(1 )SED TECHNOLOGY
INTRODUCTION
The SED technology has been developing since 1987. The flat panel display technology that employs surface conduction electron emitters for every individual display pixel can be referred to as the Surface-conduction Electron-emitter Display (SED). Though the technology differs, the basic theory that the emitted electrons can excite a phosphor coating on the display panel seems to be the bottom line for both the SED display technology and the traditional cathode ray tube (CRT) televisions.
When bombarded by moderate voltages (tens of volts), the electrons tunnel across a thin slit in the surface conduction electron emitter apparatus. Some of these electrons are then scattered at the receiving pole and are accelerated towards the display surface, between the display panel and the surface conduction electron emitter apparatus, by a large voltage gradient (tens of kV) as these electrons pass the electric poles across the thin slit. These emitted electrons can then excite the phosphor coating on the display panel and the image follows.
The main advantage of SED’s compared with LCD’s and CRT’s is that it can provide with a best mix of both the technologies. The SED can combine the slim form factor of LCD’s with the superior contrast ratios, exceptional response time and can give the better picture quality of the CRT’s. The SED’s also provides with more brightness, color performance, viewing angles and also consumes very less power. More over, the SED’s do not require a deflection system for the electron beam, which has in turn helped the manufacturer to create a display design, that is only few inches thick but still light enough to be hung from the wall. All the above properties has consequently helped the manufacturer to enlarge the size of the display panel just by increasing the number of electron emitters relative to the necessary number of pixels required. Canon and Toshiba are the two major companies working on SED’s. The technology is still developing and we can expect further breakthrough on the research.
HISTORY
Canon began SED research in 1986 and, in 2004, Toshiba and Canon announced a joint development agreement originally targeting commercial production of SEDs by the end of 2005. The 2005 target was not met, and several new targets since then have also slipped by. This failure to meet mass-production deadlines goes as far back as 1999, when Canon first told investors of its intentions to immediately begin mass-producing the technology. The lack of tangible progress has worried many investors and has prompted many critics. One critic called SED “the best display technology you’ve ever seen that may be stillborn.”[1] During the 2006 Consumer Electronics Show in Las Vegas, Nevada, Toshiba showed working prototypes of SEDs to attendees and indicated expected
availability in mid-to-late 2006. [2] Toshiba and Canon again delayed their plan to sell the television sets to the fourth quarter of 2007. [3] At the 2007 Consumer Electronics Show, no SED displays were to be found on the show floor. This led many analysts to speculate that the technology would never reach the consumer market. [4]
In October 2006, Toshiba's president announced the company plans to begin full production of 55-inch SED TVs in July 2007 at its recently built SED volume-production facility in Himeji.
In December 2006, Toshiba President and Chief Executive Atsutoshi Nishida said Toshiba is on track to mass-produce SED TV sets in cooperation with Canon by 2008. He said the company plans to start small-output production in the fall of 2007,[6] but they do not expect SED displays to become a commodity and will not release the technology to the consumer market because of its expected high price, reserving it solely for professional broadcasting applications.
(2)Echolink
Designed by Jonathan Taylor, a radio amateur with callsign K1RFD, Echolink, a computer program that runs under Microsoft Windows allows steadfast worldwide connections to be made between radio amateurs using Voice over IP (VoIP) technology on the internet for at least a part of the path between them, greatly enhancing Amateur Radio's communications capabilities. Though its similar to other VOIP tools like Skype it has the additional ability to link to an amateur radio station's transceiver.
Two modes offered to Radio amateurs using Echolink software are:
* Single User Mode - One could use the computer's microphone and speakers to connect to (or through - see below) other Echolink-enabled computers over the internet and talk to the amateur at the other end, if its internet-connected computer.
* Sysop Mode – In this mode VHF or UHF transceiver connect to their internet-connected PC with a specially-designed hardware interface. With this, a radio amateur with their own transceiver can communicate with (or through) any other Echolink-equipped station anywhere in the world within the radio range of the transceivers station.
In case of radio amateurs without the Echolink software or a computer connected to the internet Echolink networks within radio range of a sysop mode Echolink station can be put to use and its also possible to link a sysop mode Echolink station to a local repeater, further adding to the communication possibilities.
(3)WirelessHD
WirelessHD is an effort of the consortium led mainly by LG , Matsushita, NEC, Samsung, SiBEAM, Sony and Toshiba to define a standard for the next generation wireless digital network interface specification for wireless high-definition signal transmission for consumer electronics products and they intend to finalize on one standard by spring 2007. The WirelessHD (WiHD) is designed and optimized for wireless display connectivity thereby achieving high-speed rates from 2 Gbit/s to 5 Gbit/s for the CE, PC, and portable device segments in its first generation implementation. This standard aids in uncompressed, digital transmission of HD video and audio signals, making it like wireless HDMI, in theory. data rates as high as 20 Gbit/s (compared to 10.2-Gbit/s for HDMI 1.3)are possible with its core technology, permitting it to scale to higher resolutions, color depth, and range.
The signal will operate on the 60 GHz frequency band which currently requires line of sight between transmitter and receiver and apparently will sport the bandwidth required to support both current and future HD signals. This is far from the real aim of the WiHD, which would be maintain the elegance of the hang-on-the-wall plasmas and LCDs by tucking away the components and wires in a cabinet. The goal for the first line of products will be in-room, point-to-point , non line-of-sight (NLOS) at up to 10 meters. There much work to be done to improve interoperability among devices, and also to expand the capabilities of personal video players, PDAs, and other handheld devices.
(4)iburst
First manufactured by ArrayComm and later on adopted as the High Capacity – Spatial Division Multiple Access (HC -SDMA) radio interface standard (ATIS-0700004-2005) by the Alliance of Telecommunications Industry Solutions (ATIS, this wireless broadband technology favours the utilization of its bandwidth with the help of smart antennas. This mobile broadband wireless access system also called the HC-SDMA or High Capacity Spatial Division Multiple Access, has the HC-SDMA interface that offer wide-area broadband wireless data-connectivity for fixed, portable and mobile computing devices and appliances. Designed and implemented with smart antenna array techniques to substantially improve the radio frequency (RF) coverage, capacity and performance for the system, the protocol has the following features -:
it describes base station and client device RF characteristics, including output power levels, transmit frequencies and timing error, pulse shaping, in-band and out-of band spurious emissions, receiver sensitivity and selectivity
it classifies the associated frame structures for the various burst types including standard uplink and downlink traffic, paging and broadcast burst types
it clearly states the modulation, forward error correction, interleaving and scrambling for various burst types
it describes the various logical channels (broadcast, paging, random access, configuration and traffic channels) and their roles in establishing communication over the radio link
it states the procedures for error recovery and retry. The protocol supports well the Layer 3 (L3) mechanisms such as the creation and controlling of logical connections (sessions) between client device and base that includes the registration, stream start, power control, handover, link adaptation, stream closure, client device authentication and secure transmission on the data links. Currently having a connectivity speed of 1 Mbit/s, the speed can be increased to 5 Mbit/s in future with the use of HC-SDMA protocol.
The currently available commercially access options are
• iBurst Desktop modem with USB and Ethernet ports (with external power supply)
• iBurst Portable USB modem (using USB power supply.
(5) STUN
This is a network protocol which enables a client in a NAT (or multiple NATs) to find out its public address, the type of NAT behind it and the internet side port associated by the NAT with a particular local port and this whole process aids to set up UDP communication between two hosts that are both behind NAT routers. STUN stands for Simple Traversal of UDP (User Datagram Protocol) through NATs (Network Address Translators).
Protocol overview
STUN is a client-server protocol. Any VoIP phone or software package includes a STUN client, which sends a request to the STUN server. As a reply the public IP address of the NAT router and the port was opened by the NAT to allow incoming traffic back in to the network is sent to the STUN client. Such a response also helps the STUN client to identify the NAT being used as different types of NATs handle incoming UDP packets vividly. Its compatible with Full Cone, Restricted Cone, and Port Restricted Cone. (Restricted Cone or Port Restricted Cone NATs, allows packets from the endpoint through to the client from the NAT once the client has send a packet to the endpoint). Symmetric NAT (also known as bi-directional NAT) which is frequently found in the networks of large companies does not work with STUN as the IP addresses of the STUN server and the endpoint is different, and therefore the NAT mapping the STUN server is different from the mapping that the endpoint uses to send packets through to the client. Network address translation could give you more information on this.
After the client discovers its external addresses communication with its peers occurs. When the NATs are full cone,either side can initiate communication and if they are restricted cone or restricted port cone both sides must start transmitting together. The techniques described in the STUN RFC does not necessarily require using the STUN protocol; they can be used in the design of any UDP protocol. STUN comes in handy in the cases of Protocols like SIP which use UDP packets for the transfer of sound/video/text signaling traffic across the Internet. As both endpoints are often behind NAT, a connection cannot be set up in the traditional way. The STUN server communicates on UDP port 3478 but the server will hint clients to perform tests on alternate IP and port number too (STUN servers have two IP addresses).
(6) Electronic Program(me) Guide (EPG)
Also known as Interactive Program(me) Guide (IPG) or Electronic Service Guide (ESG), EPG is an on-screen guide to scheduled broadcast television programs, permitting a viewer to browse, select, and discover contents based on time, title, channel, genre, etc, using their remote control, a keyboard or a phone keypad. This technology is predominant in the digital television and radio world however EPGs exist that rely upon analogue technology (using the VBI—or vertical blanking interval). EPG broadcasts data to an application residing within middleware in a set-top box which connects to the television set and enables the application to be displayed. The signals may arrive via cable TV, satellite TV, cable radio, satellite radio, or via over-the-air terrestrial broadcast stations. If the users want to see more information about the current program and future programs they have to just navigate through an EPG on a receiving device and in the same way a viewer can plan his or her viewing and also record broadcast programs to a hard disk for later viewing when EPGs are connected to PVRs, or personal video recorders.
(7) Standard-definition television
Television systems that have a resolution that meets standards but not considered high definition, this is what Standard-definition television or SDTV refers to. This usually refers to digital television, especially while broadcasting at the same (or similar) resolution as analog systems. In ATSC, SDTV can be broadcast in 704 pixels × 480 lines with 16:9 aspect ratio (40:33 rectangular pixel), 704 pixels × 480 lines with 4:3 aspect ratio (10:11 rectangular pixel) or 640 pixels × 480 lines with 4:3 ratio (and square pixels). The refresh rate can be 24, 30 or 60 pictures per second. Digital SDTV in 4:3 aspect ratio has the same form as the regular analogue TV (NTSC, PAL, PAL2, SECAM) excluding the ghosting, snowy images and static noises but however with poor reception one may encounter various other artifacts such as blockiness and stuttering. Though ATSC and ISDB were originally developed for HDTV, they later proved their ability to deliver multiple SD video and audio streams via multiplexing, than to use the entire bit stream for one HD channel. Eventually ATSC, ISDB along with ISDB were the standards used to broadcast digital SDTV.
