Interview Questions-Basics of Interview Questions-Basics of Electronics and Communication Electronics and Communication

EnggEngg

Sanjeev BahadurSanjeev Bahadur

Doping in SemiconductorsDoping in Semiconductors

• In semiconductor production, In semiconductor production, dopingdoping deliberately introduces impurities into an deliberately introduces impurities into an extremely pure ( referred as extremely pure ( referred as intrinsicintrinsic) ) semiconductor for the purpose of changing or semiconductor for the purpose of changing or modulating its electrical properties.modulating its electrical properties.

• The impurities are dependent on the type of The impurities are dependent on the type of semiconductor. Lightly and moderately doped semiconductor. Lightly and moderately doped semiconductors are referred to as semiconductors are referred to as extrinsicextrinsic..

• Semiconductor doped to such high levels that Semiconductor doped to such high levels that it acts more like a conductor than a it acts more like a conductor than a semiconductor is referred to as semiconductor is referred to as degeneratedegenerate..

Silicon and Ge as Silicon and Ge as Semiconductor MaterialSemiconductor Material

• The semiconductor materials are either The semiconductor materials are either basic such as silicon and germanium or basic such as silicon and germanium or compound such as gallium arsenide.compound such as gallium arsenide.

• Silicon is the most used semiconductor for Silicon is the most used semiconductor for discrete devices and integrated circuits. One discrete devices and integrated circuits. One of the prominent German scientists wrote in of the prominent German scientists wrote in an article about silicon that this era is the an article about silicon that this era is the silicon era since silicon impacted and still silicon era since silicon impacted and still affecting the modern civilization affecting the modern civilization development very much.. development very much..

DiodesDiodes

• Diodes are used in circuits to stop electricity Diodes are used in circuits to stop electricity from flowing back into the circuit. They only let from flowing back into the circuit. They only let current through in one direction. The diodes in current through in one direction. The diodes in the distortion pedal are what make the the distortion pedal are what make the distortion. Diode-clipping distortion is what this distortion. Diode-clipping distortion is what this is called!is called!There is a certain way to connect diodes. It is There is a certain way to connect diodes. It is pretty straight forward.pretty straight forward.There is always some sort of line on a diode There is always some sort of line on a diode (except for LED's) but on regular diodes there is (except for LED's) but on regular diodes there is always a line always a line

Zener DiodesZener Diodes

Zener diodeZener diode is a diode which allows current is a diode which allows current to flow in the forward directionto flow in the forward direction

• A A Zener diodeZener diode is a is a diodediode which allows current to flow in which allows current to flow in the forward direction in the same manner as an ideal diode, the forward direction in the same manner as an ideal diode, but also permits it to flow in the reverse direction when the but also permits it to flow in the reverse direction when the voltage is above a certain value known as the voltage is above a certain value known as the breakdown voltagebreakdown voltage, "Zener knee voltage", "Zener voltage", , "Zener knee voltage", "Zener voltage", "avalanche point", or "peak inverse voltage"."avalanche point", or "peak inverse voltage".

• The device was named after The device was named after Clarence Clarence ZenerZener, who , who discovered this electrical property. Strictly speaking, a discovered this electrical property. Strictly speaking, a Zener diode is one in which the reverse breakdown is due Zener diode is one in which the reverse breakdown is due to electron to electron quantum quantum tunnellingtunnelling under high electric field under high electric field strength—the strength—the ZenerZener effect effect. However, many diodes . However, many diodes described as "Zener" diodes rely instead on described as "Zener" diodes rely instead on avalanche breakdownavalanche breakdown as the mechanism. Both types are as the mechanism. Both types are used with the Zener effect predominating under 5.6 V and used with the Zener effect predominating under 5.6 V and avalanche breakdownavalanche breakdown above. above.

NPN Transistor,SchematicNPN Transistor,Schematic

Shown here are schematic symbols and physical diagrams of these two transistor types.

Bipolar TransistorBipolar Transistor

• A bipolar transistor consists of a A bipolar transistor consists of a three-layer "sandwich" of doped three-layer "sandwich" of doped (extrinsic) semiconductor materials, (extrinsic) semiconductor materials, either P-N-P or N-P-N.either P-N-P or N-P-N.

• Each layer forming the transistor has Each layer forming the transistor has a specific name, and each layer is a specific name, and each layer is provided with a wire contact for provided with a wire contact for connection to a circuit. connection to a circuit.

PNP TransistorPNP Transistor

NPN TransistorNPN Transistor

Satellite DishSatellite Dish

Logic Circuits and Truth Table-Logic Circuits and Truth Table-ExamplesExamples

Example of Circuit DiagramExample of Circuit Diagram

• The The 555 timer IC555 timer IC is an is an integrated circuitintegrated circuit (chip) used in a (chip) used in a variety of variety of timertimer, pulse generation, , pulse generation, and and oscillatoroscillator applications. The 555 applications. The 555 can be used to provide time delays, can be used to provide time delays, as an as an oscillatoroscillator, and as a , and as a flip-flop elementflip-flop element. .

AmplifiersAmplifiers

SMPS Power SupplySMPS Power Supply

Switched Mode Power Switched Mode Power Supplies (SMPS).Supplies (SMPS).• D.C. to D.C. converters and D.C. to A.C. Converters D.C. to D.C. converters and D.C. to A.C. Converters

belong to the category of belong to the category of Switched Mode Power Switched Mode Power Supplies (SMPS).Supplies (SMPS).

• Various types of voltage regulators, used in Linear Various types of voltage regulators, used in Linear Power Supplies (LPS), fall in the category of dissipative Power Supplies (LPS), fall in the category of dissipative regulator, as they have  a voltage control element regulator, as they have  a voltage control element usually transistor or zener diode which dissipates usually transistor or zener diode which dissipates power equal to the voltage difference between an power equal to the voltage difference between an unregulated input voltage and a fixed supply voltage unregulated input voltage and a fixed supply voltage multiplied by the current flowing through it.multiplied by the current flowing through it.

