Dissertations / Theses on the topic 'Signal Modulation'

Advantages of optics over electronics in signal processing derive from the fact that many operations, such as addition, multiplication, correlation, and filtering, can be performed in parallel on two-dimensional data samples. However, this advantage is attainable only if information can be input/output or processed at sufficient speed and space bandwidth. Although acousto-optic devices have been used to provide impressive throughput, they are inherently one-dimensional and do not possess any information-storage capability beyond the acoustic transit time (≤50 μs). Hence, a high-resolution high-speed two-dimensional transducer (or spatial light modulator, SLM) with real-time update capability is required. Unfortunately, none of the existing SLMs perform well enough to fully utilize the inherent speed and parallelism of the optics. This dissertation addresses the development of an SLM that has the potential to meet most of the performance requirements of advanced optical information-processing applications--the photoemitter membrane light modulator (PEMLM). At the heart of the PEMLM is a microchannel plate (MCP) with a flexible membrane covering each pore. In operation, the write image incident on a photocathode, which is placed on the input side of the MCP, creates an electron image. This electron image is then amplified by the MCP and deposited onto the membrane array. The membrane elements, which are electrically and mechanically isolated from each other, are deflected by the induced electrostatic forces. These deflections represent the stored information. Readout of stored information is accomplished by sensing the phase changes induced in an optical-readout beam reflected from the deformed membrane array. A sandwich-type electrostatic grid structure positioned between the MCP and membrane greatly enhances the versatility of the PEMLM by facilitating the use of secondary emission for active electron removal and various intrinsic operations. The theoretical analysis and experimental characterizations performed on prototype devices indicates that PEMLM is capable of higher throughput than most other SLMs, with expected resolutions approaching 50 lp/mm over 10⁷ resolution elements and framing rates greater than 1 KHz. MCP gains provides quantum-limited sensitivity. The PEMLM also promises information-storage times of minutes to hours, greater than 2π phase modulation, good image quality, and an option for serial addressing. In addition, the PEMLM can intrinsically perform operations such as intensity thresholding, contrast modification, edge enhancement, binary logic, synchronous detection, and image addition/subtraction.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 125-127).
Analog RF phase modulation of optical signals has been a topic of interest for many years, mainly focusing on Intensity Modulation Direct Detection (IMDD). The virtues of coherent detection combined with the advantages of Frequency Modulation, however, have not been explored thoroughly. By employing Frequency Modulation Coherent Detection (FMCD), the wide optical transmission bandwidth of optical fiber can be traded for higher signal-to-noise performance. In this thesis, we derive the FM gain over AM modulation -- the maximum achievable signal-to-noise ratio (by spreading the signal's spectrum) for specific carrier-to-noise ratio. We then employ FMCD for a scheme of remote antennas for which we use optical components and subsystem to perform signal processing such as nulling of interfering signals. The performance of optical processing on different modulation schemes are compared, and some important conclusions are reported relating to the use of conventional FMCD, FMCD with optical discriminator (FMCD O-D), and IMDD. Specifically, the superiority of conventional FMCD is shown; and, on the other hand, the inferiority of FMCD O-D is shown (same performance as IMDD) because of the use of an O-D. Finally, the remote antenna scheme is generalized for N antennas and N users.
by Nikolas I. Andrikogiannopoulos.
S.M.

Överlagrad kommunikation är förmågan att kommunicera genom en elektrisk ledare vilken samtidigt fyller en annan funktion. För att upprätthålla kommunikationen krävs att en slags signalmodulering införs som kan slå samman information i ena änden av ledaren och urskilja samma information i den andra änden. I följande rapport kommer överlagrad kommunikation studeras för en matningsledare bestående av en DC-spänning, matningen spänningsätter en pulsgivare genom en kabel innehållande flera andra ledare. Mätningar har utförts på nuvarande system, både hur en typisk pulsgivare fungerar och hur dess installationskabel kan tänkas ha betydelse för slutresultatet. I en förstudie presenteras relevanta lösningsförslag på hur kommunikationen kan upprätthållas genom matningsledaren, förslagen med störst potential tas vidare genom att simuleringar och mätningar utförs. För att hitta de relevanta lösningarna undersöks grundläggande pulsgivarinformation tillsammans med en studie på den nuvarande marknaden. Till sist presenteras fördelar och nackdelar mellan tre olika kommunikationsexempel och tillsammans jämförs de med lösningen att dra en extra kabel vid installationen, framförallt är det prisskillnaden och platsen kretsarna tar som är av intresse. Eftersom beräkningskraftiga FPGA-kretsar var en tillgång som kunde utnyttjas skapades grunden till kommunikationen där, ingen programmering av dem beskrivs dock i rapporten. Slutgiltig lösning inkluderar kopplingen mellan en FPGA och installationskabeln. Resultatet är en robust och tillsynes säker FSK-kommunikation som har verifierats i simuleringar och fysiska uppkopplingar. Godtycklig data kan skapas i FPGA-kretsarna, skickas som halv-duplex och läsas i andra änden kabeln.

This thesis introduces a method by which low-frequency analog waveforms may be generated using delta-sigma modulation. The technique centers around a delta-sigma based oscillator which, with the exception of a continuous-time low-pass filter, is entirely digital and provides precise control over the oscillation frequency, amplitude, and phase. The incorporation of a delta-sigma modulator inside the resonator loop leads to an efficient implementation requiring 4 multi-bit adders, 4 delay elements, and a 2-input multiplexer. Two additional circuits, which generate multi-tone and piece-wise linear waveforms, are presented as extensions of the original single-tone design.
Prototypes of the proposed designs have been assembled using Field-Programmable Gate Array, and BiCMOS technologies. The test results have successfully verified the validity of the proposed concepts indicating dynamic ranges exceeding 80 dB and 60 dB for the single and multi-tone generators respectively.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Modulação Espacial é um método de transmissão por múltiplas antenas recentemente proposto,designado por MIMO-SIM, que associa informação à escola das antenas transmissoras. Isto possibilita a redução do número de cadeias de radiofrequência e, consequentemente, a imimplementação de sistemas de comunicação que consomem menos energia. O novo esquema de comunicação dos sistemas MIMO-SIM exige que, do lado redeptor, novas e eficientes estratégias de detecção do sinal transmitido sejam elaborados. O detector de máxima verossimilhança (ML), que fornece o desempenho ótimo, é de inviável implementação devido ao elevado custo computacional. Os detectores Sphere Decoding (SD) são comumente aplicados aos sistemas MIMO e atingem o desempenho ótimo a menor custo de computação. Um algoritmo SD que considera as caractéristicas do sinal SM foi desenvolvido, resultando em redução de custo computacional em relação ao detector ML e aos algoritmos SD convencionais. A elevada sensibilidade da complexidade dos algoritmos SD à variação da relação sinal-ruído (SNR) motivou o desenvolvimento de técnicas de detencção subótimas. Estratégias baseadas em detecção em grupos foram propostas, e os algoritmos de detecção aninhada MLA-M e MLA-C tiveram sua complexidade e desempenho avaliados em diferetes configurações e cenários de canal. Uma nova família de detectores, que realiza a detecção da combinação de antenas transmissoras e dos símbolos transmitidos em fases distintas, foi proposto, eo algoritmo List-BMP-LR-MMSE atingiu desempenho de detecção quase ótimo com baixo custo computacional, menos sensível à variação de SNR. Baseado na estratégia de detecção em duas fases, um novo detector de baixo custo foi desenvolvido para sistemas SM com codificação espácio-temporal.
Spatial Modulation is a recently proposed multiantenna transmission scheme, designated as SM-MIMO, that associates information to the transmit antenna selection, thus enabling the reduction of the number of radiofrequency chains and , consequently, the implementation of less power consuming communication systems. The novel SM-MIMO communication scheme requires, at the receiver side, the development of new and efficient signal detection strategies of the optimal performance, is infeasible to implement due to the high computational cost. Sphere Decoding detectors (SD) are customarily applied to MIMO systems and attain optimal performance with lower computational cost.An SD algorithm, tailored following SM signal characteristics was deloped, resulting in computational cost reduction compared to ML detector and conventional MIMO SD algorithms. The hogh computational sensitivity of SD algorithms to the signal-to-noise ratio (SNR) variation motivated the development of subboptimal detection techniques. Strategies based in group detection were propsed, and nested detection algorithms LA-M and MLA-C had their complexity and performance evaluated in different configurations and channel scenarios. A new family of detectors, that performs the detection of the transmit antenna combinations and the transmitted symbols in two distinct stages,was proposed, and List-BMP-LR-MMSE algorithm attained near -optimal detection performace with low computational complexity, less sensitive to SNR variation. Based on the two-stage detection strategy, a new low-complexity detector was developed to space-time coded SM systems.