(8) Holographic Versatile Disc (HVD)
It is an optical disc technology in the infant state of research, that utilizes the revolutionary collinear holography technique that has one red laser and one blue-green laser collimated into a single beam. The data that is programmed as laser interference fringes from a holographic layer at the top of the disc is read by the blue-green laser where as the servo information from the common CD style aluminum layer near the bottom is read by the red laser, which is used as the reference beam. This disc capable of storing 3.9 terabytes of data also has a dichroic mirror layer between the holographic data and servo data, that can reflect the blue-green laser while allowing the red laser to pass through. This feature has enhanced the performance of this storage media compared to the past holographic storage media where there was lot of interferences due to both the laser passing through also lacked in its compatibility to the current CD and DVD technology. The HVD disc technology has the capacity to store about 6,000 times of a CD-ROM, 830 times of a DVD, 160 times of a single layer blue-ray disc and 8 times of a normal hard drives as of 2006. It also has a transferable rate of 1 Gigabit/s.
(9) Holographic Associative Memory
Holographic associative memory can be considered as a type of artifical neural network, which is having close association with the family of analog, correlation-based, stimulus-responsive memories. In Holographic associative memory, the information is mapped on to the phase orientation of complex numbers operating. The ability of holographs in carrying out effective associative memory tasks, generalization and pattern recognition with changeable attention has given holographic memory the cutting edge over others. Natural memory has the capacity for dynamic search localization. As an example if we take the human visual perception, we the humans always have the tendency to focus on specific objects in pattern, that too we can do it with changing the focus from object to object. The computational model also does the same as the human does it, where the heart of this memory has a novel bi-model representation of pattern and a hologram like complex spherical weight state space. The advantage of this model is unlimited compared to its fast optical realization and underlying hyper-spherical computations.
(10) Laserfilm
Developed by McDonnell-Douglas in 1984, the laser filmisa transmissive laser based playbackmedium. Working on the topology that laser has to shine through one side of the disc to a receiving sensor on the other side, where the beam of the laser would be interrupted by a spiral of small dots on the disc,which can then modulate the laser beam to represent the video and audio information, which was then interpreted by the receiving sensor receiving the beam on the other side Made of the ordinary photographic film, similar to the Selectavision CED videodisc system, this wasn’t successfully marketed by McDonnell-Douglas, thesole manufacturer of the laser film player. Having originated from ARDEV, which was originally a subsidiary of Atlantic Richfield until 1981, this format is usually employed in flight stimulators.
(11) Ultracapacitors
Electrical energy storage is required in many applications — telecommunication devices,such as cell phones and pagers, stand-by power systems, and electric hybrid vehicles. The specifications for the various energy storage devices are given in terms of energy stored (Who) .and maximum power as well as size and weight, initial cost and life. A storage device to be suitable for a particular application must meet all the requirements. As power requirements for many applications become more demanding, the battery was found wanting. It is often reasonable to consider separating the energy and power requirements by providing for the peak power by using a pulse power device battery. For applications in which significant energy is needed in pulse form, traditional capacitors as used in electronic circuits cannot store enough energy in the volume and weight available. For these applications, the development of high energy density capacitors gained importance and which eventually lead to the development of Ultracapacitors. Ultracapacitors are basically capacitors having capacitance in the order of kilofarads and can store much larger energy as compared to ordinary capacitors, but lesser than batteries.
(12) Grating Light Valve (GLV) Technology
Display devices form an important group of devices in the electro industry. With the evolution of high definition TV (HDTV), video conferencing and other advancements in video applications, their importance is increasing. Traditionally cathode ray tubes (CRTs) are used in display devices. But the industry is searching for devices with high resolution and fill ratios that cannot be achieved in CRTs. LCDs can be use an alternative but they are not cost effective. An entirely new type of devices based on Grating Light Valve technology solves all the problems concerning resolution, fill ratio, cost, size and consumption. In addition to this GLV devices can provide digital gray scale and color reproduction. The GLV technology is based on micro electromechanical system (ME technology and can be manufactured using mainstream IC fabrication technology. providing controlled diffraction of incident light, a GLV device will produce bright dark (or even coloured) pixels in a display system. The seminar should cover, 1. Fundamental concepts 2. Architecture of GLV 3. Controlling the GLV device 4. Applying the GLV technology 5. Comparing the GLV technology
(13) FACE RECOGNITION USING ARTIFICIAL NEURAL NETWORKS
Artificial Neural Networks commonly referred to as ‘Neural Networks’ is a new branch of AI, that enabled a crude simulation of the structure of human brain electronically or in software. The inherent properties of human brain enable it to analyze complex patterns consisting of a number of elements, those individually reveal little of the total pattern, yet collectively represent easily recognizable objects. The concepts of Neural Networks have been motivated right from its inception, by the recognition that the human brain computes in an entirely different way from the conventional digital computers. The brain modeling techniques opens a new era of Computer System that learns, from experience and uses its experiential knowledge next time. This biologically inspired method is being touted as the wave of the future in computing, relieving the programmer from the cubicle of traditional algorithmic problem solving. Inherent non-linearity property of Neural Networks makes it particularly suitable in many signal-processing applications like sound, image processing etc.
(14) Flip chip Technology
In the development of packaging of electronics the aim is to lower cost, increase the packaging density, and improve the performance while still maintaining or even improving the reliability of the circuits. Flip chip microelectronic assembly is the direct electrical connection of face-down electronic components onto substrates, circuit boards, or carriers, by means of conductive bumps on the chip bond pads. Flip chip is also called Direct Chip Attach (DCA), since the chip is directly attached to the substrate, board, or carrier by the conductive bumps. Flip chip has advantage in size, performance, flexibility, reliability, and cost over other packaging methods. There are three stages in making flip chip assemblies: bumping the die or wafer, attaching the bumped die to the board or substrate, and, in most cases, filling the remaining space under the die with an electrically non-conductive material. Several varieties of flip chip assembly are solder bump, plated bump, gold stud bump, and adhesive bump suit flip chip which are used in a wide range of applications. Applications of flip chip include low to high-end workstations, routers, switches, components in graphics, DSP processors and ASIC devices.
(15) E-paper
Electronic paper (E-paper) is a portable, reusable storage and display medium that looks like paper but can be repeatedly written on (refreshed) by electronic means , thousands or millions of times. E-paper will be used for applications such as e-books, electronic newspapers, portable signs, and foldable, rollable displays. Information to be displayed is downloaded through a connection to a computer or a cell phone, or created with mechanical tools such as an electronic "pencil”. The Electronic Paper Display is reflective and can be easily read in bright sunlight or dimly lit environments while being able to be seen at virtually any angle - just like paper. Its black and white ink-on-paper look gives an appearance similar to that of the most widely read material on the planet newspaper. The unique technology results in a compact and lightweight form factor allowing it to be ideal for highly portable applications. This seminar aims to throw light on the different technological approaches working toward the complete realization of the E-paper concept.
(16) Digital Transmission Content Protection
The Digital Transmission Content Protection (DTCP) defines a cryptographic protocol for protecting audio /video entertainment content from illegal copying, intercepting and tampering as it traverses high performance digital buses, such as the IEEE 1394 standard. DTCP ensures that the copy protection mechanism is built into Digital Audio/Video devices themselves (in addition to Traditional Encryption). This seminar will outline the basic principles of cryptography; and tells us about the cryptographic functions used in it. It will briefly look at the IEEE1394 standard where it is being implemented. This seminar will nevertheless discuss DTCP including different layers of copy protection and some implementation aspects. This seminar also provides a case study of typical use of content protection in Digital TV and Digital VCR implementation. A product solution could include hardware and software implementation for the Digital Transmission Content Protection mechanism.
(17) Ditgital Steganography
Steganography is the art and science of hiding information in ways that prevent its detection. Though steganography is an ancient craft, the onset of computer technology has given it new life. Computer-based steganographic techniques introduce changes to digital covers to embed information foreign to the native covers.Digital steganography involves the hiding of data inside a sound or image file.Steganography works by replacing bits of useless or unused data in regular computer files such as graphics, sound, text, HTML, or even floppy disks with bits of different, invisible information. Steganography strips less important information from digital content and injects hidden data in its place. This is done over the spectrum of the entire image. Computer-based steganographic techniques introduce changes to digital covers to embed information foreign to the native covers. This hidden information can be plain text, cipher text or even images. The hidden information may be communicated in the form of text, binary files, or cipher text. The carrier file can be any graphic or audio files which are at least 8 times the message file. This seminar mainly deals with transform domain embedding techniques and spread spectrum image steganography techniques for digital steganography. The art of detecting, decoding, and altering messages hidden using steganography is called steganalysis.Steganalysis is aimed at detecting and extracting an embedded message from a stego-medium.It is also used for destroy or render unrecoverable that embedded message.
(18) Digital Micro mirror Device (DMD)
For the past six years, Digital Light Processing technology from Texas Instruments has made significant inroads in the projection display market. With products enabling the world’s smallest data and video projectors, HDTV’s, and digital cinema, DLP technology is extremely powerful and flexible. With success of the DMD as a spatial light modulator for projector applications, dozens of new applications are now being enabled by general- use DMD products that are recently available to developers. The same light switching speed and “on-off” (contrast) ratio that have resulted in superior projector performance, along with the capability of operation outside the visible spectrum, make the DMD very attractive for many applications, including volumetric display, holographic data storage, lithography, scientific instrumentation, and medical imaging. Texas Instruments DLP display technology digitally manipulates (or processes) light to produce film-like, all-digital images. DLP integrates a projection lamp and an electronic video signal from a source such as a VCR or computer, and the processed light produces an all-digital picture. The key to this complete digital process is the Texas Instruments Digital Micro mirror Device (DMD), a thumbnail-size semiconductor light switch. The DMD consists of an array of thousands of micro-scopic size mirrors, each mounted on a hinge structure so that it can be individually tilted back and forth. When a lamp and a projection lens are positioned in the right places in the system, DLP processes the input video signal and tilts the mirrors to generate a digital image.
(19) Digit Recognition using Neural Network
Handwritten digit recognition is the process of recognizing and classifying handwritten digits without human interaction. Its application field is very wide, for example Postal code recognition (Automatic sorting of mail by destination ZIP code), Digitizing hand written spreadsheets, tax forms etc. Patterns slightly shifted, distorted and even overwritten can be correctly recognized. Neural network aids in efficient recognition. A Multilayer Neural network trained with “Backpropagation “algorithm is used. Kirsch masks are adopted for extracting feature vectors and a multi layer clustered neural network is used for classifying numerals efficiently. The neural network will be trained with a database consisting of handwritten digits provided by writers of various ages with many different sizes and writing styles. Numerals poorly drawn or cannot be classified are rejected. A very high recognition rate, even above 90% could be obtained while using neural network.
(20) Dual-Core Processors
Computer performance has been driven largely by decreasing the size of the chips while increasing the number of transistors they contain. In accordance with Moore’s law, this has caused chip speed to rise and prices to drop. However transistors can’t shrink forever. As components grow thinner, chip manufactures have struggled to cap power usage and heat generation. Even performances enhancing approaching like running multiple instructions per thread have bottomed out. In response manufactures are building chips with multiple cooler running, more energy-efficient processing cores instead of one increasingly powerful core. Multi-core processors don’t necessarily run as the fastest single core processor, but they improve the overall performance by handling more work in parallel. Dual-core processors represent a major evolution in computing technology. This important development is coming at a time when businesses and consumers are beginning to require the benefits offered by these processors due to exponential growth in digital data.