• The switching regulator acts as a continuously The switching regulator acts as a continuously variable power converter and hence its efficiency is variable power converter and hence its efficiency is barely affected by the voltage differencebarely affected by the voltage difference . .

SMPSSMPS

• The input D.C. Supply is chopped at a higher The input D.C. Supply is chopped at a higher frequency around 15 to 50 kHz using an active frequency around 15 to 50 kHz using an active device like the BJT, power MOSFET or SCR and the device like the BJT, power MOSFET or SCR and the converter transformer. Here the size of the ferrite converter transformer. Here the size of the ferrite core reduces inversely with the frequency. core reduces inversely with the frequency.

• The lower limit is around 5 kHz for silent operation The lower limit is around 5 kHz for silent operation and an upper limit of 50 kHz to limit the losses in and an upper limit of 50 kHz to limit the losses in the choke and in active switching elements. the choke and in active switching elements.

• The transformed wave form is rectified and The transformed wave form is rectified and filtered. A sample of the output voltage is used as filtered. A sample of the output voltage is used as the feedback signal for the drive circuit for the the feedback signal for the drive circuit for the switching transistor to achieve regulation.switching transistor to achieve regulation.

RAM and ROMRAM and ROM

Block Diagram-ComputerBlock Diagram-Computer

Cache MemoryCache Memory

• Small memories on or close to the Small memories on or close to the CPUCPU can operate faster than the can operate faster than the much larger main memory. Most CPUs since the 1980s have used one much larger main memory. Most CPUs since the 1980s have used one or more caches, and modern high-end embedded, desktop and server or more caches, and modern high-end embedded, desktop and server microprocessorsmicroprocessors may have as many as half a dozen, each specialized for may have as many as half a dozen, each specialized for a specific function. Examples of caches with a specific function are the a specific function. Examples of caches with a specific function are the D-cache and I-cache (data cache and instruction cache).D-cache and I-cache (data cache and instruction cache).

• Translation lookaside buffer Main article: Translation lookaside buffer Main article: Translation Translation lookasidelookaside buffer buffer• A A memory management unitmemory management unit (MMU) that fetches page table entries from (MMU) that fetches page table entries from

main memory has a specialized cache, used for recording the results main memory has a specialized cache, used for recording the results of of virtual addressvirtual address to to physical addressphysical address translations. This specialized cache translations. This specialized cache is called a is called a translation translation lookasidelookaside buffer buffer (TLB (TLB]]

• Disk cache:Disk cache:

• Page cachePage cache• While CPU caches are generally managed entirely by hardware, a While CPU caches are generally managed entirely by hardware, a

variety of software manages other caches. The variety of software manages other caches. The page cachepage cache in in main memorymain memory, which is an example of disk cache, is managed by the , which is an example of disk cache, is managed by the operating system operating system kernelkernel..

Disk BufferDisk Buffer

• While the hard drive's hardware While the hard drive's hardware disk bufferdisk buffer is sometimes misleadingly is sometimes misleadingly referred to as "disk cache", its main functions are to write sequencing and referred to as "disk cache", its main functions are to write sequencing and read pre fetching. Repeated cache hits are relatively rare, due to the small read pre fetching. Repeated cache hits are relatively rare, due to the small size of the buffer in comparison to the drive's capacity. However, high-end size of the buffer in comparison to the drive's capacity. However, high-end disk controllersdisk controllers often have their own on-board cache of hard disk often have their own on-board cache of hard disk data blocksdata blocks..

• Finally, a fast local hard disk can also cache information held on Finally, a fast local hard disk can also cache information held on even slower data storage devices, such as remote servers (even slower data storage devices, such as remote servers (web cacheweb cache) or local ) or local tape drivestape drives or or optical jukeboxesoptical jukeboxes. Such a scheme is the . Such a scheme is the main concept of main concept of hierarchical storage managementhierarchical storage management..

• Web cacheWeb cache• Web browsers and Web browsers and web proxy serversweb proxy servers employ web caches to store employ web caches to store

previous responses from previous responses from web serversweb servers, such as , such as web pagesweb pages and and imagesimages. Web . Web caches reduce the amount of information that needs to be transmitted caches reduce the amount of information that needs to be transmitted across the network, as information previously stored in the cache can often across the network, as information previously stored in the cache can often be re-used. This reduces bandwidth and processing requirements of the be re-used. This reduces bandwidth and processing requirements of the web server, and helps to improve web server, and helps to improve responsivenessresponsiveness for users of the web. for users of the web.

• Web browsers employ a built-in web cache, but some Web browsers employ a built-in web cache, but some internet service providersinternet service providers or organizations also use a caching proxy server, or organizations also use a caching proxy server, which is a web cache that is shared among all users of that network.which is a web cache that is shared among all users of that network.

Intel Core 2 Duo Processor& Intel Core 2 Duo Processor& MotherboardMotherboard

VLSI ChipVLSI Chip

chip VLSI VL82C106 Super I/O

PlotterPlotter

Raster and Vector GraphicsRaster and Vector Graphics

Satellite DishSatellite Dish

• When the signal reaches the viewer's house, it When the signal reaches the viewer's house, it is captured by the satellite dish. A satellite dish is captured by the satellite dish. A satellite dish is just a special kind of antenna designed to is just a special kind of antenna designed to focus on a specific broadcast source.focus on a specific broadcast source.

• The standard dish consists of a The standard dish consists of a parabolicparabolic (bowl-shaped) surface and a central (bowl-shaped) surface and a central feed feed hornhorn..

• To transmit a signal, a controller sends it To transmit a signal, a controller sends it through the horn, and the dish focuses the through the horn, and the dish focuses the signal into a relatively narrow beam.signal into a relatively narrow beam.

The curved dish focuses incoming radio waves onto the feed horn

Radio SpectrumRadio Spectrum

• Radio spectrumRadio spectrum refers to the part of the refers to the part of the electromagnetic spectrumelectromagnetic spectrum corresponding to corresponding to radio frequenciesradio frequencies – that is, frequencies lower than – that is, frequencies lower than around 300 GHz (or, equivalently, wavelengths longer than about around 300 GHz (or, equivalently, wavelengths longer than about 1 mm). 1 mm). Electromagnetic wavesElectromagnetic waves in this frequency range, called in this frequency range, called radio wavesradio waves, are used for , are used for radio communicationradio communication and various other and various other applications, such as heating.applications, such as heating.