Les systèmes mondiaux de navigation par satellite (GNSS) sont de plus en plus présents dansnotre vie quotidienne. Des nouveaux utilisateurs émergent avec des besoins opérationnelssupplémentaires, ce qui implique une évolution constante des systèmes de navigation actuels.Dans le cadre de Galileo (système GNSS européen) et en particulier dans Galileo E1 OpenService (OS), l’addition d’un nouveau signal d’acquisition pourrait contribuer à améliorer larésilience dans la phase d’acquisition et à réduire le temps pour géo-localiser notre récepteur(TTFF). La conception d'un nouveau signal GNSS est toujours un compromis entre plusieursfigures de mérite. Les plus pertinents sont la précision de la position, la sensibilité de récepteur etle TTFF. Cependant, si l’on considère que la phase d’acquisition du signal le principal objectif, lasensibilité et le TTFF ont une pertinence plus grande. Compte tenu de ce qui précède, dans cettethèse, il est présenté la conception conjointe d'un signal GNSS avec la structure de message afinde proposer un nouveau signal Galileo de deuxième génération, qui offre bonne sensibilité derécepteur ainsi que une réduction dans le TTFF. Plusieurs aspects ont été abordés afin deconcevoir la nouvelle composante de signal. Premièrement, la définition de la modulation doitprendre en compte la compatibilité des fréquences radioélectriques afin de provoquer un niveaude brouillage acceptable dans la bande. De plus, la modulation devrait fournir de bonnespropriétés de corrélation et une bonne résistance contre les multi trajets afin d'améliorer lasensibilité du récepteur. Deuxièmement, le choix du nouveau code PRN est également crucialpour faciliter la phase d’acquisition. Un critère de modélisation basé sur une fonction de coûtpondéré est utilisé pour évaluer la performance des codes PRN. Cette fonction de coût considèredifférent facteurs telles que l'autocorrélation, la corrélation croisée et la densité spectrale depuissance. Troisièmement, une conception conjointe entre la structure de message et le schémade codage de canal peut fournir à la fois une réduction du TTFF et une amélioration de larésilience des données décodées. Alors, une nouvelle méthode de conception de la structure demessage et du schéma de codage de canal pour le nouveau signal est proposée. Cette méthodefournit les instructions pour concevoir une structure de message dont le schéma de codage decanal est caractérisé pour les propriétés full diversity, maximum distance separable et ratecompatibility. Le codage de canal est essentiel pour améliorer les performances de démodulationde données, en particulier dans les environnements très obstrué ou avec d’interférences.Cependant, ce processus peut être très sensible au calcul correct de l'entrée du décodeur. Desaméliorations significatives ont été obtenues en considérant «soft » décodeurs, via le calcul deslog-likelihood ratio (LLR). Malheureusement, la connaissance complète des informations d'état ducanal (CSI) était généralement prise en compte, ce qui est rarement le cas dans des scénariosréels. Dans cette thèse, nous fournissons de nouvelles méthodes pour calculer desapproximations linéaires du LLR, sous les canaux de fading et interférence, en considérantcertaine information statistique sur le CSI. Finalement, transmettre un nouveau signal dans lamême fréquence porteuse et en utilisant le même amplificateur de puissance (HPA) génère descontraintes dans les méthodes de multiplexage, car une enveloppe constante ou quasi constanteest nécessaire pour réduire les distorsions non linéaires. Également, la conception dumultiplexage devrait offrir une efficacité énergétique élevée afin de ne pas gaspiller l'énergietransmis du satellite. Considérant le précédent, dans cette thèse, nous évaluons différentesméthodes de multiplexage, qui cherchent l’intégration de un nouveau signal binaire dans la bandeGalileo E1
Global Navigation Satellite System (GNSS) are present in our daily lives. Moreover, new users areemerging with further operation needs involving a constant evolution of the current navigationsystems. In the current framework of Galileo (GNSS European system) and especially within theGalileo E1 Open Service (OS), adding a new acquisition aiding signal could contribute to providehigher resilience at the acquisition phase, as well as to reduce the time to first fix (TTFF).Designing a new GNSS signal is always a trade-off between several performance figures of merit.The most relevant are the position accuracy, the sensitivity and the TTFF. However, if oneconsiders that the signal acquisition phase is the goal to design, the sensitivity and the TTFF havea higher relevance. Considering that, in this thesis it is presented the joint design of a GNSS signaland the message structure to propose a new Galileo 2nd generation signal, which provides ahigher sensitivity in the receiver and reduce the TTFF. Several aspects have been addressed inorder to design a new signal component. Firstly, the spreading modulation definition must considerthe radio frequency compatibility in order to cause acceptable level of interference inside the band.Moreover, the spreading modulation should provide good correlation properties and goodresistance against the multipath in order to enhance the receiver sensitivity and to reduce theTTFF. Secondly, the choice of the new PRN code is also crucial in order to ease the acquisitionphase. A simple model criterion based on a weighted cost function is used to evaluate the PRNcodes performance. This weighted cost function takes into account different figures of merit suchas the autocorrelation, the cross-correlation and the power spectral density. Thirdly, the design ofthe channel coding scheme is always connected with the structure of the message. A joint designbetween the message structure and the channel coding scheme can provide both, reducing theTTFF and an enhancement of the resilience of the decoded data. In this this, a new method to codesign the message structure and the channel coding scheme for the new G2G signal isproposed. This method provides the guideline to design a message structure whose the channelcoding scheme is characterized by the full diversity, the Maximum Distance Separable (MDS) andthe rate compatible properties. The channel coding is essential in order to enhance the datademodulation performance, especially in harsh environments. However, this process can be verysensitive to the correct computation of the decoder input. Significant improvements were obtainedby considering soft inputs channel decoders, through the Log Likelihood Ratio LLRs computation.However, the complete knowledge of the channel state information (CSI) was usually considered,which it is infrequently in real scenarios. In this thesis, we provide new methods to compute LLRlinear approximations, under the jamming and the block fading channels, considering somestatistical CSI. Finally, to transmit a new signal in the same carrier frequency and using the sameHigh Power Amplifier (HPA) generates constraints in the multiplexing design, since a constant orquasi constant envelope is needed in order to decrease the non-linear distortions. Moreover, themultiplexing design should provide high power efficiency to not waste the transmitted satellitepower. Considering the precedent, in this thesis, we evaluate different multiplexing methods,which search to integrate a new binary signal in the Galileo E1 band while enhancing thetransmitted power efficiency. Besides that, even if the work is focused on the Galileo E1, many ofthe concepts and methodologies can be easily extended to any GNSS signal

