Microprocessor VIVA Questions with Answers

Most Recently Asked MPMC Viva Questions with Answers:

1.What is a Microprocessor?
Microprocessor is a CPU fabricated on a single chip, program-controlled device, which fetches the instructions from memory, decodes and executes the instructions.

2. What is Instruction Set?
 It is the set of the instructions that the Microprocessor can execute.

3. What is Bandwidth ?
 The number of bits processed by the processor in a single instruction.

4. What is Clock Speed ?
Clock speed is measured in the MHz and it determines that how many instructions a processor can processed.The speed of the microprocessor is measured in the MHz or GHz.

5. What are the features of Intel 8086 ?
Features:
·  Released by Intel in 1978
·  Produced from 1978 to 1990s
·  A 16-bit microprocessor chip.
·  Max. CPU clock rate:5 MHz to 10 MHz
·  Instruction set:  x86-16
·  Package: 40 pin DIP
·  16-bit Arithmetic Logic Unit
·  16-bit data bus  (8088 has 8-bit data bus)
·  20-bit address bus - 220 = 1,048,576 = 1 meg
·  The address refers to a byte in memory.

6.What are the flags in 8086?
In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign flag.

7.Why crystal is a preferred clock source?
Because of high stability, large Q (Quality Factor) & the frequency that doesn’t drift with aging. Crystal is used as a clock source most of the times.

8.What is Tri-state logic?
Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tri-state logic has a third line called enable line.

9.What happens when HLT instruction is executed in processor?
The Micro Processor enters into Halt-State and the buses are tri-stated.

10.What is Program counter?
Program counter holds the address of either the first byte of the next instruction to be fetched for execution or the address of the next byte of a multi byte instruction, which has not been completely fetched. In both the cases it gets incremented automatically one by one as the instruction bytes get fetched. Also Program register keeps the address of the next instruction.

11.What is 1st / 2nd / 3rd / 4th generation processor?
The processor made of PMOS / NMOS / HMOS / HCMOS technology is called 1st / 2nd / 3rd / 4th generation processor, and it is made up of 4 / 8 / 16 / 32 bits.

12.What is the Maximum clock frequency in 8086?
5 Mhz is the Maximum clock frequency in 8086.

13.What is meant by Maskable interrupts?
An interrupt that can be turned off by the programmer is known as Maskable interrupt.

14.What is Non-Maskable interrupts?
An interrupt which can be never be turned off (ie. disabled) is known as Non-Maskable interrupt

15.What are the different functional units in 8086?
Bus Interface Unit and Execution unit, are the two different functional units in 8086.

16.What are the various segment registers in 8086?
Code, Data, Stack, Extra Segment registers in 8086.

17.What does EU do?
Execution Unit receives program instruction codes and data from BIU, executes these instructions and store the result in general registers.

18.Which Stack is used in 8086? k is used in 8086?
FIFO (First In First Out) stack is used in 8086.In this type of Stack the first stored information is retrieved first.

19.What are the flags in 8086?
In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign flag.

20.What is SIM and RIM instructions?
SIM is Set Interrupt Mask. Used to mask the hardware interrupts.
RIM is Read Interrupt Mask. Used to check whether the interrupt is Masked or not.

21.What are Flag registers?
A:-Divided into 2 parts:-Condition code or status flags and machine control flags.
S-Sign Flag:-Is to set when the result of any computation is negative.
Z-Zero Flag:-Is to set if the result of the computation or comparison performed by the previous instruction is zero.
C-Carry Flag:-Is set when there is carry out of MSB in case of addition or a borrow in case of subtraction.
T-Trap Flag:-Is set,the processor enters the single step execution mode.
I-Interrupt Flag:-Is set,the maskable interrupts are recognized by the CPU.
D-Direction Flag:-Is set for autoincrementing or autodecrementing mode in string manipulation instructions.
AC-Auxiliary Carry Flag:-Is set if there is a carry from the lowest nibble during addition or borrow for the lowest nibble.
O-Overflow Flag:-Is setif the result of a signed operation is large enough to be accommodated in a destination register.

22.Write the flags of 8086?
The 8086 has nine flags and they are
1. Carry Flag (CF)                6. Overflow Flag (OF)
2. Parity Flag (PF)                 7. Trace Flag (TF)
3. Auxiliary carry Flag (AF)   8. Interrupt Flag (IF)
4. Zero Flag (ZF)                  9. Direction Flag (DF)
5. Sign Flag (SF)

23. What are the interrupts of 8086?
The interrupts of 8085 are INTR and NMI. The INTR is general maskable interrupt and NMI is non-maskable interrupt.

24. How clock signal is generated in 8086? What is the maximum internal clock frequency of 8086?
The 8086 does not have on-chip clock generation circuit. Hence the clock generator chip, 8284 is connected to the CLK pin of8086. The clock signal supplied by 8284 is divided by three for internal use. The maximum internal clock frequency of8086 is 5MHz.

25. Write the special functions carried by the general purpose registers of 8086?
The special functions carried by the registers of 8086 are the following.
Register Special function
1. AX 16-bit Accumulator
2. AL 8-bit Accumulator
3. BX Base Register 4. CX Count Register 5. DX .Data Register

26.What is the need for Port?
The I/O devices are generally slow devices and their timing characteristics do not match with processor timings. Hence the I/O devices are connected to system bus through the ports.

27.What is a port?
The port is a buffered I/O, which is used to hold the data transmitted from the microprocessor to I/O device or vice-versa.

28.What is processor cycle (Machine cycle)?
The processor cycle or machine cycle is the basic operation performed by the processor. To execute an instruction, the processor will run one or more machine cycles in a particular order.

29.What is Instruction cycle?
The sequence of operations that a processor has to carry out while executing the instruction is called Instruction cycle. Each instruction cycle of a processor indium consists of a number of machine cycles.

30.What is fetch and execute cycle?
In general, the instruction cycle of an instruction can be divided into fetch and execute cycles. The fetch cycle is executed to fetch the opcode from memory. The execute cycle is executed to decode theinstruction and to perform the work instructed by the instruction.