• The generation of radio waves is strictly regulated by the The generation of radio waves is strictly regulated by the government in most countries, coordinated by an international government in most countries, coordinated by an international standards body called the standards body called the International Telecommunications UnionInternational Telecommunications Union (ITU). Different parts of the radio spectrum are allocated for (ITU). Different parts of the radio spectrum are allocated for different radio transmission technologies and applications. In some different radio transmission technologies and applications. In some cases, parts of the radio spectrum is sold or licensed to operators of cases, parts of the radio spectrum is sold or licensed to operators of private radio transmission services (for example, cellular telephone private radio transmission services (for example, cellular telephone operators or broadcast television stations).operators or broadcast television stations).

• Ranges of allocated frequencies are often referred to by their Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television provisioned use (for example, cellular spectrum or television spectrumspectrum

VHF-Very High FrequenciesVHF-Very High Frequencies

• Very high frequencyVery high frequency ( (VHFVHF) is the ) is the ITUITU designation for designation for the range of the range of radio frequencyradio frequency electromagnetic waveselectromagnetic waves from from 30 30 MHzMHz to 300 to 300 MHzMHz, with corresponding wavelengths of , with corresponding wavelengths of ten to one meters. Frequencies immediately below VHF ten to one meters. Frequencies immediately below VHF are denoted are denoted high frequencyhigh frequency (HF), and the next higher (HF), and the next higher frequencies are known as frequencies are known as ultra high frequencyultra high frequency (UHF). (UHF).

• Common uses for VHF are Common uses for VHF are FM radioFM radio broadcasting, broadcasting, televisiontelevision broadcasting, land mobile stations broadcasting, land mobile stations (emergency, business, private use and military), long (emergency, business, private use and military), long range data communication up to several tens of range data communication up to several tens of kilometres with kilometres with radio modemsradio modems, , amateur radioamateur radio, and , and marine communicationsmarine communications..

• Air traffic controlAir traffic control communications and air navigation communications and air navigation systems (e.g. systems (e.g. VORVOR, , DMEDME & & ILSILS) work at distances of 100 ) work at distances of 100 kilometres or more to aircraft at cruising altitude.kilometres or more to aircraft at cruising altitude.

AM and FMAM and FM

• AMAM (or (or Amplitude ModulationAmplitude Modulation) and ) and FMFM (or (or Frequency ModulationFrequency Modulation) are ways of ) are ways of broadcasting radio signals. Both transmit the broadcasting radio signals. Both transmit the information in the form of electromagnetic waves. information in the form of electromagnetic waves.

• AM works by modulating (varying) the AM works by modulating (varying) the amplitudeamplitude of the signal or carrier transmitted according to of the signal or carrier transmitted according to the information being sent, while the frequency the information being sent, while the frequency remains constant.remains constant.

• This differs from FM technology in which This differs from FM technology in which information (sound) is encoded by varying the information (sound) is encoded by varying the frequency of the wave and the amplitude is kept frequency of the wave and the amplitude is kept constant. constant.

Amplitude ModulationAmplitude Modulation

• In AM, a radio wave known as the "carrier" or In AM, a radio wave known as the "carrier" or "carrier wave" is modulated in amplitude by "carrier wave" is modulated in amplitude by the signal that is to be transmitted. The the signal that is to be transmitted. The frequency and phase remain the same.frequency and phase remain the same.

• AM has poorer sound quality compared with AM has poorer sound quality compared with FM, but is cheaper and can be transmitted FM, but is cheaper and can be transmitted over long distances. It has a lower bandwidth over long distances. It has a lower bandwidth so it can have more stations available in any so it can have more stations available in any frequency range.AM radio ranges from 535 to frequency range.AM radio ranges from 535 to 1705 KHz (OR) Up to 1200 bits per second.1705 KHz (OR) Up to 1200 bits per second.

AM-Tx and RxAM-Tx and Rx

• Transmitter and receiver are simple Transmitter and receiver are simple but syncronization is needed in case but syncronization is needed in case of SSBSC AM carrier. of SSBSC AM carrier.

Frequency ModulationFrequency Modulation

• In FM, a radio wave known as the "carrier" or In FM, a radio wave known as the "carrier" or "carrier wave" is modulated in frequency by "carrier wave" is modulated in frequency by the signal that is to be transmitted.the signal that is to be transmitted.

• The amplitude and phase remain the same.FM The amplitude and phase remain the same.FM is less prone to interference than AM. is less prone to interference than AM. However, FM signals are impacted by physical However, FM signals are impacted by physical barriers.barriers.

• FM has better sound quality due to higher FM has better sound quality due to higher bandwidth.FM radio ranges in a higher bandwidth.FM radio ranges in a higher spectrum from 88 to 108 MHz. (OR) 1200 to spectrum from 88 to 108 MHz. (OR) 1200 to 2400 bits per second.2400 bits per second.

FM-TX and RXFM-TX and RX

• Transmitter and receiver are more Transmitter and receiver are more complex as variation of modulating complex as variation of modulating signal has to be converted and signal has to be converted and detected from corresponding detected from corresponding variation in frequencies.(i.e. voltage variation in frequencies.(i.e. voltage to frequency and frequency to to frequency and frequency to voltage voltage

Signal-to-noise ratioSignal-to-noise ratio (often (often abbreviated abbreviated SNRSNR or or S/NS/N• Signal-to-noise ratioSignal-to-noise ratio (often abbreviated (often abbreviated SNRSNR or or

S/NS/N) is a measure used in science and engineering ) is a measure used in science and engineering that compares the level of a desired that compares the level of a desired signalsignal to the level to the level of background of background noisenoise. It is defined as the ratio of signal . It is defined as the ratio of signal power to the noise power, often expressed in power to the noise power, often expressed in decibelsdecibels. A ratio higher than 1:1 (greater than 0 dB) indicates . A ratio higher than 1:1 (greater than 0 dB) indicates more signal than noise. While SNR is commonly more signal than noise. While SNR is commonly quoted for electrical signals, it can be applied to any quoted for electrical signals, it can be applied to any form of signal (such as isotope levels in an form of signal (such as isotope levels in an ice coreice core or or biochemical signalingbiochemical signaling between cells). between cells).

