Sunday, 27 April 2014

Operating System Important Questions Units Wise For External Exams

Operating System Important Questions Units Wise For External Exams

Unit 1-Intro to OS
1.What is an Operating System? Differentiate between the two views of OS? IMP
2.What are the goals of an OS? IMP
3.What are the components of Operating System?
4.What are the services provided by Operating System? IMP
5.What are OS operations? Explain.
6.Give advantages of multiprocessor systems. Give features of symmetric and asymmetric
multiprocessing systems. IMP
7.Explain the below terminologies in Operating Systems
Multiprogramming systems, Multitasking systems, Multiprocessor systems. IMP
8.Describe layered approach to the design of an OS and its advantages.
9.Explain any two computing environment.
10.Explain Virtual Machine(VM) with example and diagram.What are its benefits? IMP

Unit  2-Process Mgmt
1.What is a process? With a state diagram, explain states of a process. Also write
structure of Process Control Block(PCB). IMP
2.Differentiate between long term, medium and short term schedulers.
(or explain diff type of schedulers). IMP
3.Define IPC (Interprocess Communication). Explain two models of IPC.
4.What are cooperating processes? Discuss direct and indirect communication,
5.Define the five scheduling criteria considered in Process Scheduling.
6.Explain process creation and termination.
7.Discuss three common ways of establishing relationship between user and kernel thread.
8.What is a thread? Why is it called a LWP? Discuss multithreading models. IMP
9.Discuss threading issues. IMP
10.For the processes listed below, calculate average waiting time and turnaround
time using FCF and Pre-emptive SJF
Process      Arrival Time   Burst Time            
P1 0.0 1.5
P2 1.5 3
P3 3.0 1
P4 3.0 7.5
11. For the processes listed below, calculate average waiting time and turnaround
time using SJF(Non- pre-emptive) and SRTF(Pre-emptive)
Process      Arrival Time   Burst Time            
P0 0 6
P1 1 3
P2 2 1
P3 3 4

12.Consider 5 processes with below arrival time, burst time and priority. Find the average waiting time and average turnaround time using
i) SRTF ii) Pre-emptive priority iii) RR (q=1)
   Process      Arrival Time            Burst Time            Priority
P1 0 7 3
P2 3 2 2
P3 4 3 1
P4 4 1 1
P5 5 3 3

Unit  3-Process Synchronization

13.Describe a critical section problem IMP
14.Describe ‘test and set‘and ‘swap’ instructions
15.Explain the Dining Philosphers problem. IMP
16.What are monitors. Explain monitor soln to Dining Philosphers problem. IMP
17.Explain the solution for classical synchronization bounded buffer problem using semaphores. IMP
18.Explain signal and wait instructions.


1)Describe the necessary conditions for a deadlock situation to arise in a system. - IMP
2)How can deadlocks be prevented? (Or explain deadlock prevention).
3)Explain various approaches for deadlock recovery. IMP
4)Define the terms: safe state and safe sequence. Give an algo to find whether or nota system is in a safe state.
5)Explain resource request algo.
6)Explain deadlock handling. Explain Bankers algo.
7)Consider the below snapshot:
Allocation Max Available
ABCD             ABCD   ABCD
P0 0 0 1 2 0 0 1 2   1 5 2 0
P1 1 0 0 0 1 7 5 0  
P2 1 3 5 4 2 3 5 6  
P3 0 6 3 2 0 6 5 2  
P4 0 0 1 4 0 6 5 6
Answer the below questions using Banker’s algo:
1)What is the content of the matrix need?
2)Is the system in safe state?
3)If a request from process P1 arrives for (0,4,2,0) can the request be granted immediately? IMP
8)Consider the below snapshot:
Allocation   Max Available
ABC               ABC   ABC
P0 0 1 2 0 1 2   5 2 0
P1 0 0 0 7 5 0  
P2 3 5 4 3 5 6  
P3 6 3 2 6 5 2  
P4 0 1 4 6 5 6
Answer the below questions using Banker’s algo:
1)What is the content of the matrix need?
2)Is the system in safe state? If yes, write the safe sequence.
9)Consider the below snapshot:
Allocation   Max Available
ABC               ABC   ABC
P0 0 1 0 7 5 3   3 3 2
P1 2 0 0 3 2 2  
P2 3 0 2 9 0 2  
P3 2 1 1 2 2 2  
P4 0 0 2 4 3 3
Check whether the system is safe state or not. If yes, write the safe sequence. Further if P1 requests(1,0,2) determine if it can be granted immediately.


