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The objective of this project is to develop efficient very large scale integrated (VLSI) error-correcting encoders and decoders to be used in sensor network applications. In addition, decoders with adjustable error-correcting capability will be designed so that trade-offs can be made on signal transmission power and receiver power. During this project period, novel schemes were proposed to further increase the speed and reduce the area of the interpolation-based generalized minimum distance (GMD) decoder of Reed-Solomon (RS) codes. In addition, the complexity analysis of the GMD decoder was generalized to take into account different codeword length, code rate and parallel processing factor. A reduced-complexity parallel interpolator has also been developed for the low-complexity Chase (LCC) algebraic soft-decision RS decoding algorithm. Compared to previous designs, it not only has much smaller area, but can run at higher speed. Adopting this design, the overall decoder can achieve substantially higher efficiency. Another achievement of this year is that the LCC decoder has been optimized, so that it can also carry out high-speed hard-decision decoding with negligible hardware overhead.

scan winprefetch is a C++ and thread-safe Windows prefetch scanner for the bulk extractor framework that decodes prefetch files. The decoder analyzes disk images for Windows prefetch files. At the completion of analyzing each prefetch file found on the disk image, a text file is created containing a XML output detailing all found prefetch files.

This paper described the design and implementation of a prototype transmitter and a prototype demodulator/decoder for space-time coded SOQPSK-TG for aeronautical telemetry. The design exercise showed that the space-time coding concept can be reduced to hardware. The laboratory bit error rate tests showed that the performance of the prototype demodulator in a 2-transmit/1-receive antenna configuration is comparable to that of existing SOQPSK demodulators in a 1-transmit/1-receive antenna configuration., The original document contains color images. Prepared in collaboration with Brigham Young University, Provo, UT. Sponsored in part by the Test Resource Management Center, Test and Evaluation Science and Technology Program.

Se conoce como servicios de acceso condicional aquellos querestringen a través de medidas técnicas su disfrute en forma inteligiblea usuarios previamente autorizados, normalmente los que han abonadoun canon. La “picaresca” para acceder gratuitamente a estos servicios hagenerado una floreciente industria “pirata” dedicada a la distribución dedispositivos ilícitos que facilitan tal acceso fraudulento y que ocasionaimportantes perjuicios económicos a sus prestadores. Situación quese agrava porque la respuesta legal de los países comunitarios frente aeste nuevo fenómeno delictivo no es uniforme, lo que genera nefastasconsecuencias en el desarrollo de estos servicios y, sobre todo, en elfuncionamiento del mercado común de la UE. Por ello, la Directiva98/84/CE relativa a la protección jurídica de estos servicios pretendearmonizar las disposiciones de los Estados miembros en esta materia.En el presente trabajo se analiza y compara cómo se incorpora estanorma a los Ordenamientos jurídicos alemán y español, que optanpor una protección penal de estos servicios, no exigida por la anteriordirectiva., Services of conditional access are known as those that restrict, through technical measures, all those that were previously authorized for their enjoyment in an intelligible form, usually those who have paid a fee. The “rogue” to enjoy these services free of charge brings out an “alternative” industry dedicated to the distribution of illegal devices that facilitate the fraudulent access to the conditional access services and causes significant economic damage to the providers of such services. The situation is worse, because the legal response of EU countries against this new criminal phenomenon is not uniform, leading to harmful consequences in the development of these services and mainly in the functioning of the common EU market. So, Directive 98/84/EC concerning the legal protection of these services seeks to set up an uniform supervisory framework of these services in the various national laws. The research analyzes and compares how the German and Spanish legal systems incorporate this rule, which choose a criminal protection of these services that is not required by the previous directive.