La demande de débit en augmentation constante requiert des canaux de communication fiables et robustes. Les réseaux optiques terrestres ainsi que les liens sous-marins représentent le cœur de l'infrastructure des télécommunications au niveau mondial, et transportent des centaines de canaux fréquentiels modulés à haut débit. Ces liens se composent non seulement de kilomètres de fibre mais aussi de composants optiques comme les amplificateurs à fibre dopée à l'erbium (EDFA) pour relever régulièrement la puissance des signaux atténués, ou encore des commutateurs sélectifs en longueur d'onde (WSS) qui routent le signal vers leur destination. Dans cette thèse, nous nous intéressons à une pénalité spécifique qui survient dans ces systèmes et qui réduit le débit d'information dans une propagation optique. Les composants optiques discrets présentent typiquement une anisotropie en polarisation : un déséquilibre de perte (ou gain) apparaît entre les deux polarisations d'un signal optique multiplexé en polarisation. Cet effet non unitaire appelé pertes dépendant de la polarisation (abrégé PDL en anglais) dégrade la qualité de transmission dans les systèmes optiques actuels et futurs.Dans le cadre des transmissions multiplexés en polarisation, nous caractérisons la perte de capacité induite par la PDL. Pour commencer, des modèles de canal sont attentivement étudiés et deux approches sont présentées : un canal avec des éléments PDL distribués avec un bruit également distribué, ou alors un canal équivalent simplifié en un seul élément. Nous analysons les limites fondamentales de communication associées à ces modèles. Nous montrons en outre que la capacité d'un canal PDL dépend en pratique de l'orientation de l'état de polarisation du signal incident. Nous passons ensuite en revue l'état de l'art de schémas de modulation atténuant l'effet de PDL puis nous proposons deux nouveaux schémas de modulation multi-dimensionnels qui augmentent la performance minimum et moyenne du canal. Ces deux modulations sont des transformations unitaires de symboles M-QAM qui n'utilisent pas de degrés de liberté autres que les quatre déjà utilisés pour chaque longueur d'onde (encodage en phase et quadrature de phase sur les deux états de polarisation). Nous proposons succinctement une extension de ces premiers résultats à des communications optiques plus généralement multiplexés en dimension spatiale et impactées par des pertes dépendantes de mode, qui présentent un déséquilibre de gain identique. Au-delà de la construction de modulations au niveau du transmetteur, nous étudions la perte de performance en présence de PDL d'une chaîne de traitement de signal conventionnelle et séquentielle par comparaison avec une égalisation et décodage joint. Cette perte additionnelle de capacité résultant du traitement séquentiel non optimal est évaluée pour différents formats de modulations ainsi que différents points de fonctionnement. Enfin, nous exposons une validation expérimentale des deux schémas de modulation proposés, aussi bien sur un élément de PDL seul ou sur un canal PDL distribué, et montrons comme attendu une robustesse augmentée vis-à-vis de la PDL
Large amounts of ever-increasing global data traffic require sound and reliable communication channels. Optical terrestrial networks and submarine links are at the very heart of the global telecom infrastructure, and carry hundreds of frequency channels modulated at very high rates. These links include not only kilometers of fiber but also optical elements such as Erbium-Doped Fiber-Amplifiers (EDFA) to amplify periodically the attenuated signals and Wavelength Selective Switches (WSS) to route the signals to their assigned destinations. In this thesis, we explore a specific rate-degrading impairment of the optical propagation that raises in those systems. Discrete optical elements often exhibit a polarization anisotropy that emerges as a gain or loss imbalance between the two polarization tributaries of the polarization-multiplexed optical signals. This non-unitary effect called Polarization Dependent Loss (PDL) impairs the quality of transmission in current and next-generation optical systems.In the context of polarization-multiplexed signals, we assess the capacity loss induced by PDL. First, channel models are carefully studied and two approaches are described: a channel with distributed PDL elements and distributed noise or a simplified single-element equivalent channel. Making use of these models, we then analyze their fundamental limits of communications. We show that the PDL channel capacity depends in practice on the state-of-polarization orientation of the incident signal. We then review the state-of-the art of PDL-mitigating modulation schemes and propose two new multi-dimensional signaling schemes that enhance worst-case and average performance. These two modulations are unitary transforms of M-QAM symbols and do not make use of additional degrees of freedom apart from the four already-used dimensions per wavelength (in-phase and quadrature channels of two polarization states). We briefly extend these first results to space-division-multiplexed optical communications impaired by mode dependent loss (MDL) that present a similar gain imbalance. Beyond signal shaping at the transmitter side, we study the performance loss of a conventional, sequential signal processing chain at the receiver side in presence of PDL, in comparison with a joint equalization-decoding scheme. The additional capacity loss due to the mismatch sequential processing is evaluated for several modulation formats and at different operating points. Finally, we report an experimental validation of the two proposed signaling schemes, both on a single PDL element and on a distributed PDL channel, demonstrating the predicted enhanced robustness to PDL

This work presents high-order, arbitrary-band delta-sigma oscillators. They are a class of digital circuits which, augmented with a minimum of analog circuitry requiring no trimming, generate fully programmable, high-quality analog sinusoidal signals. A generalization of previous work, they can meet arbitrary signal-band and SNR specifications at a minimum digital hardware cost, and without the previously reported stability problems. It is shown that multitone generation requires but simple modifications to the basic oscillator topology; this signal generation scheme is thus highly attractive for endowing mixed-signal integrated circuits and systems with self-test capabilities. Delta-sigma oscillators can be useful in other applications as well.
An essential building block of delta-sigma oscillators is a one-bit digital delta-sigma modulator with unity Signal-Transfer-Function. A complete, computer-aided design method, relying on a novel high-order modulator topology allowing the use of power-of-two coefficients, is formulated and justified. Although the resulting modulators are aimed specifically at usage in delta-sigma oscillators, they can find applications in oversampled D/A conversion in general as they require a minimal amount of digital hardware.
DSMOD is the computer-aided design tool which was developed to automate the design, simulation and prototyping processes. It implements a number of involved design algorithms, and allows for a quick comparison of theoretical, simulated and prototype behavior, with the use of a graphical user interface. It is written mostly for MATLAB and is thus highly portable and expandable.
The measurements performed on prototypes prove the soundness, flexibility and efficiency of DSMOD. They also prove that low hardware cost and high performance levels are attainable with the novel delta-sigma modulator and oscillator topologies presented here.

Aspects of modern communication systems is the overall theme of this thesis with emphasis placed on multicarrier modulation. The work considers four facets of such systems; namely duplexing design, interference mitigation, channel estimation and multiuser detection. The first area deals with duplexing design for very high bit rate digital subscriber lines (VDSL) using discrete multitone modulation (DMT). We present a novel method based on DMT - the Zipper duplex method. Zipper is proposed for VDSL in different standardization bodies worldwide - International (ITU), North America (ANSI) and in Europe (ETSI) where it also has been accepted as a part of the VDSL standard. Zipper has superior flexibility and spectrum efficiency. This is obtained by freely assigning different subcarriers for the up- and downstream direction. In one design Zipper operates fully network synchronized by using a masterclock. In an asynchronous design Zipper operates without any reference to a masterclock which is a requirement for unbundled networks but reduces some of the flexibility. To obtain highest flexibility in unbundled networks, without using a masterclock, an algorithm is derived that self-synchronizes all Zipper modems. Another area deals with interference- and distortion mitigation. Narrowband interference (NBI) in orthogonal frequency division multiplexing- (OFDM) and DMT-based systems is considered. NBI can be very harmful for both radio- and wireline systems. We introduce two efficient NBI cancellers for OFDM and DMT. One canceller is based on a deterministic polynomial model of the NBI. The other canceller models it as a narrowband stochastic process and use the linear minimum mean square error (LMMSE) criterion for the cancellation. We lower its complexity by using the theory of optimal rank reduction. Impulse noise is a different type of harmful interference that can be encountered in VDSL. In this thesis we study the effects of impulse noise in DMT-based VDSL systems and present a robust generalized likelihood ratio test for detecting impulse noise. It is used for obtaining reliable erasures in a Reed-Solomon decoding scheme which reduces the probability of symbol errors significantly. Pilot symbol assisted modulation (PSAM) can be used in OFDM for tracking the distortion variations in a fading radio channel. We analyze the pilot symbol spacing in PSAM as a trade-off between high effective SNR and good channel tracking capabilities for two channel estimators with different complexities. Code division multiple access (CDMA) is part of the standard for the third generation of mobile phones. In this thesis we present a low complexity multiuser detector for a wireless DS-CDMA system. With a pipelined structure it can produce maximum likelihood sequence detector (MLSD) decisions on many of the received bits by only performing additions after the front end matched filters.
Godkänd; 2001; 20061113 (haneit)

Thesis (M.S.)--Missouri University of Science and Technology, 2008.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed February 13, 2008) Degree granted by Missouri University of Science and Technology, formerly known as University of Missouri--Rolla. Includes bibliographical references (p. 44-45).

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 1990.
Thesis Advisor(s): Moose, P. H. Second Reader: Christi, R. "September 1990." Description based on title screen as viewed on March 22, 2010. DTIC Identifier(s): Amplitude Modulation. Author(s) subject terms: Facsimile, MFM, Communications. Includes bibliographical references (p. 43-44). Also available in print.