Smart Card ID Seminar PPT with pdf

Abstract
Abstract—In today’s world carrying a number of plastic smart cards to establish our identity has become an integral segment of our routine lives. Identity establishment necessitates a pre stored readily available data about self and to the administrator to authenticate it with claimer’s personal information. There is a distinct requirement of a technological solution for nationwide multipurpose identity for any citizen across the board. Number of options has been exercised by various countries and every option has its own pros and cons. However, it has been observed that in most of the cases Smart Card solution has been preferred by a user and administrator both. The use of Smart cards are so prevalent that be it any profession, without incorporating its application, identity of any individual is hardly considered complete.

In this paper, the principle aim is to discuss the viability of Smart Card technology as an identity solution and its ability to perform various functions with strong access control that increases the reliability of Smart Cards over other technologies. It outlines the overview of smart card technology along with its key applications. Security concerns of smart card have been discussed through an algorithm with the help of a division integer proposition. Possibilities of upgrading it with evolving technology offer it as a universal acceptability of identification. Capability of storing desired amount of information by an administrator to compute multiple operations to authenticate a citizen dictates its widening acceptability and an endeavor has been made in this paper to explain it through a proposed system flow chart.

INTRODUCTION:
One takes today a burden of carrying a wallet with full of cards to establish his/her identity like official ID card, canteen cards, library cards, driving license, etc. Smart card ID has a potential to replace all these cards by a single smart ID cards to serve the desired purpose. Varieties of smart cards are available as on date with progressive technologies where developers use different data structures and standards for programming. In this paper, we will discuss about viability of smart cards as a solution to requirement of nationwide multipurpose smart ID for each and every citizen with continuous evolving technology. Our aim is to propose a viable technological solution for a single multipurpose smart ID card to do away with carrying multiple cards by an individual. It will assist governments across the globe in better administration with cost effective solution for multiple application single smart ID cards. It will also need management of a large database with processing and scalable computing to home on desired ID. Data centers handling these big data are contributing in reducing the delay and costs in data processing and improving the quality of service to include certain discrete services using internet based services.

A smart card is an electronic device with micro-processor based system containing embedded integrated circuits which can process and store a large chunk of data and applications . A smart card reader is used to access the stored information and it is also called smart called terminal when a card is plugged into this reader. Apart from the card reader, radio frequencies are also used to operate a smart card. Different protocols are being used for different types of card readers to communicate between card and the reader. The standard of security adopted in the smart cards defines the degree of protection about sensitivity and confidentiality of data against the breaches. The issue with smart cards is its data storage capacity and processing capability. If we choose to associate any new application with smart card then the security mechanism would require consume more space which in turn necessitates use of lightweight security algorithm. In this paper a hypothetical case of a division integer algorithm is taken and then a viable system has been proposed to ensure appropriate security measures and to combat epidemics of cyber-crimes. In this respect, all the states need stringent legislations with effective law enforcement to prevent any frauds . The objective of this paper is to touch upon smart card technology and its viability as single ID alternative with desired identity standards by various states and to study its viability with feasible applications

SMART CARD: AN OVERVIEW
A smart card is known as a portable device which can compute, store and carry the data in an embedded processor chip for verification of personal identity in a secure repository. A smart card can also store a data in relation to any individual in the form of a barcode which are extracted through an optical scanner. Barcode is a representation of data displayed in a stripe of alternate black and white lines which is machine readable optically illustration of an object that carries it. Barcodes are depicted in a smart card by parallel lines with varied spacing‘s and widths. The initial smart cards were contact based while the contactless smart cards came in the early 90s. Later, smart card with contactless ICs completely revolutionized the smart card applications and its utility. The contactless smart cards offer a high order of comfort to a user whereas it can be read without any physical contacts with bar code readers. It also extends an advantage over contact smart cards in terms of costs, durability and reliability [6]. An easy carriage of such smart cards in a wallet offers a good convenience to the users. A dedicated and secure transmission protocol is employed in a contactless smart card which offers it an excellent security. A magnetic tape is attached in the form of a stripe in the magnetic stripe smart cards. Memory smart cards are having a peculiar feature of storing and carry information which may be personal financial or any other specific information. An embedded circuitry of IC on a card is referred as microprocessor smart cards which can process and store the subject data.

A sideway structural view of a plastic smart card is illustrated in Fig. 1 above. In order to protect the smart card chip from bends, it is generally placed on one of the edges of the smart cards. An Epoxy layer on this magnetic stripe is also visible when we take a view of its internal structure. Various applications, communication protocols and manufacturing specifications are defined by International Standardization Organization (ISO). Currently, there are following ISO standards for smart cards:

A. Physical Characteristics:
Initial ISO standard (ISO 7816-1) in 1987 defined the card size of a smart card as 0.76 mm thick, 53.98 mm height and 85.6 mm wide. It has again been revised in 1998

B. Electronic Contacts:
ISO standard (ISO 7816-2) defined the size and location of the electronic contacts in smart cards. This too has been revised in 1998.

C. Electrical Signals:
ISO standard (ISO 7816-3) defined transmission protocol along with the nature of electrical signals in smart cards. It has been thrice in 1992, 1994 and 1998.

D. Communication Protocols:
ISO standard (ISO 7816-4) defined the communication protocols in different types of applications and file structure to be stored in these applications in smart cards. It has been revised twice in 1995 and 1998.
E. Language:
ISO standard (ISO 7816-7) defined the commands of query language used in smart cards. This has been revised again in 1998. The use of internet technology has changed the whole perception of security systems. Smart card technology too is not an exception. Identification of an individual is to do more with secure authentication rather secure identification. Individual credentials are required to be stored in a secured manner for which a portable smart card provides a good platform. The transactions made through the magnetic stripe of smart cards are processed by an electronic connection between the smart card and the service provider. Processor and memory chip in a smart card allows storing of required data which are processed by a smart card reader when connected through a centralized database [8]. Unlike the contact smart cards in which they have electrical contacts with a card reader, contactless smart cards operate through a transmission frequency and an internal antenna coil. It can be picked up and read through the external aerial.
The two most common materials utilized for manufacturing of smart cards are Acrylonitrile Butadiene Styrene (ABS) and Polyvinyl Chloride (PVC). There are two main categorizations of smart cards, namely, as processor enabled and memory smart cards. A relative comparison based on the various features between the two is shown above in Table I. Out of these two, memory smart cards are considered as basic smart cards with limited data storage capability with a nonvolatile memory features. These cards are transmitting data in only one direction and also termed as asynchronous smart cards and they are used offline only. On the other hand, processor enabled cards are using semiconductor technology and being a sophisticated cards they are also called as ‗true smart cards‘. These cards have smart chip which operates cryptographic functions and encryption technology to process secure data transmission [9].