(21) Cellular Geolocation
Locating The Mobile user has become one of the growing demands of the mobile industry. In USA a law has been passed known as E-911(Enhanced 911) which states that the network provider should provide the location information of the mobile user to the operator of emergency call 911 if he gets a call. Besides there are other advantages to the user like he can know and demand services that are available at his current location by using cellular geo-location technique. Various technologies has been developed in this field. Some of the methods are those based on Signal Strength, Angle Of Arrival Of the signal, Time Of Arrival and Assisted GPS.The choice of any method depends on the level of accuracy needed and cost of implementation and use. The seminar includes an overview of the different location methods their advantages and disadvantages, and the error possibilities associated with them.
(22) Intel Express Chipsets
It’s quite natural that new technologies are emerging from time to time. The technology leader should not be backward in this process. Intel has been showing its leadership by developing new and new technologies like processors. This time Intel shows its power by the development of a new chipset series. Chipsets are not always cared by everyone. All focus on the Processors. But a processor without a good chipset to support its capabilities is not of full use. Here Intel makes a breakthrough by the development of new 9XX series chipsets. This seminar talks on the new chipsets of Intel, the 9XX series. The seminar discuss the breakthrough capabilities of the new Chipsets, The PCI Express Bus, The Graphics Media Accelerator 900, The Matrix storage technology, Intel High Definition Audio etc with a focus on the PCI Express Bus. It is because of the fact that there is no merit gained by using a very fast processor and fast memories or graphic cards with a slow interconnect between them. There PCI Express Bus comes into play. PCI Express will serve as a general purpose I/O interconnect for a wide variety of future computing and communications platforms. Key PCI attributes, such as its usage model and software interfaces are maintained whereas its bandwidth-limiting, parallel bus implementation is replaced by a long-life, fully-serial interface. A split-transaction protocol is implemented with attributed packets that are prioritized and optimally delivered to their target. The GMA 900 is the successor of Intel Extreme Graphics 2. RAID 0/1 technologies included in matrix storage method improves the storage.
(23) WirelessUSB
Abbreviated as "WUSB" this short-range, high-bandwidth wireless radio communication combines the speed and ease-of-use of USB 2.0 with the expediency of wireless technology and is based on the WiMedia Alliance's Ultra-WideBand (UWB) common radio platform, which is capable of sending 480 Mbit/s at distances up to 3 meters and 110 Mbit/s at up to 10 meters. However USB Implementers Forum discourages the practice of calling it WUSB and prefers to call the technology "Certified Wireless USB" to differentiate it from competitors (see below, "Competitors"). Though local regulatory policies may restrict the legal operating range for any given country, Wireless USB was designed to operate in the frequency range of 3.1 to 10.6 GHz.
Uses
WUSB are used in devices that are now connected via regular USB cables, such as game controllers, printers, scanners, digital cameras , MP3 players, hard disks and flash drives , and it is also suitable for transferring parallel video streams.
(24) BLUE EYES TECHNOLOGY
Blue Eyes technology aims at creating computational Machines with perceptual and sensory abilities like those of human beigns. Blue Eyes system is thus a versatile system which can be modified to cater to the working environment. The Blue Eyes system has hardware with software loaded on it Blue Eyes systemcan be applied in every working environment requiring permanent operator''s attention for it. The hardware comprises of data acquisition unit and central system unit. The heart of Data acquisition unit is ATMEL 89C52 microcontroller Bluetooth technology is used for communication and coordination between the two units.Blue eye system can be applied in every working environment which requires pemanent operator''s attention. Blue eyes sytem provides technical means for monitoring and recording human operator''s physiological condition. A blue eyes is a project aiming to be a means of stress reliever driven by the advanced, technology of syudying the facial expressions for judgment of intensity of stress handled. In totality blue eyes aims at adding perceptual abilities which would end up in a healthy stress free environment and can be applied in every working environment requiring permanent operator''s attention.
Blue Eyes from IBM
According to IBM’s web page:
“Blue Eyes uses non-obtrusive sensing technology, such as video cameras and microphones, to identify and observe a user’s actions, and to extract key information, such as where the user is looking and what the user is saying verbally and gesturely. These cues are analyzed to determine the user’s physical, emotional, or informational state.”
(25) On-chip micro-biosensor for the detection of human CD4+ cells based on AC impedance and optical analysis
The current study was undertaken to fabricate a small micro-electrode on-chip to rapidly detect and quantify human CD4+ cells in a minimal volume of blood through impedance measurements made with simple electronics that could be battery operated implemented in a hand held device. The micro-electrode surface was non-covalently modified sequentially by incubation with solutions of protein G', human albumin, monoclonal mouse anti-human CD4, and mouse IgG. The anti-human CD4 antibody served as the recognition and capture molecule for CD4+ cells present in human blood. The binding of these biomolecules to the micro-electrodes was verified by impedance and cyclic voltammetry measurements. An increase in impedance was detected for each layer of protein adsorbed onto the micro-electrode surface. This process was shown to be highly repeatable. Increased impedance was measured when CD4+ cells were captured on the micro-electrode, and the impedance also increased as the number of captured cells increased. Fluorescence microscopy of captured cells immunolabeled with anti-human CD4, CD8, and CD19 antibodies, and the nuclear label DAPI, confirmed that only CD4+ cells were captured. The results were highly dependent on the specimen preparation method used. We conclude that the on-chip capture system can efficiently quantify the number of CD4+ cells.
(26) Spintronics
Spintronics (a neologism meaning "spin transport electronics"[1][2]), also known as magnetoelectronics, is an emerging technology which exploits the intrinsic spin of electrons and its associated magnetic moment, in addition to its fundamental electronic charge, in solid-state devices.
Contents
1 History
2 Theory
3 Metals-based spintronic devices
3.1 Applications
4 Semiconductor-based spintronic devices
4.1 Applications
5 See also
6 References
7 Further reading
8 External links
History
The research field of Spintronics emerged from experiments on spin-dependent electron transport phenomena in solid-state devices done in the 1980s, including the observation of spin-polarized electron injection from a ferromagnetic metal to a normal metal by Johnson and Silsbee (1985),[3] and the discovery of giant magnetoresistance independently by Albert Fert et al.[4] and Peter Grünberg et al. (1988).[5] The origins can be traced back further to the ferromagnet/superconductor tunneling experiments pioneered by Meservey and Tedrow,[6] and initial experiments on magnetic tunnel junctions by Julliere in the 1970s.[7] The use of semiconductors for spintronics can be traced back at least as far as the theoretical proposal of a spin field-effect-transistor by Datta and Das in 1990.[8]
Theory
Electrons are spin-1/2 fermions and therefore constitute a two-state system with spin "up" and spin "down". To make a spintronic device, the primary requirements are to have a system that can generate a current of spin polarized electrons comprising more of one spin species -- up or down -- than the other (called a spin injector), and a separate system that is sensitive to the spin polarization of the electrons (spin detector). Manipulation of the electron spin during transport between injector and detector (especially in semiconductors) via spin precession can be accomplished using real external magnetic fields or effective fields caused by spin-orbit interaction.
Spin polarization in non-magnetic materials can be achieved either through the Zeeman effect in large magnetic fields and low temperatures, or by non-equilibrium methods. In the latter case, the non-equilibrium polarization will decay over a timescale called the "spin lifetime". Spin lifetimes of conduction electrons in metals are relatively short (typically less than 1 nanosecond) but in semiconductors the lifetimes can be very long (microseconds at low temperatures), especially when the electrons are isolated in local trapping potentials (for instance, at impurities, where lifetimes can be milliseconds).
Metals-based spintronic devices
The simplest method of generating a spin-polarised current in a metal is to pass the current through a ferromagnetic material. The most common application of this effect is a giant magnetoresistance (GMR) device. A typical GMR device consists of at least two layers of ferromagnetic materials separated by a spacer layer. When the two magnetization vectors of the ferromagnetic layers are aligned, the electrical resistance will be lower (so a higher current flows at constant voltage) than if the ferromagnetic layers are anti-aligned. This constitutes a magnetic field sensor.
Two variants of GMR have been applied in devices: (1) current-in-plane (CIP), where the electric current flows parallel to the layers and (2) current-perpendicular-to-plane (CPP), where the electric current flows in a direction perpendicular to the layers.
Other metals-based spintronics devices:
Tunnel Magnetoresistance (TMR), where CPP transport is achieved by using quantum-mechanical tunneling of electrons through a thin insulator separating ferromagnetic layers.
Spin Torque Transfer, where a current of spin-polarized electrons is used to control the magnetization direction of ferromagnetic electrodes in the device.
Applications
The storage density of hard drives is rapidly increasing along an exponential growth curve, in part because spintronics-enabled devices like GMR and TMR sensors have increased the sensitivity of the read head which measures the magnetic state of small magnetic domains (bits) on the spinning platter. The doubling period for the areal density of information storage is twelve months, much shorter than Moore's Law, which observes that the number of transistors that can cheaply be incorporated in an integrated circuit doubles every two years.
MRAM, or magnetic random access memory, uses arrays of TMR or Spin torque transfer devices. MRAM is nonvolatile (unlike charge-based DRAM in today's computers) so information is stored even when power is turned off, potentially providing instant-on computing. Motorola has developed a 256 kb MRAM based on a single magnetic tunnel junction and a single transistor. This MRAM has a read/write cycle of under 50 nanoseconds. Another design in development, called Racetrack memory, encodes information in the direction of magnetization between domain walls of a ferromagnetic metal wire.
Semiconductor-based spintronic devices
In early efforts, spin-polarized electrons are generated via optical orientation using circularly-polarized photons at the bandgap energy incident on semiconductors with appreciable spin-orbit interaction (like GaAs and ZnSe). Although electrical spin injection can be achieved in metallic systems by simply passing a current through a ferromagnet, the large impedance mismatch between ferromagnetic metals and semiconductors prevented efficient injection across metal-semiconductor interfaces. A solution to this problem is to use ferromagnetic semiconductor sources (like manganese-doped gallium arsenide GaMnAs), increasing the interface resistance with a tunnel barrier, or using hot-electron injection.
Spin detection in semiconductors is another challenge, which has been met with the following techniques:
Faraday/Kerr rotation of transmitted/reflected photons
Circular polarization analysis of electroluminescence
Nonlocal spin valve (adapted from Johnson and Silsbee's work with metals)
Ballistic spin filtering
The latter technique was used to overcome the lack of spin-orbit interaction and materials issues to achieve spin transport in Silicon, the most important semiconductor for electronics.
Because external magnetic fields (and stray fields from magnetic contacts) can cause large Hall effects and magnetoresistance in semiconductors (which mimic spin-valve effects), the only conclusive evidence of spin transport in semiconductors is demonstration of spin precession and dephasing in a magnetic field non-colinear to the injected spin orientation. This is called the Hanle effect.
Applications
Advantages of semiconductor-based spintronics applications are potentially lower power use and a smaller footprint than electrical devices used for information processing.[18] Also, applications such as semiconductor lasers using spin-polarized electrical injection have shown threshold current reduction and controllable circularly polarized coherent light output.[19] Future applications may include a spin-based transistor having advantages over MOSFET devices such as steeper sub-threshold slope.
External links
"Spintronics". Scientific American. June 2002. http://www.sciam.com/article.cfm?articleID=0007A735-759A-1CDD-B4A8809EC588EEDF.