Signal detection and modulation classification are becoming increasingly important in a variety of wireless communication systems such as those involving spectrum management and electronic warfare and surveillance, among others. The majority of the signal detection and modulation classification algorithms available in the literature assume that the additive noise has a Gaussian distribution. However, while this is a good model for thermal noise, various studies have shown that the noise experienced in most radio channels, due to a variety of man-made and natural electromagnetic sources, is non-Gaussian and exhibits impulsive characteristics. Unfortunately, conventional signal processing algorithms developed for Gaussian noise conditions are known to perform poorly in the presence of non-Gaussian noise. For this reason, the main goal of this dissertation is to develop statistical signal processing algorithms for the detection and modulation classification of signals in radio channels where the additive noise is non-Gaussian. One of the major challenges involved in the design of these algorithms is that they are expected to operate with limited or no prior knowledge of the signal of interest, the fading experienced by the signal, and the distribution of the noise added in the channel. Therefore, this dissertation develops new techniques for estimating the parameters that characterize the additive non-Gaussian noise process, as well as the fading process, in the presence of unknown signals. These novel estimators are an integral contribution of this dissertation. The signal detection and modulation classification problems considered here are treated as hypothesis testing problems. Using a composite hypothesis testing procedure, the unknown fading and noise process parameters are first estimated and then used in a likelihood ratio test to detect the presence or identify the modulation scheme of a signal of interest. The proposed algorithms, which are developed for different non-Gaussian noise models, are shown to outperform conventional algorithms which assume Gaussian noise conditions and also algorithms based on other impulsive noise mitigation techniques. This dissertation has three major contributions. First, in environments where the noise can be modeled using a Gaussian mixture distribution, a new expectation-maximization algorithm based technique is developed for estimating the unknown fading and noise distribution parameters. Using these estimates, a hybrid likelihood ratio test is used for modulation classification. Second, a five-stage scheme for signal detection in symmetric α stable noise environments, based on a class of robust filters called the matched myriad filters, is presented. New algorithms for estimating the noise distribution parameters are also developed. Third, a modulation classifier is proposed for environments in which the noise can be modeled as a time-correlated non-Gaussian random process. The proposed classifier involves the use of a whitening filter followed by likelihood-based classification. A new H_â filter-based technique for estimating the whitening filter coefficients is presented.
Ph. D.

In this thesis, the use of subbanding and sigma-delta modulation in interference/noise cancellation is intensively studied and a sigma-delta modulated subbanded adaptive interference/noise cancellation system is proposed. The filter bank is fully sigma-delta modulated. The output signal from the filter bank is then used to produce the input to the adaptive filter. The adaptive filter is partially sigma-delta modulated. The output is demodulated at the final stage. Maintaining the sigma-delta modulated signal representation throughout the system results in considerable savings in complexity. The performance of the proposed system is studied and compared to the regular non sigma-delta modulated case regarding complexity, convergence speed and steady state error. The effect of the oversampling rate used in the sigma-delta modulation as well as the quality of the demodulator is also considered. It is shown that in the case of interference cancellation a comb filter is sufficient, while in the case of noise canceller a good quality demodulator is essential. The thesis concludes by highlighting the tradeoffs between the hardware complexity reduction and the overall system performance.

The means by which the dietary cancer chemopreventive agents, curcumin, epigallocatechin-3-gallate (EGCG) and indole-3-carbinol (I3C) inhibit growth of human breast cell lines was investigated by examining their effects on various signal transduction pathways. Curcumin inhibited the growth of HBL 100, T47D and MDA 468 cell lines to a similar extent (IC50 5M), while EGCG and I3C were most effective against the MDA 468 line (IC50 10M and 40M respectively). Curcumin inhibited epidermal growth factor (EGF)-stimulated phosphorylation of the EGF receptor (EGFR) in MDA 468 cells, phosphorylation and activity of extracellular regulated kinases (ERK) 1 and 2 in all three cell lines and Akt phosphorylation induced by several agents in HBL 100 cells. Curcumin inhibited the ability of anisomycin to activate c-jun N terminal kinase (JNK) and MAPK kinase 4 (MKK4), although it did not inhibit activation of p38. Further studies suggested that the target curcumin upstream of JNK may lie at the MAPK kinase kinase (MEKK) level. EGCG did not inhibit EGFR or ERK phosphorylation. Instead an increase in phosphorylation was observed. Nor did this agent inhibit JNK activity in pre-treated cells, although inhibition was observed when it was added directly to the assay. Similarly EGCG was a potent inhibitor of p38 activity in vitro, but did not affect its ability to activate the downstream kinase MAPK activating protein kinase-2 (MAPKAP K2) when added to cells. I3C had no effect on ERK phosphorylation, JNK or p38 activity. The global effect of curcumin treatment (10M) on transcription was investigated using cDNA microarrays. Several genes were shown to be affected, including downregulation of a number of matrix metalloproteinases.

Approved for public release; distribution is unlimited.
Algorithms for blind equalization and data recovery of orthogonal frequency-division multiplexed (OFDM) signals transmitted through fading channels are implemented and simulated in this thesis. The channel is estimated without knowledge of the transmitted sequence (i.e., blindly) using a least mean squares (LMS) adaptive filter and filter bank precoders. This method was used to estimate channel characteristics using both binary and quadrature phase-shift keying signals. Additionally, the method was analyzed for robustness with a poor initial estimate of channel characteristics, with the addition of white Gaussian noise to the signal, and with non-stationary channel conditions. In addition, it is shown that the proposed method is particularly suited in situations with deep fading channels, where some of the subcarriers have a very low SNR. Simulations for both aspects of this thesis were conducted using MATLAB, and the results are presented.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.
Includes bibliographical references (p. 119-121).
by Wade Patrick Torres.
M.S.

Present trends in communication links between devices have opted for wireless instead of wired solutions. As a consequence, unlicensed bands have seen a rise in the interference level as more and more devices are introduced into the market place that take advantage of these free bands for their communication needs. Under these conditions, the receiver's ability to recognize and identify the presence of interference becomes increasingly important. In order for the receiver to make an optimal decision on the signal-of-interest, it has to be aware of the type (modulation) of interference as well as how the received signals are affected (channel) by these impediments in order to appropriately mitigate them. This dissertation addresses the blind (unaided) identification of the signal modulations and the channel in a Multiple Input Multiple Output (MIMO) system. The method presented herein takes advantage of the modulation induced periodicities of the signals in the system and uses higher-order cyclostationary statistics to extract the signal and channel unknowns. This method can be used to identify more signals in the system than antenna elements at the receiver (overloaded case). This dissertation presents a system theoretic analysis of the problem as well as describes the development of an algorithm that can be used in the identification of the channel and the modulation of the signals in the system. Linear and non-linear receivers are examined at the beginning of the manuscript in order to review the a priori information that is needed for each receiver configuration to function properly.
Ph. D.