In general, biometric technology is used to establish the identity of the user. These cards have bi-directional data transmission, possess significant memory and they are also termed as ‗synchronous smart cards‘ and difficult to be duplicated. Data storage in such smart cards is nonvolatile and stored in EEPROM. An electronic module of a smart card apart from an input/output component consists of different types of memories which include Read Only Memory (ROM), A (Random Access Memory), an electronically erasable Memory (EEPROM) and a non-volatile memory (NVM) as illustrated in Fig. 2 above. It is placed in the second layer of embedded processor chip of smart card as illustrated in the Fig. 1. These memory chips are incorporated in such electronic modules based on the projected requirement and at the same time presence of all memory chips is not sacrosanct. Bringing all these memories in a single integrated chip together not only reduces the size significantly, combining it with cryptography technology it also increases the security of smart card

SMART CARD APPLICATIONS
The major advantage of a smart card over a normal ID card is its capacity to store larger amount of information and its programmability for various applications. Its feature of having a possibility through contactless readers gives it an edge over similar technologies in pursuits of finding a nationwide single ID for multiple usages. The term ‗smart, relates with a particular type of application like memory/magnetic stripe/optical/microprocessor cards. The larger application of smart cards is its utility in financial transactions with faster processing of revenues or payments . Its capability to carry the related information of an individual and to deliver it at desired destination distinguishes it from other such applications in identifying the veracity of the individual. Smart card applications include its use as GSM mobile phone for the identity requirements. It‘s wider use as a banking card in the form of debit/credit cards or being a tamper-proof/counterfeit device increase its popularity. Electronic coupons and credit programs are other attractive applications of smart cards [28]. The inherent security and flexibility of smart cards increases its utility. With improved data storage and security supplemented with provisioning of encryption and decryption by a user offers high rate of convenience to users. Some notable applications of smart cards are as:

A. ID Validation:
The basic premise of storing the individual information is to verify him/her for any further uses in smart cards. Currently. A large number of organizations and institutions including government and private both are using smart card to extend access control to their members/employees only after due verification of their ID based on their personal information stored in their smart ID cards. It‘s viability as an option for secure ID credential verification makes it a lucrative tool to be adopted by every potential organization.

B. Data Authentication:
Information with respect to the user is authenticated by the data already stored in the smart card or a token system also known as knowledge arrangement based may be exercised for the purpose [29]. Token systems are generally employed in applications like passport verifications; credit cards, driving license, etc. whereas knowledge based authentications are exercised in applications with tokens system like PIN numbers.

C. Financial Transactions:
Smart cards are very handy as a tool for financial transactions both in traditional and web based applications. A cash value can be stored in smart cards to use it as credit cards. It‘s potential to support both consumers and business against lower rate of transactions widens its applicability in marketing targeted programs in financial services.

D. Telecom Sector:
Provisioning of secure cellular communication is assisted by smart cards. New apps and functions are providing real time download capabilities by smart cards [30], [31]. A SIM card given by cellular operators to their subscribers and its use of multimedia applications like pay TV cards are making a very productive tool amongst normal public.

E. Loyalty Marketing Programs:
A huge number of loyalty programs are being run by smart cards based applications by various business houses in services like retail shopping, telecommunications, air travel, etc. in which customers are being offered very attractive discounts. Such applications not only make business market very competitive, it also helps to normal public to receive benefits at relatively lower rates.

F. Secure Computer Networks:
A secure access for networks can be assured through digital signatures of a user. They are utilized in granting only specified people to have the access to a particular computer network. This mechanism is very handy and vital for the security related organizations. Encryption technology is making today computer networks more secure than the erstwhile networks.

G. Healthcare:
Professionals from healthcare services are using smart card based applications to gain access for continuous updating of their data and its processing. A colossal amount of information is being shared in the form of drug prescription, physician details, dosage, etc. by these professionals. Patients use smart cards to provide their pre stored medical history with doctors and in making payments of their medical treatments as well.
H. Other Smart Card Applications:
Its flexibility and potential to have repository of information supports it in vast number of applications. With secured online transactions in many commercial activities augurs well for both the service provider and subscribers. A wide range of services which are exploiting the smart card based applications include agricultural products, Life Insurance sector, vending machines, libraries, restaurants, laundry services, set top box facilities, software based games for kids, electronic toll collection, information technology, mass transit, parking facilities, e-passports etc. are just the few names to be counted [33]. Utility services like payment transaction, call counters, memory storage etc. employ smart card based applications.

CONCLUSION:
The emphasis on correct identification of every citizen is the basic proposition of all the sovereign governments across the globe. Perceived security threats to existing identification technologies are compelling factors to pursuit for evolving smart card technology. Security mechanism incorporating the complex encryption technology in place by this technology makes it more attractive compared to similar other available applications. This is a tool which offers to store and use the minimum desired data against a set of people or entity [42]. A suitable authentication scheme and security algorithm for faster and protected processing of data is always a challenge for any such technology. The above proposed study illustrates that user acceptance for constant evolving smart card technology will be the most prominent factor for the expected outcome. Further studies on the smart card system are likely to bring better dividends on issues as discussed in the subjects to be dealt with in above mentioned future scope.


BIBLIOGRAPHY:
[1] Munizaga, Marcela A and Carolina Palma, ―Estimation of a disaggregate multimodal public transport origin-destination matrix from passive smartcard data from Santiago to Chile" in Transportation Research Part C: Emerging Technologies 2012, vol. 24 pp. 11-17.

[2] Sven Vowe, Ulrich Waldmann, Andreas Poller and Sven Türpe, "Electronic Identity Cards for User Authentication Promise and Practice", IEEE Security & Privacy January/February 2012, vol.10, No. 1, pp. 48-53.
[3] Y. Wang and X. Ma, "Development of a data-driven platform for transit performance measures using smart card and GPS data" J. Transp. Eng 2014, vol. 140 no. 12 pp. 4026-4053.

