of oscillation is varied between 950 kHz and 2050 kHz.

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UNIT-2

ASSIGNMENT- UNIT2(CO2)

1. Draw the h-parameter equivalent model of transistor in CE configuration and define the four h- parameters.
2. Explain the construction of JFET (either n-channel or p-channel).
3. Explain the current components of a BJT in detail with a neat sketch.

 

Short Answer Questions:

1. Write the differences between JFET and BJT.
2. What are three possible configurations of BJT?
3. Define α, β and γ of a BJT write the relationship between them.
4. What are three possible regions of a transistor (write about cut-off, active and saturation regions).
5. What is base width modulation?
6. Define four h-parameters of transistor. And draw general h-parameter model of a BJT.
7. Define the following
8. Bandwidth of an amplifier.
9. Gain or amplification factor.
10. Compare CE, CB and CC transistors.( in terms of input resistance, o/p resistance, current gain, voltage gain, phase shift and applications).
11. What are the advantages of FET over BJT?
12. Why FET is more preferable than BJT?
13. How FET is known as uni polar device ? how do you compare FET with BJT?
14. Why FET is called as voltage controlled device?
15. What are the parameters of FET?
16. What are the three possible configurations of FET?
17. Give the relationship between g_m , r_d and µ.
18. Draw the equivalent circuit diagram of FET in CS configuration.
19. Why BJT is called as Current controlled device.
20. Draw transfer and output characteristics of FET.
21. Draw the symbols of NPN transistor,n channel FET and SCR.
22. If the emitter of a transistor is open will there be any collector current.

Long Answer Questions:

1. What is CB configuration? Draw the input and output characteristics of CB transistor. Explain in detail.
2. Define α and β of a transistor and derive the relationship between them.
3. Explain the current components of BJT in detail.
4. Explain how transistor is working as an amplifier?
5. Explain the working of CE amplifier with a neat circuit diagram. Derive expression for input resistance, and current gain using h parameter equivalent circuit.
6. Draw the hybrid equivalent circuit of an NPN BJT in CE configuration. Derive expressions for Av, Ai, Ri,
7. Calculate the values of Ic and Ib, for a transistor with α=.99,Ico=5µA,Ib=20µA.
8. Draw a simple inverter circuit and explain its operation.
9. Draw the h-parameter model of CE transistor and explain how h-parameters are calculated from CE characteristics.
10. Explain the construction and working of FET (either n-channel or p-channel).
11. Draw output and transfer characteristics of FET explain the working of /FET through them.
12. Derive the relationship between g_m, r_d and µ.
13. Write the comparisons between FET and BJT.
14. How FET is working as an amplifier?
15. Explain the working operation of NPN and PNP transistors.
16. Explain various operation regions of a transistor in detail.
17. What is CE configuration? Draw the input and output characteristics of CB transistor. Explain in detail.
18. What is CC configuration? Draw the input and output characteristics of CB transistor. Explain in detail.
19. What are the disadvantages of BJT? Why FET is preferred over BJT? Give the applications of FET.
20. Explain the working of JFET And explain the parameters of JFET.

 

 

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Basic Electronics Important questions  –Unit-1

Note: Read the questions in the following order   i. Assignment questions ii. Class test  iii. Expected questions iv.  Tutorials For every unit.

 Unit1:

ASSIGNMENT- UNIT 1 

1.  Explain the working of Bridge rectifier in detail with a neat circuit diagram and derive the expression for ripple factor and efficiency. 10M.
2. Explain the working of PN-junction diode in detail in forward and reverse bias conditions. 10M.
3. A 230v, 60 Hz voltage is applied to the primary of a step down center tapped transformer of a FWR with turns ratio 5:1 is connected to a load resistance of 1 KΩ i. i. Determine voltage across the load. ii. DC current through the load. If there is a resistance of 100Ω for the transformer secondary and diode forward Resistance is given as 10Ω.