RaceTrack:InformationWeek (April 11, 2008)
IBM (2003)
Wired: update on MRAMs, 2003 Jul
Spintronics research targets GaAs.
Spintronics at Indian Institute of Science, Bangalore, India
Spintronics at SUNY Albany's College of Nanoscale Science and Engineering
Spintronics information community site
IBM to use 'spintronics' to increase computer memory capacity (April 12, 2008)
Semiconductor spintronics lab at University of Maryland
Spintronics Tutorial
Retrieved from http://en.wikipedia.org/wiki/Spintronics
(27) Universal Mobile Telecommunications System
Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) cell phone technologies, which is also being developed into a 4G technology. Currently, the most common form of UMTS uses W-CDMA as the underlying air interface. It is standardized by the 3GPP, and is the European answer to the ITU IMT-2000 requirements for 3G cellular radio systems.
To differentiate UMTS from competing network technologies, UMTS is sometimes marketed as 3GSM, emphasizing the combination of the 3G nature of the technology and the GSM standard which it was designed to succeed.
Contents
1 Preface
2 Features
3 Deployment
4 Technology
5 UMTS 3G handsets and modems
5.1 External modems
6 Interoperability and global roaming
7 Spectrum allocation
8 Other competing standards
9 Problems and issues
10 See also
11 Literature
12 References
13 External links
Preface
This article discusses the technology, business, usage and other aspects encompassing and surrounding UMTS, the 3G successor to GSM which utilizes the W-CDMA air interface and GSM infrastructures. Any issues relating strictly to the W-CDMA interface itself may be better described in the W-CDMA page.
Features
UMTS, using W-CDMA, supports up to 21 Mbit/s data transfer rates in theory[1] (with HSDPA), although at the moment users in deployed networks can expect a transfer rate of up to 384 kbit/s for R99 handsets, and 7.2 Mbit/s for HSDPA handsets in the downlink connection. This is still much greater than the 9.6 kbit/s of a single GSM error-corrected circuit switched data channel or multiple 9.6 kbit/s channels in HSCSD (14.4 kbit/s for CDMAOne), and—in competition to other network technologies such as CDMA2000, PHS or WLAN—offers access to the World Wide Web and other data services on mobile devices.
Precursors to 3G are 2G mobile telephony systems, such as GSM, IS-95, PDC, CDMA PHS and other 2G technologies deployed in different countries. In the case of GSM, there is an evolution path from 2G, to GPRS, also known as 2.5G. GPRS supports a much better data rate (up to a theoretical maximum of 140.8 kbit/s, though typical rates are closer to 56 kbit/s) and is packet switched rather than connection oriented (circuit switched). It is deployed in many places where GSM is used. E-GPRS, or EDGE, is a further evolution of GPRS and is based on more modern coding schemes. With EDGE the actual packet data rates can reach around 180 kbit/s (effective). EDGE systems are often referred as "2.75G Systems".
Since 2006, UMTS networks in many countries have been or are in the process of being upgraded with High Speed Downlink Packet Access (HSDPA), sometimes known as 3.5G. Currently, HSDPA enables downlink transfer speeds of up to 21 Mbit/s. Work is also progressing on improving the uplink transfer speed with the High-Speed Uplink Packet Access (HSUPA). Longer term, the 3GPP Long Term Evolution project plans to move UMTS to 4G speeds of 100 Mbit/s down and 50 Mbit/s up, using a next generation air interface technology based upon Orthogonal frequency-division multiplexing.
The first national consumer UMTS networks launched in 2002 with a heavy emphasis on telco-provided mobile applications such as mobile TV and video calling. The high data speeds of UMTS are now most often utilised for Internet access: experience in Japan and elsewhere has shown that user demand for video calls is not high, and telco-provided audio/video content has declined in popularity in favour of high-speed access to the World Wide Web - either directly on a handset or connected to a computer via Wi-Fi, Bluetooth, Infrared or USB.
Technology
UMTS combines the W-CDMA, TD-CDMA, or TD-SCDMA air interfaces, GSM's Mobile Application Part (MAP) core, and the GSM family of speech codecs. In the most popular cellular mobile telephone variant of UMTS, W-CDMA is currently used. Note that other wireless standards use W-CDMA as their air interface, including FOMA.
UMTS over W-CDMA uses a pair of 5 MHz channels. In contrast, the competing CDMA2000 system uses one or more arbitrary 1.25 MHz channels for each direction of communication. UMTS and other W-CDMA systems are widely criticized for their large spectrum usage, which has delayed deployment in countries that acted relatively slowly in allocating new frequencies specifically for 3G services (such as the United States).
The specific frequency bands originally defined by the UMTS standard are 1885–2025 MHz for the mobile-to-base (uplink) and 2110–2200 MHz for the base-to-mobile (downlink). In the US, 1710–1755 MHz and 2110–2155 MHz will be used instead, as the 1900 MHz band was already utilized.[2] While UMTS2100 is the most widely-deployed UMTS band, some countries' UMTS operators use the 850 MHz and/or 1900 MHz bands (independently, meaning uplink and downlink are within the same band), notably in the US by AT&T Mobility, and in Australia by Telstra on the Next G network.
For existing GSM operators, it is a simple but costly migration path to UMTS: much of the infrastructure is shared with GSM, but the cost of obtaining new spectrum licenses and overlaying UMTS at existing towers is high.
UMTS is an alternative Radio Access Network (RAN) to GERAN (which is the 2G GSM air interface including GSM/EDGE). UMTS and GERAN can share a Core Network (CN), allowing (mostly) transparent switching between the RANs according to available coverage and service needs. The CN can be connected to various backbone networks like the Internet, ISDN. UMTS (and GERAN) include the three lowest layers of OSI model. The network layer (OSI 3) includes the Radio Resource Management protocol (RRM) that manages the bearer channels between the mobile terminals and the fixed network, including the handovers.
UMTS 3G handsets and modems
All of the major 2G phone manufacturers (that are still in business) are now manufacturers of 3G phones. The early 3G handsets and modems were specific to the frequencies required in their country, which meant they could only roam to other countries on the same 3G frequency (though they can fall back to the older GSM standard). Canada and USA have a common share of frequencies, as do most European countries. The article UMTS frequency bands is an overview of UMTS network frequencies around the world.
There are almost no 3G phones or modems available supporting all 3G frequencies (UMTS850/900/1700/1900/2100MHz). However, many phones are offering more than one band which still enables extensive roaming. For example, a tri-band chipset operating on 850/1900/2100MHz, such as that found in Apple's iPhone, allows usage in the majority of countries where UMTS is deployed.
External modems
Using a cellular router, PCMCIA or USB card, customers are able to access 3G broadband services, regardless of their choice of computer (such as a tablet PC or a PDA). Some software installs itself from the modem, so that in some cases absolutely no knowledge of technology is required to get online in moments.
Using a phone that supports 3G and Bluetooth 2.0, multiple Bluetooth-capable laptops can be connected to the Internet. The phone acts as gateway and router, but via Bluetooth rather than wireless networking (802.11) or a USB connection.
Interoperability and global roaming
UMTS phones (and data cards) are highly portable—they have been designed to roam easily onto other UMTS networks (assuming your provider has a roaming agreement). In addition, almost all UMTS phones (except in Japan) are UMTS/GSM dual-mode devices, so if a UMTS phone travels outside of UMTS coverage during a call the call may be transparently handed off to available GSM coverage. Roaming charges are usually significantly higher than regular usage charges.
Most UMTS licensees consider ubiquitous, transparent global roaming an important issue. To enable a high degree of interoperability, UMTS phones usually support several different frequencies in addition to their GSM fallback. Different countries support different UMTS frequency bands – Europe initially used 2100MHz while the most carriers in the USA use 850Mhz and 1900Mhz. T-mobile has plans to launch their upcoming network at 1700Mhz. A UMTS phone and network must support a common frequency to work together. Because of the frequencies used, early models of UMTS phones designated for the United States will likely not be operable elsewhere and vice versa. There are now 11 different frequency combinations used around the world—including frequencies formerly used solely for 2G services.
UMTS phones can use a Universal Subscriber Identity Module, USIM (based on GSM's SIM) and also work (including UMTS services) with GSM SIM cards. This is a global standard of identification, and enables a network to identify and authenticate the phone user (actually only the (U)SIM, not the user is authenticated). Roaming agreements between networks allow for calls to a customer to be redirected to them while roaming and determine the services (and prices) available to the user. In addition to user subscriber information and authentication information, the (U)SIM provides storage space for phone book contact. Handsets can store their data on their own memory or on the (U)SIM card (which is usually more limited in its phone book contact information). A (U)SIM can be moved to another UMTS or GSM phone, and the phone will take on the user details of the (U)SIM, meaning it is the (U)SIM (not the phone) which determines the phone number of the phone and the billing for calls made from the phone.
Japan was the first country to adopt 3G technologies, and since they had not used GSM previously they had no need to build GSM compatibility into their handsets and their 3G handsets were smaller than those available elsewhere. In 2002, NTT DoCoMo's FOMA 3G network was the first commercial W-CDMA network—it was initially incompatible with the UMTS standard at the radio level but used standard USIM cards, meaning USIM card based roaming was possible (transferring the USIM card into a UMTS or GSM phone when travelling). Both NTT and SoftBank Mobile (which launched 3G in December 2002) now use the standard UMTS, and their PDC 2G networks run in parallel.
Spectrum allocation
Main article: UMTS frequency bands
Over 130 licenses have already been awarded to operators worldwide (as of December 2004), specifying W-CDMA radio access technology that builds on GSM. In Europe, the license process occurred at the tail end of the technology bubble, and the auction mechanisms for allocation set up in some countries resulted in some extremely high prices being paid for the original 2100 MHz licenses, notably in the UK and Germany. In Germany, bidders paid a total €50.8 billion for six licenses, two of which were subsequently abandoned and written off by their purchasers (Mobilcom and the Sonera/Telefonica consortium). It has been suggested that these huge license fees have the character of a very large tax paid on future income expected many years down the road. In any event, the high prices paid put some European telecom operators close to bankruptcy (most notably KPN). Over the last few years some operators have written off some or all of the license costs. More recently, a carrier in Finland has begun using 900 MHz UMTS in a shared arrangement with its surrounding 2G GSM base stations, a trend that is expected to expand over Europe in the next 1–3 years.
The 2100 MHz UMTS spectrum allocated in Europe is already used in North America. The 1900 MHz range is used for 2G (PCS) services, and 2100 MHz range is used for satellite communications. Regulators have, however, freed up some of the 2100 MHz range for 3G services, together with the 1700 MHz for the uplink. UMTS operators in North America who want to implement a European style 2100/1900 MHz system will have to share spectrum with existing 2G services in the 1900 MHz band.
AT&T Wireless launched UMTS services in the United States by the end of 2004 strictly using the existing 1900 MHz spectrum allocated for 2G PCS services. Cingular acquired AT&T Wireless in 2004 and has since then launched UMTS in select US cities. Cingular renamed itself AT&T and is rolling out some cities with a UMTS network at 850 MHz to enhance its existing UMTS network at 1900 MHz and now offers subscribers a number of UMTS 850/1900 phones.