[4] M. Batty, C. Zhong, J. Wang, E. Manley, F. Chen, Z. Wang and G. Schmitt, "Variability in regularity: Mining temporal mobility patterns in London Singapore and Beijing using smart-card data" PLoS ONE 2016, vol. 11 no. 2 pp. 1-15.
[5] M. Mesbah, A.A. Alsger and L. Ferreira, "Use of smart card fare data to estimate public transport origin–destination matrix" Transp. Res. Rec. J. Transp. Res. Board 2015, vol. 2535, pp.89-94.

Best X-Vision Seminar Topics For CSE

Abstract
We present the concept of X-Vision, an enhanced Augmented Reality (AR)-based visualization tool, with the realtime sensing capability in a tagged environment. We envision that this type of a tool will enhance the user-environment interaction and improve the productivity in factories, smartspaces, home & office environments, maintenance/facility rooms and operation theatres, etc. In this paper, we describe the design of this visualization system built upon combining the object’s pose information estimated by the depth camera and the object’s ID & physical attributes captured by the RFID tags. We built a physical prototype of the system demonstrating the projection of 3D holograms of the objects encoded with sensed information like water-level and temperature of common office/household objects. The paper also discusses the quality metrics used to compare the pose estimation algorithms for robust reconstruction of the object’s 3D data.

INTRODUCTION:
Superimposing information on to the real-world, the concept commonly known to us as Augmented reality (AR), has been rapidly evolving over the past few years due to the advances in computer vision, connectivity and mobile computing. In recent years, multiple AR-based applications have touched everyday lives of many of us: few such examples are Google translate’s augmented display [12] to improve productivity, AR GPS navigation app for travel [22], CityViewAR tool for tourism [17], etc. All these applications require a method to implement a link between the physical and digital worlds. Often this link is either ID of the object or information about the physical space, for instance, an image in Google translate app or GPS location in AR navigation tool.

This link can be easily established in a informationally structured environments using visual markers, 2D barcodes and RFID tags. Among the three, RFID tags have an unique leverage with the ability to wirelessly communicate within couple of meters of distance without requiring line of sight access. In addition, RFID tags can be easily attached to inventory and consumer products in large numbers at extremely low per unit costs. Passive RFID, in particular, has many applications in object tracking [14], automatic inventory management [15], pervasive sensing [5], etc. In a tagged environment, with RFID infrastructure installed, information * Equal Contribution Fig. 1. Left: A user wearing the system sees a cup with overlaid temperature information. Right: System components: an Intel RealSense D415 RGB-D camera is attached on a HoloLens via a custom mount. of tagged object’s ID and physical attributes can be wirelessly retrieved and mapped to a digital avatar.

AR-Based Smart Environment
AR brings digital components into a person’s perception of the real world. Today, advanced AR technologies facilitates the interactive bidirectional communication and control between a user and objects in the environment. Two main branches exist for AR associated research. In one branch, researchers attempt to design algorithms to achieve accurate object recognition and 3D pose estimation for comprehensive environment understanding. Research in this direction provides theoretic supports for industry products. In the other branch, efforts have been devoted to applying existing computer vision techniques to enhance user-environment interaction experience for different purposes. Research work on this track benefits areas, such as education , tourism and navigation, by improving user experience. Our work follows this trend by fusing object recognition and 3D pose estimation techniques with RFID sensing capabilities, aiming to create a smart environment.

Emerging RFID Applications
RFID is massively used as identification technology to support tracking in supply chain, and has so far been successfully deployed in various industries. Recently industry’s focus seems shifting towards generating higher value from the existing RFID setups by tagging more & more items and by developing new applications using tags that allow for sensing, actuation & control [8] and even gaming. Another such exciting application with industrial benefit is fusion with emerging computer vision and AR technologies. Fusion of RFID and AR is an emerging field and there are recent studies combining these technologies for gaming and education, yet we see lot of space to explore further especially going beyond ID in RFID. One of the earlier papers studied the use of RFID to interact with physical objects in playing a smartphone-based game which enhanced the gaming experience. Another study used a combination of smart bookshelves equipped with RFID tags and mixedreality interfaces for information display in libraries. Another study explores the use of AR with tags to teach geometry to students. These studies show a good interest in the community to explore mixed reality applications using tags for object IDs. In this paper, we use RFID for not just ID but also to wirelessly sense the environment and object’s attributes to create a more intimate and comprehensive interaction between the humans and surrounding objects.

Object Identification and Pose Estimation
Our system uses an Intel RealSense D415 depth camera to capture color and depth information. It is attached to an HoloLens via a custom mount provided by [9], and faces in the same direction as the HoloLens (Figure 1). The captured images are used to identify the in-view target object and estimate its pose.

Object Identification:
Object recognition is a well-studied problem, and we adopt the local feature based method in our system, since it is suitable for small-scale database. Generally, to identify an in-view object from a given database, the local feature based method first extracts representative local visual features for both the scene image and template object images, and then matches scene features with those of each template object. The target object in the view is identified as the template object with the highest number of matched local features. If the number of matched features of all template objects is not sufficiently large (below a predetermined threshold), then the captured view is deemed to not contain a target. Our system follows this scheme, and uses SURF algorithm to compute local features, since compared to other local feature algorithms, such as SIFT , SURF is fast and good at handling images with blurring and rotation.

Pose Estimation:
After identifying the in-view object, our system estimates its position and rotation, namely 3D pose, in the space, thus augmented information can be rendered properly. We achieve this by constructing point cloud of the scene, and aligning the identified object’s template point cloud with it. Many algorithms exist for point cloud alignment, and we adapt widely-used Iterative Closest Point (ICP) algorithm [4] in our system, since it usually finds a good alignment in a quick manner. To obtain better pose estimation results, especially for non-symmetric objects (i.e. mug), a template object usually contains point clouds from multiple viewpoints. Yet, the performance of ICP relies on the quality of the initialization. Our system finds a good initial pose by moving a template object’s point cloud to the 3D position that is backprojected from the centroid of matched local feature coordinates in the scene image. The coordinates of correctly matched local feature are the 2D projections of target object surface points, thus back-projecting their centroid should return a 3D point close to target object surface points.