•Size of logical address space or memory = 2m
•Size of page =2n
•Then high order m-n bits give page no. and lower order n bits give offset.
•Number of pages= Size of logical address space or memory / Size of page
•Number of frames= Size of  physical address space or memory / Size of frame
•Page size=Frame size
•Page table size = number of pages * size of each page table entry
       = (Size of logical address space or memory / Size of page )* size of each page table entry
1.Given memory partitions of 270,150,600(KB)(in order) how would each of first-fit, best-fit and worst fit algorithms place the processes of 100,212 and 270(KB) in order.
2.Memory partitions of 100KB,500KB,200KB,300KB,500KB(in order) are available. How would first fit, best fit and worst fit algo place the processes of 212KB,417KB,112KB and 426KB(in order). Which algo makes efficient use of memory?
3.For a particular implementation of simple paged allocation, the page size is fixed to 4K and the total size of program is 16 Kilobytes. What is the total number of pages that are required for this program? Also calculate number of bits in the logical address.
4.For a logical address space of 8 pages of 1024 words mapped to a physical memory of 32 frames, find the number of bits in the logical address and number of bits in the physical address.- -IMP
5.Consider the system with 32-bit logical address space. Page size is 4KB and each entry in the page table is 2 Bytes long. How much memory is required for page table? What is the size of the main memory?
6.On a simple paging system with a page table containing 512 entries of 15 bits, page size of 1024 bytes, answer the following:
7.How many bits specify the offset with the page?
8.How many bits are there in the logical address?
9.What is the size of logical address space?
10.How many bits specify the page frame number?
11.How many bits are there in the physical address?
Effective Access Time for PAGING with TLB
12.Calculate the effective access-time if 20 nanoseconds is taken to access TLB,100 nanosec to access from memory and 100 nanoseconds to access frame number,
i) if hit ratio is 80% ii) if hit ratio is 98% -IMP
Soln: i) If we fail to find the page number in the associative registers (20 nanoseconds), then we must first access memory for the page table and frame number (100 nanoseconds), and then access the desired byte in memory (100 nanoseconds), for a total of 220 nanoseconds. To find the effective access time, we must weigh each case by it probability:
Effective access time = 0.80 * 120 + 0.20 * 220
= 140 nanoseconds
We suffer a 40-percent slowdown in memory access time (from 100 to 140 nanoseconds).
ii)For a 98-percent hit ratio, we have
effective access time = 0.98 * 120 + 0.02 * 220 = 122 nanoseconds
The increased hit rate produces only a 22-percent slowdown in memory access time.
13.Assume we have a paged memory system with associative registers (TLB) to hold the most active page table entries. If the page table is normally held in memory and memory access time is 1 microsec, what would be the effective access time if 85% of all memory references find their entries in the associative registers. Assume the associative registers access time is zero.
14.For a memory access system with a TLB we have TLB hit ratio of 0.9, memory access time 110 nanosecs, TLB search time 20 nanosecs. Calculate the effective memory access time.
Performance of Demand Paging
Page Fault Rate or probability of page fault    0 ? p ? 1.if p = 0 no page faults and p = 1, every reference is a fault.
Effective Access Time (EAT) = (1 – p) x memory access + p x page fault time
15.Given page-fault service time 8 msec, memory access time 100 nanosecs, page fault rate 0.0002. Calculate the effective access time (in sec).
16.On a system using demand paged memory it takes 0.12 microsec to satisfy a memory request. If the page is not in memory the request takes 5000 microsec. What would be the page fault rate needed to be to achieve an access time 1000 microsec? Assume the system is only running a single process and the CPU is idle during the page swaps.
17.Consider the following reference string:
7 0 1 2 0 3 0 4 2 3 0 3 2 1 2 0 1 7 0 1
for a memory with three frames. How many page faults would occur for FIFO, OPTIMAL, ad LRU Page replacement algorithms?  Which is the most efficient among them?- -IMP


Chapter -10 File System
1.Write notes on: i)File types ii)file operationsii)file attributes iv)file structure
2.Explain different file access methods.- IMP
3.Explain different directory structures.(or Explain one e.g.tree or acyclic graph structure)- IMP
Chapter -11 File System Implementation
4.Explain different disk allocation methods methods.(Explain one e.g. indexed method)- IMP
5.Explain methods of implementing directories.
6.Explain methods of  free space management- IMP


Chapter -12 Secondary storage structure
1.What is disk scheduling? Explain all disk scheduling algorithms in brief.
2.Explain disk formatting.
3.Explain bad block handling.
4.Consider a disk queue with requests for I/O to blocks on below cylinders in order:
98,183,37,122,14,124,65,67. If disk head is initially at 53, calculate the head movements when the following scheduling are used i)FCFS  ii)SSTF iii)SCAN iv) LOOK—IMP
5.A drive has 5000 cylinders numbered 0 to 4999. The drive is currently serving a request at cylinder 143 and the previous request was at cylinder 125. The queue of pending requests in FIFO order is: 86,1470,913,1774,948,1509,1022,1750,130. Starting from the current head position, what is the total distance travelled by the disk arm(in cylinders) to satisfy the requests using FCFS,SSTF,SCAN,LOOK. Illustrate with figure
Chapter -17 Protection
6.What are goals of protection? IMP
7.Explain access matrix model of protection.-IMP
8.Explain domain of protection.
9.Explain system and program threats. IMP
10.What are worms and viruses?
11.Distinguish between system protection and system security.
for a memory with three frames. How many page faults would occur for FIFO, OPTIMAL, ad LRU Page replacement algorithms?  Which is the most efficient among them?- -IMP

18.Consider the following reference string:
R= 0 1 2 3 0 1 4 0 1 2 3 4
Calculate the number of page faults when number of frames is equal to 3 and 4 using FIFO algo. Do you notice Belady’s anamoly.
19. A process references 5 pages A,B,C,DE in the following order:
Assuming that the replacement algo is “LRU” and “FIFO”, find out the number of page faults during the sequence of references, with an empty main memory with 3 frames.
20.Consider the following reference string:
1 2 3 5 2 3 5 7 2 1 2 3 8 6 4 3 2 2 3 6
for a memory with three frames. How many page faults would occur for FIFO, OPTIMAL, and LRU Page replacement algorithms?
21.Consider the following reference string:
0 9 0 1 8 1 8 7 8 7 1 2 8 2 7 8 2 3 8 3
for a memory with three frames. How many page faults would occur for FIFO, OPTIMAL, and LRU Page replacement algorithms?
22.What do you mean by a address binding? Explain with the necessary steps, the binding of instructions and data to memory addresses.
23.Describe execution time binding.
24.What is memory fragmentation? Explain internal and external fragmentation with a neat diagram. How are they overcome?¬-IMP
25.Explain the technique used to overcome external fragmentation.
26.Give differences between i) internal and external fragmentation ii) paging and segmentation.- -IMP
27.Explain i) Worst fit ii) First fit iii) Best fit storage allocation.
28.Explain the concept of paging using TLB--IMP
29.Describe TLB. How it improves memory access time with an example?
30.Explain basic concept of segmentation with respect to memory management.
31.What is Virtual Memory? Explain with examples.
32.With a diagram, discuss the steps involved in handling a  page fault. -IMP
33.What is need of page replacement?
34.Describe various page replacement algorithms. Explain them with an example.
35.What do you mean by a copy-on-write? Where it is used? Explain in brief.
36.What is thrashing?- -IMP
37.What is swapping?