T-Mobile's rollout of UMTS in the US will focus on the 2100/1700 MHz bands, whereas UMTS coverage in Canada is being provided on the 850 MHz band of the Rogers Wirless network. In 2008, Australian telco Telstra replaced its existing CDMA network with a national 3G network, branded as NextG, operating in the 850 MHz band. Telstra currently provides UMTS service on this network, and also on the 2100 MHz UMTS network, through a co-ownership of the owning and administrating company 3GIS. This company is also co-owned by Hutchison 3G Australia, and this is the primary network used by their customers. Optus is currently rolling out a 3G network operating on the 2100 MHz band in cities and most large towns, and the 900 MHz band in regional areas. Vodafone is also building a 3G network using the 900 MHz band. The 850 MHz and 900 MHz bands provide greater coverage compared to equivalent 1700/1900/2100 MHz networks, and are best suited to regional areas where greater distances separate subscriber and base station.
Carriers in South America are now also rolling out 850 MHz networks.
Other competing standards
There are other competing 3G standards, such as CDMA2000 and TD-SCDMA, though UMTS can use the latter's air interface standard.
On the Internet access side, competing systems include WiMAX and Flash-OFDM. Different variants of UMTS compete with different standards. While this article has largely discussed UMTS-FDD, a form oriented for use in conventional cellular-type spectrum, UMTS-TDD, a system based upon a TD-CDMA air interface, is used to provide UMTS service where the uplink and downlink share the same spectrum, and is very efficient at providing asymmetric access. It provides more direct competition with WiMAX and similar Internet-access oriented systems than conventional UMTS.
Both the CDMA2000 and W-CDMA air interface systems are accepted by ITU as part of the IMT-2000 family of 3G standards, in addition to UMTS-TDD's TD-CDMA, Enhanced Data Rates for GSM Evolution (EDGE) and China's own 3G standard, TD-SCDMA.
CDMA2000's narrower bandwidth requirements make it easier than UMTS to deploy in existing spectrum along with legacy standards. In some, but not all, cases, existing GSM operators only have enough spectrum to implement either UMTS or GSM, not both. For example, in the US D, E, and F PCS spectrum blocks, the amount of spectrum available is 5 MHz in each direction. A standard UMTS system would saturate that spectrum.
In many markets however, the co-existence issue is of little relevance, as legislative hurdles exist to co-deploying two standards in the same licensed slice of spectrum.
Most GSM operators in North America as well as others around the world have accepted EDGE as a temporary 3G solution. AT&T Wireless launched EDGE nationwide in 2003, AT&T launched EDGE in most markets and T-Mobile USA has launched EDGE nationwide as of October 2005. Rogers Wireless launched nation-wide EDGE service in late 2003 for the Canadian market. Bite Lietuva (Lithuania) was one of the first operators in Europe to launch EDGE in December 2003. TIM (Italy) launched EDGE in 2004. The benefit of EDGE is that it leverages existing GSM spectrums and is compatible with existing GSM handsets. It is also much easier, quicker, and considerably cheaper for wireless carriers to "bolt-on" EDGE functionality by upgrading their existing GSM transmission hardware to support EDGE than having to install almost all brand-new equipment to deliver UMTS. EDGE provides a short-term upgrade path for GSM operators and directly competes with CDMA2000.
[edit] Problems and issues
Some countries, including the United States and Japan, have allocated spectrum differently from the ITU recommendations, so that the standard bands most commonly used for UMTS (UMTS-2100) have not been available. In those countries, alternative bands are used, preventing the interoperability of existing UMTS-2100 equipment, and requiring the design and manufacture of different equipment for the use in these markets. As is the case with GSM900 today, standard UMTS 2100 MHz equipment will not work in those markets. However, it appears as though UMTS is not suffering as much from handset band compatibility issues as GSM did, as many UMTS handsets are multi-band in both UMTS and GSM modes. Quad-band GSM (850, 900, 1800, and 1900 MHz bands) and tri-band UMTS (850, 1900, and 2100 MHz bands) handsets are becoming more commonplace.
The early days of UMTS saw rollout hitches in many countries. Overweight handsets with poor battery life were first to arrive on a market highly sensitive to weight and form factor. The Motorola A830, a debut handset on Hutchison's 3 network, weighed more than 200 grams and even featured a detachable camera to reduce handset weight. Another significant issue involved call reliability, related to problems with handover from UMTS to GSM. Customers found their connections being dropped as handovers were possible only in one direction (UMTS ? GSM), with the handset only changing back to UMTS after hanging up. In most networks around the world this is no longer an issue.
Compared to GSM, UMTS networks initially required a higher base station density. For fully-fledged UMTS incorporating video on demand features, one base station needed to be set up every 1–1.5 km (0.62–0.93 mi). This was the case when only the 2100 MHz band was being used, however with the growing use of lower-frequency bands (such as 850 and 900 MHz) this is no longer so. This has led to increasing rollout of the lower-band networks by operators since 2006.
Even with current technologies and low-band UMTS, telephony and data over UMTS is still more power intensive than on comparable GSM networks. Apple, Inc. cited[3] UMTS power consumption as the reason that the first generation iPhone only supported EDGE. Their release of the iPhone 3G quotes talk time on UMTS as half that available when the handset is set to use GSM. As battery and network technology improves, this issue is lessening in severity.
(28) Vacuum Electronics for the 21st Century
Recent trends and future opportunities for modern RF vacuum electronics.
ABSTRACT:
Today's modern RF vacuum electronic device is a far cry from the glass envelop "vacuum tube" of the past, employing robust metal-ceramic construction with light-weight high field rare-earth magnets and low temperature thermionic dispenser cathodes for reliable, long-life operation. Vacuum electronics continue to be the technology of choice for many areas of high-power microwave and millimeter-wave application due to their unparalleled performance in power, power density, frequency, efficiency, and bandwidth; applications of vacuum microwave power devices are numerous and indeed growing.
Over the past decade, dramatic strides have been taken in device performance and capability, primarily as a result of advances device modeling and design, the availability of improved high-power materials and components, and the application of advanced vacuum processing and construction techniques. The most familiar types of microwave tubes were invented during the 1930s and 1940s and may broadly be classified as "slow wave" devices (phase velocity of the electromagnetic circuit wave slower than the speed of light in free space). These device types include helix and coupled cavity traveling wave tubes (TWTs), klystrons, magnetrons, and crossed field amplifiers, all of which have been further developed to provide higher power and wider bandwidth than their predecessors with greater efficiency, and reduced size and weight. A hybrid amplifier architecture, the microwave power module (MPM), combining the best features of solid-state and vacuum electronic technologies, has recently been developed to provide breakthrough transmitter performance, especially in terms of power per unit volume. Finally, at very high frequencies, an entirely new family of powerful "fast-wave" devices has been developed, including gyrotron oscillators, gyro-amplifiers, and free electron lasers (FELs). The gyro-devices have produced megawatt output power with pulse duration greater than one second in the frequency range 100 to 200 GHz. FELs promise to provide high power, continuously tunable, coherent sources over an extensive spectral range from millimeter wavelengths to the ultraviolet.
This presentation will highlight recent trends in today's technology and identify several opportunities for future development.
(29) Virtual Keyboard
A virtual keyboard is a software and/or hardware component that allows a user to enter characters. A virtual keyboard can usually be operated with multiple input devices, which may include an actual keyboard, a computer mouse, a headmouse, and an eyemouse. On a desktop PC, one purpose of a virtual keyboard is to provide an alternative mechanism for disabled users that cannot use a physical keyboard. Another major use for an on-screen keyboard is for bi- or multi-lingual users, who continually need to switch between different character sets and/or alphabets. Although hardware keyboards are available with dual layouts (for example Cyrillic/Latin letters in various national layouts), the on-screen keyboard provides an handy substitute while working at different stations or on laptops, which seldom come with dual layouts. The standard on-screen keyboard utility on most Windows systems allows hot-key switching between layouts from the physical keyboard (typically alt-shift but this is user configurable), simultaneously changing both the hardware and the software keyboard layout. In addition, a symbol in the sys-tray alerts the user to the currently active layout. Although Linux supports this fast manual keyboard-layout switching function, most popular Linux on-screen keyboards such as gtkeyboard, Matchbox-keyboard or Kvkbd do not react correctly. Kvkbd for example defines its visible layout according to the first defined layout in Keyboard Preferences rather than the default layout, causing the application to output incorrect characters if the first layout on the list is not the default. Activating a hot-key layout switch will cause the application to change its output according to another keyboard layout, but the visible on-screen layout doesn't change, leaving the user blind as to which keyboard layout he is using. Until these deficiencies are corrected, Linux on-screen keyboards remain of limited usefulness for multi-lingual / multi-alphabet users.
Virtual keyboards can be categorized by the following aspects:
physical keyboards with distinct keys comprising electronically changeable displays integrated in the keypads
virtual keyboards with touchscreen keyboard layouts or sensing areas
[1] optically projected keyboard layouts or similar arrangements of "keys" or sensing areas
[2][3] optically detected human hand and finger motions
[4] JavaScript virtual keyboards used to translate the input from one keyboard layout to another
In stylus-operated personal data assistants, which lack a physical keyboard, it is common for the user to input text by tapping a virtual keyboard built into the operating system of the PDA. Virtual keyboards are also used as features of emulation software for systems that have fewer buttons than a computer keyboard would have.
An optical virtual keyboard has been invented and patented by IBM engineers in 1992 It optically detects and analyses human hand and finger motions and interprets them as operations on a physically non-existent input device like a surface having painted keys. In that way it allows to emulate unlimited types of manually operated input devices such as a mouse or keyboard. All mechanical input units can be replaced by such virtual devices, optimized for the current application and for the user's physiology maintaining speed, simplicity and unambiguity of manual data input.
On the Internet, various JavaScript virtual keyboards have been created, allowing users to type their own languages on foreign keyboards, particularly in Internet cafes.
(30) Virtual surgery
Virtual surgery refers to a virtual reality simulation of surgical procedures. These simulations are used to practice often dangerous surgical procedures without the need for an actual patient. The virtual reality simulation is used as an analog for the actual surgery where doctors can practice on a virtual patient before performing the surgery. Types of surgeries commonly simulated are laparoscopic surgery where the surgeon cannot physically see the operation being performed. Virtual surgery uses a computer screen displaying a 3-dimensional graphic of the organs being operated on. Various surgical tools or gloves are connected to motion sensors and haptic or tactile feedback mechanisms where the user can physically feel the difference in simulated tissue and organs. The user can "perform surgery" upon the virtual organs by manipulating the tools, which are also displayed on the screen as the user moves them, and the tools also provide force-feedback and collision detection to indicate to the user when they are pushing on or moving some organs or tissue. By inputting data from computerized tomography (CT) and magnetic resonance imaging (MRI) scans the patient can be replicated in the virtual environment. The advantages of this type of simulation is surgeons can practice operations multiple time with out the use of cadavers or animals. Surgery simulation would give an objective evaluation of a surgeon dexterity combined with a more intensive training activity. It would allow the simulation of rare pathological cases and could simulate the interaction with several organs. Complications can be introduced during the surgery testing the user on real world scenarios. Also virtually trained students are more proficient and make fewer errors, and thus are better prepared to assist during surgery.