A new framework of compressive sensing (CS), namely statistical compressive sensing (SCS), that aims at efficiently sampling a collection of signals that follow a statistical distribution and achieving accurate reconstruction on average, is introduced. For signals following a Gaussian distribution with Gaussian or Bernoulli sensing matrices of O(k) measurements considerably smaller than the O(k log(N/k)) required by conventional CS where N is the signal dimension, and with an optimal decoder implemented with linear filtering, significantly faster than the pursuit decoders applied in conventional CS, the error of SCS is shown tightly upper bounded by a constant times the k-best term approximation error, with overwhelming probability. The failure probability is also significantly smaller than that of conventional CS. Stronger yet simpler results further show that for any sensing matrix, the error of Gaussian SCS is upper bounded by a constant times the k-best term approximation with probability one, and the bound constant can be efficiently calculated. For signals following Gaussian mixture models, SCS with a piecewise linear decoder is introduced and shown to produce for real images better results than conventional CS based on sparse models., Supported in part by ARO.

Multiple antennas at both the transmitter and receiver is known output (MIMO) as multiple-input multiple-system. This has emerged as the most promising technique for improving the performance of wireless digital transmission systems as well as allowing higher data rates to be obtained for a given bandwidth. A consequence of the MIMO wireless communications revolution is that multipath scattering of the transmitted signal has moved from being a problem to being a valuable resource. This has happened to such extent that MIMO systems have come to rely on this resource. However, away from dense urban and indoor environments such as Australian rural and remote areas with wide open spaces and flat or smooth undulating terrain such rich scattering can be hard to find. This research seeks to develop MIMO schemes which will give robust and reliable performance in environments that can change rapidly from rich scattering environment to clear line of sight between transmitter and receiver. Wirelesss communications system which are robust to changing environment conditions are a particular important factor in military communication systems as well as for civilian emergency services. In this work, polarization is proposed as a source of diversity in wireless communications. Polarization diversity is particularly suited to the Australian rural and remote environment where wide open spaces and flat or smooth undulating terrain give rise to line of sight conditions between the transmitter and the receiver. The polarization diversity of transmitted signals is mostly preserved by the line-of-sight environment presenting an opportunity for transmitter and receiver diversity techniques, Another aspect of the research presented here is the development of fast, fixed complexity, decoding algorithms for space-time codes that are robust to the changing transmission conditions. Reliable high rate transmission over the MIMO system ca only be achieved through "space-time coding".

The move towards e-government has seen many institutions put special focus on the need for security, especially that of authentication. Single-factor password-based systems have been proven inadequate in safeguarding online financial and e-government service transactions. Industry adoption of Two-Factor Authentication (2FA) has also been piecemeal. To mitigate these deficiencies, the Singapore Government, in 2008, put forth a Call-for-Collaboration (CFC) seeking industry and academic participation in defining a National Authentication Framework (NAF), with the dual aim of providing for a national-level 2FA system and broadening the market for authentication services, and, in so doing, provide the user with a better authentication experience. This thesis will detail, discuss, and compare the various token types and identity frameworks (PKI, SAML, WS-F, OpenID, and Infocard) that make up an authentication system, and make recommendations on the best combination of technologies, protocols, and standards that, when implemented, would not only fulfill the requirements of the CFC, but also position it well for future enhancement., The original document contains color images.

Compressed Sensing seeks to capture a discrete signal x included in R(N_ with a small number n of linear measurements. The information captured about x from such measurements is given by the vector y = Phi-x included in R(n) where Phi is an n x N matrix. The best matrices, from the viewpoint of capturing sparse or compressible signals are generated by random processes, e.g. their entries are given by i.i.d. Bernoulli or Gaussian random variables. The information y holds about x is extracted by a decoder mapping R(n) into R(N). Typical decoders are based on L1-minimization and greedy pursuit. The present paper studies the performance of decoders based on thresholding. For quite general random families of matrices , decoders are constructed which are instance-optimal in probability by which we mean the following. If x is any vector in R(N), then with high probability applying to y = x gives a vector x := delta-(y) such that ||x -x(hat)|| less than or equal to C(0)-sigma(k)(x)L2 for all k less than or equal to an/logN provided a is sufficiently small (depending on the probability of failure). Here sigma-k(x)L2 is the error that results when x is approximated by the k sparse vector which equals x in its k largest coordinates and is otherwise zero. It is also shown that results of this type continue to hold even if the measurement vector y is corrupted by additive noise: y = Phi-x + e where e is some noise vector. In this case sigma-k(x)L2 is replaced by sigma-k(x)L2 + ||e||L2 ., Sponsored in part by Army Research Office (ARO) contracts W911NF-05-1-0227 and W911NF-07-1-0185.