Operating System Important Questions And Easy Units For Exams

Operating System Important Questions And Easy Units For Exams

1.Explain the Types of System Calls in detail
2.xplin how hardwar protection can be achieved and discus in dtail the dualmd of oprn.
3.Explain in detail any two operating system structures
4.List out the services provided by operating system in detail
5.Describe the differences among short-term, medium-term, and long-term scheduling.
1.Explain briefly any four CPU scheduling algorithms with examples
2.Explain Banker's deadlock-avoidance algorithm with an illustration
3.xplain what semaphres are, their usage,implemention givn to avoid busy waiting and binary semaphores
4.Define critical section problem and discuss the three requirements that a
solution to the critical section problem must satisfy
1.Discuss the following page replacement algorithms, giving a suitable page
reference string (i) LRU (ii) FIFO and (iii) Optimal
2.Explain the most commonly used techniques for structuring the page table
3.Explain  the  concept  of  demand  paging.  How  can  demand  paging  be
implemented with virtual memory?
4.Explain in detail about memory management in linux
1.Explain the various directory structure in detail
2.Explain in detail the free space management with neat diagram
3.Explain various file allocation methods in detail.
4.what are the directory implementation techniques available ?Explain in detail
1.Explain  in  detail  various  disk  scheduling  algorithms  with  suitable example
2.Explain the services provided by a kernel I/O subsystem
3.Write short notes on the following   (i)  I/O Hardware (ii)  RAID structure

Computer Organization Important Questions For External Exams Unit Wise

Computer Organization Important Questions For External Exam Unit Wise

1) What are functional units? Discuss the basic functional units of a computer?
2) With a neat diagram explain the basic operational concepts of computer?
a) Explain various types of buses?
b) Discuss the functions of system software?
4) Discuss and differentiate multi computers and multi processors.
5) Explain the different types of data representation?
6) Explain about the error detection codes with parity checker circuit?


1) Explain with example the implementation of register transfer?
2) Discuss in detail about various arithmetic operations.
3) Explain the following operations in detail
a) Basic micro operations.
b) Arithmetic shift.
c) Circular shift.
d) Rotate shift.

4) What is an instruction code? Explain in detail various addressing modes.
5) Explain the instruction cycle with a neat flow chart.
6) Explain the data transfer and manipulation instructions.
7) Define interrupt? Explain the types of interrupts.
8) Define and discuss the types of registers.


1) Explain with neat diagram, the address selection for control memory.
2) Explain the design of control unit.
3) Define and discuss the differences between hardwired control unit and micro programmed control unit.
1) Define the Static RAM (SRAM). Explain the working of SRAM cell with a neat diagram.
2) Define the Dynamic RAM (DRAM). Explain the working of DRAM with a neat diagram.
3) Define the Read Only Memory. Explain in detail the types of ROM’s.
4) Define and discuss the types of replacement algorithms.
5) Define Virtual Memory. Explain the process of converting virtual addresses to physical addresses with a neat diagram.
6) Explain the following secondary storage devices
   a) Magnetic disk.
   b) Magnetic tape.

7) Explain the following mapping functions
   a) Associative mapping.
   b) Direct mapping.
   c) Set Associative mapping.


1) Explain about asynchronous data transfer and asynchronous communication interface.
2) Explain about modes of transfer.
3) Explain about interrupt priorities.
4) Explain about DMA in detail.


1) Explain the Flynn’s classification to accomplish parallel processing.
2)a) Define pipelining? Explain the structure of pipelining with an example.
b) Explaining the implementation of four stage pipelining.

3) List out the limitations of instruction pipeline.
4) List out the advantages of RISC and CISC
5) Define vector processing. Explain the characteristics of vector processing.
6) Explain the instruction format of vector processor.
7) What is array processor? Explain the two categories of array processor

1) List out several of characteristics of multi processors.
2) What is meant by interconnection structure? Mention the various types of interconnection structures.
3) Define the following in detail
a) Inter Process Arbitration.
b) Inter Process Communication.
c) Synchronization.

4) Explain about cache coherence in detail.
5) Discuss about the shared memory multi processors.

Computer Organization Important Questions And Easy Units

Computer Organization Important Questions And Easy Units


1.      Define addressing mode. Classify addressing modes and explain each type with example
2.      Explain the architecture of basic computer with neat diagram.
3.      Design a combination circuit whose input is a 4-bit number and whose output is a two’s compliment
of the input number.


1.      Describe in detail booth's multiplication algorithms and its hardware implementation.
2.      With suitable diagram explain how multiplication can be performed using a multistage carry-save
adder circuit and also
implementation of a pipelined carry-save multiplier.
3.      Draw non-restoring division algorithm for unsigned integer with suitable example.


1.Describe various factors that reduce the performance of pipelined CPU and mechanism to overcome it?
2. What are superscalar processors? Explain the typical structure of a typical superscalar processor?
3 . Describe the organization of a typical micro-programmed control unit with the help of a neat  diagram.


1.      Draw the neat sketch of memory hierarchy and explain the need of cache memory
2.      Explain the organization of magnetic disk in detail.
3.      Explain optical memories in detail.
4.      Explain the organization of Random access memories


1.      Explain the Programmed I/O and DMA mode of data transfer.
2.      Define Interrupt. Explain it types in detail
3.      Explain the DMA mode of data transfer.