RFID Sensing
An office space already equipped with the RFID infrastructure is used as the tagged-environment for the experiments in this study. The space is set up using the Impinj Speedway Revolution RFID reader, connected to multiple circularly polarized Laird Antennas with gain of 8.5 dB. The reader system is broadcasting at the FCC maximum of 36 dBm EIRP. For the tag-sensors, we make use of the Smartrac’s paper RFID tags with Monza 5 IC as the backscattered-signal based water level sensors and custom designed tags with EM 4325 IC as the temperature sensors. We use the Low Level Reader Protocol (LLRP) implemented over Sllurp (Python library) to interface with RFID readers and collect the tag-data.
Purely-passive or semi-passive tags can be designed to sense multiple physical attributes and environmental conditions. One approach is based on tag-antenna’s response to changed environments as a result of sensing event. Change in signal power or response frequency of the RFID tag due to this antenna’s impedance shift can be attributed to sensing events like temperature rise [24], presence of gas concentration [19], soil moisture [13] etc. Another approach is to use IC’s onboard sensors or external sensors interfaced with GPIOs [7]. In this study, we use both the antenna’s impedance shift approach to detect water-level and the IC’s on-board temperature sensor to detect the real-time temperature in a coffee cup.

Working Range Testing
Object recognition accuracy of our system is affected by the camera-object separation. The minimum distance recommended by the depth camera manufacturer is 30 cm. As the separation increases, the quality of the depth data deteriorates and beyond 1 m, texture details of target objects are hard to capture. Similarly, RFID tag-reader communication is affected by the tag-reader separation. If the separation is too large, the power reaching the tag is too low to power the IC and backscatter the signal to the reader. We define a score called normalized RSSI for generalized comparison between different material-range-signal strength experiments. Score of 1 denotes a good backscattered signal strength of -20 dBm at the reader and a score of 0 means signal strength is below the sensitivity of the reader (-80 dBm).

Recognition accuracy and normalized RSSI scores are obtained for different objects in this study by varying the cameraobject and reader-object separation distances (see Fig.8). From our observations, to achieve a reliable sensing and good quality visualization, we set an acceptable score of 0.5-1 for both the metrics. We propose a 40-75 cm working range between the camera & target object, and less than 100-150 cm working range between the tagged objects & readers for good quality and reliable visualization. One of our ultimate goals is to package the camera and reader on to the head mount so that a need for separate RFID infrastructure is eliminated.

CONCLUSION:
We present the working of an enhanced augmented-vision system named X-Vision which superimposes physical objects with 3D holograms encoded with sensing information captured from the tag-sensors attached to everyday objects. Two testing cases, water level and temperature sensing, are demonstrated in this paper. Further experiments are also performed to evaluate the pose estimation pipeline and working range of the system

Paper Published by Yongbin Sun , Sai Nithin R. Kantareddy , Rahul Bhattacharyya , and Sanjay E. Sarma, Auto-ID Labs, Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge, USA

BIBLIOGRAPHY:
[1] Ankur Agrawal, Glen J Anderson, Meng Shi, and Rebecca Chierichetti. Tangible play surface using passive rfid sensor array. In Extended Abstracts of the 2018 CHI Conference on Human Factors in Computing Systems, page D101. ACM, 2018.

[2] Andr´es Ayala, Graciela Guerrero, Juan Mateu, Laura Casades, and Xavier Alam´an. Virtual touch flystick and primbox: two case studies of mixed reality for teaching geometry. In International Conference on Ubiquitous Computing and Ambient Intelligence, pages 309–320. Springer, 2015.
[3] Herbert Bay, Tinne Tuytelaars, and Luc Van Gool. Surf: Speeded up robust features. In European conference on computer vision, pages 404– 417. Springer, 2006.

[4] Paul J Besl and Neil D McKay. Method for registration of 3-d shapes. In Sensor Fusion IV: Control Paradigms and Data Structures, volume 1611, pages 586–607. International Society for Optics and Photonics, 1992.

40+ TOP MOST EDC LAB VIVA Questions and Answers

Below are the list of Freequently Asked  ECE VIVA Questiions and Answers for Engineering students.

1. What is Electronic?
The study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles.

2. What is communication?
Communication means transferring a signal from the transmitter which passes through a medium then the output is obtained at the receiver. (or)communication says as transferring of message from one place to another place called communication.

3. Different types of communications? Explain.
Analog and digital communication.
As a technology, analog is the process of taking an audio or video signal (the human voice) and translating it into electronic pulses. Digital on the other hand is breaking the signal into a binary format where the audio or video data is represented by a series of "1"s and "0"s.
Digital signals are immune to noise, quality of transmission and reception is good, components used in digital communication can be produced with high precision and power consumption is also very less when compared with analog signals.

4. What is sampling?
The process of obtaining a set of samples from a continuous function of time x(t) is referred to as sampling.

5. State sampling theorem?
It states that, while taking the samples of a continuous signal, it has to be taken care that the sampling rate is equal to or greater than twice the cut off frequency and the minimum sampling rate is known as the Nyquist rate.

6. What is cut-off frequency?
The frequency at which the response is -3dB with respect to the maximum response.

7. What is pass band?
Passband is the range of frequencies or wavelengths that can pass through a filter without being attenuated.

8. What is stop band?
A stopband is a band of frequencies, between specified limits, in which a circuit, such as a filter or telephone circuit, does not let signals through, or the attenuation is above the required stopband attenuation level.

9. Explain RF?
Radio frequency (RF) is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves. Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits or electromagnetic radiation.

10. What is modulation? And where it is utilized?
Modulation is the process of varying some characteristic of a periodic wave with an external signals.
Radio communication superimposes this information bearing signal onto a carrier signal.
These high frequency carrier signals can be transmitted over the air easily and are capable of travelling long distances.
The characteristics (amplitude, frequency, or phase) of the carrier signal are varied in accordance with the information bearing signal.
Modulation is utilized to send an information bearing signal over long distances.

11. What is demodulation?
Demodulation is the act of removing the modulation from an analog signal to get the original baseband signal back. Demodulating is necessary because the receiver system receives a modulated signal with specific characteristics and it needs to turn it to base-band.

12. Name the modulation techniques?
For Analog modulation--AM, SSB, FM, PM and SM
Digital modulation--OOK, FSK, ASK, Psk, QAM, MSK, CPM, PPM, TCM, OFDM

13. Explain AM and FM?
AM-Amplitude modulation is a type of modulation where the amplitude of the carrier signal is varied in accordance with the information bearing signal.
FM-Frequency modulation is a type of modulation where the frequency of the carrier signal is varied in accordance with the information bearing signal.