Short Answer Questions:

1. Write the expression of diode current equation and explain each term in detail.
2. Define cut in or threshold voltage of a diode. Give the values of Vof Si and Ge diode.
3. Write the differences between Extrinsic and Intrinsic semiconductors.
4. What are P-type and N-type semiconductors?
5. Write in detail about Drift and Diffusion currents.
6. Draw the Energy Band Diagrams of an insulator, semiconductor, Conductor.
7. Write the differences between insulators, conductors and semi conductors.
8. Define the following   a. Mobility b. Conductivity  c. Mass Action law. d.Fermi level in semi conductors.
9. Draw the diagrams for Fermi-level in Intrinsic, N-type and P-type semi conductors and write the formula for E_F in the above two cases.
10. Define Hall Effect and write the uses or applications of Hall Effect.
11. What properties of semi conductor are defined from Hall Effect?
12. What is a diode and write the applications of Diode.
13. Draw the VI-Characteristics of a diode. And calculate Static and Dynamic resistances from the characteristics.
14. Write about diffusion and Transition capacitances of a diode.
15. Define avalanche breakdown and zener breakdown.
16. What is avalanche effect and zener effect?
17. What is a rectifier? Differentiate between Half Wave Rectifier and Full Wave Rectifier.
18. Draw the equivalent circuit of practical Diode under forward bias and Reverse Bias.
19. Draw the equivalent circuit of ideal Diode under forward bias and Reverse Bias.
20. Define Peak Inverse Voltage (PIV) of a diode in a rectifier circuit. Write the PIV values in HWR, FWR and Bridge Rectifier.
21. Define the following i. Ripple factor       ii. Regulation or Percentage of Regulation. iii. From factor and peak factor. iv. Efficiency of a rectifier  v. RMS value and average value of voltage or current wave in half wave rectifier.
22. Write the applications of Zener Diode.
23. Explain how Zener diode works as a regulator.
24. What is the concentration of holes in Si crystals having donor concentration of 1.4 x 10²⁴/m³ when the intrinsic carrier concentration is 1.4 x 10¹⁸/m³ ? Find the ratio of electron to hole concentration.
25. Problems on motilities of n-type and p-type semiconductors.
26. An n-type Ge crystal has a current density of 100A/m². The crystal has a resistivity of 0.5 Ω-m and electron mobility of 0.4 m²/V-s. Calculate the drift velocity and the time taken by the electron to travel 10 micrometer in the crystal. Assume q= 1.6 x 10^-19
27. Problems on Fermi levels.
28. Problems on diode current equation in forward bias and reverse bias.
29. Write the advantages of full wave and bridge rectifiers over half wave rectifier.

Long Answer Questions:

1. Define Hall Effect. Derive the expression for Hall voltage and hall coefficient and explain the uses of Hall Effect.
2. Derive the expression for transition and diffusion capacitances of a diode.
3. Explain the working of Zener Diode as a regulator.
4. Derive the expression for ripple factor and efficiency of a Half Wave rectifier and full wave rectifier.
5. Derive the expression for ripple factor and efficiency of a bridge rectifier.
6. Compare half wave rectifier, FWR and Bridge rectifier in terms of (ripple factor, percentage of regulation, efficiency, PIV, from factor and peak factor etc…… read the comparison table in text book).
7. How will you find the dynamic and static resistance of the diode using a graph?
8. What is an ideal diode? How can it be represented as a switch? Draw the equivalent circuit and its characteristics.
9. Draw the VI-Characteristics of a PN junction diode in forward and reverse biased conditions. Define forward resistance and reverse resistances and explain how they can be obtained from the characteristics.
10. Draw the circuit diagram of a half wave rectifier and explain its operation with wave forms.
11. Draw the circuit diagram of bridge rectifier and explain its operation with wave forms.
12. Draw the circuit diagram of a full wave rectifier and explain its operation with wave forms. What is its advantage over half wave rectifier?
13. What is static resistance of the diode? How will you find the dynamic resistance?
14. Explain the zener and avalanche thermal breakdown mechanisms. What will be their thermal coefficients?
15. How is a PN junction formed? Draw the circuit diagram of PN-Junction diode in forward bias and reverse bias. Explain its operation and give VI-characteristics.
16. What is a rectifier? Draw the circuit diagram for bridge rectifier with LC-filter and explain its operation.
17. Explain bridge wave rectifier with circuit diagram and output wave forms. Find      i. RMS value of current.   ii. Ripple factor.  iii. TUF   iv. Efficiency   v. Peak factor.
18. Explain avalanche breakdown and zener breakdown in PN diode.
19. Derive the expression for ripple factor of a FWR (or HWR/ Bridge) with shunt capacitance filter.
20. Derive the expression for ripple factor of a FWR (or HWR/ Bridge) with series inductance filter.
21. Derive the expression for ripple factor of a FWR (or HWR/ bridge) with LC π section filter.
22. Derive an expression for current in a diode.
23. Compare drift and diffusion currents.