[ES] Los sistemas de transmisión óptica no-coherente se emplean actualmente en las redes ópticas de corto alcance (< 80 km), como son las redes de ámbito metropolitano. La implementación más común en el estado del arte se basa en sistemas que emplean multiplexación por división en longitud de onda (WDM, wavelength division multiplexing) de cuatro longitudes de onda (¿) proporcionando un régimen binario de 100 Gbps (4¿×25 Gbps). En los últimos años, los sistemas de transmisión ópticos no-coherentes están evolucionando desde 100 Gbps a 400 Gbps (4¿×100 Gbps). Dado que este mercado comprende un gran número de sistemas, el coste es un parámetro importante que debe ser lo más bajo posible. El objetivo de esta tesis es investigar distintos aspectos del procesado de señal en general y, específicamente, investigar nuevas técnicas de procesado digital de señal (DSP, digital signal processing) que puedan ser utilizadas en sistemas de transmisión óptica no-coherentes empleando la modulación por amplitud de pulsos (PAM, pulse-amplitude modulation). Para que una técnica DSP sea interesante en el contexto de una red óptica WDM no-coherente, esta debe mitigar de manera efectiva al menos una de las tres limitaciones principales que afectan a estos sistemas: limitaciones de ancho de banda, limitaciones por dispersión cromática (CD), y el ruido. En esta tesis se proponen y examinan una serie de algoritmos cuyo su rendimiento es analizado mediante simulación y experimentalmente en laboratorio: - Feed-forward equalizer (FFE): este es el esquema de ecualización más común que se emplea principalmente en las transmisiones ópticas no-coherentes de alto régimen binario. Puede compensar grandes limitaciones en el ancho de banda. - Estimación de la secuencia de máxima verosimilitud (MLSE): el MLSE es un detector óptimo y, por lo tanto, proporciona las mejores prestaciones en detección cuando se abordan las limitaciones por CD y de ancho de banda. - Conformación geométrica de la constelación: en los esquemas de modulación de intensidad óptica multinivel, la distancia entre los niveles de amplitud puede ajustarse adecuadamente (de manera que no son equidistantes) a fin de aumentar la tolerancia de la señal frente al ruido. - Conformación probabilística: técnica diseñada específicamente para esquemas de modulación multinivel. Esta técnica ajusta la probabilidad de cada nivel de amplitud de modo que se incrementa la tolerancia al ruido óptico. - Señalización de respuesta parcial (PRS, partial signaling response): este es un enfoque basado en DSP donde una interferencia entre símbolos (ISI, inter-symbol interference) controlada es introducida intencionalmente de tal manera que la señal resultante requiere menos ancho de banda. La técnica PRS puede adaptarse para combatir también el efecto de CD. - Pre-énfasis digital (DPE, digital pre-emphasis): esta técnica consiste en aplicar el inverso de la función de transferencia del sistema a la señal en el transmisor, lo que reduce el impacto de las limitaciones de ancho de banda en el receptor. - Modulación con codificación Trellis (TCM, Trellis-coded modulation): esquema de modulación que combina elementos de corrección de errores (FEC, forward error correction) con técnicas de partición en conjuntos y modulación multidimensional para generar una señal más resistente al ruido. - Modulación multidimensional por partición en conjuntos: muy similar a TCM, pero sin ningún elemento FEC. Tiene menos ganancias que TCM en términos de tolerancia al ruido, pero no es tan sensible al ISI. Utilizando estas técnicas, esta tesis demuestra que es posible lograr una transmisión óptica con régimen binario de 100 Gbps/¿ empleando componentes de bajo coste. En esta tesis también demuestra regímenes binarios de más de 200 Gbps, lo que indica que la transmisión óptica no-coherente con modulación PAM puede ser una solución viable y eficiente en coste
[CAT] Actualment, s'utilitzen sistemes òptics no coherents en xarxes òptiques de curt abast ( < 80 km), com són les xarxes d'àmbit metropolità. La implementació més comuna que podem trobar en l'estat de l'art es correspon amb sistemes emplenant multiplexació per divisió en longitud d'ona (WDM, wavelength division multiplexing) de quatre longituds d'ona (¿) proporcionant un règim binari de 100 Gbps (4¿×25 Gbps). En els últims anys, els sistemes de transmissió òptica no-coherents han evolucionat des de 100 Gbps cap a 400 Gbps (100 Gbps/¿). Atès que el mercat de sistemes de curt abast compren un gran volum de dispositius òptics instal·lats, el cost unitari és molt important i ha de ser el més baix possible. L'objectiu d'aquesta tesi és analitzar aspectes del processament de senyal en general i, específicament, investigar noves tècniques de processament digital de senyal (DSP, digital signal processing) que puguen ser utilitzades en sistemes de transmissió òptica no-coherent que utilitzen la modulació per amplitud d'impulsos (PAM, pulse-amplitude modulation). Per tal que una tècnica DSP es considere interessant per a una xarxa òptica WDM no-coherent, aquesta ha de mitigar efectivament almenys una de les tres principals limitacions que afecten aquests sistemes: limitacions d'ample de banda, limitacions per dispersió cromàtica (CD), i el soroll. En aquesta tesi s'examinen una sèrie d'algoritmes, el seu rendiment s'analitza per simulació i experimentalment en laboratori: - Feed-forward equalizer (FFE): aquest és l'esquema d'equalització més comú i s'utilitza bàsicament en les transmissions òptiques no coherents d'alt règim binari. Pot compensar grans quantitats de limitacions d'ample de banda. - Estimació de la seqüència de probabilitat màxima (MLSE): el MLSE és un detector òptim i, per tant, proporciona el millor rendiment quan es tracta de limitacions d'ample de banda i de CD. - Conformació geomètrica de la constel·lació: en esquemes de modulació òptica d'intensitat multinivell es pot ajustar la distància entre els nivells d'amplitud (de manera que ja no són equidistants) per augmentar la tolerància del senyal al soroll. - Conformació probabilística: una tècnica dissenyada específicament per als esquemes de modulació multinivell; ajusta la probabilitat de cada nivell d'amplitud de manera que augmenta la tolerància al soroll òptic. - Senyalització de resposta parcial (PRS, partial signaling response): és un enfocament basat en DSP on la interferència entre símbols (ISI, inter-symbol interference) controlada s'introdueix intencionalment de manera que el senyal resultant requereix menys ample de banda. La tècnica PRS es pot adaptar per combatre els efectes del CD. - Pre-èmfasi digital (DPE, digital pre-emphasis): aquesta tècnica consisteix a aplicar la inversió de la funció de transferència del sistema a la senyal en el transmissor de manera que es redueix l'impacte de les limitacions d'ample de banda en la senyal en el receptor. - Modulació amb codificació Trellis (TCM, Trellis-coded modulation): esquema de modulació que combina els elements de correcció d'errors avançats (FEC, forward error correction) amb tècniques de partionament de conjunts i modulació multidimensional per generar un senyal més resistent al soroll. - Modulació multidimensional per partició en conjuntes: molt similar a TCM però sense elements FEC. Té guanys menors que TCM en termes de tolerància al soroll, però no és tan sensible a l'ISI. Mitjançant l'ús d'aquestes tècniques, aquesta tesi demostra que és possible aconseguir una transmissió òptica amb un règim binari de 100 Gbps/¿ utilitzant components de baix cost. Esta tesi també demostra règims binaris de més de 200 Gbps, el que indica que la tecnologia no-coherent amb modulació PAM és una solució viable i eficient en cost per a una nova generació de sistemes transceptors òptics WDM funcionant a 800 Gbps (4¿×200 G
[EN] Non-coherent optical transmission systems are currently employed in short-reach optical networks (reach shorter than 80 km), like metro networks. The most common implementation in the state-of-the-art is the four wavelength (¿) 100 Gbps (4¿×25 Gbps) wavelength division multiplexing (WDM) transceiver. In recent years non-coherent optical transmissions are evolving from 100 Gbps to 400 Gbps (4¿×100 Gbps). Since in the short-reach market the volume of optical devices being deployed is very large, the cost-per-unit of the devices is very important, and it should be as low as possible. The goal of this thesis is to investigate some general signal processing aspects and, specifically, digital signal processing (DSP) techniques required in non-coherent pulse-amplitude modulation (PAM) optical transmission, and also to investigate novel algorithms which could be applied to this application scenario. In order for a DSP technique to be considered an interesting solution for non-coherent WDM optical networks it has to effectively mitigate at least one of the three main impairments affecting such systems: bandwidth limitations, chromatic dispersion (CD) and noise (in optical or electrical domain). A series of algorithms are proposed and examined in this thesis, and their performance is analyzed by simulation and also experimentally in the laboratory: - Feed-forward equalization (FFE): this is the most common equalizer and it is basically employed in every high-speed non-coherent optical transmission. It can compensate high bandwidth limitations. - Maximum likelihood sequence estimation (MLSE): the MLSE is the optimum detector and thus provides the best performance when it comes to dealing with CD and bandwidth limitations. - Geometrical constellation shaping: in multilevel optical intensity modulation schemes the distance between amplitude levels can be adjusted (such that they are no longer equidistant) in order to increase the signal's tolerance to noise. - Probabilistic shaping: another technique designed specifically for multilevel modulation schemes; it adjusts the probability of each amplitude level such that the tolerance to optical noise is increased. - Partial response signaling (PRS): this is a DSP-based approach where a controlled inter-symbol interference (ISI) is intentionally introduced in such a way that the resulting signal requires less bandwidth. PRS can be customized to also mitigate CD impairment, effectively increasing transmission distances up to three times. - Digital pre-emphasis (DPE): this technique consists in applying the inverse of the transfer function of the system to the signal at the transmitter side which reduces the impact of bandwidth limitations on the signal at the receiver side. - Trellis-coded modulation (TCM): a modulation scheme that combines forward error correction (FEC) elements with set-partitioning techniques and multidimensional modulation to generate a signal that is more resistant to noise. - Multidimensional set-partitioned modulation: very similar with TCM but without any FEC elements. It has lower gains than TCM in terms of noise tolerance but is not so sensitive to ISI. By using the techniques enumerated above, this thesis demonstrates that is possible to achieve 100 Gbps/¿ optical transmission bitrate employing cost-effective components. Even more, bitrates higher than 200 Gbps are also demonstrated, indicating that non-coherent PAM is a viable cost-effective solution for next-generation 800 Gbps (4¿×200 Gbps) WDM transceivers.
Prodaniuc, C. (2019). Advanced Signal Processing for Pulse-Amplitude Modulation Optical Transmission Systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/117315
TESIS

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 1990.
Thesis Advisor(s): Moose, P. H. Second Reader: Terman, F. W. "June 1990." Description based on title screen as viewed on October 19, 2009. DTIC Descriptor(s): Signal processing, input, control, industries, real time, computers, signal to noise ratio, rates, coding, receivers, errors, data acquisition, vector analysis, throughput, microcomputers, data rate, modulation, data processing equipment, decoding, plug in units, frequency DTIC Indicator(s): Packet communications, frequency modulation, program listings, signal to noise ratio. Author(s) subject terms: MFM, Differential encoding, D16QAM Includes bibliographical references (p. 68). Also available in print.