14. Where do we use AM and FM?
AM is used for video signals for example TV. Ranges from 535 to 1705 kHz.
FM is used for audio signals for example Radio. Ranges from 88 to 108 MHz.

15. What is a base station?
Base station is a radio receiver/transmitter that serves as the hub of the local wireless network, and may also be the gateway between a wired network and the wireless network.

16. How many satellites are required to cover the earth?
3 satellites are required to cover the entire earth, which is placed at 120 degree to each other. The life span of the satellite is about 15 years.

17. What is a repeater?
A repeater is an electronic device that receives a signal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances without degradation.

18. What is an Amplifier?
An electronic device or electrical circuit that is used to boost (amplify) the power, voltage or current of an applied signal.

19. Example for negative feedback and positive feedback?
Example for –ve feedback is ---Amplifiers And for +ve feedback is – Oscillators.

20. What is Oscillator?
An oscillator is a circuit that creates a waveform output from a direct current input. The two main types of oscillator are harmonic and relaxation. The harmonic oscillators have smooth curved waveforms, while relaxation oscillators have waveforms with sharp changes.

21. What is an Integrated Circuit?
An integrated circuit (IC), also called a microchip, is an electronic circuit etched onto a silicon chip. Their main advantages are low cost, low power, high performance, and very small size.

22. What is crosstalk?
Crosstalk is a form of interference caused by signals in nearby conductors. The most common example is hearing an unwanted conversation on the telephone. Crosstalk can also occur in radios, televisions, networking equipment, and even electric guitars.

23. What is resistor?
A resistor is a two-terminal electronic component that opposes an electric current by producing a voltage drop between its terminals in proportion to the current, that is, in accordance with Ohm's law:
V = IR.

25. What is inductor?
An inductor is a passive electrical device employed in electrical circuits for its property of inductance. An inductor can take many forms.

26. What is conductor?
A substance, body, or device that readily conducts heat, electricity, sound, etc. Copper is a good conductor of electricity.

27. What is a semi conductor?
A semiconductor is a solid material that has electrical conductivity in between that of a conductor and that of an insulator(An Insulator is a material that resists the flow of electric current. It is an object intended to support or separate electrical conductors without passing current through itself); it can vary over that wide range either permanently or dynamically.

28. What is diode?
In electronics, a diode is a two-terminal device. Diodes have two active electrodes between which the signal of interest may flow, and most are used for their unidirectional current property.

29. What is transistor?
In electronics, a transistor is a semiconductor device commonly used to amplify or switch electronic signals. The transistor is the fundamental building block of computers, and all other modern electronic devices. Some transistors are packaged individually but most are found in integrated circuits.

30. What is op-amp?
An operational amplifier, often called an op-amp , is a DC-coupled high-gain electronic voltage amplifier with differential inputs[1] and, usually, a single output. Typically the output of the op-amp is controlled either by negative feedback, which largely determines the magnitude of its output voltage gain, or by positive feedback, which facilitates regenerative gain and oscillation.

31. What is a feedback?
Feedback is a process whereby some proportion of the output signal of a system is passed (fed back) to the input. This is often used to control the dynamic behaviour of the system.

32. Advantages of negative feedback over positive feedback?
Much attention has been given by researchers to negative feedback processes, because negative feedback processes lead systems towards equilibrium states. Positive feedback reinforces a given tendency of a system and can lead a system away from equilibrium states, possibly causing quite unexpected results.

33. What is Barkhausen criteria?
Barkhausen criteria, without which you will not know which conditions, are to be satisfied for oscillations.
“Oscillations will not be sustained if, at the oscillator frequency, the magnitude of the product of the
transfer gain of the amplifier and the magnitude of the feedback factor of the feedback network ( the magnitude of the loop gain ) are less than unity”.
The condition of unity loop gain -Aβ = 1 is called the Barkhausen criterion. This condition implies that
Aβ= 1and that the phase of - Aβ is zero.

34. What is CDMA, TDMA, FDMA?
Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency.
An analogy to the problem of multiple access is a room (channel) in which people wish to communicate with each other. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different directions (spatial division). In CDMA, they would speak different languages. People speaking the same language can understand each other, but not other people. Similarly, in radio CDMA, each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can understand each other.

35. explain different types of feedback?
Types of feedback:
Negative feedback: This tends to reduce output (but in amplifiers, stabilizes and linearizes operation). Negative feedback feeds part of a system's output, inverted, into the system's input; generally with the result that fluctuations are attenuated.
Positive feedback: This tends to increase output. Positive feedback, sometimes referred to as "cumulative causation", is a feedback loop system in which the system responds to perturbation (A perturbation means a system, is an alteration of function, induced by external or internal mechanisms) in the same direction as the perturbation. In contrast, a system that responds to the perturbation in the opposite direction is called a negative feedback system.
Bipolar feedback: which can either increase or decrease output.

36. What are the main divisions of power system?
The generating system,transmission system,and distribution system.

37. What is Instrumentation Amplifier (IA) and what are all the advantages?
An instrumentation amplifier is a differential op-amp circuit providing high input impedances with ease of gain adjustment by varying a single resistor.

38. What is meant by impedance diagram? 
The equivalent circuit of all the components of the power system are drawn and they are interconnected is called impedance diagram.

39. What is the need for load flow study?
The load flow study of a power system is essential to decide the best operation existing system and for planning the future expansion of the system. It is also essential for designing the power system.

40. What is the need for base values? 
The components of power system may operate at different voltage and power levels. It will be convenient for analysis of power system if the voltage, power, current ratings of the components of the power system is expressed with referance to a common value called base value.

Commonly Asked Embedded Systems viva questions with answers

Frequently Asked Embedded Systems viva questions with answers:

Q1. What is an embedded system?
Ans. An embedded system is a special purpose computer system which is completely encapsulated by device it control. It is a programmed hardware device in which the hardware chip is programmed with specific function. It is a combination of hardware and software.