IC Applications

1. (a) Derive closed loop voltage gain, input resistance, output resistance and band-
width for inverting amplifier with feedback arrangement. [10+6]

(b) Explain any one of the frequency compensation technique in connection with

2. (a) Explain how Op-amp used as a integrator and differentiator.

(b) With the help of a neat circuit diagram, explain the operation of instrumen-
tation amplifier of obtain the expression for its o/p voltage VO. [8+8]

3. (a) Define a Notch filter. Give its application.

(b) Determine the order of the Butterworth low-pass filter so that at ? = 1.5?3dB,
the magnitude response is down by at least 30 dB.

(c) Design a notch filter for fo =8 kHz and quality factor Q=10. Choose C=500pf
and assume necessary data. [5+6+5]

4. (a) Describe the operation of an analog phase detector.

(b) Analyze the behavior of an analog phase detector through necessary circuit
diagram, waveforms, mathematical expressions and characteristic curves.[8+8]

5. (a) Sketch and explain the transfer characteristic of a DAC with necessary equa-

(b) LSB of a 9-bit DAC is represented by 19.6 m Volts. If an input of 9 zero bits
is represented by 0 volts.
i. Find the output of the DAC for an input, 10110 1101 and 01101 1011.
ii. What is the Full scale Reading (FSR) of this DAC? [8+8]

6. (a) Draw the schematic circuits of CMOS NAND and CMOS NOR gates and
explain their functions with the help of Truth-Table.

(b) What are the advantages and disadvantages of CMOS over TTL gate?

(c) Which is the fastest saturated logic gate? and Why? [8+4+4]

7. (a) Write short notes on n- Bit parallel adder.

(b) Design a driver circuit for LCD display. [8+8]

8. (a) Explain with an example why asynchronous inputs are required in flip flops.

(b) Explain the operation of edge triggered T flip- flop. [8+8]

set 2

1. (a) What is cross over distortions and how it is eliminated in differential amplifier?

(b) Explain different methods of external frequency compensation in an Op-amp.

(c) Design an amplifier with a gain of +5 using one Op-amp ( make necessary
assumptions). [4+6+6]

2. (a) What is a clipper? With circuit diagram, explain the operation of positive
and negative clippers.

(b) Describe the principle of operation of a precision half wave rectifier with wave
forms. [10+6]

3. (a) Derive the expression for frequency of oscillation of a RC phase shift oscillator
and explain the operation of the circuit.

(b) Design a second order low pass filter at a high cut off frequency of 1 KHz.
Derive the transfer function of the above filter. [8+8]

4. (a) Draw and explain the functional diagram of a 555 Timer.

(b) Explain the function of ‘reset’ pin. [14+2]

5. (a) Sketch and explain the transfer characteristic of a DAC with necessary equa-

(b) LSB of a 9-bit DAC is represented by 19.6 m Volts. If an input of 9 zero bits
is represented by 0 volts.
i. Find the output of the DAC for an input, 10110 1101 and 01101 1011.
ii. What is the Full scale Reading (FSR) of this DAC? [8+8]

6. List out advantages, disadvantages & applications of MOS logic. [16]

7. (a) Design 1:8 Demultiplexer using two 1:4 Demultiplexer?

(b) Realize the following expression using 74×151 ICs and 74×139 IC [8+8]

8. (a) Distinguish between Combinational circuits and sequential circuits.

(b) Write short notes on Clocked SR flip flop. [8+8]


1. (a) List out the ideal characteristics of an Op-amp.

(b) With neat block diagram explain the function of various building blocks of an

(c) Draw the equivalent circuit of an Op-amp. [3+10+3]

2. (a) Explain the operation of Zero crossing detector.

(b) Briefly mention the disadvantages of using Zero crossing detector and how it
is overcome in Schmitt Trigger?

(c) Draw a circuit using Op-amp which can work as adder (inverted and non-
inverted) and explain how it works. [4+4+8]

3. (a) Design a II order Butterworth Low-pass filter for a cut off frequency of 1KHz
and for a given normalized polynomial of S2+1.414S+1. Assume necessary

(b) In the above circuit given (figure 3(b)ii) if the integrator components are
R1=120 K and C1 = 0.01µF,R3= 6.8 K R2= 1.2K, determine
i. Peak-to-peak triangular output amplitude.
ii. The frequency of triangular wave. [8+8]
Figure 3(b)ii

4. (a) Design a 555 Astable multivibrator to operate at 10 KHz with 40% duty cycle.

(b) Explain in which the 555 timer can be used as Astable multivibrator. [8+8]

5. (a) Draw the block diagram for a 2-bit parallel-comparator A/D converter and
explain the operation of the system.

(b) Draw a schematic diagram of a ladder network D/A converter. Explain the
operation of the converter. [8+8]

6. (a) Explain the operation of open drain output of CMOS?

(b) Explain the behavioral difference between simple transistor logic inverter and
Schottky logic inverter? [8+8]

7. (a) What is multiplexer? Draw the logic diagram of 4 to 1 line multiplexer?
(b) Design half adder using NAND gates only? [8+8]

8. (a) Explain with the help of neat diagram the simple structure of MOS ROM.
(b) Design MOD 5 synchronous counter. [8+8]

SET    4

1. (a) Give the pin diagram of IC741 and give its specifications.

(b) Discuss the differences between the differential amplifiers used in the first two
stages of Op-amp. [8+8]

2. (a) Explain the operation of Zero crossing detector.

(b) Briefly mention the disadvantages of using Zero crossing detector and how it
is overcome in Schmitt Trigger?

(c) Draw a circuit using Op-amp which can work as adder (inverted and non-
inverted) and explain how it works. [4+4+8]

3. (a) The cutoff frequency of a certain first order low pass filter is 2 KHz. Convert
this low pass filter to have a cutoff frequency of 3 KHz by using the frequency
scaling technique.

(b) How do we get a Notch filter from a band pass filter.