Physical layer authentication techniques exploit signal characteristics to uniquely identify radios. We describe how multicarrier systems may use such techniques to stealthily authenticate while maintaining high levels of security and robustness. We show that with channel state information (CSI) at the transmitter and receiver, multicarrier authentication systems can further improve performance by carefully allocating the authentication power over each carrier., See also ADM002187. Presented at the Army Science Conference (26th) held in Orlando, Florida on 1-4 December 2008. Published in the Proceedings of the Army Science Conference (26th), 2008. The original document contains color images.

During the project period, the PI and one graduate research assistant have conducted extensive research guided by the proposal that we submitted. Three main objectives are achieved: (1) thoroughly studied the fundamental limits of low complexity decoder; (2) proposed differential decoder based timing synchronization method; and (3) designed turbo decoders to enhance the receiver performance. Supported by this project, 7 journal papers and 10 conference proceeding papers have been published/submitted, and collaborations with ARL and defense industry (General Dynamics) have been established. In addition, during this period, new ideas and approaches along this topic have emerged to better finish up the rest of the project period and develop continued proposal for possible future funding.

It is highly desirable to have a video coding framework that can flexibly distributed coding complexity between the video encoder and decoder. However, today's video compression techniques impose a rigid computational complexity distribution between the video encoder and decoder. Specifically, video decoders are very simple but encoders are computationally complex as they need to carry out motion estimation and mode decision. Distributed video coding has shown great potentials in enabling flexible complexity distribution between the video encoder and decoder. Previous work on distributed video coding has studied two extreme operating points of complexity distribution: (1) Complex encoder with light-weight decoder to achieve maximum compression efficiency and (2) Light encoder and complex decoder to achieve robustness against transmission packet drops (at the cost of reduced compression efficiency). In this project, our main goal is to explore the middle ground between these two extreme points. In particular, we study the effect of doing coarse motion search at the encoder., The original document contains color images.

We have developed a high-speed pipelined superconductor look-up table to generate programmable predistortion functions for direct linearization of radio frequency "RF" power amplifiers. The look-up table comprises an address decoder and a memory matrix with throughput above 10 GHz. The decoder performs code-matching of each input word and its conversion into a row address of the memory matrix. We discuss different possible implementations of the address decoder, including a preferred one for integrated circuit implementation. The memory matrix consists of RS flip-flops with nondestructive readout connected in series for slow-speed contents writing. Each row of the memory matrix contains a number, which can be read out by signal from the decoder. We present the design and the results of experimental evaluation of the look-up table and its components., Published in the Jnl. of IEEE Transactions on Applied Superconductivity v17, n2, p561-564, Jun 2007. Sponsored in part by CERDEC SBIR contracts.

The MIT-LL/AFRL MT system is a statistical phrase-based translation system that implements many modern SMT training and decoding techniques. Our system was designed with the long-term goal of dealing with corrupted ASR input and limited amounts of training data for speech-to-speech MT applications. This paper will discuss the architecture of the MIT-LL/AFRL MT system, improvements over our 2005 system, and experiments with manual and ASR transcription data that were run as part of the IWSLT-2006 evaluation campaign., Presented at the International Workshop on Spoken Language Translation, IWSLT 2006, in Kyoto, Japan, on 27-28 Nov 2006; published in proceedings of the same p71-76. Prepared in collaboration with the Air Force Research Laboratory, Wright-Patterson AFB, OH. The original document contains color images.

This paper deals with a multi-user downlink MIMO-OFDM scheme with perfect channel knowledge at both the transmit and receive sides. The objective is to optimize the average BER while fulfilling each user's rate and satisfying a global transmit power constraint. Space Division Multiple Access (SDMA) is investigated and three new iterative schemes are proposed to compute the linear pre/decoders. The results exhibit, inter alia, that orthogonalizing the channels does not lead to the best results. © 2005 IEEE.