Automatic modulation classification detects the modulation type of received communication signals. It has important applications in military scenarios to facilitate jamming, intelligence, surveillance, and threat analysis. The renewed interest from civilian scenes has been fuelled by the development of intelligent communications systems such as cognitive radio and software defined radio. More specifically, it is complementary to adaptive modulation and coding where a modulation can be deployed from a set of candidates according to the channel condition and system specification for improved spectrum efficiency and link reliability. In this research, we started by improving some existing methods for higher classification accuracy but lower complexity. Machine learning techniques such as k-nearest neighbour and support vector machine have been adopted for simplified decision making using known features. Logistic regression, genetic algorithm and genetic programming have been incorporated for improved classification performance through feature selection and combination. We have also developed a new distribution test based classifier which is tailored for modulation classification with the inspiration from Kolmogorov-Smirnov test. The proposed classifier is shown to have improved accuracy and robustness over the standard distribution test. For blind classification in imperfect channels, we developed the combination of minimum distance centroid estimator and non-parametric likelihood function for blind modulation classification without the prior knowledge on channel noise. The centroid estimator provides joint estimation of channel gain and carrier phase o set where both can be compensated in the following nonparametric likelihood function. The non-parametric likelihood function, in the meantime, provide likelihood evaluation without a specifically assumed noise model. The combination has shown to have higher robustness when different noise types are considered. To push modulation classification techniques into a more timely setting, we also developed the principle for blind classification in MIMO systems. The classification is achieved through expectation maximization channel estimation and likelihood based classification. Early results have shown bright prospect for the method while more work is needed to further optimize the method and to provide a more thorough validation.

Cognitive Radio (CR) is an emerging wireless communications technology that addresses the inefficiency of current radio spectrum usage. CR also supports the evolution of existing wireless applications and the development of new civilian and military applications. In military and public safety applications, there is no information available about the signal present in a frequency band and hence there is a need for a CR receiver to identify the modulation format employed in the signal. The automatic modulation classifier (AMC) is an important signal processing component that helps the CR in identifying the modulation format employed in the detected signal. AMC algorithms developed so far can classify only signals from a single user present in a frequency band. In a typical CR scenario, there is a possibility that more than one user is present in a frequency band and hence it is necessary to develop an AMC that can classify signals from multiple users simultaneously. One of the main objectives of this dissertation is to develop robust multiuser AMC's for CR. It will be shown later that multiple antennas are required at the receiver for classifying multiple signals. The use of multiple antennas at the transmitter and receiver is known as a Multi Input Multi Output (MIMO) communication system. By using multiple antennas at the receiver, apart from classifying signals from multiple users, the CR can harness the advantages offered by classical MIMO communication techniques like higher data rate, reliability, and an extended coverage area. While MIMO CR will provide numerous benefits, there are some significant challenges in applying conventional MIMO theory to CR. In this dissertation, open problems in applying classical MIMO techniques to a CR scenario are addressed. A blind equalizer is another important signal processing component that a CR must possess since there are no training or pilot signals available in many applications. In a typical wireless communication environment the transmitted signals are subjected to noise and multipath fading. Multipath fading not only affects the performance of symbol detection by causing inter symbol interference (ISI) but also affects the performance of the AMC. The equalizer is a signal processing component that removes ISI from the received signal, thus improving the symbol detection performance. In a conventional wireless communication system, training or pilot sequences are usually available for designing the equalizer. When a training sequence is available, equalizer parameters are adapted by minimizing the well known cost function called mean square error (MSE). When a training sequence is not available, blind equalization algorithms adapt the parameters of the blind equalizer by minimizing cost functions that exploit the higher order statistics of the received signal. These cost functions are non convex and hence the blind equalizer has the potential to converge to a local minimum. Convergence to a local minimum not only affects symbol detection performance but also affects the performance of the AMC. Robust blind equalizers can be designed if the performance of the AMC is also considered while adapting equalizer parameters. In this dissertation we also develop Single Input Single Output (SISO) and MIMO blind equalizers where the performance of the AMC is also considered while adapting the equalizer parameters.
Ph. D.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California
This paper describes some of the signal conditioning and processing circuits that were developed to reconstruct the doppler video signal from a radar receiver under test. The reconstructed doppler video signal is then digitized and put into a telemetry frame for transmission to a ground receiving station.

Modulation classification of digital communications signals plays an important role in both military and civilian sectors. It has the potential of replacing several receivers with one universal receiver. An automatic modulation classifier can be defined as a system that automatically identifies the modulation type of the received signal given that the signal exists and its parameters lie in a known range. This thesis addresses the need for a universal modulation classifier capable of classifying a comprehensive list of digital modulation schemes. Two classification approaches are presented: a decision-theoretic (DT) approach and a neural network (NN) approach. First classifiers are introduced that can classify ASK, PSK, and FSK signals. A decision tree is designed for the DT approach and a NN structure is formulated und trained to classify these signals. Both classifiers use the same key features derived from the intercepted signal. These features are based on the instantaneous amplitude, instantaneous phase, and instantaneous frequency of the intercepted signal, and the cumulates of its complex envelope. Threshold values for the DT approach are found from the minimum total error probabilities of the extracted key features at SNR of 20 to -5dB. The NN parameters are found by training the networks on the same data. The DT and NN classifiers are expanded to include CPM signals. Signals within the CPM class are also added to the classifiers and a separate decision tree and new NN structure are found far these signals. New key features to classify these signals are also introduced. The classifiers are then expanded further to include multiple access signals, followed by QAM, PSK8 and FSK8 signals. New features arc found to classify these signals. The final decision tree is able to accommodate a total of fifteen different modulation types. The NN structure is designed in a hierarchical fashion to optimise the classification performance of these fifteen digital modulation schemes. Both DT and NN classifiers are able to classify signals with more than 90% accuracy in the presence of additive white Gaussian within SNR ranging from 20 to 5dB. However, the performance of the NN classifier appears to be more robust as it degrades gradually at the SNRs of 0 and -5dB. At -5dB, the NN has an overall accuracy of 73.58%, whereas the DT classifier achieves only 47.3% accuracy. The overall accuracy of the NN classifier, over the combined SNR range of 20 to -5dB, is 90.7% compared to 84.56% for the DT classifier. Finally, the performances of these classifiers are tested in the presence of Rayleigh fading. The DT and NN classifier structures are modified to accommodate fading and again, new key features are introduced to accomplish this. With the modifications, the overall accuracy of the NN classifier, over the combined SNR range of 20 to -5dB and 120Hz Doppler shift, is 87.34% compared to 80.52% for the DT classifier.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada
Caterpillar Inc. has been testing construction and mining equipment using Computerized Analysis Vans for two decades. During our latest van upgrade, we chose to move to PCM/FM from FM/FM mainly to increase the channel count. We also replaced our old signal conditioning that used span and balance potentiometers with computer programmable signal conditioning. This new signal conditioning requires that the gain and balance point be calculated for every channel on each test. The formulas for these calculations depend on the sensor, the signal conditioning card used, and the test requirements. Due to the number and variety of machines tested at the Caterpillar Proving Grounds, these calculations needed to be automated. Using a few initial parameters and the information from our sensor calibration database, each channel’s balance point, gain, and expected slope are calculated. This system has increased productivity, accuracy, and consistency over manually calculating these parameters. This paper covers the sensor database, the calculated parameters and an overview of the way the system works.