(c) What are the advantages of active filters over passive filters. [8+4+4]

4. (a) Give the block diagram of PLL and explain about each block in detail.

(b) Define the following terms with reference to PLL.
i. Lock range.
ii. Capture range.
iii. Pull-in-time. [10+6]

5. (a) Draw and compare the conversion times for tracking and successive approxi-
mation ADC devices.

(b) A dual slope ADC uses a 12bit counter and a 8 MHz clock rate. The max
input voltage is +10V. The maximum integrator o/p voltage should be -8V,
when the counter has cycled through 2n counts. The capacitor used in the
integrator is 0.1µF. Find the value of the resistor of the integrator. [8+8]

6. (a) Explain the following terms with reference to TTL gate?
i. Logic levels.
ii. DC Noise margin.
iii. Low-state unit load.
iv. High-state fan out.

(b) List out TTL families and compare them with reference to propagation delay,
power consumption, speed-power product and low level input current? [8+8]

7. (a) Design the combinational circuit for common cathode 7 segment display/driver?

(b) Write short notes on gray code to Binary converter. [8+8]

8. (a) Write a note on applications, advantages and disadvantages of SRAM.

(b) Design MOD 6 synchronous counter. [8+8]


ANTENNAS AND PROPOGATION Very Important Questions 

CHAPTER 1: Antenna Basics

  1. Define the following parameters w.r.t antenna:
                                                               i.      Radiation resistance.
                                                             ii.      Beam area.
                                                            iii.      Radiation intensity.
                                                           iv.      Directivity.
                                                             v.      Gain.
                                                           vi.      Isotropic radiator.
                                                          vii.      Directive gain.
                                                        viii.      Hertzian dipole.
                                                           ix.      Power gain.
                                                             x.      Efficiency.
                                                           xi.      Power density.
                                                          xii.      Steradians & radians.
  1. With the help of neat diagrams explain the principle of radiation in antennas.
  2. Explain the antenna as a transmitting device and as a receiving device.
  3. Write a note on radiation pattern and radiation lobes.
  4. Draw the radiation pattern of: (i) Directional antenna.   (ii) Isotropic antenna.
  5. Explain different types of aperture.
  6. Define aperture of an antenna and find its relation with directivity.
  7. Explain effective height of an antenna.
  8. Derive FRIIS transmission formula and explain its significance.
  9. Derive an expression for power radiated by an isotropic antenna.
  10. Derive the relation between directivity and beam solid angle.
  11. Derive the relationship between radiation resistance and efficiency.
  12. Derive an expression for field intensity at a distant point.
  13. Write short notes on: (a) Fields of an oscillating dipole
    (b) Antenna field zones.
  1. Show that  an isotropic radiator radiating 1 KW power gives a field of 173mv/m at a distance of 1 Km.
  2. Find the directivity of an antenna having radiation resistance of 72 Ħ and loss resistance of 12 Ħ and a gain of 20.
  3. What is the maximum effective aperture of a microwave antenna which has a directivity of 900?
  4. Using FRISS transmission formula find the maximum power received at a distance of 0.75 Km over a free space. A 100 MHz circuit consisting of a transmitting antenna of 30dB gain and a receiving antenna with a 25dB gain is used. The power input to the transmitting antenna is 120W.
  5. A radio station radiates a total power of 10KW and a gain of 30. Find the field intensity at a distance of 100Km from the antenna. Assume free space propagation.
  6. Find the number of square degrees in the solid angle on a spherical surface that is between ?=20o and 40o and ?=30o and 70o.
  7. Calculate the length of half wave dipole antenna meant to have wavelength at 60MHz.
  8. Calculate the gain of an antenna with a circular aperture of diameter 3m at a frequency of 5 GHz.
  9. An antenna radiates a total power of 100W in the direction of maximum radiation, the field strength at a distance of 10Km was found to be 12mV/m. What is the gain of the antenna? Assume free space propagation. If ?=90% find directivity.
  10. An antenna has a radiation resistance of 72Ħ loss resistance of 8Ħ power gain of 12dB. Determine the antenna efficiency and directivity.
  11. An antenna has a loss resistance of 10Ħ power gain of 20 and directivity gain of 22. Calculate the radiation resistance.
  12. Calculate the effective length of a ă/2 antenna gives Rr=73 Ħ effective aperture 0.13 ă2.
  13. An antenna radiates power equally in all directions. The total power delivered to the radiator is 100 KW. Calculate the power density at distance of (i) 100m (ii) 1000m.

CHAPTER 2: Point Sources
28.Dpoint source. Explain different types of power pattern.
  1. Explain power theorem.
  2. Find the directivity for the following intensity patterns:
  3. Hemispheric power pattern of a uni directional antenna.
  4. Unidirectional cosine power pattern.
  5. Bi directional sine power pattern.
  6. Bi directional sin2 power pattern.
  7. Unidirectional cos2 power pattern.
  8. Show that directivity for unidirectional operation is 2(n+1) for an intensity variation of U=UmCosn ?.