Q2. What are the characteristics of embedded system? 
Ans. The Characteristics of the embedded systems are as follows-
1. Sophisticated functionality
2. Real time behavior
3. Low manufacturing cost
4. Low power consumption
5. User friendly
6. Small size

Q3. What are the types of embedded system? 
Ans. They are of 4 types
1. General computing
2. Control System
3. Digital Signal Processing
4. Communication and network

Q4. What is digital signal controller ?
Ans. DSC is 16 bit RISC machine that combines control advantages of micro-controller and digital signal processing to produce tightly coupled single chip-single instruction stream solution for embedded system design.

Q5. What are the components of embedded system?
Ans. Microcontroller, microprocessor, DSC, DSP, busses, system clock, Read only Memory(ROM), RAM, Real time clock these are the components of embedded system.

Q6. Why we use embedded systems?
Ans. Embedded systems avoid lots of electronic components and they have rich built in functionality. They reduces the cost and maintenance cost and the probability of failure of embedded system is less so embedded system are in very much use now a days.

Q7. What are the languages used in embedded system?
Ans. Assembly language and C are  basically used for embedded system. Java and ADA are also preferred.

Q8. How does combination of functions reduce memory requirement in embedded system?
Ans. By using functions the amount of code that has to be dealt with is reduced thus redundancy is eliminated for everything common in function.

Q9. What is the significance of watchdog timer in ES?
Ans. It is a timing device which is set to predefined time interval and some task is to be performed at that time. It is used to reset original state when an inappropriate event take place.It is usually operated by counter device.

Q10. What is the difference between mutexes and semaphores?
Ans. Semaphores are the synchronization tool to overcome critical section problem.
Mutex is also a tool that is used to provide deadlock free mutual exclusion. It protects access to every critical data item, if the data is locked and is in use,it either waits for the thread to finish or awakened to release the lock from its inactive state.

Q11. What is the difference between FIFO and the memory?
FIFO (first in first out) is a memory structure where data’s can be stored and retrieved. This is a queue where memory is a storage device which can hold data’s dynamically or at any desired locations and can be retrieved in any order.

Q12. What is an anti-aliasing filter?
Anti-aliasing filter reduces errors due to aliasing.

Q13. How to implement a fourth order Butter worth LP filter at 1 KHz if sampling frequency is 8 KHz?
A fourth order butter worth filter can be made as cascade of two second order LP filters with zeta of 0.924 and 0.383. One can use a bilinear transformation approach for realising second order LP filters. Using this technique described well in many texts, one can make second order LP filters and cascade them

Q14. Is 8085 an embedded system?
It’s not an embedded system. B’coz it will be a part of an embedded system and it does not work on any software.

 Q15.What is the role of segment register?
In the 8086 processor architecture, memory addresses are specified in two parts called the segment and the offset. Segment values are stored in the segment registers. There are four or more segment registers: Code Segment (CS) contains segment of the current instruction (IP is the offset), Stack segment (SS) contain stack of the segment (SP is the offset), DS is the segment used by default for most data operations; ES is an extra segment register.

Q16.What type of registers contains an INTEL CPU?
 Special function registers like accumulator, program controller (PC), data pointer (DPTR), TMOD and TCON (timing registers), 3 register banks with r0 to r7, Bit addressable registers like B.

 Q17. What is the difference between microprocessor and micro controller?
Microprocessor is managers of the resources (I/O, memory) which lie out-side of its architecture.
Micro controllers have I/O, memory etc. built into it and specifically designed for control.

Q18. DMA deals with which address (physical/virtual addresses)?
DMA deals with physical addresses. DMA controller is a device which directly drives the data and address bus during data transfer. So it is purely physical address.

 Q19. What is the difference between testing and verification?
Verification is a front end process and testing is a post silicon process. Verification is to verify the functionality of the design during the design cycle. Testing is find manufacturing faults.

Most Important Microprocessor VIVA Questions with Answers

Tricky MPMC Viva Questions with Answers:

1.What is a Microprocessor?
Microprocessor is a CPU fabricated on a single chip, program-controlled device, which fetches the instructions from memory, decodes and executes the instructions.

2. What is Instruction Set?
 It is the set of the instructions that the Microprocessor can execute.

3. What is Bandwidth ?
 The number of bits processed by the processor in a single instruction.

4. What is Clock Speed ?
Clock speed is measured in the MHz and it determines that how many instructions a processor can processed.The speed of the microprocessor is measured in the MHz or GHz.

5. What are the features of Intel 8086 ?
Features:
·  Released by Intel in 1978
·  Produced from 1978 to 1990s
·  A 16-bit microprocessor chip.
·  Max. CPU clock rate:5 MHz to 10 MHz
·  Instruction set:  x86-16
·  Package: 40 pin DIP
·  16-bit Arithmetic Logic Unit
·  16-bit data bus  (8088 has 8-bit data bus)
·  20-bit address bus - 220 = 1,048,576 = 1 meg
·  The address refers to a byte in memory.

6.What are the flags in 8086?
In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign flag.

7.Why crystal is a preferred clock source?
Because of high stability, large Q (Quality Factor) & the frequency that doesn’t drift with aging. Crystal is used as a clock source most of the times.

8.What is Tri-state logic?
Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tri-state logic has a third line called enable line.

9.What happens when HLT instruction is executed in processor?
The Micro Processor enters into Halt-State and the buses are tri-stated.

10.What is Program counter?
Program counter holds the address of either the first byte of the next instruction to be fetched for execution or the address of the next byte of a multi byte instruction, which has not been completely fetched. In both the cases it gets incremented automatically one by one as the instruction bytes get fetched. Also Program register keeps the address of the next instruction.

11.What is 1st / 2nd / 3rd / 4th generation processor?
The processor made of PMOS / NMOS / HMOS / HCMOS technology is called 1st / 2nd / 3rd / 4th generation processor, and it is made up of 4 / 8 / 16 / 32 bits.

12.What is the Maximum clock frequency in 8086?
5 Mhz is the Maximum clock frequency in 8086.

13.What is meant by Maskable interrupts?
An interrupt that can be turned off by the programmer is known as Maskable interrupt.

14.What is Non-Maskable interrupts?
An interrupt which can be never be turned off (ie. disabled) is known as Non-Maskable interrupt

15.What are the different functional units in 8086?
Bus Interface Unit and Execution unit, are the two different functional units in 8086.

16.What are the various segment registers in 8086?
Code, Data, Stack, Extra Segment registers in 8086.

17.What does EU do?
Execution Unit receives program instruction codes and data from BIU, executes these instructions and store the result in general registers.