Les moderms VDSL (Very high rateDigital Subscriber Line) sont la dernière génération de modems à haut débit (jusqu'à 50 Mb/s) utilisant comme support physique de transmission la ligne téléphonique et succèdent aux modems ADSL (Asymetric Digital Subscriber Line). Ces types de modems utilisent tous deux une modulation multiporteuse : la modulation DMT (Discrete Multi-Tone) pour communiquer entre eux. L'objectif de ce travail est la présentation de la modulation DMT appliquée à la technologie VDSL et l'étude de nouveaux algorithmes de traitement numérique du signal en modulation multiporteuse permettant d'améliorer les performances des modems VDSL en terme de débit ou de complexité algorithmique. Après avoir introduit les dispositifs numériques d'émission et de réception d'un signal DMT utilisé en technologie VDSL, nous listerons les principaux bruits d'un système VDSL en indiquant à chaque fois les méthodes classiques permettant d'annuler ou au moins de limiter leurs impacts sur les performances du mode. On présentera alors la technique dite "Zipper" permettant une très grande flexibilité dans l'allocation des bandes de fréquences affectées aux sens montant et descendant. Lorsque plusieurs lignes téléphoniques sont regroupées dans un même câble, il se crée un bruit provenant des utilisateurs partageant le câble, appelé diaphonie. Ces perturbations étant un des principaux facteurs limitant les performances d'un modem VDSL, la suite de ce travail sera consacrée à la présentation de procédés innovants d'annulation d'écho et de diaphonies permettants d'améliorer de façon significative les performances du modem. Ce travail s'achèvera par l'étude d'une modulation multiporteuse filtrée apelée FMT (Filtered Multi-Tone) dont la particularité est de permettre une meilleure indépendance spectrale entre les porteuses. On s'intéressera à l'optimisation conjointe des filtres d'émission-réception et des coefficients d'égalisation d'un système de communication FMT.

The proliferation of products from the consumer electronics industry (especially the communications market) has led to increasing consumer demand for cheaper, smaller form factor, efficient and low power consumption products with high computation power. This growing demand for cheaper and more efficient products has made it more desirable for Integrated Circuit (IC) manufacturers to integrate both analogue and digital circuits on the same silicon substrate in order to realise high performance mixed-signal IC's at cost effective prices. The concomitant technology advancements in the IC manufacturing process, especially in the Complementary Metal Oxide Semiconductor (CMOS) process and improvements made in the capabilities of Computer-Aided Design (CAD) tools is making greater system integration possible. However, one aspect of the process that is the bottleneck of yet further system integration and lower design lead time is test. While the digital sections of mixed-signal IC's are taking microseconds to test using well established digital structural test techniques which exploit efficient Design for Test (DFT) structures, the analogue sections are still being tested using functional test methods and consequently consume several seconds of expensive test time. The work presented in this thesis addresses the test problems associated with the analogue sections of mixed-signal IC's. Specifically, the work was aimed at developing an efficient and unified embedded mixed-signal test system capable of being adopted for both analogue circuit characterisation and production testing of mixed-signal IC's in order to reduce overall test time and cost. In this context, an Analogue Test Response Compaction Technique (ATRCT) has been developed using Delta-Sigma Modulation (AIM). This compaction technique produces a signature for an analogue macro under test, which relates to both the amplitude and frequency of the analogue output response. Fault simulation results relating to a two-stage CMOS operational amplifier and continuous-time state variable filter have shown that fault-coverage of greater than 80% is attainable when the ATRCT is employed in a production testing of linear analogue macros. Based on the ATRCT, a hardware efficient Analogue Built-In Selt-Test (ABIST) scheme is proposed. This work has also developed two characterisation techniques suitable for embedded linear analogue macros: 1) An alternative hardware efficient method of measuring the impulse response of linear analogue macros using AIM, which could be conveniently incorporated in an ABIST scheme. Simulation results of the AIM-based impulse response measurement system have shown that the accuracy of the technique is within ±0.5% of the expected impulse responses. 2) An analogue fault detection routine that uses AIM and correlation techniques to detect analogue amplitude and frequency faults within linear analogue macros. Combining the proposed AIM-based impulse response measurement technique with the proposed ABIST scheme or analogue fault detection routine will enable an efficient and unified embedded mixed-signal test system to be designed.

Au cours de cette thèse, nous avons mis en place un système de reconnaissance de modulations numériques dans un contexte non coopératif où ne sont connue ni la période symbole ni la réponse du canal de transmission. Le mémoire comprend trois parties qui traitent respectivement du choix de l’égaliseur, de l’estimateur de la période symbole et du dispositif de compensation du résidu de porteuse, enfin de la mise au point du système de reconnaissance complet. La première partie de la thèse présente une synthèse des diverses méthodes d’égalisation aveugle disponibles actuellement quand la période symbole est connue et le résidu de porteuse est nul. Nous avons étudié des méthodes exploitant les moments du second ordre permettant d’identifier le canal et des méthodes exploitant les moments d’ordre supérieur estimant directement un égaliseur du canal. Une brève analyse de chacune des méthodes montre les performances asymptotiques que l’on peut attendre de chacune d’elle dans un contexte réaliste où le filtre de mise en forme est à bande réduite. A partir de ces résultats, nous nous sommes orienté vers l’utilisation du critère de Godard puisque c’est l’algorithme qui semble fournir les meilleurs estimateurs. La seconde partie est consacrée à l’estimation de la période symbole et du résidu de porteuse. Après un rappel des méthodes classiques d’estimation de la période symbole basées sur des sommes de corrélation cyclique ou de moments d’ordre supérieur cycliques, nous proposons d’utiliser une métrique plus adéquate pour sommer les corrélations cycliques. Simulations à l’appui, nous montrons que ce nouvel estimateur apporte de substantiels gains par rapport aux approches classiques. Pour l’estimation du résidu de porteuse, nous nous proposons d’utiliser une solution classique basée sur l’analyse du périodogramme du signal élevé à une puissance de 2. Enfin, nous proposons un schéma global du système d’égalisation en y ajoutant quelques adaptations pour pouvoir traiter les modulations réelles ainsi que les modulations décalées. Au cours d’une campagne de simulations, nous avons observé un taux de reconnaissance moyen d’environ 95 pourcent à 20 dB de rapport signal sur bruit et pour une fenêtre d’observation de 1000 symboles

Detecting and correcting errors occurring in the transmitted data through a channel is a task of great importance in digital communication. In Error Correction Coding (ECC), some redundant data is added with the original data while transmitting. By exploiting the properties of the redundant data, the errors occurring in the data from the transmission can be detected and corrected. In this thesis, a new coding algorithm named Signal Point Target Code has been studied and various properties of the proposed code have been extended. Signal Point Target Code (SPTC) uses a predefined shape within a given signal constellation to generate a parity symbol. In this thesis, the relation between the employed shape and the performance of the proposed code have been studied and an extension of the SPTC are presented. This research presents simulation results to compare the performances of the proposed codes. The results have been simulated using different programming languages, and a comparison between those programming languages is provided. The performance of the codes are analyzed and possible future research areas have been indicated.

The dietary constituents curcumin, resveratrol, epigallocatechin-3-gallate (EGCG), but not indole-3-carbinol (I3C) inhibited the activation of NF-kB in B lymphoblasts and HUVEC. EGCG inhibited NF-kB activation in human umbilical vein endothelial cells (HUVECs) by blocking the activity of IKKa, thus preventing subsequent phosphorylation and degradation of IkBa. In B lymphoblasts inhibition of NF-kB activation by EGCG, appeared to be independent of the effect on IkBa. EGCG also prevented the formation of inducible extracellular and intracellular ROS in B lymphoblasts. EGCG inhibited the growth of B lymphoblasts and HUVEC, which was mediated through a cell cycle arrest and induction of apoptosis. Further analysis of this growth inhibitory effect, identified a number of important cell growth regulators that were a target of EGCG. In HUVEC, EGCG growth inhibition appeared to involve p53, CDK1, cyclin D1, and HMOX-1, but was independent of Pin1 and XIAP. In B lymphoblasts, EGCG growth inhibition appeared to be independent of any significant affect on p53, CDK1, cyclin D1, pin1 and XIAP, but may involve the loss of NF-kB activity or increases in HMOX-1 protein. Treatment with EGCG produced changes in the expression of a number of disease relevant genes including HMOX-1, as detected by microarray analysis. This increase in HMOX-1 mRNA corresponded to an increase in HMOX-1 protein. In B lymphoblasts, further analysis revealed that the increase in HMOX-1 was dependent on the PI3K and p38 pathways. The data obtained facilitate the design of preventive dietary intervention studies in healthy volunteers or groups of at risk patients.