CHAPTER 3: Antenna Arrays
  1. Write a note on antenna arrays. Mention the factors on which the resultant pattern
  2. depends.
  3. Differentiate between BSA and EFA.
  4. Draw the radiation pattern of 
  5. 2 isotropic point sources of same amplitude and phase that are ?/2 apart along X axis symmetric w.r.t origin & ƒÂ=0
  6. 2 isotropic point sources of same amplitude and phase that are ?/2 apart along X axis symmetric w.r.t origin & ƒÂ=ƒÎ
  7. 2 isotropic point sources of same amplitude and  opposite phase that are ?/2 apart along X axis symmetric w.r.t origin & ƒÂ=0
  8. 2 isotropic point sources of same amplitude and phase that are ?/2 apart along X axis with 1 source at origin & ƒÂ=0
  9. 2 isotropic point sources of same amplitude and in phase quadrature. 
  10. Derive an expression for electric field intensity of array of n isotropic sources of equal amplitude and spacing and having a phase difference of ƒÕ.
  11. Explain the principle of pattern multiplication.
  12. Obtain the electric field intensity of non isotropic but similar point sources.
  13. obtain the radiation pattern of 4 sources forming a uniform BSA with a spacing of ?/2.
  14. Obtain BWFN & HPBW for BSA.
  15. Obtain BWFN & HPBW for EFA.
  16. Explain Hansen Woodyard condition for increased directivity.
  17. 4 sources have equal magnitude & are spaced ?/2 apart. Maximum field is to be in line with sources. Plot the field pattern of the array given ƒÕ=0.
  18. Find BWFN for uniform EFA & extended EFA. Given (i) n=4 (ii) d= ?/2.
  19. The principle lobe width of uniform 10 elements of BSA was observed to be 30o at a frequency of 30MHz. Estimate the distance between the individual elements of the array.
  20. A uniform linear array consists of 16 isotropic sources with a spacing of ?/4 & phase difference ƒÂ= - 90o. Calculate HPBW & effective aperture.
  21. The main lobe width of 8 elements of BSA was observed to be 45o at a frequency of 20MHz. Estimate the distance. N=8.
  22. An EFA is composed of elements with the axis at right angles to the line of the array is required to have a power gain of 20. Calculate the array length and width of the major lobe between the nulls.
  23. Calculate exact & approximate BWFN for BSA given n=4 & d= ?/2..
  24. A BSA operating at 200cm wavelength consists of 4 dipoles spaced ?/2 apart & having Rr=73Ħ. Each element carries radio frequency in same phase & of magnitude 0.5 A. Calculate (i) radiated power. (ii) HPBW.
  25. Complete the field pattern & find BWFN & HPBW for a linear uniform array of 6 isotropic sources spaced ?/2 apart. The power is applied with equal amplitude and in phase.
  26. An array of 4 isotropic antennas is placed along a straight line. Distance between the elements is ?/2. The peak is to be obtained in the direction from the axis of the array. What should be the phase difference between the adjacent elements? Compute the pattern and find BWFN & HPBW.

CHAPTER 4: Electric dipole and thin linear antenna.
  1. Starting from the concepts of magnetic vector and electric scalar potentials derive the expressions for field components of short dipole.
  2. Derive the expression for radiation resistance of Hertzian dipole.
  3. Distinguish between far field and near field.
  4. Derive an expression for power density of short dipole.
  5. Derive an expression for intrinsic impedance of short dipole.
  6. Derive the expression for electric & magnetic fields of linear antenna.
  7. Derive the expression for radiation resistance of linear antenna.
  8. Find the radiation resistance of Hertzian dipole whose wavelength is ?/8.
  9. S.T directivity of short dipole is 1.5.
  10. A thin dipole is ?/15 long. If its loss resistance is 1.5 Ħ, find its efficiency.
  11. A short dipole antenna was observed to have Rr=2 Ħ at 1MHz. Calculate its length.
  12. Calculate the efficiency of an antenna operated at 500 KHz and having a resistance 12 Ħ and effective height=30m.
  13. 2m long vertical wire carries a current of 5A at 1MHz find the strength of the radiated field at 30Km in the direction at right angles to the axis of the wire. Assume that the wire is in free space.
  14. A plain wave is incident on a short dipole. The wave is linearly polarized with electric field in the Y-direction. The current on the dipole is assumed constant and in the same phase over entire length. The antenna loss resistance=0. Find the dipole maximum effective aperture and directivity.

CHAPTER 5: Loop antenna.

  1. Write a note on loop antenna.
  2. Derive electric and magnetic fields of a loop antenna.
  3. Compare far fields of small loop and short dipole.
  4. Derive an expression for radiation resistance of a loop antenna.

CHAPTER 6: Helical antenna and Yagi-Uda array

  1. Write a note on helical antenna and helical geometry.
  2. Derive the relation between circumference spacing turn lengths and pitch angle of a helix.
  3. Show the limiting cases of a helix when :
                                                               i.      Spacing is zero.
                                                             ii.      Diameter is zero.
  1. Explain helix modes of operation.
  2. Explain the following parameters of monoflair axial helix antenna: (a) Gain (b) Bam width (c) Impedance.
  3. Write short note on Yagi-Uda array antenna.

CHAPTER 7: Antenna types.
1        Write short note on:
                                                               i.      1 Slot antenna.
                                                             ii.      Complementary antenna.
                                                            iii.      Horn antenna and its types.
                                                           iv.      Log periodic antenna.
                                                             v.      Broad band frequency independent antenna.
                                                           vi.      Antennas for terrestrial mobile communication systems.
                                                          vii.      Antennas for ground penetrating Radar.
                                                        viii.      Embedded antennas.
                                                           ix.      Ultra Wide band antennas for digital applications.
                                                             x.      Plasma antenna.
2        Explain different types of reflectors.
3        Explain parabolic reflectors.
4        Explain the types of feed systems for a reflector.
5        Differentiate between circular and rectangular horn antenna.

CHAPTER 8: Wave propagation.

6        Write short notes on:
7        Wave propagation.
                                                               i.      2.Scatter systems.
  1. Surface wave propagation.
                                                               i.      4.Surface wave tilting.
                                                             ii.      5.Space wave propagation.
                                                            iii.      6.Ionosphere propagation.
                                                           iv.      7.Structure of ionosphere.
                                                             v.      8.Sky wave propagation.
                                                           vi.      9Duct propagation.
  1. Derive an expression for tilt angle.
  2. Derive an expression for distance of communication.
  3. Obtain an expression for space wave field component taking into account a direct wave field component and a reflected wave from the earth surface.
  4. Derive an expression for refractive index.
  5. Define the following and derive the relevant expressions:
                                                               i.      Critical frequency.
                                                             ii.      Maximum usable frequency.
                                                            iii.      Virtual height.
                                                           iv.      Skip distance.