This report results from a contract tasking Technische Universitat Dresden (Technical University of Dresden in Germany) as follows: Grantee will investigate and characterize MP3 encoders and statistically analyze MP3 data to enable detection of embedded information in MP3 files and streaming data. This may also assist with identification of the origin of MP3 files (i.e. provide information regarding the type of MP3 encoder used to generate sample data). As detailed in the technical proposal the research consists of three parts. The first task is to survey the discipline to identify the available MP3 encoders and generate a data pool for analysis. The second task is analysis of the encoders and statistical classification of the data they produce. The third task is to characterize the robustness of techniques developed by testing the approach on known and unknown reference data., The original document contains color images.

JIDA Objectives: 1. Improve effective throughput, 2. Reduce decoder latency, -reduce number of decoder iterations by having the authentication module declare packet "authentic" or "correct" packet., Presented at the NATO Workshop on Cross-Layer Issues in the Design of Tactical Mobile Ad Hoc Wireless Networks, held at the Naval Research Lab, Washington, DC, on 2-3 June 2004. See also ADM002082, RTO-TR-IST-030, Information Management over Disadvantaged Grids. The original document contains color images.

Christine Large, who has been Director at Bletchley Part since 1998, describes how human ingenuity and, in particular, the Poles' early contribution, led to breaking a seemingly insoluble problem: the Enigma machine. She speaks in reference to Dillwyn Knox's seminal meeting with Marian Rejewski and the collaboration between men and machines that flowed thereafter. Some human factors that can lead to vital "breaks" are highlighted. Bletchley Park's current role in Anglo-Polish diplomatic relations, including a joint public information campaign instigated as a result of the film, "Enigma," is explained., See also ADM001577. Presented at the RTO HFM Symposium on "The Role of Humans in Intelligent and Automated Systems," held in Warsaw, Poland, 7-9 Oct 2002. Published in report number RTO-MP-088. The original document contains color images.

Perceptual watermarking is a promising technique towards the goal of producing invisible watermarks. It involves the integration of formal perceptual models in the watermarking process, with the purpose of determining those portions of an image that can better tolerate the distortion imposed by the embedding and ensuring that the watermarking will inflict the least possible degradation on the original image. In a previous study the Discrete Cosine Transform was used, and the watermark embedding was done in a non- uniform matter with criteria based on both the host image and the watermark. The decoder model employed made use of apriori access to unmarked and marked images as well as to the watermark. A fair level of success was achieved in this effort. In our research we refine this scheme by integrating a perceptual model and by proposing a modification to the decoder model that makes possible the successful recovery of the watermark without apriori access to it. The proposed perceptual scheme improves the watermark's transparency while at the same time maintains sufficient robustness to quantization and cropping., The original document contains color images.

Smart card technology is essentially about a credit card with a brain. Smart cards have an embedded microchip that allows the card to hold digital data up to the available memory installed on the card. Smart cards first became popular in the financial industry in Europe, however, they have quickly gained favor in the United States. The Department of Defense (DoD) also saw the utility in using smart card technology. The DoD began tests with smart cards that sought to take advantage of the many capabilities present in this technology. Not merely content to use the card as just an identification (ID) card, the military wanted to exploit the smart card's ability to store large amounts of encrypted data.

A good decoding algorithm is critical to the success of any statistical machine translation system. The decoder's job is to find the translation that is most likely according to set of previously learned parameters (and a formula for combining them). Since the space of possible translations is extremely large, typical decoding algorithms are only able to examine a portion of it, thus risking to miss good solutions. In this paper, we compare the speed and output quality of a traditional stack-based decoding algorithm with two new decoders: a fast greedy decoder and a slow but optimal decoder that treats decoding as an integer-programming optimization problem.