History Flight simulators have been a milestone in the training and evaluation of pilots. In analogy to this development the systems presented here can also be described as flight simulators for surgeons.
Commercially available virtual surgery simulators
LapSim (Surgical Science Sweden AB, Göteborg, Sweden)
LAP Mentor (Simbionix Ltd., Lod, Israel)
Mentice MIST (Mentice AB, Göteborg, Sweden)
SEP - SimSurgery Education Platform (SimSurgery AS, Oslo, Norway)
ProMIS (Haptica Ltd., Dublin, Ireland)
HystSim (VirtaMed AG, Zurich, Switzerland)
(31) Remotely-Queried Embedded Microsensors
ABSTRACT: Sensors embedded in structural composites have been a topic of research in recent years.Embedded sensors can be used to monitor and optimize the manufacturing process, to monitor performance during use, and for structural health monitoring in highperformance applications. For several years, embedded optical fibers were the predominant type of sensor. There are well-known reasons that optical fiber sensors have not yet been fully embraced in industry including the cost of equipment and sensors, the fragility of the optical fiber itself, and the need to provide ingress and egress from the
structure. Recent work by the authors and others has produced prototype wireless electronic sensors of various types that address these shortcomings.The US Office of Naval Research is funding a multidisciplinary team to consolidate progress made in earlier programs towards self-contained microsensors to be embedded in a composite structure and queried using methods that do not require physical connections. The
sensors are to be left in place for the lifetime of the structure, are powered by the querying apparatus, and require no penetrations through the surface of the structure.
This paper describes the integrated approach taken to realize the goal of an interrogatable strain rosette that is embedded 0.25” below the surface of a graphite composite
plate. It also describes the progress to date of the sensor system itself.
KEYWORDS: Microsensors, Micromachines, Smart Structures, Embedded Sensors, Remotely-Queried, Remotely-Queried Sensors, Strain Gages, Strain Sensors.
INTRODUCTION: This research is funded by the US Office of Naval Research (ONR), contract number N00014-97-C-0274, with Mr. James Kelly as program manager. MTS Systems Corporation is the prime contractor and systems integrator. Other team members
include the Applied Physics Laboratory of Johns Hopkins University, Boeing Company, Electronic Identification Devices, Inc., the Illinois Institute of Technology,
Stanford University, and University of Minnesota, and the University of Utah.
The program is continuation of research begun in the Remotely-Queried Embedded Microsensors (RQEM) program sponsored by the Naval Research laboratory.
RQEM developed a working prototype of the sensor and solved many of the difficult research issues.
Use of the sensor during fabrication monitoring has the objectives of both producing process feedback to optimize the fabrication process and gathering data on various
process parameters. Other life cycle monitoring objectives are to predict failure of structures, and to monitor wear and strain on structures (e.g., to characterize structure
lifetime). The primary target materials for structures are various composites, including glass and carbon fiber reinforced thermoset and thermoplastic resins. The program has several high-level requirements for the ARRQEM sensor systems [MTS 95a]. The primary requirement is to measure various physical phenomena (e.g., strain, pressure, temperature) within a composite structure. Other requirements include:
1. Low recurring cost (including consumable components like sensors and installation costs)
2.Usable lifetime commensurate with the instrumented structure
3.Interrogatable from a minimum distance of several inches with no physical contact
Accommodate a varying number of different types of sensors in close proximity, and a varying number of similar sensors in close proximity
No significant effect on the instrumented structure (e.g., do not exceed the critical flaw size)
A means to correlate the measured effects with true effects in the structure under observation.
We are also exploring methods to ensure maximumtransfer of the effect of interest into the microsensor (e.g.,maximum strain transfer from the structure to the strain
gauge). The prototype concepts will be verified by embedding thedevices in aircraft components and testing in lab and in flight.
(32) Power-management techniques for multimedia mobile phones
Asia and other markets are racing to launch digital TV and streaming video and music in handheld formats. These technologies bring benefits, but designers still face the constraints of incorporating multimedia functions in small form factors in the face of increasing battery life.
Now that Asia and other markets race to deploy portable-media technology in the form of multimedia phones, designers must take a step back and consider power-management issues for these handheld devices (see sidebar "Asia looks to multimedia as the new 'new thing'"). Consumers have come to expect the small form factor and the long battery life on the 2G and 2.5G GSM (Global System for Mobile communication) or CDMA (code-division multiple-access) phones available today. The challenges to mobile-phone designers now are to include the new multimedia functions and still maintain the small, low-profile form factor of the handsets, as well as their long battery life. No one wants to deploy a handset that users would have to recharge after two hours of operation.
New application processors can deliver the necessary media-processing functions, but it comes at the price of higher power consumption. And the new devices change the users' profiles, as well. New audio and video functions mean longer audio-playback time, so audio amplification needs to be more efficient. Moreover, as audio and video functions on mobile phones mature, competition will increase the standard of audio quality and output power. All of these added power drains must somehow fit into an already-constrained power budget. Designers must tackle these challenges at all levels of system design, and, although the industry has focused on the digital SOCs (systems on chips) that form the hearts of these handsets, the analog portion of the handset can also help solve these design problems.
To achieve a small-phone form factor, designers commonly use an integrated power-management unit, which simplifies the power-supply design and makes the end product smaller than it would be if it required the use of several discrete power sections. Paradoxically, however, just as the fast development of multimedia functions in the handsets has increased the need for compactness and power efficiency, it has also led to increased usage of stand-alone voltage regulators. Power-management units are simply too weak to support the increasing power requirements of today's multimedia-rich application processors. And shorter mobile-development-cycle time has not allowed designers to wait for the power-management unit's output power to catch up. As a result, stand-alone voltage regulators supply the extra system power that mobile handsets require.
Thus, designers must carefully select stand-alone regulators. Apart from total cost, the top three criteria in the selection of a stand-alone voltage regulator are low noise, low power consumption, and small form factor. The low-dropout regulator is usually a designer's first choice. Low-dropout regulators are simple to design, they generate no significant amount of noise, and they provide fast response. However, to minimize the power loss and heat that are inevitable with linear regulation, experts often recommend low-dropout regulators only in low-power applications or in cases in which the output voltages are close to the input voltages. Lithium-ion cells in typical handset applications have output-voltage ranges of 4.2 to 3V, making the low-dropout regulator suitable to supply the 3.3 or 3V that analog-I/O circuits commonly require. Despite their inefficiency, low-dropout regulators provide clean power to sensitive circuits, such as RF stages.
In contrast, microprocessor-core voltages are constantly decreasing because of smaller process geometries; 1.8, 1.5, and even 1.2V have become common in SOCs. At these voltages, the difference between the input and the output voltage of the regulator becomes too large for the low-dropout regulator to achieve acceptable efficiency. If a low-dropout regulator supplies such low core voltage, the loss in power conversion drastically reduces the battery life, and the increase in heat dissipation within the handset enclosure eventually reduces the product's lifetime.
The ideal voltage regulator for new processors is not the simple, quiet low-dropout regulator, but a dc/dc step-down converter with power efficiency greater than 90% and low heat dissipation (Figure 1). An appropriate synchronous step-down converter can supply the core voltage of a low-voltage, deep-submicron chip set, as well as the higher voltage to the I/O circuitry. Buck converters with internal synchronous rectifiers can eliminate the use of some external Schottky diodes and offer efficiency of 90 to 96% in full operation over 0.9 to 3.3V with output current as high as 600 mA. Synchronous PWM converters have their own drawbacks in this application, however: They are inefficient under light loads. In mobile phones, the application microprocessors spend most of their time in standby mode. By decreasing their operating power, the microprocessors put the dc/dc converter into the light-loading zone in which efficiency drops to less than 90%. To reduce power consumption in the long-standby time, designers may want to consider using an alternative power supply that employs PFM (pulse-frequency modulation). In this mode, the switching frequency is proportional to the loading, and the overall efficiency thus remains high. Some converters today can automatically switch between modes depending on the demand.
To reduce power-supply size, vendors have moved up to switching frequencies of 1 to 2 MHz for their buck converters. To demonstrate the effect of the switching frequency, consider three similar converters. A 1-MHz step-down converter uses an optimized inductor-capacitor filter with inductance of 10 µH and output capacitance of 10 µF. In contrast, a similar regulator that switches at 1.5 MHz requires respective output-filter-component values of 2.2 µH and 10 µF. Similarly, with a 3-MHz oscillation frequency, the optimized inductor-capacitor-filter values are 2.2 µH and 4.7 µF, respectively.
This comparison shows that the higher the switching frequency, the smaller the inductor and output capacitor necessary and, thus, the smaller the parts. In multimedia-mobile design with tight pc-board constraints, you should use converters with higher switching frequency to minimize the size and reduce the cost of the passive components. The 3×3-mm SOT23-5 industry-standard package is the common choice for synchronous step-down converters. However, smaller package options, such as chip-scale and DFN packages, are also available to meet even tighter size requirements.
A dc/dc buck converter is the best choice for powering application processors. On the other hand, low-noise, low-dropout regulators typically power RF-sensitive analog circuits with input voltages of 2.8 to 3.3V. Ultimately, only further integration can significantly reduce board area in these designs. Accordingly, vendors are beginning to introduce integrated power ICs with both buck and low-noise, low-dropout regulators (Figure 2).
Audio-playback challenges
Portable multimedia functions pose two challenges to audio amplification in mobile phones. First, multimedia phones need to allow continuous music and video playback for at least two hours; long audio-playback time is a key selection criterion on multimedia phones. Second, audio experience on mobile devices must approach that of a home audio system. Users expect clean, powerful stereo audio with bass-boost playback. Today, mobile phones use Class AB audio amplifiers. A typical Class AB audio amplifier offers high audio quality with typical THD+N (total harmonic distortion plus noise) of less than 0.1%. These amplifiers also have good power-supply-rejection ratios, and, thanks to the linear nature of Class AB amplifiers, they present no risk of interfering with the RF system on board. Although they have low power efficiency, they find wide use in short-duration, low-power-audio applications, such as hands-free speakers for voice and ring-tone playback.
But, as MP3 becomes a popular application on mobile-media platforms and playback time increases from a few minutes to hours, Class AB's low efficiency and high heat output will no longer meet the challenge. New designs are now instead employing Class D audio amplifiers. Nominal power consumption for audio amplification in midrange phones is less than 100 mW, and maximum output power is 700 mW. Comparing the efficiency of a typical Class AB and a selected Class D audio amplifier shows that, at 50 mW, the Class D amp has an efficiency of 80%, whereas the Class AB offers a mere 20%. For the higher power operating range of 100 to 500 mW, Class D amplifiers offer a stable 85 to 90% efficiency, but the efficiency of Class AB remains 30 to 60% (Figure 3).
Due to their low efficiency and hence high heat generation, Class AB amplifiers in these applications cannot be robust enough to deliver output power higher than 1W without saturation or distortion. Thanks to the switching-mode operation in Class D amplifiers, they efficiently amplify the audio signal and thus can deliver higher output power to support high-volume audio playback. You can achieve as much as 1.4W output to an 8O speaker at a THD+N of less than 1%. Because low-frequency sound generation requires considerable power, especially with small speaker areas, this extra amplifier power helps to boost the bass sound, which is an important feature in music and gaming audio playback.