 Tutorial -1 Questions

1. A Full Wave Rectifier has a Secondary Voltage of 230V from one-end of the transformer to ground. then calculate i. DC load Current. ii. RMS value of output current. If diode has a resistance of 10Ω and the resistance of secondary winding is negligible. Given R_L=5KΩ.
2. Find the conductivity of P-type semi conductor, if the concentration of holes is 4.2X10²²atoms/m³ and mobility of holes is 1800 Cm²/V.
3. Write the expression for Hall voltage and find Hall voltage if the Magnetic field strength of 1000 Wb/m² where the current flowing through the semi conducting material is 9A. Width of semi conducting material is 2m with resistivity of 100 Mhos-m. Also find the Hall coefficient?

4. Write a short note on P-type and N-type semi conductors.

 

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ASK Generation & Detection:

1. Define ASK. Write the practical applications of ASK.
2. Draw the waveforms of ASK scheme.
3. Draw the Phasor diagrams of ASK.
4. Write the equation of ASK wave.
5. What are the applications of ASK?
6. What are the advantages and disadvantages of ASK?
7. Write the expression for Probability of error of ASK.
8. What is the BW of ASK?
9. Draw the signal constellation diagram of ASK.
10. Draw the block diagram of ASK generator. Explain its working.
11. Draw the block diagram of coherent ASK demodulator. Explain its working.
12. Draw the block diagram of non-coherent ASK demodulator. Explain its working.
13. How ASK is different from AM?
14. If bit rate is 10µsec then calculate the band width of ASK.
15. Which is the efficient modulation scheme among ASK and PSK give the reason.
16. Write the relation between complementary error function and Q-Function.
17. Write the P_e of ASK in terms of Q function.
18. What is meant by Signal space diagram?
19. A source generates three symbols with probability 0.25,0.25 and 0.5 at a rate of 3000 symbols/sec Assuming the symbols are generated independently from the source the most efficient source encoder would have average bit rate of——————————.

FSK Generation & Detection:

1. Define FSK. Write the practical applications of FSK.
2. Draw the waveforms of FSK scheme.
3. Draw the Phasor diagrams of FSK.
4. Write the equation of FSK wave.
5. What are the advantages and disadvantages of FSK?
6. Write the expression for Probability of error of FSK.
7. What is the BW of FSK?
8. List some applications of FSK.
9. Draw the block diagram of FSK generator and explain its working.
10. Draw the block diagram of coherent FSK demodulator and explain its working.
11. Draw the block diagram of non-coherent FSK demodulator and explain its working.
12. Show that FSK is inferior to PSK by 3dB for a given probability of error.
13. Define digital modulation schemes.
14. Identify the differences between Pass band and Base band Communication.
15. What is a matched filter?
16. What are the properties of matched filter?
17. What is MSK? What is the need for Minimum Shift Keying?
18. For the given 8 bit data 10111010 draw the FSK output waveform.
19. Draw the constellation diagram of FSK.
20. What will happen if the same frequency is used for both the carriers?
21. Draw FM signal and FSK signal differentiate those two signals.
22. What are the applications of FM?
23. How FSK is different from FM?
24. Write the probability of error expression of FSK in-terms of Q function.
25. Write the relation between complementary error function and Q-Function.
26. Among FSK and PSK which is the most efficient scheme and why?