Most sensory systems need to discriminate between wide ranges of behaviorally relevant signals. In order to achieve this, neurons need to adjust their response properties, such as firing rate and filtering capabilities. In the experiments presented in this thesis, I studied modifications mediated by serotonin in the response properties of neurons that receive direct sensory inputs from peripheral sensors in the weakly electric fish. These neurons also receive a rich serotonergic innervation from the raphe nuclei. In a first set of studies, in an in vitro preparation I found that the effect of serotonin is mediated through down regulation of two different potassium channels, namely SK and M channels. Using specific blockers in vitro, I found that SK and M potassium channels contributed to the observed effects of serotonin through a reduction in after hyperpolarization (AHP). Blocking of either channel resulted in burst firing and decreased the time constant of spike frequency adaptation. Surprisingly, SK an M channel block had opposite effects on frequency tuning of neurons. Blocking SK channels increased oscillations in membrane potential in the theta range, thus increasing the response of neurons to low frequency stimuli. In contrast, blocking M channels resulted in an increase in high frequency tuning. Occlusion experiments showed that serotonin down regulates both SK and M channels, the overall effect being a reduction in the response of neurons to low frequency stimuli (i.e., <40Hz).To study the effect of serotonin on neuronal activity and information coding at the network level, I performed sharp electrode intracellular and extracellular recordings from pyramidal neurons in immobilized behaving fish. I either applied serotonin or electrically stimulated the raphe nuclei. Similar to the slice preparation, serotonin induced burst activity by reducing the AHP. Furthermore, I found that serotonin improves detection of low-frequency beats – which mimic the presence of same sex animal in the electrical field – as measured by an increase in phase-locking of responses to low frequency sinusoidal stimuli. Surprisingly, in contrast to in vitro conditions, serotonin application resulted in an increase in neuronal responses to low frequency stimuli. This finding suggests that serotonin also affects the feedback inputs that are not present in vitro, but remain intact in vivo.Previous studies have shown a positive correlation between serotonergic activity and harm avoidance in different animals. Here, I found that detection of small chirp stimuli improved in the presence of serotonin, as shown by a decrease in the variability and latency of the first spike after the stimulus. Since small chirp is an aggressive signal used for initiating fights between male fish, these findings suggest that serotonin release is beneficial for faster detection of stimuli and harm avoidance behaviors. These results provide electrophysiological correlates for known behavioral effects of serotonin. In contrast, prey-like and courtship signals were not affected in any way by serotonin injection. Taken together, these results provide a link between changes in membrane properties of neurons by serotonin (i.e., down-regulation of potassium channels) to a change in the firing pattern and consequently the filtering properties of neurons, which is reflected in better detection of signals related to same sex interactions and aggressive behaviors. Furthermore, this neuromodulator commands a "shut up and listen" order for the animal in threatening conditions: serotonin reduces the rate of chirp generation and increases small chirp detection. Thus, the findings of studies in the present thesis provide evidence at the cellular and network levels for the role of neuromodulators in adjusting response properties of neurons in order to better detect behaviorally relevant stimuli at the systems level.
La plupart des systèmes sensoriels doivent faire la différence entre un large panel de signaux qui peuvent être pertinent comportementalement. Pour réaliser cette différentiation, un neurone doit ajuster les propriétés de sa réponse, comme sa fréquence de décharge ou sa capacité de filtrage. Une façon d'ajuster ces propriétés neuronale est d'utiliser des substances endogènes comme la sérotonine, la dopamine, ou l'histamine. Lors des expériences présentées dans cette thèse, j'étudie les modifications engendrées par la sérotonine, sur les propriétés de réponse de neurones qui sont directement connectes a des capteurs sensoriels périphériques chez le poisson «faiblement électrique». Cette zone reçoit une innervation « sérotonergique » importante en provenance des noyaux raphe. Dans un premier groupe d'expériences, j'ai trouve, dans une préparation in vitro, que les effets de la sérotonine sont régulés par deux canaux a potassium différents : canal SK et canal M. En utilisant des bloqueurs spécifiques, j'ai trouve que les canaux a potassium SK et M contribuent aux effets de la sérotonine: réduction après hyperpolarisation (AHP). Bloquer l'un ou l'autre des canaux a pour conséquence une rafale de potentiels d'action et une diminution de la constante de temps de l'adaptation de la fréquence de décharge. Etonnamment, bloquer les canaux SK et M a un effet oppose sur l'ajustement fréquentiel du neurone. Bloquer les canaux SK augmente les oscillations du potentiel de membrane dans la gamme thêta, ce qui a pour conséquence d'augmenter la réponse neuronal aux basses fréquences. Bloquer les canaux M a pour conséquence une augmentation de l'ajustement neuronal aux hautes fréquences.Les expériences d'occlusion ont montrées que la sérotonine régule les deux canaux SK et M, avec un effet global de diminution de la réponse neuronal aux basses fréquences (<40Hz). La sérotonine a aussi pour effet d'augmenter la décharge des neurones pyramidaux avec des rafales d'activité et des potentiels d'action transportant de l'information sur les basses et hautes fréquences, respectivement. Dans le but d'étudier les effets de la sérotonine sur l'activité neuronale et le codage de l'information au niveau des réseaux neuronaux j'ai réalisé des enregistrements intracellulaire et extracellulaire des neurones pyramidaux chez le poisson immobilisé. J'ai soit délivré de la sérotonine soit stimule électriquement le noyau raphe. De la même façon que pour la préparation in vitro, la sérotonine provoque une rafale de potentiel d'actions à cause de la réduction de l'AHP. De plus, j'ai trouve que la sérotonine améliore la détection des battements a basse fréquence, ce qui simule la présence d'un animal de même sexe dans le champ électrique. Cela a été mesure par une augmentation de l'asservissement de la phase de la réponse aux sinusoïdes à basse fréquence. Il est surprenant de constater qu'à l'inverse des résultats in vitro, l'application de la sérotonine a pour conséquence l'augmentation de la densité de l'information mutuelle. Pris dans leur ensemble, ces résultats montrent comment des changements de propriétés de membrane induit par la sérotonine (Diminution de l'activité des canaux a potassium) ont des conséquences sur le modèle de décharge et incidemment, sur les propriétés de filtrage du neurone, ce qui se reflète dans une meilleur détection des signaux lie aux interactions avec des pairs de même sexe et aux comportements agressifs. De plus, ce neuromodulateur commande un ordre de « tais toi et écoutes » pour l'animal en condition de menace : la sérotonine réduit la production de pépiement et améliore la détection de petit pépiements. Les résultats des études présentées dans cette thèse, fournissent donc des évidences au niveau cellulaire et au niveau des réseaux neuronaux du rôle de neuromodulateurs dans l'ajustement des propriétés de réponses du neuronales dans le but de mieux détecter des stimuli pertinent au niveau du system.

This dissertation is concerned with the development and performance analysis of non-linear receivers for detection of weak narrow-band signals in multivariate non-Gaussian clutter. The novelty of the detection scheme lies in the utilization of both the complex measurement and the multivariate non-Gaussian character of the clutter. Two clutter models are developed based on the available partial information. Model (I) is based on the a priori knowledge of the first-order density, correlation structure of the amplitude, and the circular symmetric assumption of the in-phase and quadrature phase components. Model (II) is based on the first-order in-phase and quadrature phase densities and the complex correlation structure. These models completely specify a multivariate complex nonGaussian density and can be used for clutter generation. A class of optimum non-linear receiver structures based on weak signal level, canonically known as Locally Optimum Detectors (LOD) are derived under clutter Model (I). This can be considered to be a generalization of the LOD for the independent and identically distributed (i.i.d) clutter. The detectors utilize complex measurements and their structures depend on whether the underlying hypothesis testing model is real or complex. The performance of each of the proposed detector structures, based on the concept of Efficacy, is formulated. Then, the performance of the detectors are evaluated with respect to a reference detector using Asymptotic Relative Efficiency (ARE) criterion. Numerical evaluation of the performance expression is carried out for constant signal in Weibull distribution for various density parameters. Simulation results indicate that the performance of the developed detectors, based on ARE, is superior to (i.i.d) LOD detector and matched filter. Finally, the sensitivity of the detector performance to parameter variation of the structural non-linearities is investigated.
Ph. D.