• The signal-to-noise ratio, the The signal-to-noise ratio, the bandwidthbandwidth, and the , and the channel capacitychannel capacity of a of a communication channelcommunication channel are are connected by the connected by the Shannon–Hartley theoremShannon–Hartley theorem

Satellite telephoneSatellite telephone, , SSatellite phoneatellite phone• A A satellite telephonesatellite telephone, , satellite phonesatellite phone, or , or

satphonesatphone is a type of is a type of mobile phonemobile phone that that connects to orbiting connects to orbiting satellitessatellites instead of instead of terrestrial terrestrial cell sitescell sites..

• They provide similar functionality to terrestrial They provide similar functionality to terrestrial mobile telephones; mobile telephones; voicevoice, , short messaging serviceshort messaging service and low-bandwidth and low-bandwidth internetinternet access are supported through most access are supported through most systems.systems.

• Depending on the architecture of a particular Depending on the architecture of a particular system, coverage may include the entire system, coverage may include the entire EarthEarth, or , or only specific regions.only specific regions.

SatphoneSatphone

• A fixed installation, such as one used aboard a ship, may A fixed installation, such as one used aboard a ship, may include large, rugged, rack-mounted electronics, and a include large, rugged, rack-mounted electronics, and a steerable steerable microwavemicrowave antenna on the mast that antenna on the mast that automatically tracks the overhead satellites.automatically tracks the overhead satellites.

• Smaller installations using Smaller installations using VoIPVoIP over a two-way over a two-way satellite broadbandsatellite broadband service such as service such as BGANBGAN or or VSATVSAT bring the bring the costs within the reach of leisure vessel owners. costs within the reach of leisure vessel owners. InternetInternet service satellite phones have notoriously poor reception service satellite phones have notoriously poor reception indoors, though it may be possible to get a consistent signal indoors, though it may be possible to get a consistent signal near a window or in the top floor of a building if the roof is near a window or in the top floor of a building if the roof is sufficiently thin.sufficiently thin.

• The phones have connectors for external antennas that The phones have connectors for external antennas that can be installed in vehicles and buildings. The systems also can be installed in vehicles and buildings. The systems also allow for the use of repeaters, much like terrestrial mobile allow for the use of repeaters, much like terrestrial mobile phone systems.phone systems.

Geosynchronous satelliteGeosynchronous satellite

• A A geosynchronous satellitegeosynchronous satellite is a is a satellitesatellite in in geosynchronous orbitgeosynchronous orbit, with an orbital period the same , with an orbital period the same as the Earth's rotation period. Such a satellite returns as the Earth's rotation period. Such a satellite returns to the same position in the sky after each to the same position in the sky after each sidereal daysidereal day, and over the course of a day traces out a path in the , and over the course of a day traces out a path in the sky that is typically some form of sky that is typically some form of analemmaanalemma.Orbit si .Orbit si about 36000 kms above a point of Earth.about 36000 kms above a point of Earth.

• A special case of geosynchronous satellite is the A special case of geosynchronous satellite is the geostationary satellitegeostationary satellite, which has a , which has a geostationary orbitgeostationary orbit – a circular geosynchronous orbit – a circular geosynchronous orbit directly above the Earth's equator. Another type of directly above the Earth's equator. Another type of geosynchronous orbit used by satellites is the geosynchronous orbit used by satellites is the Tundra elliptical orbitTundra elliptical orbit

Advantage of Advantage of Geosynchronous Geosynchronous satellites satellites • Geosynchronous satellites have the advantage of Geosynchronous satellites have the advantage of

remaining permanently in the same area of the sky, remaining permanently in the same area of the sky, as viewed from a particular location on Earth, and as viewed from a particular location on Earth, and so permanently within view of a given ground so permanently within view of a given ground station. Geostationary satellites have the special station. Geostationary satellites have the special property of remaining permanently fixed in exactly property of remaining permanently fixed in exactly the same position in the sky, meaning that ground-the same position in the sky, meaning that ground-based antennas do not need to track them but can based antennas do not need to track them but can remain fixed in one direction. remain fixed in one direction.

• Such satellites are often used for communication Such satellites are often used for communication purposes; a purposes; a geosynchronous networkgeosynchronous network is a is a communication network based on communication communication network based on communication with or through geosynchronous satellites.with or through geosynchronous satellites.

Cybersecurity standardsCybersecurity standards

• Cybersecurity standardsCybersecurity standards are security are security standards which enable organizations to standards which enable organizations to practice safe security techniques to stop practice safe security techniques to stop cybersecurity attackscybersecurity attacks..

• These guides provide general outlines as These guides provide general outlines as well as specific techniques for implementing well as specific techniques for implementing cybersecuritycybersecurity..

• For certain standards, For certain standards, cybersecurity cybersecurity certificationcertification by an accredited body can be by an accredited body can be obtained. There are many advantages to obtained. There are many advantages to obtaining certification including the ability obtaining certification including the ability to get cybersecurity insurance.to get cybersecurity insurance.

Digital signal processingDigital signal processing ((DSPDSP))• Digital signal processingDigital signal processing ( (DSPDSP) ) is the mathematical manipulation of is the mathematical manipulation of

an information signal to modify or improve it in some way. It is an information signal to modify or improve it in some way. It is characterized by the representation of discrete time, discrete characterized by the representation of discrete time, discrete frequency, or other discrete domain frequency, or other discrete domain signalssignals by a sequence of numbers by a sequence of numbers or symbols and the processing of these signals.or symbols and the processing of these signals.