 

PSK Generation & Detection:

1. Define PSK. Write the practical applications of PSK.
2. Draw the waveforms of PSK scheme.
3. Draw the signal space diagram of PSK.
4. Write the equation of PSK wave.
5. What are the applications of PSK?
6. What are the advantages and disadvantages of PSK?
7. Write the expression for Probability of error of PSK in terms of erfc()
8. Write the expression for Probability of error of PSK in terms Q().
9. Write the difference between erf(x) and erfc(x)..
10. What is the BW of PSK?
11. What are antipodal signals?
12. Give the equation for average probability of symbol error for coherent binary PSK.
13. Explain how QPSK differs from PSK in terms of transmission bandwidth and bit information it carries.
14. What are the advantages of M-ary modulation scheme?
15. Draw the constellation diagram for QPSK.
16. Compare FSK and PSK.
17. What do we infer from constellation diagrams of various modulation schemes?
18. Draw the block diagram of PSK generator. Explain its working.
19. Draw the block diagram of coherent PSK detector. Explain its working.
20. How non coherent PSK is advantageous over coherent PSK?
21. Other name of Non-coherent PSK is———–.
22. Write the expression for a Gaussian function———————.

 

DPSK Generation & Detection:

11. Define DPSK.
12. Draw the waveforms of DPSK scheme.
13. Write the equation of DPSK.
14. What are the applications of DPSK?
15. What are the advantages and disadvantages of DPSK?
16. Write the expression for Probability of error of DPSK.
17. What is the BW of DPSK?
18. What are the applications of DPSK?
19. Draw the DPSK system and explain its working.
20. If the input sequence to a DPSK modulator is 10011100 write the following sequences, Deferentially encoded sequence if previous bit is 0 And the phase of the encoded sequence.
21. The capacity of a band limited AWGN channel in terms of KBPS if the average received signal to noise power spectral density is 1000 and the BW is approximately infinite is…………..
22. For error free channel conditional probability is ————-.
23. The modulation technique that provides minimum probability of error is———-.

QPSK Generation & Detection:

1. Define QPSK.
2. Draw the waveforms of QPSK scheme.
3. Draw the Phasor diagrams of QPSK.
4. Write the equation of QPSK wave.
5. What are the applications of QPSK?
6. What are the advantages and disadvantages of QPSK?
7. Write the expression for Probability of error of QPSK.
8. Draw the block diagram of QPSK modulator. Explain its working.
9. Draw the block diagram of coherent QPSK de modulator. Explain its working.
10. Write the table for four di-bits with phases used in a QPSK modulation scheme.
11. Write the equation of QPSK wave.
12. What is the BW of QPSK?
13. What are the applications of QPSK?
14. Draw the constellation diagram for QPSK.
15. In Minimum Shift Keying the relation between the signal frequencies and bit rate are————.
16. A pulse for is passed through a matched filter then the impulse response of matched filter is—————————.
17. A lossless channel means—————–.
18. A distortion less channel means————————-.
19. Write the channel matrix for a Binary symmetric channel——————–.

Losses in fibre optics:

1. Define Transmission loss of Optical fibre?
2. What are various losses in fibre optics?
3. What are step index graded index optical fibers?

Data Formats:

1. Compare NRZ-I and NRZ- L.
2. What is the use of data formatting?
3. Compare NRZ and biphase encoding.
4. What is the relationship between quantization levels and number of bits in a code word?
5. Give the advantages of Manchester encoding.
6. Assume a data stream is made of ten 0s. Encode this stream using the following encoding schemes.
7. How much change can you find for each scheme? a)NRZ b)RZ c)Bi phase

8. List out the merits & demerits of each data formats.
9. Represent the given data 11010100 in Manchester encoding and NRZ –M scheme.

Delta Modulation & Demodulation:

1. What is Delta Modulation?
2. A message signal m(t) has a BW of 1KHz and exhibits a maximum rate of change of change of 2 Volts/sec the signal is sampled at a sampling frequency of 20 KHz and Quantized using a delta modulator the minimum step size to avoid slope overload is———-
3. Which type of Quantization is used in DM?
4. What are two types of quantization errors?
5. What is granular noise?
6. What is slope overload distortion?
7. Draw the block diagram of Delta Modulation system.
8. What are the advantages and disadvantages of DM system?
9. What happens to the output signal if the variation of the message signal is

• greater than the step size
• less than the step size

10. What is the advantage of delta modulation over PCM?
11. Compare DPCM, PCM& Delta modulation.
12. How to reduce the quantization noise that occurs in DM?
13. A band pass signal has a spectral range that extends from 20 to 82 KHz. Find the acceptable sampling frequency.