18.Which Stack is used in 8086? k is used in 8086?
FIFO (First In First Out) stack is used in 8086.In this type of Stack the first stored information is retrieved first.

19.What are the flags in 8086?
In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign flag.

20.What is SIM and RIM instructions?
SIM is Set Interrupt Mask. Used to mask the hardware interrupts.
RIM is Read Interrupt Mask. Used to check whether the interrupt is Masked or not.

21.What are Flag registers?
A:-Divided into 2 parts:-Condition code or status flags and machine control flags.
S-Sign Flag:-Is to set when the result of any computation is negative.
Z-Zero Flag:-Is to set if the result of the computation or comparison performed by the previous instruction is zero.
C-Carry Flag:-Is set when there is carry out of MSB in case of addition or a borrow in case of subtraction.
T-Trap Flag:-Is set,the processor enters the single step execution mode.
I-Interrupt Flag:-Is set,the maskable interrupts are recognized by the CPU.
D-Direction Flag:-Is set for autoincrementing or autodecrementing mode in string manipulation instructions.
AC-Auxiliary Carry Flag:-Is set if there is a carry from the lowest nibble during addition or borrow for the lowest nibble.
O-Overflow Flag:-Is setif the result of a signed operation is large enough to be accommodated in a destination register.

22.Write the flags of 8086?
The 8086 has nine flags and they are
1. Carry Flag (CF)                6. Overflow Flag (OF)
2. Parity Flag (PF)                 7. Trace Flag (TF)
3. Auxiliary carry Flag (AF)   8. Interrupt Flag (IF)
4. Zero Flag (ZF)                  9. Direction Flag (DF)
5. Sign Flag (SF)

23. What are the interrupts of 8086?
The interrupts of 8085 are INTR and NMI. The INTR is general maskable interrupt and NMI is non-maskable interrupt.

24. How clock signal is generated in 8086? What is the maximum internal clock frequency of 8086?
The 8086 does not have on-chip clock generation circuit. Hence the clock generator chip, 8284 is connected to the CLK pin of8086. The clock signal supplied by 8284 is divided by three for internal use. The maximum internal clock frequency of8086 is 5MHz.

25. Write the special functions carried by the general purpose registers of 8086?
The special functions carried by the registers of 8086 are the following.
Register Special function
1. AX 16-bit Accumulator
2. AL 8-bit Accumulator
3. BX Base Register 4. CX Count Register 5. DX .Data Register

26.What is the need for Port?
The I/O devices are generally slow devices and their timing characteristics do not match with processor timings. Hence the I/O devices are connected to system bus through the ports.

27.What is a port?
The port is a buffered I/O, which is used to hold the data transmitted from the microprocessor to I/O device or vice-versa.

28.What is processor cycle (Machine cycle)?
The processor cycle or machine cycle is the basic operation performed by the processor. To execute an instruction, the processor will run one or more machine cycles in a particular order.

29.What is Instruction cycle?
The sequence of operations that a processor has to carry out while executing the instruction is called Instruction cycle. Each instruction cycle of a processor indium consists of a number of machine cycles.

30.What is fetch and execute cycle?
In general, the instruction cycle of an instruction can be divided into fetch and execute cycles. The fetch cycle is executed to fetch the opcode from memory. The execute cycle is executed to decode theinstruction and to perform the work instructed by the instruction.

Tricky Micro Wave Engineering Lab Viva Questions with answers free download

Common Microwave Engineering VIVA Questions and Answers:

1. What is Microwave Engineering?
Ans. Microwave engineering is the study and design of microwave circuits , components , and systems. Fundamental principles are applied to analysis , design and measurement techniin this field.The short wavelengths involved distinguish this discipline from electronic engineering . This is because there are different interactions with circuits, transmissions and propagation characteristics at microwave frequencies.a

2. Define s-matrix and its properties?
Ans. In a microwave junction there is an interaction of three or more components.There will be an output port, in addition there may be reflection from the junction of other ports. Totally there may be many combination, these are represented easily using a matrix called S matrix.
Properties of s- matrix
1. it possess symmetric properties sij=sji
2. it possess unitary property
3. [s][s]*=[i]

3. Write the applications of microwave engineering?
Ans. Following are the applications of microwave engineering-
1. Antenna gain is proportional to the electrical size of the antenna. At higher frequencies, more antenna gain is therefore possible for a given physical antenna size, which has important consequences for implementing miniaturized microwave systems.
2. More bandwidth can be realized at higher frequencies. Bandwidth is critically important because available frequency bands in the electromagnetic spectrum are being rapidly depleted.
3. Microwave signals travel by line of sight are not bent by the ionosphere as are lower frequency
signals and thus satellite and terrestrial communication links with very high capacities are possible.

4. Why is s-matrix used in MW analysis?
Ans. Matrix is used in MW analysis to overcome the problem which occurs when H,Y & Z parameter are used in high frequencies.

5. What are the advantages of ABCD matrix?
Ans. The advantages of ABCD matrix are as follows-
1. They are used in power transmission lines
2. They are helpful in case of cascade networks.

6. What are junctions ? Give some example
 Ans. A microwave circuit consists of several microwave devices connected in some way to achieve the desired transmission of MW signal. The interconnection of two or more microwave may be regarded as MW junction.
E.g.: TEE, HYBRID RING

7. What are non-reciprocal devices ?Give two examples?
Ans. The devices which are having the properties that the forward characteristics are not equal to the reverse characteristics are called non-reciprocal devices.

8. What are the applications of reflex klystron?
Ans. The main applications of a reflex klystron are as follows-
1. Signal source in MW generator
2. Local oscillators in receivers
3. It is used in FM oscillator in low power MW links.
4. In parametric amplifier as pump source.

9. What is the purpose of slow wave structures used in TWT amplifiers?
Ans. Slow wave structures are special circuits that are used in microwave tubes to reduce wave velocity in a certain direction so that the electron beam and the signal wave can interact. In TWT, since the beam can be accelerated only to velocities that are about a fraction of the velocity of light, slow wave structures are used.

10.Give two examples for two port junctions?
Ans. Following are the two examples of two port junctions-
1. The junction of two rectangular guides of unequal height
2. A symmetrical junction consisting of two similar rectangular guides joined by an Intermediate guide of greater width.