• The goal of DSP is usually to measure, filter and/or compress The goal of DSP is usually to measure, filter and/or compress continuous real-world continuous real-world analog signalsanalog signals. Usually, the first step is . Usually, the first step is conversion of the signal from an analog to a digital form, by conversion of the signal from an analog to a digital form, by samplingsampling and then digitizing it using an and then digitizing it using an analog-to-digital converteranalog-to-digital converter (ADC), which (ADC), which turns the analog signal into a stream of discrete digital values. Often, turns the analog signal into a stream of discrete digital values. Often, however, the required output signal is also analog, which requires a however, the required output signal is also analog, which requires a digital-to-analog converterdigital-to-analog converter (DAC). Even if this process is more complex (DAC). Even if this process is more complex than analog processing and has a than analog processing and has a discrete value rangediscrete value range, the application , the application of computational power to signal processing allows for many of computational power to signal processing allows for many advantages over analog processing in many applications, such as advantages over analog processing in many applications, such as error detection and correctionerror detection and correction in transmission as well as in transmission as well as data compressiondata compression

• Digital signal processing and Digital signal processing and analog signal processinganalog signal processing are subfields of are subfields of signal processingsignal processing. DSP applications include . DSP applications include audioaudio and and speech signal processingspeech signal processing, sonar and radar signal processing, sensor , sonar and radar signal processing, sensor array processing, spectral estimation, statistical signal processing, array processing, spectral estimation, statistical signal processing, digital image processingdigital image processing

2D and 3D visualization2D and 3D visualization

managed as a single design with 2D and 3D visualization.

Today’s complex products require a new design approach where multiple boards can be

3D product visualization3D product visualization

• 3D product visualization is becoming 3D product visualization is becoming a critical need as the electrical and a critical need as the electrical and mechanical designs converge with mechanical designs converge with little room for error. Detection at the little room for error. Detection at the prototype phase may be too late. prototype phase may be too late.

Computer-aided Computer-aided technologiestechnologies ( (CAx)CAx)• Computer-aided technologiesComputer-aided technologies ( (CAx CAx is a broad term that means the is a broad term that means the

use of use of computercomputer technology to aid in the technology to aid in the designdesign, analysis, and , analysis, and manufacture of products.manufacture of products.

• Advanced CAx tools merge many different aspects of the Advanced CAx tools merge many different aspects of the product lifecycle managementproduct lifecycle management (PLM), including design, (PLM), including design, finite element analysisfinite element analysis (FEA), manufacturing, production planning, (FEA), manufacturing, production planning, productproduct

• Computer-aided designComputer-aided design (CAD) (CAD)• Computer-aided engineeringComputer-aided engineering (CAE) (CAE)• Computer-aided industrial designComputer-aided industrial design (CAID) (CAID)• Computer-aided manufacturingComputer-aided manufacturing (CAM) (CAM)• Computer-aided requirements captureComputer-aided requirements capture (CAR) (CAR)• Computer-aided rule definitionComputer-aided rule definition (CARD) (CARD)• Computer-aided rule executionComputer-aided rule execution (CARE) (CARE)• Computer-aided software engineeringComputer-aided software engineering (CASE) (CASE)• Computer-assisted surgeryComputer-assisted surgery (CAS) (CAS)

– Computer-aided surgical simulation (CASS)Computer-aided surgical simulation (CASS)• Computational fluid dynamicsComputational fluid dynamics (CFD) (CFD)

Chip-Package-Board Co-Chip-Package-Board Co-designdesign

• Poor I/O assignments on a newly Poor I/O assignments on a newly designed package can leave a PCB designed package can leave a PCB unroutable. Merging the packaging unroutable. Merging the packaging and PCB design into a single design and PCB design into a single design solution significantly increases solution significantly increases design quality. design quality.

Flow Architect Studio 3DFlow Architect Studio 3D

Flow Architect Studio 3D Flow Architect Studio 3D

• Flow Architect Studio 3DFlow Architect Studio 3D is a software is a software package for design and presentation. package for design and presentation. It enables you to design and visualize It enables you to design and visualize in in 3D3D, any scene you need for , any scene you need for example: buildings, interiors, spaces example: buildings, interiors, spaces or your products.or your products.

• Flow helps you to present your work Flow helps you to present your work to others with screenshots, movies to others with screenshots, movies and a real-time and a real-time virtual 3D walkthroughvirtual 3D walkthrough

Digital image processingDigital image processing

• Digital image processing is the use of computer Digital image processing is the use of computer algorithmsalgorithms to perform to perform image processingimage processing on on digital imagesdigital images. As a subcategory or field of . As a subcategory or field of digital signal processingdigital signal processing, digital image processing , digital image processing has many advantages over has many advantages over analog image processinganalog image processing..

• It allows a much wider range of algorithms to be It allows a much wider range of algorithms to be applied to the input data and can avoid problems applied to the input data and can avoid problems such as the build-up of noise and signal distortion such as the build-up of noise and signal distortion during processing. Since images are defined over during processing. Since images are defined over two dimensions (perhaps more) digital image two dimensions (perhaps more) digital image processing may be modeled in the form of processing may be modeled in the form of multidimensional systemsmultidimensional systems

PhotogrammetryPhotogrammetry

• PhotogrammetryPhotogrammetry is the science of making is the science of making measurements from photographs, especially for measurements from photographs, especially for recovering the exact positions of surface points. recovering the exact positions of surface points. Moreover, it may be used to recover the motion Moreover, it may be used to recover the motion pathways of designated reference points located on any pathways of designated reference points located on any moving object, on its components and in the moving object, on its components and in the immediately adjacent environment.immediately adjacent environment.

• Photogrammetry may employ high-speed imaging and Photogrammetry may employ high-speed imaging and remote sensingremote sensing in order to detect, measure and record in order to detect, measure and record complex 2-D and 3-D motion fields (see also complex 2-D and 3-D motion fields (see also sonarsonar, , radarradar, , lidarlidar etc.). Photogrammetry feeds the measurements etc.). Photogrammetry feeds the measurements from remote sensing and the results of from remote sensing and the results of imagery analysisimagery analysis into into computational modelscomputational models in an attempt to successively in an attempt to successively estimate, with increasing accuracy, the actual, 3-D estimate, with increasing accuracy, the actual, 3-D relative motions within the researched field.relative motions within the researched field.