14. Find the Fourier series expansion of an Impulse train.
15. Mention the applications of DM.
16. Write the condition to eliminate Slope over load distortion in Delta Modulation for a single tone message signal.
17. Write the condition to eliminate Slope over load distortion in Delta Modulation for some arbitrary signal.
18. We chose oversampling in DM system. True or False?
19. How DPCM is different from DM?
20. Draw the waveforms of DM demodulation and Demodulation.
21. Differentiate Coherent and Non coherent modulation schemes.
22. Explain the working DM system.
23. Draw the Wave forms and explain two distortions in DM system.

Pulse Code Modulation:

1. What is PCM? Does PCM come under Digital Modulation technique?
2. What are the applications of PCM?
3. What is the need for Regenerative repeaters in PCM?
4. Draw the block diagram of PCM system.
5. Define µ-law and A-law. And draw the characteristics of two laws.
6. What is meant by Quantization?
7. Differentiate Uniform and Non uniform Quantization techniques.
8. What is meant by companding in PCM?
9. What are the advantages and disadvantages of PCM?
10. What is the difference between ADC & PCM?
11. Name some ADC circuits?
12. Which ADC is fastest ADC circuit?
13. What is slope overload distortion?
14. Draw the waveforms of PCM modulation and demodulation.
15. State sampling theorem.
16. What is aliasing?
17. Give the expression for aliasing error and the bound for aliasing error.
18. What is quantization?
19. What are the various steps involved in A/D conversion.
20. Define step size.
21. What is the importance of regenerative repeater?
22. List out the three basic functions of regenerative repeater.
23. What is companding?
24. Write the mean square quantization error if the step size is S.
25. What is a mid tread Quantizer?
26. What is a mid rise Quantizer?
27. What do you mean by quantizing process?
28. What will happen when sampling rate is greater than Nyquist rate?
29. What will happen when sampling rate is less than Nyquist rate?
30. Find the A/D Converter output for input DC voltage of 3.6V.
31. In digital telephony, (a) what kind of modulation is used? (b)Give the typical sampling rate, output data rate and speech signal Bandwidth.
32. Mention some applications of PCM.
33. What is the function of Sample and Hold circuit?
34. Write the expression for SNR in decibels of a PCM system.
35. For a DAC the required resolution is 25mv and the total input is 5V. the number of bits required would be——————————————.

 

Digital Communications Unit-3 Quiz with Solutions

UNIT3

QUIZ3[CO3]

1. The number of Parity check bits in an (n, k) Linear Block codes are (    b      )      a.n                b. (n-k)                       c.  (n+k)                       d. k
2. The Hamming Weight of the following code words 10011101 & 00111100 is      (   c   ) 2M.                                                                                                                                       a. None of these      b. 4, 5              c.5, 4                           d.3,4
3. A cyclic code can be generated using———————— and A block can be generated using——————-.(   c   )                                  a.Generator matrix & Generator polynomial.                                                          b.Generator matrix & Generator matrix.                                                            c.Generator polynomial & Generator matrix.                                                            d.None of the above.
4. The rate of a Block code is the ratio of(    c     )                                                                a.Message length to Block length.                 b.Block length to message length.  c.Message weight to Block length.                 d.None of the mentioned.
5. The syndrome in LBC is calculated using , where Y represents received code word   (     a       ) 2M                                                                                                                      a. S= Y H^T          b. S = YH                    c. S= Y^T H                  d. S= Y^T H^T
6.  A non-Zero value of Syndrome in a Block code represents ( b    ) 2M.                  a.No error during transmission.     b.An error occurred during transmission.   c.Both a and  b                                         d.None of the above.
7. The transmitted code word(X) in an LBC can be obtained from received code word( Y) by using the equation (  a   ), where E represents error vector.              a. X= E + Y           b.  X = X.Y                  c. X= E.Y                    d. X= X/Y

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