This thesis describes the development and simulation of the newly proposed IEEE 802.11a physical layer and demonstrates the effects of Additive White Gaussian Noise (AWGN) and multipath on its performances. The IEEE 802.11a standardization group has selected Orthogonal Frequency Division Multiplexing (OFDM) as the basis for the new 5 GHz standard, targeting a range of data rates from 6 up to 54 Mbps. Coded OFDM (COFDM) is a channel coding and modulation scheme which mitigates the adverse effects of fading by using wideband multicarrier modulation combined with time interleaving and a convolutional error correcting code. A guard interval is inserted at the transition between successive symbols to absorb the intersymbol interference created by the time domain spread of the mobile radio channel. The decoding process is performed using differential demodulation in conjunction with a hard decision Viterbi decoder. The simulation results shown a COFDM system capable of indoor environment communications in the presence of known multipath and noise conditions. The results obtained also show that the COFDM configuration is immune to Doppler shift of 5 to 15 Hz.

Turbo code becomes popular for the next generation wireless communication systems because of its remarkable coding performance. One of the problems for decoding turbo code in the receiver is the complexity and the high power consumption since multiple iterations of Soft Output Viterbi Algorithm (SOVA) have to be carried out to decode a data frame. In this paper, we address the issues of reducing the complexity and power consumption of the turbo code decoder. An approach using cyclic redundancy checking (CRC) to adaptively terminate the SOVA iteration of each frame is presented. This results in system that has variable workload of which the amount of computation required for each data frame is different. Dynamic voltage scaling is then used to further reduce the power consumption. However, since the workload is not yet known at the time when the data is being decoded, optimum voltage assignment is not feasible. In this work, we propose two heuristic algorithms to assign supply voltage for different decoding iterations. Simulation results show that significant reduction of power consumption is achieved comparing with system using fixed supply voltage.

Transport Layer (OSI Layer 3) switching and routing provides routing flexibility but not high throughput. Link layer (OSI Layer 2) switching provides high throughput but not the routing flexibility needed to manage topology change and load fluctuations in the network. Neither Layer 3 routing nor Layer 2 switching protocols were originally designed to support confidentiality and integrity of data, and authentication of participants. Proposals to integrate security may have positive results for data confidentiality, integrity and authentication, but often result in additional overhead, increased transmission latency, and decreased throughput. An added difficulty is reconciling standards and protocols when integrating heterogeneous routing networks with homogenous switching networks while minimizing impact on throughput. This thesis examined current Internet extensions and architectures as well as IP security services and Layer 2 switching in IP-based networks. Requirements for a framework for a proposed security protocol include: Link Layer switching and routing; independence of particular communication protocols and standards; IP packet filtering and routing according to predetermined security policies and with no significant impact on throughput; and continued routing flexibility of IP. This security protocol, called Link Layer (Link Layer Packet Filtering (LLPF)), filters packets at the Link Layer, and boasts two innovations: use of an authentication trailer and multiple cryptographic keys with short cryptoperiods., Master's thesis.

This document describes the Software Requirement Specifications (SRS) and the Recommendations Software Specifications (RSS) for a Bit Analysis System (BIAS) for the Royal Dutch Army. This BIAS is a system to analyse intercepted long haul digital communications links. The SRS is developed according to MlL-STD-498. The resulting SRS shall be used to define and implement a BIAS or redefine an existing analysis program., Text in English. Summary in Dutch.

A switching arrangement is disclosed that interconnects a plurality of processors forming a multi-processor computer system. The switching arrangement comprises optical delay lines that cooperate with microwave switching devices to, provide high speed switching of data packets of the Multi-processor computer system. The optical delay lines temporarily store data packets for a sufficient time to allow for the contention resolution circuit to establish priority for any of the data packets that may be competing for a single source. The switching arrangement allows for the servicing of the data packets within a maximum of a few cycles of the clock rate of the computer system and a minimum of less than one clock cycle., Supersedes PAT-APPL-504 196-95.

The programmable logic array is one of the most fascinating and fast developing areas of technology. Field programmable gate arrays are becoming prevalent in design as the density of the gate arrays goes up. In this thesis study, a fast encoding/decoding algorithm, Extended Golay Coding, is implemented in Xilinx XC4000 family programmable gate array (FPGA) architecture. The encoder/decoder is designed using the Xilinx XACT tool with the Mentor Graphics schematic capture Design Architect (DA) and Quicksimll simulation interfaces. With the static RAM bits onboard the new Xilinx FPGAs, the architecture is more powerful, and it is relatively easy to upgrade the old design based on the needs of the users. In this thesis, fast encoder/decoder is implemented with transmission word redundancy and interleaving. This is based on the data link layer description of the Misted 181-144A. The FPGA static RAM bits are used for the encode and decode ROM of the algorithm that makes the coder faster. Modular approach and design hierarchy made design tasks easier and upgradable in this study. The timing simulations of some design modules will be presented. Due to the complexity of the circuits, it is found that the design has to be migrated to a higher density chip than X04003 used in the simulations.