MP3 players—and, most likely, future mobile-media devices—often use an external cradle with 4O stereo speakers. This requirement provides another challenge to the audio amplifier, which you can best meet by operating the device at a higher voltage, such as 5 to 5.5V. This approach, in turn, requires a dc/dc boost converter to provide a constant 5V to power the two Class D amplifiers that a stereo application requires (Figure 4).
EMI considerations
A Class D amplifier operates in a constant-frequency PWM-switching mode. Thus, it may produce EMI that can interfere with nearby RF-circuit operation. Two key techniques can help prevent EMI interference with the RF system. First, you should place the Class D amplifier close to the speaker. In the case of stereo applications, you should use two monophonic amplifiers rather than a single stereo chip, so that you can place the two amplifiers next to the two speakers, usually at the sides of the handset. Apart from this step, designers should also connect an EMI filter, such as a ferrite bead, to the output of the amplifier. The EMI filter acts as a bandpass filter to remove the high-frequency switching signal from the audio output before it can propagate along the traces to the RF circuitry.
Read more In-Depth Technical Features
Market forces are driving mobile-multimedia devices to replace mobile phones in both mature and developing markets. In these new mobile-media centers, vendors are upgrading processors and releasing chip sets at such a pace that integrated-power approaches from the power vendors can't keep up. Thus, designers of the new mobile-media centers must turn to discrete power and audio devices to meet the extra system requirements and to deliver new models with short time to market.
New synchronous buck converters offer high efficiency, are easy to design-in, and help designers to develop small systems with low system cost. Similarly, Class D audio amplifiers with high power efficiency prolong audio-playback time to meet new market demand. Class D amplifiers also deliver high output power to support the compelling audio playback critical in MP3, TV, and gaming functions.
--------------------------------------------------------------------------------
Author Information
Crystal Lam is a product-line manager for ON Semiconductor's analog low-voltage power-management products in the company's Toulouse, France, development center.
Asia looks to multimedia as the new "new thing"
By Margery Conner, Technical Editor
The Asian market is once again leading the way in innovative mobile-phone applications—this time as go-everywhere multimedia platforms. According to this article's author, Crystal Lam, product-line manager at the Analog Low Power Management Business Unit at On Semiconductor, the new MPEG-4 phones currently popular in Korea and China are the first devices in the coming onslaught of streaming-music and -video phones. "In Asia, portable TV is no longer a dream," she says. The devices allow users to download and play streaming video and MP3 music. In Asia, portable TV is becoming a reality. With the S-DMB (satellite-digital-multimedia-broadcasting) service Korea launched last May, consumers can watch TV programs on their handsets for a monthly subscription fee. China subsequently introduced the service and launched the first digital-TV-broadcast service based on the DMB standard in Shanghai last November. Lam predicts that network operators will subsidize the phone price with the revenues from data transfer and subscriptions, making the new multimedia phones available at an affordable price.
Even traditional content providers are taking a leading role in driving mobile-media-technology development. Seven months after the launch of the S-DMB service, Korean TV channels released a free TV-broadcast service based on the T-DMB (terrestrial-DMB) standard. Despite the reluctance of the network operators to promote the T-DMB phones, Samsung has released seven T-DMB handsets, and LG has presented its T-DMB-enabled PDA with a 3.5-in. LCD screen that can broadcast a TV program during a 2.5-hour window each day. Whichever digital-TV standard prevails, Asian phone manufacturers are all preparing for digital-TV services to enter the market during the next 18 months.
(33) Flexible Display Systems
Research on flat panel displays (FPD), which started inthe 1960s, has finally reached the commercialization stage in the form of large plasma display panels (PDPs) and
liquid crystal displays (LCDs). This research will hopefully lead to FPDs with larger displays, higher picture quality, lower power consumption, and lower prices. A spin-off of this trend is the growing demand for enhanced picture quality broadcasting in media such as Hi-Vision (HDTV) and in data services. In the future, broadcasting,
communications, personal computers will have fused together to form a common media by which interactive broadcasting and mobile reception via digital terrestril
broadcasting will be available in most areas. The demand for ubiquitous and easy-to-use displays as human interfaces will also increase. One of these interfaces will be
a lightweight, flexible display that can be rolled up or folded. It might be possible for anyone to carry a large home display device simply by rolling it up. While the dream of a flexible display has a long history, roll-up and paper-like displays are now estimated to be commercially feasible by around 2014. It has also become apparent that the advent of flexible display systems will have a significant impact on the market, not only because
of the ubiquitous and convenient systems that could be supported, but also because of the potential to provide unconventional visual effects that are not possible with
conventional systems. Moreover, the manufacturing technology for these displays will likely be low-cost and environmentally friendly. Studies on display systems and materials have just begun, and it is unwise to give definitive statements about such a display system for television. That said, however, the following pages describing the issues and prospects of flexible displays will hopefully give the reader an overall introduction to the present research.
2. Impact of Flexible Displays
The move from the cathode ray tube (CRT) display to the FPD is a major transition; electron beam scanning systems are rapidly being replaced with matrix displays
(a sequential display with a cell structure corresponding to pixel dots). The main effects of this transition are a significant space saving that makes large wallmountable
TV screens practical and enhanced mobility, as in the case of the laptop computer. A flexible display system is expected to have a significant impact, i.e., beyond that of conventional FPD systems. That impact is detailed below.
1) Ubiquitous, Convenient System
The weight of a 40-inch diagonal flexible display constructed on a 0.2-mm-thick plastic substrate would be approximately 500 g. This is two orders of magnitude lighter than a conventional wall-mounted PDP, LCD, or CRT display (Figure 1). Its volume would be at least three orders of magnitude smaller than that of a CRT display. It will be able to be rolled up or folded, transported anywhere, and operated indoors or outside. These
characteristics will drastically diversify TV viewing styles and promote the distribution of the contents.
2) Fusion of Medias
A display device is an essential piece of hardware for a variety of media, including broadcasting, communications, and personal computers. Accordingly, if a display device possesses paper-like properties, electric media and paper media will fuse to diversify viewing styles. Moreover, if a flexible display is equipped with an information storage function, e.g., printing of TV screen image, it will open up an array of application possibilities.
3) Visual Effects of Curved Display
Some movie theaters have curved screens and there are subjective evaluation results showing that a slightly curved display (a concave surface as viewed by an observer) is
preferable to a flat display. Some research using simulation method also supports the idea that a curved display presents a stronger sensation of reality. A curved display
can attain a larger viewing angle, which could lead to an enhanced sensation of reality even with a relatively small display device. Since there have been no systematic or
extensive experiments conducted using a direct-view-type display, it is also anticipated that a flexible display system will serve as a research tool for such visual effects. The
capability of displaying images on a surface with an arbitrary degree of curvature will contribute to a wide range of applications in the medical, transportation, and
educational fields, among others.
4) Low-energy, Low-cost Manufacturing Technology
The current PDP system employs a manufacturing process that requires temperatures of 400 to 500 during the screen-printing, firing, and vacuum-sealing steps. Present LCDs, which use amorphous silicon thin film transistor (a-Si TFT) for driving, must be fabricated at high temperature (up to 300 ). The present technology also uses up a lot of raw materials, e.g., a massive amount of glass substrate. On the other hand, flexible displays using a plastic substrate can be manufactured at near ambient
temperature, and very little raw material is used up for the approximately 0.2-mm-thick substrate. The flexibility of the plastic substrate and display material will enable
space-saving production through rolling technology such as roll up and roll over. Beyond the benefits of lower costs, these fabrication technologies would have less impact on
the environment.
(34) Ultra Wideband
Ultra-wideband
Ultra-wideband (aka UWB, ultra-wide band, ultraband, etc.) is a radio technology that can be used at very low energy levels for short-range high-bandwidth communications by using a large portion of the radio spectrum. This method is using pulse coded information with sharp carrier pulses at a bunch of center frequencies in logical connex. UWB has traditional applications in non cooperative radar imaging. Most recent applications target sensor data collection, precision locating and tracking applications.
This article discusses the meaning of ultra-wideband in the field of radio communications.
UWB communications transmit in a way that doesn't interfere largely with other more traditional 'narrow band' and continuous carrier wave uses in the same frequency band. However first studies show that the rise of noise level by a number of UWB transmitters puts a burden on existing communications services. This may be hard to bear for traditional systems designs and may affect the stability of such existing systems.
Contents
• 1 Overview
o 1.1 Concept
o 1.2 Regulatory Impact in USA and UK
• 2 Theoretical discussion
o 2.1 Multiple antenna technologies
• 3 Applications
• 4 See also
• 5 References
• 6 External links
o 6.1 Standardization
o 6.2 Regulations
o 6.3 Resources
Overview
Ultra-Wideband (UWB) is a technology for transmitting information spread over a large bandwidth (>500 MHz) that should, in theory and under the right circumstances, be able to share spectrum with other users. Regulatory settings of FCC are intended to provide an efficient use of scarce radio bandwidth while enabling both high data rate personal-area network (PAN) wireless connectivity and longer-range, low data rate applications as well as radar and imaging systems.
Ultra Wideband was traditionally accepted as pulse radio, but the FCC and ITU-R now define UWB in terms of a transmission from an antenna for which the emitted signal bandwidth exceeds the lesser of 500 MHz or 20% of the center frequency. Thus, pulse-based systems—wherein each transmitted pulse instantaneously occupies the UWB bandwidth, or an aggregation of at least 500 MHz worth of narrow band carriers, for example in orthogonal frequency-division multiplexing (OFDM) fashion—can gain access to the UWB spectrum under the rules. Pulse repetition rates may be either low or very high. Pulse-based radars and imaging systems tend to use low repetition rates, typically in the range of 1 to 100 megapulses per second. On the other hand, communications systems favor high repetition rates, typically in the range of 1 to 2 giga-pulses per second, thus enabling short-range gigabit-per-second communications systems. Each pulse in a pulse-based UWB system occupies the entire UWB bandwidth, thus reaping the benefits of relative immunity to multipath fading (but not to intersymbol interference), unlike carrier-based systems that are subject to both deep fades and intersymbol interference.
Concept
A significant difference between traditional radio transmissions and UWB radio transmissions is that traditional systems transmit information by varying the power level, frequency, and/or phase of a sinusoidal wave. UWB transmissions transmit information by generating radio energy at specific time instants and occupying large bandwidth thus enabling a pulse-position or time-modulation. The information can also be imparted (modulated) on UWB signals (pulses) by encoding the polarity of the pulse, the amplitude of the pulse, and/or by using orthogonal pulses. UWB pulses can be sent sporadically at relatively low pulse rates to support time/position modulation, but can also be sent at rates up to the inverse of the UWB pulse bandwidth. Pulse-UWB systems have been demonstrated at channel pulse rates in excess of 1.3 giga-pulses per second using a continuous stream of UWB pulses (Continuous Pulse UWB or "C-UWB"), supporting forward error correction encoded data rates in excess of 675 Mbit/s Ref. Such a pulse-based UWB method using bursts of pulses is the basis of the IEEE 802.15.4a draft standard and working group, which has proposed UWB as an alternative PHY layer.
One of the valuable aspects of UWB radio technology is the ability for a UWB radio system to determine "time of flight" of the direct path of the radio transmission between the transmitter and receiver at various frequencies. This helps to overcome multi path propagation, as at least some of the frequencies pass on radio line of sight. With a cooperative symmetric two-way metering technique distances can be measured to high resolution as well as to high accuracy by compensating for local clock drifts and stochastic inaccuracies.