Rugged ComputersRugged ComputersLatitude 12 Rugged Extreme                                               12" fully rugged flip-hinge convertible notebook                                               that adapts to changing conditions with a crisp                                               outdoor-readable display and glove-capable                                               multi-touch.

What Is A Klystron? And What Is A Klystron? And How Does It WorkHow Does It Work• Now that we have caught up on basic tube theory, and understand how a beam of electrons Now that we have caught up on basic tube theory, and understand how a beam of electrons

can be formed in a vacuum, we are well on our way to understanding how a KLYSTRON can be formed in a vacuum, we are well on our way to understanding how a KLYSTRON operates. operates.

If we have a device, which generates a beam of electrons, we notice that the electrons flow in If we have a device, which generates a beam of electrons, we notice that the electrons flow in a smooth steady stream at a particular uniform velocity. The area of the tube that the electron a smooth steady stream at a particular uniform velocity. The area of the tube that the electron beam travels down is known as the DRIFT TUBE. If we insert, within the beam a grid, we can beam travels down is known as the DRIFT TUBE. If we insert, within the beam a grid, we can use this grid to control the beam. As we increase the positive potential on the grid, (assuming use this grid to control the beam. As we increase the positive potential on the grid, (assuming that we do not go over a certain potential which is less than the anode voltage), the electrons that we do not go over a certain potential which is less than the anode voltage), the electrons will be attracted to the grid, and by means of attraction, will be accellerated. On the other will be attracted to the grid, and by means of attraction, will be accellerated. On the other hand, should we decrease the potential, making it more negative, it will have the opposite hand, should we decrease the potential, making it more negative, it will have the opposite effect on the beam, and try to slow down the electrons. effect on the beam, and try to slow down the electrons.

We insert two grids, properly spaced for our experiment, and apply an alternating current We insert two grids, properly spaced for our experiment, and apply an alternating current source to the grids, such that as one grid swings positive, the other swings negative. This source to the grids, such that as one grid swings positive, the other swings negative. This would mean that the electrons which are aproaching the positive going grid will be speeding would mean that the electrons which are aproaching the positive going grid will be speeding up, as the ones aproaching the negative going grid will be slowing down. As the phase of the up, as the ones aproaching the negative going grid will be slowing down. As the phase of the AC cycle changes 180 degrees, we have the same effect, only backwards. The result would be a AC cycle changes 180 degrees, we have the same effect, only backwards. The result would be a sort of "slinky" effect, where the electron beam is interrupted, and moves along in bursts. This sort of "slinky" effect, where the electron beam is interrupted, and moves along in bursts. This effect is known as VELOCITY MODULATION. In German, they say that electrons are moving in effect is known as VELOCITY MODULATION. In German, they say that electrons are moving in "Klystern". (Klyster is the German word for CLUSTER or BUNCH). Hence, the name Klystron. "Klystern". (Klyster is the German word for CLUSTER or BUNCH). Hence, the name Klystron.

On the other end of our experimental Klystron, we have two more grids installed. The purpose On the other end of our experimental Klystron, we have two more grids installed. The purpose of these are to "feel" the now pulsing beam of electrons as it passes by them on their way to of these are to "feel" the now pulsing beam of electrons as it passes by them on their way to the anode. Note that an electron does not have to come into direct contact with a wire in order the anode. Note that an electron does not have to come into direct contact with a wire in order to induce an electric current in it. All it has to do is pass near enough to generate the current to induce an electric current in it. All it has to do is pass near enough to generate the current in the wire via mutual inductance. in the wire via mutual inductance.

Maxwell's equationsMaxwell's equations

• Maxwell's equationsMaxwell's equations are a set of are a set of partial differential equationspartial differential equations that, together with the that, together with the Lorentz forceLorentz force law, form the foundation of law, form the foundation of classical electrodynamicsclassical electrodynamics, classical , classical opticsoptics, and , and electric circuitselectric circuits. These fields in turn underlie modern electrical and communications . These fields in turn underlie modern electrical and communications technologies. Maxwell's equations describe how technologies. Maxwell's equations describe how electricelectric and and magnetic fieldsmagnetic fields are generated are generated and altered by each other and by and altered by each other and by chargescharges and and currentscurrents. They are named after the Scottish . They are named after the Scottish physicist/mathematician physicist/mathematician James Clerk MaxwellJames Clerk Maxwell, who published an early form of those , who published an early form of those equations between 1861 and 1862.equations between 1861 and 1862.

• The equations have two major variants. The "microscopic" set of Maxwell's The equations have two major variants. The "microscopic" set of Maxwell's equations uses total charge and total current, including the complicated charges equations uses total charge and total current, including the complicated charges and currents in materials at the and currents in materials at the atomicatomic scale; it has universal applicability but may be scale; it has universal applicability but may be unfeasible to calculate. The "macroscopic" set of Maxwell's equations defines two new unfeasible to calculate. The "macroscopic" set of Maxwell's equations defines two new auxiliary fields that describe large-scale behavior without having to consider these atomic auxiliary fields that describe large-scale behavior without having to consider these atomic scale details, but it requires the use of parameters characterizing the electromagnetic scale details, but it requires the use of parameters characterizing the electromagnetic properties of the relevant materialsproperties of the relevant materials..

• The term "Maxwell's equations" is often used for The term "Maxwell's equations" is often used for other formsother forms of Maxwell's equations. For of Maxwell's equations. For example, example, space-time formulationsspace-time formulations are commonly used in high energy and gravitational are commonly used in high energy and gravitational physics. These formulations, defined on physics. These formulations, defined on space-timespace-time rather than space and time separately, rather than space and time separately, are are manifestlymanifestly compatible with compatible with specialspecial and and general relativitygeneral relativity. In . In quantum mechanicsquantum mechanics and and analytical mechanicsanalytical mechanics, versions of Maxwell's equations based on the , versions of Maxwell's equations based on the electricelectric and and magnetic potentialsmagnetic potentials are preferred. are preferred.