A radar decoder circuit for converting NRZL Data to radar video data which is supplied to a radar video display screen. The radar video circuit includes an Erasable Programmable Logic Device which decodes incoming NRZL data to identify a frame sync having twenty four data bits. When the frame sync is identified the location of sixteen bits of synchro data is also determined. The synchro data is then latched into a latch within the Erasable Programmable Logic Device for processing by a Digital-to-Synchro Converter. Control signals for effecting a transfer of the synchro data to the Digital-W-Synchro Converter are provided by enable and latch signal generating circuit within the Erasable Programmable Logic Device. The Digital-to-Synchro Converter converts the digital synchro data to analog synchro signals which are supplied to the radar video display allowing the display to indicate the direction the radar from which the NRZL data is received is pointing. The Erasable Programmable Logic Device also includes a marker generating circuit which generates a ten kilometer marker pulse signal and a fifty kilometer marker pulse signal for-use by the radar video display as well as trigger pulse signal which is used as timing reference indicator by the radar video display., Supersedes PAT-APPL-552 455-95.

A decoder circuit for receiving a video input signal which includes Manchester coded data bits and a range tone component having a frequency of about 102.6 kilohertz. A phase lock loop circuit detects the presence of the 102.6 kilohertz range tone component and then generates a system clock signal which is phase locked to the range tone component of the video input signal. The system clock signal is provided to a clock generating circuit which generates a clock signal having four phases. The phase lock loop circuit also provides a logic signal which is supplied to a data detecting circuit allowing the data detecting circuit to convert the Manchester coded data bits to digital data bits., Supersedes PAT-APPL-242 399-94.

The NILE UHF fixed frequency waveform employs an RS (48,30) error control code with 8-bit characters. The code is used both to correct errors and to identify when the decoder has failed to produce a correct codeword. When this code is used on a memoryless binary symmetric channel, the probability of codeword error is 10(exp-5) when the channel bit error probability is 0.5%, and the probability of undetected decoder error is upper bounded by 2.8 (10-6) for all channel bit error probabilities. Synchronization acquisition, employing a 255-bit reference sequence, is far more tolerant to bit errors than the waveform itself. The probability of false synchronization in a random noise environment is less than 10(exp-6) when the correlator threshold is set at 90. With this threshold the probability of missed synchronization is less than 10(exp-6) for a 20% channel bit error probability. Synchronization performance is acceptable for truncated received sequences up to truncation levels of 50%.

An electronics circuit receives a sub frame of encoded doppler data having Groups One through N of data words with the first three words of Group N comprising a frame sync signal which is compared to a reference signal with a sync pulse being generated whenever the signals are identical. This sync pulse is supplied to three counters to load each counter with a predetermined count. The first counter counts the number of words in each Group; the second counter counts the number of Groups in a sub frame and the third counter indicates the location of Automatic Gain Control and Word Width data within the sub frame. Encoded within each group of a Sub Frame are one or mone clusters of doppler words with a fourth counter indicating the location of these clusters of doppler words. A word decoder circuit in response to a gain signal and a word width data signal decodes each word of each group of the sub frame having doppler data to extract the doppler data., Supersedes PAT-APPL-418 968-95.

This paper discusses the designs of the resistor loop phase shifter,input encoder, and output decoder used in a phase quantization digital radio frequency memories (DRFM), and analyzes the relationship between instantaneous bandwidth and sampling frequency of the phase quantization DRFM. The results show that the instantaneous bandwidth of the phase quantization DRFM is equal to, in numeral. the sampling frequency, which is the same as the I, Q double channel amplitude quantization DRFM., Trans. of Unknown Chinese Source p27-31 nd.