Another valuable aspect of pulse-based UWB is that the pulses are very short in space (less than 60 cm for a 500 MHz wide pulse, less than 23 cm for a 1.3 GHz bandwidth pulse), so most signal reflections do not overlap the original pulse, and thus the traditional multipath fading of narrow band signals does not exist. However, there still is multipath propagation and inter-pulse interference for fast pulse systems which have to be mitigated by coding techniques.
Regulatory Impact in USA and UK
Ultra-Wideband (UWB) may be used to refer to any radio technology having bandwidth exceeding the lesser of 500 MHz or 20% of the arithmetic center frequency, according to Federal Communications Commission (FCC). A February 14, 2002 Report and Order by the FCC [1] authorizes the unlicensed use of UWB in 3.1–10.6 GHz. The FCC power spectral density emission limit for UWB emitters operating in the UWB band is -41.3 dBm/MHz. This is the same limit that applies to unintentional emitters in the UWB band, the so called Part 15 limit. However, the emission limit for UWB emitters can be significantly lower (as low as -75 dBm/MHz) in other segments of the spectrum.
Deliberations in the International Telecommunication Union Radiocommunication Sector (ITU-R) have resulted in a Report and Recommendation on UWB in November 2005. National jurisdictions around the globe are expected to act on national regulations for UWB very soon. The UK regulator Ofcom announced a similar decision [2] on 9 August 2007. Other national regulatory bodies apparently are somewhat reluctant to allow common unlicensed use.
More than four dozen devices have been certified under the FCC UWB rules, the vast majority of which are radar, imaging or locating systems[citation needed].
Theoretical discussion
One performance measure of a radio in applications like communication, locating, tracking, radar, is the channel capacity for a given bandwidth and signaling format. Channel capacity is the theoretical maximum possible number of bits per second of information that can be conveyed through one or more links in an area. According to the Shannon–Hartley theorem, channel capacity of a properly encoded signal is proportional to the bandwidth of the channel and to the logarithm of signal-to-noise ratio (SNR)—assuming the noise is additive white Gaussian noise (AWGN). Thus channel capacity increases linearly by increasing bandwidth of the channel to the maximum value available, or equivalently in a fixed channel bandwidth by increasing the signal power exponentially. By virtue of the huge bandwidths inherent to UWB systems, huge channel capacities could be achieved in principle (given sufficient SNR) without invoking higher order modulations that need very high SNR to operate.
Ideally, the receiver signal detector should match with the transmitted signal in bandwidth, signal shape and time. Any mismatch results in loss of margin for the UWB radio link.
Channelization (sharing the channel with other links) is a complex problem subject to many practical variables. Typically two UWB links can share the same spectrum by using orthogonal time-hopping codes for pulse-position (time-modulated) systems, or orthogonal pulses and orthogonal codes for fast-pulse based systems.
Current forward error correction technology, as demonstrated recently in some very high data rate UWB pulsed systems (like Low density parity check code) can--perhaps in combination with Reed–Solomon error correction--provide channel performance very closely approaching the Shannon limit (See Shannon–Hartley theorem). When stealth is required, some UWB formats (mainly pulse-based) can fairly easily be made to look like nothing more than a slight rise in background noise to any receiver that is unaware of the signal’s complex pattern.
Multipath (distortion of a signal because it takes many different paths to the receiver) is an enemy of narrow-band radio. It causes fading where wave interference is destructive. Some UWB systems use "rake" receiver techniques to recover multi path generated copies of the original pulse to improve performance on receiver. Other UWB systems use channel equalization techniques to achieve the same purpose. Narrow band receivers can use similar techniques, but are limited due to the poorer resolution capabilities of narrow band systems.
There has been much concern over the interference of narrow band signals and UWB signals that share the same spectrum; traditionally the only radio technology that operated using pulses was spark-gap transmitters, which were banned due to excessive interference. However, UWB is much lower power. The subject was extensively covered in the proceedings that led to the adoption of the FCC rules in the US, and also in the meetings relating to UWB of the ITU-R that led to the ITU-R Report and Recommendations on UWB technology. In particular, many common pieces of equipment emit impulsive noise (notably hair dryers) and the argument was successfully made that the noise floor would not be raised excessively by wider deployment of wideband transmitters of low power.
Multiple antenna technologies
• Distributed MIMO: To increase the transmission range, this scheme exploits distributed antennas among different nodes.
• Multiple antenna: Multiple antenna such as MIMO has been used to increase the system throughput and the reception reliability. Since UWB has almost impulse like channel response, the combination with multiple antenna techniques is preferable as well. Coupling MIMO spatial multiplexing with UWB's already high throughput gives the possibility of short-range networks with multi-gigabit rates.
Applications
Due to the extremely low emission levels currently allowed by regulatory agencies, UWB systems tend to be short-range and indoors applications. However, due to the short duration of the UWB pulses, it is easier to engineer extremely high data rates, and data rate can be readily traded for range by simply aggregating pulse energy per data bit using either simple integration or by coding techniques. Conventional OFDM technology can also be used subject to the minimum bandwidth requirement of the regulations. High data rate UWB can enable wireless monitors, the efficient transfer of data from digital camcorders, wireless printing of digital pictures from a camera without the need for an intervening personal computer, and the transfer of files among cell phone handsets and other handheld devices like personal digital audio and video players.
UWB is used as a part of location systems and real time location systems. The precision capabilities combined with the very low power makes it ideal for certain radio frequency sensitive environments such as hospitals and healthcare. Another benefit of UWB is the short broadcast time which enables implementers of the technology to install orders of magnitude more transmitter tags in an environment relative to competitive technologies. USA based Parco Merged Media Corporation was the first systems developer to deploy a commercial version of this system in a Washington, DC hospital.
UWB is also used in "see-through-the-wall" precision radar imaging technology, precision locating and tracking (using distance measurements between radios), and precision time-of-arrival-based localization approaches. [1] It exhibits excellent efficiency with a spatial capacity of approximately 1013 bit/s/m².[citation needed]
UWB has been a proposed technology for use in personal area networks and appeared in the IEEE 802.15.3a draft PAN standard. However, after several years of deadlock, the IEEE 802.15.3a task group[2] has been dissolved[3] in 2006.
(35) LMDS FROM HIGH ALTITUDE AERONAUTICAL PLATFORMS
Abstract—System level design considerations for high altitude aeronautical platforms operating in the LMDS band are examined. Propagation effects in the LMDS band are outlined, followed by a brief introduction to different platform scenarios. Ground-based and platformbased Fixed Wireless Access scenarios are considered,and it is shown that using a platform, considerably longer link lengths can be used. The effects on performance of platform displacement from its desired locationwith both fixed and steerable antennas are also examined. It is shown that steerable antennas are of most use when fixed stations are immediately below the platform, with no benefit for fixed stations on the edge of coverage.
I. INTRODUCTION
With an ever increasing demand for capacity for future generation multimedia applications, service providers are looking to utilise the frequency allocation dedicated to Local Multi-Point Distribution Systems (LMDS). In this frequency band, signals experience high attenuation due to rain, so appropriate link margins must be used in order to guarantee availability and Quality of Service. One possible solution is to use High-Altitude Aeronautical Platforms (HAAPs), which are situated in the stratosphere, 17-22km above the ground. Such platforms have the potential capability to serve a large number of users, situated over a large geographical area, using considerably less communications infrastructure than that required if delivered by a terrestrial
network. The paper provides a brief introduction to the propagation environment found in the LMDS band, including the main limiting factor of rain on signal attenuation, as well as attenuation due to the atmospheric effects of oxygen, water vapour and clouds. An overview of several proposed HAAPs are examined with comparisons being made between possible ground-based cellular and platform-based systems. These are then used to determine the possible link capacity for an availability of 99.99% for several scenarios.
Obviously one of the most difficult engineering challenges is the development of the flight controls to keep such platforms in place; therefore the second area examined in the
paper is the effect on received signal power of platform displacement. Possible solutions to maintain availability in the presence of both rain and displacement are identified.
Subscribe to:
Post Comments (Atom)
VIRUS REMOVAL
ReplyDeleteIs Your Computer Sluggish or Plagued With a Virus? – If So you Need Online Tech Repairs
As a leader in online computer repair, Online Tech Repairs Inc has the experience to deliver professional system optimization and virus removal.Headquartered in Great Neck, New York our certified technicians have been providing online computer repair and virus removal for customers around the world since 2004.
Our three step system is easy to use; and provides you a safe, unobtrusive, and cost effective alternative to your computer service needs. By using state-of-the-art technology our computer experts can diagnose, and repair your computer system through the internet, no matter where you are.
Our technician will guide you through the installation of Online Tech Repair Inc secure software. This software allows your dedicated computer expert to see and operate your computer just as if he was in the room with you. That means you don't have to unplug everything and bring it to our shop, or have a stranger tramping through your home.
From our remote location the Online Tech Repairs.com expert can handle any computer issue you want addressed, like:
• - System Optimization
• - How it works Software Installations or Upgrades
• - How it works Virus Removal
• - How it works Home Network Set-ups
Just to name a few.
If you are unsure of what the problem may be, that is okay. We can run a complete diagnostic on your system and fix the problems we encounter. When we are done our software is removed; leaving you with a safe, secure and properly functioning system. The whole process usually takes less than an hour. You probably couldn't even get your computer to your local repair shop that fast!
Call us now for a FREE COMPUTER DIAGONISTIC using DISCOUNT CODE (otr214424@gmail.com) on +1-914-613-3786 or chat with us on www.onlinetechrepairs.com.
Problem: HP Printer not connecting to my laptop.
ReplyDeleteI had an issue while connecting my 2 year old HP printer to my brother's laptop that I had borrowed for starting my own business. I used a quick google search to fix the problem but that did not help me.
I then decided to get professional help to solve my problem. After having received many quotations from various companies, i decided to go ahead with Online Tech Repair (www.onlinetechrepairs.com).
Reasons I chose them over the others:
1) They were extremely friendly and patient with me during my initial discussions and responded promptly to my request.
2) Their prices were extremely reasonable.
3) They were ready and willing to walk me through the entire process step by step and were on call with me till i got it fixed.
How did they do it
1) They first asked me to state my problem clearly and asked me a few questions. This was done to detect any physical connectivity issues with the printer.
2) After having answered this, they confirmed that the printer and the laptop were functioning correctly.
3) They then, asked me if they could access my laptop remotely to troubleshoot the problem and fix it. I agreed.
4) One of the tech support executives accessed my laptop and started troubleshooting.
5) I sat back and watched as the tech support executive was navigating my laptop to spot the issue. The issue was fixed.
6) I was told that it was due to an older version of the driver that had been installed.
My Experience
I loved the entire friendly conversation that took place with them. They understood my needs clearly and acted upon the solution immediately. Being a technical noob, i sometimes find it difficult to communicate with tech support teams. It was a very
different experience with the guys at Online Tech Repairs. You can check out their website www.onlinetechrepairs.com or call them on 1-914-613-3786.
Would definitely recommend this service to anyone who needs help fixing their computers.
Thanks a ton guys. Great Job....!!