• Since the mid-20th century, it has been understood that Maxwell's equations are not exact Since the mid-20th century, it has been understood that Maxwell's equations are not exact laws of the universe, but are a classical approximation to the more accurate and laws of the universe, but are a classical approximation to the more accurate and fundamental theory of fundamental theory of quantum electrodynamicsquantum electrodynamics. In most cases, though, quantum . In most cases, though, quantum deviations from Maxwell's equations are immeasurably small. Exceptions occur when the deviations from Maxwell's equations are immeasurably small. Exceptions occur when the particleparticle nature of light is important or for very strong electric fields. nature of light is important or for very strong electric fields.

ImagesImages

Traveling Wave Tubes, Klystrons & Traveling Wave Tubes, Klystrons & MagnetronsMagnetrons

• Electron Energy magnets and assemblies Electron Energy magnets and assemblies are used in sophisticated, performance-are used in sophisticated, performance-critical components of advanced critical components of advanced technology systems, such as traveling technology systems, such as traveling wave tubes (TWTs), klystrons, and wave tubes (TWTs), klystrons, and magnetrons. magnetrons.

• These are all used to amplify signals at These are all used to amplify signals at microwave frequencies for high-microwave frequencies for high-performing radar, communications and performing radar, communications and electronic countermeasure systems.electronic countermeasure systems.

WaveguidesWaveguides

Beam waveguide Beam waveguide antennaantenna• A A beam waveguide antennabeam waveguide antenna is a particular is a particular

type of type of parabolic antennaparabolic antenna that transports the that transports the signal between a stationary signal between a stationary transmittertransmitter or or receiverreceiver and a movable dish by means of a and a movable dish by means of a beam waveguide. With a conventional "front beam waveguide. With a conventional "front fed" parabolic antenna, the fed" parabolic antenna, the antenna feedantenna feed, the , the small antenna that transmits or receives the small antenna that transmits or receives the radio waves reflected by the dish, is suspended radio waves reflected by the dish, is suspended at a at a focusfocus, in front of the dish, and moves as the , in front of the dish, and moves as the antenna is repositioned to track specific targets. antenna is repositioned to track specific targets.

InternetInternet

• The Internet is a global system of interconnected The Internet is a global system of interconnected computer networkscomputer networks that use the standard that use the standard Internet protocol suiteInternet protocol suite (TCP/IP) to link several billion (TCP/IP) to link several billion devices worldwide. It is an international devices worldwide. It is an international network of networksnetwork of networks that that consists of millions of private, public, academic, business, and consists of millions of private, public, academic, business, and government government packet switchedpacket switched networks, linked by a broad array of networks, linked by a broad array of electronic, wireless, and optical networking technologies. The Internet electronic, wireless, and optical networking technologies. The Internet carries an extensive range of information resources and services, such as carries an extensive range of information resources and services, such as the inter-linked the inter-linked hypertexthypertext documents and documents and applicationsapplications of the of the World Wide WebWorld Wide Web (WWW), the (WWW), the infrastructureinfrastructure to support email, and to support email, and peer-to-peerpeer-to-peer networks for networks for file sharingfile sharing and and telephonytelephony..

• The origins of the Internet date back to research commissioned by The origins of the Internet date back to research commissioned by the the United States governmentUnited States government in the 1960s to build robust, fault-tolerant in the 1960s to build robust, fault-tolerant communication via computer networks. While this work, together with work communication via computer networks. While this work, together with work in the United Kingdom and France, led to important precursor networks, in the United Kingdom and France, led to important precursor networks, they were not the Internet. There is no consensus on the exact date when they were not the Internet. There is no consensus on the exact date when the modern Internet came into being, but sometime in the early to mid-the modern Internet came into being, but sometime in the early to mid-1980s is considered reasonable.1980s is considered reasonable.

• From that point, the network experienced decades of sustained From that point, the network experienced decades of sustained exponential growth as generations of institutional, exponential growth as generations of institutional, personalpersonal, and , and mobilemobile computers were connected to it. computers were connected to it.

TCP/IPTCP/IP

• TCP/IP, TCP/IP, TTransmission ransmission CControl ontrol PProtocol/rotocol/IInternet nternet PProtocol, is a suite of communications rotocol, is a suite of communications protocols used to interconnect network devices protocols used to interconnect network devices on the Internet.on the Internet.

• TCP/IP implements layers of protocol stacks, TCP/IP implements layers of protocol stacks, and each layer provides a well-defined network and each layer provides a well-defined network services to the upper layer protocol. TCP and services to the upper layer protocol. TCP and IP are the two protocols used by TCP/IP, as well IP are the two protocols used by TCP/IP, as well as the (higher) application, (lower) data link as the (higher) application, (lower) data link and (lower) physical layer protocols and (lower) physical layer protocols

Decimal to Binary conversion Decimal to Binary conversion exampleexample

Parity BitParity Bit

• Hamming codeHamming code • In In communicationscommunications, parity checking refers to the use of , parity checking refers to the use of parity parity bits bits

to check that to check that datadata has been transmitted accurately. The parity bit has been transmitted accurately. The parity bit is added to every data unit (typically seven or eight bits ) that are is added to every data unit (typically seven or eight bits ) that are transmitted. The parity bit for each unit is set so that all transmitted. The parity bit for each unit is set so that all bytes bytes have either an odd number or an even number of set bits.have either an odd number or an even number of set bits.

• Assume, for example, that two Assume, for example, that two devicesdevices are communicating with are communicating with even even parityparity(the most common form of parity checking). As the (the most common form of parity checking). As the transmitting device sends data, it counts the number of set bits transmitting device sends data, it counts the number of set bits in each group of seven bits. If the number of set bits is even, it in each group of seven bits. If the number of set bits is even, it sets the parity bit to 0; if the number of set bits is odd, it sets the sets the parity bit to 0; if the number of set bits is odd, it sets the parity bit to 1. In this way, every byte has an even number of set parity bit to 1. In this way, every byte has an even number of set bits. On the receiving side, the device checks each byte to make bits. On the receiving side, the device checks each byte to make sure that it has an even number of set bits. If it finds an odd sure that it has an even number of set bits. If it finds an odd number of set bits, the receiver knows there was an error during number of set bits, the receiver knows there was an error during transmission.transmission.