CHAPTER 9: Ionosphere propagation.

  1. Briefly explain characteristics of different ionized layers in ionospheric propagation.
  2. Calculate the critical frequency for a medium at which the wave reflects if the maximum electron density is 1.24*10 6 electrons/cm3.
  3. Which propagation will aid the following frequencies and why. (a) 120KHz. (b) 10MHz. (c) 300 MHz. (d) 30GHz.
  4. Estimate the surface wave tilt in degrees over an earth of 12mm conductivity and relative permittivity 20 at a wave length of 300m.
  5. A transmitter radiates 100Wof power at a frequency of 50MHz, so that space wave propagation takes place. The transmitting antenna has a gain of 5 and its height is 50m. The receiving antenna height is 2m. It is estimated that a field strength of 100 ?V/m is required to give a satisfactory result. Calculate the distance between transmitter and receiver.

Analog Communication Important Questions For External Exams And Easy Units

Analog Communication Important Questions For External Exams And Easy Units


1.Define Noise, Figure of Merit, and Signal to Noise ratio. List out the assumptions of Noise calculation
in communication system.

2.Give the general representation of noise in communication system and Calculate the power spectral density of it.

3.Calculate the power spectral density of Noise in case of DSB-SC and also calculate Figure of merit.

4.Calculate the power spectral density of Noise in case of SSB-SC and also calculate Figure of merit.

5.Calculate Figure of merit in case of Amplitude modulated wave.

6.Prove that for very low noise case Envelope detection method is identical to synchronous detection.

7.Explain Envelop detection method for high Noisy case.

8.Calculate Figure of merit in case of Non linear demodulation.

9.Compare Non linear demodulation and Synchronous detection with the help of equations.

10.Give the block diagram of Frequency demodulation and calculate Figure of merit for it.

11.Bring out the relationship between AM and FM Noise performance.

12. Explain the phasor diagram of FM Noise.

13.What is threshold effect in FM? What is the technique to improve the threshold of FM wave.

14.Discuss in brief about Pre-emphasis.

15.Discuss in brief about De-emphasis.

16.Explain Noise in phase modulation and derive the expression to calculate the Figure of Merit.

17.Compare AM and PM on the basis of Noise performance.

18.The received signal power in an AM signal with a modulating signal of frequency 5 KHz is 10-12? and
receiver input noise PSD is 10-20?/Hz. Assuming the noise power to be restricted to the message signal band width.
Find input signal to noise ratio at the input receiver.

19.In a DSB-SC system, the signal is extending from 97 KHz to 103 KHz with a carrier frequency of 100 KHz.
If the received signal power is 80 P?, and the noise PSD at the receiver input is 10-14 ?/Hz,
find the output signal to noise ratio.

20.Calculate the transmission bandwidth and the required transmitter power of DSB-SC,
SSB-SC and AM-DSB with carrier systems for transmitting an audio signal,
which has a Bandwidth of 15 KHz with an So/No of 50 db.
The channel introduces a 40 db power loss and the channel noise is PSD ?/2= 10-9 ?/Hz.
Assume m2. X2 (t) = 0.5.

21.Prove that narrow band FM offers no improvement in SNR over AM

22.It is given the threshold level for AM is equivalent to the input (SNR)I = 10.
Assume this conclusion is also valid for FM.
Find the (SNR)o at the threshold level for FM and also find the modulation index ß that produces (SNR)o = 30 dB at
the threshold.

23.An AM receiver, operating with a sinusoidal modulating signal and 30% modulation,
has output SNR of 30dB. Find the corresponding carrier-to-noise ratio.
By how many dB can we decrease the carrier-to-noise ratio so that the system is operating just above threshold?

24.Given an FM broadcast system with parameter ?f = 75 kHz and B =15 kHz. Assuming Sx
= ½, find the output SNR and calculate the improvement (in dB) over the base band system.

25.Prove that the performance of an SSB modulation system using synchronous detection is equivalent to the performance
of both DSB and base band system.


1.Name the constituent stages of A.M. radio transmitter and briefly give the function of each stage.

2.What are the main requirements of a radio transmitter regarding the carrier frequency? Briefly discuss
these requirements.

3.Enumerate the precautions necessary in the design and operation of an L-C oscillator for use as a Master
oscillator in a radio transmitter.

4.Draw the block diagram of SSB transmitter using filters for side band suppression and explain its working.

5.Give the block diagram of radio telegraph transmitter using on-off keying.

6.Describe the principle methods of on-off keying.

7.Give the block diagram and describe the working of FSK transmitter.

8.Give the reason for keying transients due to amplitude on-off keying. How can these keying transients be kept below?

9.Draw the block diagram and describe the working of a simple FM transmitter using reactance modulator.

10.What are the principle of sources of frequency drift in reactance modulator FM transmitter and how
can such a drift be reduced.

11.Draw the circuit and explain the working of reactance modulator FM transmitter using AFC frequency stabilization.

12.Give the principle of Armstrong method of frequency modulation.

13.What are the Sources of distortion in Armstrong method and how to reduce it

14.Draw the block diagram of Armstrong FM transmitter and describe its working

15.Classify Radio transmitters in detail

16.What is class C Amplifier? Explain its use in radio transmitters

17.Distinguish between AM and Fm Radio. List out their applications

18.Explain the necessity of buffer and driver amplifiers in radio transmitters

19.Draw the block diagram of an SSB-SC transmitter employing side band suppression filter and explain.

20.Explain what happens to the carrier and side bands when passing the AM or FM signal through a mixer
as compared to a frequency multiplier

21.A transmitter has carrier output power 100w and an efficiency of 75%. How much power is
supplied by the modulating amplifier for 100% modulation and 50 % modulation

22.A collector modulated class-C amplifier has output power of 1000w and an efficiency of 80%.
Determine the dc supply power and power dissipation for 100% modulation

23.An SSB transmitter with carrier amplitude of 10 v is being tested using triangular modulating
signal with peak voltage of 0.5v. The transmitter is connected to a dummy load of 50 O. Calculate the actual
power dissipated into load

24.A direct FM transmitter has reactance modulator with frequency sensitivity Kf = 2 KHz/v and a peak deviation of 500 Hz.
This modulator is followed by a buffer and doubler, Tripler followed by a power amplifier.
Find the Oscillator frequency if the transmitter is to operate at a carrier frequency of 150 MHz

25.A carrier wave of frequency 1 MHz is modulated 50% by a sine wave of 5 KHz.
The resulting AM signal is passed through a parallel resonant circuit (RLC) tuned to carrier frequency and has
Q = 175.Determine the percentage modulation of the output signal.

26.In the transmitter reactance modulator, the input resistance of transistor is 500 ohms with ß = 100.
What is the equivalent capacitance? If ß swings from 50 to 120, what are the values of minimum and maximum values of
capacitance? The circuit has R2 = 10 KO, C2 = 1000 pf.

27.A given AM broadcast station transmits a total power of 50 kw for single tone modulation with m=0.7071.
Find Carrier power and transmission efficiency

28.Compare low level modulation and high level modulation of radio transmitters

29.What is electromagnetic spectrum? List out the frequency bands, their channel characteristics,
frequencies and applications.

30.Why are limiters and Pre emphasis filters used in FM radio transmitters


1. Draw the block diagram and explain the working of a TRF receiver. List out its advantages and disadvantages.

2. Explain the working principle of a super heterodyne receiver with the help of neat block diagram

3. Explain the necessity of a mixer in a receiver. Give a circuit schematic and explain

4. Draw the block diagram and explain the operation of an ISB receiver.

5. Draw the block diagram of Super heterodyne receiver designed to receive FM signals and explain its working

6. Discuss the need for limiter and de-emphasis circuit in FM receivers

7. Illustrate the FM detection by a PLL with the help of its Schematic

8. With a neat sketch, explain the working of a communication receiver

9. What are the special features of communications receiver? Brief them

10. Draw the squelch circuit and explain its operation

11. Explain the operation of a noise limiter in FM receivers?

12. Describe the fading phenomenon and its types in detail.

13. What is meant by diversity reception? Explain different techniques

14. Discuss the capture effect in detail. List out its advantages and disadvantages

15. Explain the differences between AM and FM receivers

16. Explain the IF amplifier circuit and its purpose in the receiver

17. Draw the two stage IF amplifier and explain its operation

18. Explain about spurious responses in radio receivers and how they can be reduced

19.When a super heterodyne receiver is tuned to 555KHz, its local oscillator provides the mixer
with an input at 1010KHz, what is the image frequency? The antenna at receiver is connected to mixer
via a tuned circuit whose loaded Q is 40. What will be rejection ratio for the calculated image frequency?

20. Calculate the image rejection of a receiver having an RF amplifier,
and a 455 KHz IF with Q’s of relevant coils as 65 at an incoming frequency of 120 KHz and 20 MHz.

21. Calculate the image rejection of a double conversion receiver,
which has a first IF of 2 MHz and a Second IF of 200 KHz,
an RF amplifier whose tuned circuit has a Q of 75and which is tuned to a 30 MHZ signal.

22. Bring out the advantages of a dual gate MOSFET over BJT for use in radio circuits

23. List out the consequences of choosing the IF very high and very low

24. Write a short notes on Notch filters

25. Explain the procedure for LO Tuned circuit alignment

26. Explain the importance of AVC and explain its operation

27. Explain various types of Tone control circuits

28. What are the special features of DAGC

29. Explain the advantages of RF stage and explain the action of RF amplifier

30. Explain the purpose and working of Tracking Circuits


1. What is Time Division Multiplexing? Explain in detail
2. What is meant by Pulse Amplitude Modulation and explain any one-modulation technique in detail
3. What is meant by Pulse Width Modulation Explain the generation of Pulse width modulation?
4. What is meant by Pulse Width Modulation Explain the demodulation of Pulse width modulation?
5. What is meant by Pulse Positon Modulation Explain the generation of Pulse Position modulation?
6. What is meant by Pulse Position Modulation Explain the demodulation of Pulse Position modulation?
7. Compare the performance of PAM, PWM, and PPM
8. What is Pulse modulation? Explain in brief various types of pulse modulation with neat sketches.
9. Explain in brief about Bit interleaving in TDM.
10. What is Multiplexing? Compare FDM and TDM.
11.Explain the PAM Noise performance
12. What is Sampling. Derive Sampling Theorem for Band pass Signals.
13. Explain the generation of PAM Signal using Diode Bridge Modulator.
14. Explain the generation of PAM Signal using Sample and Hold Circuit
15. Explain the generation of PAM Signal using transistor Modulator
16. Explain how to demodulate PAM Signal using Equalizer
17. Explain how to demodulate PAM Signal using a Holding circuit
18. Explain the generation of PWM Signal using Monostable Multivibrator.
19.Compare Analog Modulation and Pulse modulation.
20. Explain Natural Sampling with neat sketches
21. Explain Flat Top Sampling with neat sketches.
22. Derive the equation to calculate the Channel bandwidth for a PAM Signal.
23. Explain Single polarity and Double Polarity PAM techniques

24. Consider a signal m(t) = 10 Cos1000pt. Cos 4000pt.
Find the minimum sampling rate based on sampling theorem for low pass and band pass signals.