• The sender and receiver must both agree to use parity checking The sender and receiver must both agree to use parity checking and to agree on whether parity is to be odd or even. If the two and to agree on whether parity is to be odd or even. If the two sides are not configured with the same sides are not configured with the same parity senseparity sense, , communication will be impossiblecommunication will be impossible

Hamming CodesHamming Codes

• In telecommunication, In telecommunication, Hamming codesHamming codes are are a family of linear error-correcting codes that a family of linear error-correcting codes that generalize the Hamming(7,4)-code invented generalize the Hamming(7,4)-code invented by Richard Hamming in 1950. Hamming codes by Richard Hamming in 1950. Hamming codes can can detect up to two-bit errorsdetect up to two-bit errors or or correct one-correct one-bit errors without detection of uncorrected bit errors without detection of uncorrected errorserrors. By contrast, the simple parity code . By contrast, the simple parity code cannot correct errors, and can detect only an cannot correct errors, and can detect only an odd number of bits in error. Hamming codes odd number of bits in error. Hamming codes are perfect codes, that is, they achieve the are perfect codes, that is, they achieve the highest possible rate for codes with their highest possible rate for codes with their block length and minimum distance 3 block length and minimum distance 3

• Due to the limited redundancy that Hamming codes Due to the limited redundancy that Hamming codes add to the data, they can only detect and correct add to the data, they can only detect and correct errors when the error rate is low. This is the case in errors when the error rate is low. This is the case in computer memory (ECC memory), where bit errors computer memory (ECC memory), where bit errors are extremely rare and Hamming codes are widely are extremely rare and Hamming codes are widely used. In this context, an extended Hamming code used. In this context, an extended Hamming code having one extra parity bit is often used. Extended having one extra parity bit is often used. Extended Hamming codes achieve a Hamming distance of , Hamming codes achieve a Hamming distance of , which allows the decoder to distinguish between which allows the decoder to distinguish between when at most one bit error occurred and when two when at most one bit error occurred and when two bit errors occurred. In this sense, extended Hamming bit errors occurred. In this sense, extended Hamming codes are single-error correcting and double-error codes are single-error correcting and double-error detecting, abbreviated as detecting, abbreviated as SECDEDSECDED..

System SoftwareSystem Software

• Actually, a system software is any computer software which manages and controls Actually, a system software is any computer software which manages and controls computer hardware so that application software can perform a task. Operating computer hardware so that application software can perform a task. Operating systems, such as Microsoft Windows, Mac OS X or Linux, are prominent examples of systems, such as Microsoft Windows, Mac OS X or Linux, are prominent examples of system software. System software contrasts with application software, which are system software. System software contrasts with application software, which are programs that enable the end-user to perform specific, productive tasks, such as programs that enable the end-user to perform specific, productive tasks, such as word processing or image manipulation. word processing or image manipulation.

System software performs tasks like transferring data from memory to disk, or System software performs tasks like transferring data from memory to disk, or rendering text onto a display device. Specific kinds of system software include rendering text onto a display device. Specific kinds of system software include loading programs, operating systems, device drivers, programming tools, compilers, loading programs, operating systems, device drivers, programming tools, compilers, assemblers, linkers, and utility software. assemblers, linkers, and utility software.

Software libraries that perform generic functions also tend to be regarded as system Software libraries that perform generic functions also tend to be regarded as system software, although the dividing line is fuzzy; while a C runtime library is generally software, although the dividing line is fuzzy; while a C runtime library is generally agreed to be part of the system, an OpenGL or database library is less obviously so. agreed to be part of the system, an OpenGL or database library is less obviously so.

If system software is stored on non-volatile memory such as integrated circuits, it is If system software is stored on non-volatile memory such as integrated circuits, it is usually termed firmware while an application software is a subclass of computer usually termed firmware while an application software is a subclass of computer software that employs the capabilities of a computer directly and thoroughly to a software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform. This should be contrasted with system software task that the user wishes to perform. This should be contrasted with system software which is involved in integrating a computer's various capabilities, but typically does which is involved in integrating a computer's various capabilities, but typically does not directly apply them in the performance of tasks that benefit the user. not directly apply them in the performance of tasks that benefit the user.

Application softwareApplication software

• Typical examples of software applications are word processors, Typical examples of software applications are word processors, spreadsheets, and media players. spreadsheets, and media players.

Multiple applications bundled together as a package are sometimes Multiple applications bundled together as a package are sometimes referred to as an application suite. Microsoft Office and referred to as an application suite. Microsoft Office and OpenOffice.org, which bundle together a word processor, a OpenOffice.org, which bundle together a word processor, a spreadsheet, and several other discrete applications, are typical spreadsheet, and several other discrete applications, are typical examples. The separate applications in a suite usually have a user examples. The separate applications in a suite usually have a user interface that has some commonality making it easier for the user to interface that has some commonality making it easier for the user to learn and use each application. And often they may have some learn and use each application. And often they may have some capability to interact with each other in ways beneficial to the user. capability to interact with each other in ways beneficial to the user. For example, a spreadsheet might be able to be embedded in a word For example, a spreadsheet might be able to be embedded in a word processor document even though it had been created in the separate processor document even though it had been created in the separate spreadsheet application. spreadsheet application.

User-written software tailors systems to meet the user's specific User-written software tailors systems to meet the user's specific needs. User-written software include spreadsheet templates, word needs. User-written software include spreadsheet templates, word processor macros, scientific simulations, graphics and animation processor macros, scientific simulations, graphics and animation scripts. Even email filters are a kind of user software. Users create scripts. Even email filters are a kind of user software. Users create this software themselves and often overlook how important it is. this software themselves and often overlook how important it is.

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• Source of information: InternetSource of information: Internet

• World famous Swami World famous Swami Vivekananda(below)Vivekananda(below)