International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Bit errors often occur in a wireless communications link when impairments alter the transmitted signal. It is advantageous to be able to predict how well a system will tolerate transmission problems. This paper details laboratory performance measurements and comparisons in terms of evaluating configurations of a digital receiver for Feher patented Quadrature Phase Shift Keying (FQPSK-B) demodulation. The transmitted signal is subjected to calibrated levels of impairments while the receiver performance is monitored in real-time.

Cavity ring-down spectroscopy has been used over the last twenty years as a highly sensitive absorption spectroscopic technique to measure light attenuation in gases, liquids, and solid samples. An optical cavity is used as a multi-pass cell, and the decay time of the light intensity in the cavity is measured, thereby rendering the techniques insensitive to light intensity fluctuations. Optical waveguides are used to build the optical cavities presented in this work. The geometries of such waveguides permit the use of very small liquid sample volumes while retaining the advantages of cavity ring-down spectroscopy. In this thesis cavity ring-down measurements are conducted, both, in the time domain and by measuring phase-shifts of sinusoidally modulated light, and the two methods are theoretically connected using a simple mathematical model, which is then experimentally confirmed. A new laser driver, that is compatible with high powered diode lasers, has to be designed to be able to switch from time domain to frequency domain measurements. A sample path length enhancement within the optical cavity is explored with the use of liquid core waveguides. The setup was optimised with respect to the matrix liquid, the geometrical matching of waveguide geometries, and the shape of liquid core waveguide ends. Additionally, a new technique of producing concave lenses at fibre ends has been developed and the output of a general fibre lens is simulated. Finally, liquid core waveguides are incorporated into a fibre-loop ring-down spectroscopy setup to measure the attenuation of two model dyes in a sample volume of <1 µL. The setup is characterized by measuring concentrations of Allura Red AC and Congo Red from 1 µM to a limit of detection of 5 nM. The performance of the setup is compared to other absorption techniques measuring liquid samples. / Thesis (Ph.D, Chemistry) -- Queen's University, 2013-04-23 14:08:16.33

Notre étude concerne la mesure du déphasage optique non linéaire (NL) d’ordre trois. Deux catégories de procédés seront abordées : i) la technique interférométrique à décalage de phase qui permet la caractérisation de la phase avec une bonne résolution spatiale, ce qui est crucial pour un faisceau focalisé dans le milieu non linéaire. Cette technique utilise le critère des moindres carrés associé à plusieurs interférogrammes. Mise en œuvre à l'aide d'un modulateur spatial de lumière, elle fournit un calibrage pratique pour chaque déphasage considéré. La fiabilité de la méthode proposée est vérifiée par comparaison directe avec la méthode de transformation de Fourier ; ii) les méthodes innovantes de type Z-scan combinées avec un montage imageur. Elles seront ici appliquées aux mesures des coefficients NL d’ordre trois et d’ordres supérieurs. Nous montrerons que la flexibilité d’emploi d'une caméra CCD permet un meilleur pointage et suivi en temps réel du faisceau. Enfin nous nous intéresserons au montage Dark-field Z-scan bénéficiant des avantages de la microscopie à champ sombre à fort contraste. Ces améliorations ouvrent potentiellement un nouveau champ d’exploration microscopique pour l’investigation et la cartographie des effets non linéaires. / Our study concerns the measurement of the nonlinear (NL) optical phase shift of order three. Two categories of methods will be addressed: i) the phaseshift interferometric technique that allows phase characterization with good spatial resolution, which is crucial for a focused beam in the non-linear medium. This technique uses the least squares criterion associated with several interferograms. Implemented using a spatial light modulator, it provides a practical calibration for each phase shift considered. The reliability of the proposed method is verified by direct comparison with the Fourier transformation method; ii) innovative Z-scan methods combined with an imager assembly. They will be applied here to measurements of the NL coefficients of order three and higher. We will show that the flexibility of using a CCD camera allows for better pointing and real-time tracking of the beam. Finally, we will focus on the Dark-field Z-scan setup, which benefits from the advantages of high contrast dark field microscopy. These improvements potentially open up a new field of microscopic exploration for the investigation and mapping of non-linear effects.

The scope of this dissertation is to investigate the merits and implications of using multilevel modulation formats in optical communications systems. Following the trend in academia and industry, special focus is placed on quadrature phase-shift keying (QPSK), and specifically on polarization division multiplexed (PDM) QPSK. A special kind of receiver is investigated thoroughly, the digital coherent receiver, the equivalent of the coherent quadrature demodulator in classical communications nomenclature. A large number of digital signal processing (DSP) algorithms are implemented, some of them novel, and their performance is examined, analyzed, and compared in a number of practical system scenarios. The impact of transmitter / receiver imperfections and a number of optical fiber impairments on system performance is studied. Experimental results taken from proof-of-concept experiments are also analyzed. / Η διατριβή αυτή έχει ως σκοπό τη μελέτη οπτικών τηλεπικοινωνιακών συστημάτων που χρησιμοποιούν τετραδικές διαμορφώσεις φάσης, πολυπλεξία κατά πόλωση και σύμφωνους ψηφιακούς δέκτες διαφοροποίησης φάσης και πόλωσης. Μελετήθηκαν αλγόριθμοι επεξεργασίας σήματος κατάλληλοι για εξάλειψη της επίδρασης των φαινομένων διάδοσης και των μη ιδανικοτήτων οπτικών τηλεπικοινωνιακών συστημάτων. Η μελέτη έγινε με προσομοίωση Monte-Carlo, με χρήση ημιαναλυτικής μεθόδου προσδιορισμού της πιθανότητας σφάλματος τηλεπικοινωνιακού συστήματος και με ανάλυση πειραματικών δεδομένων. Τα πειραματικά δεδομένα ελήφθησαν από οπτικό τηλεπικοινωνιακό σύστημα με τετραδική διαμόρφωση φάσης και πολυπλεξία κατά πόλωση με ρυθμούς συμβόλων 0.1-10 GBd (0.4-40 Gb/s). Μελετήθηκαν αλγόριθμοι επανένωσης των πολώσεων, αλγόριθμοι αποπολύπλεξης των πολώσεων, αλγόριθμοι διόρθωσης της ανισοσταθμίας ορθογωνιότητας, αλγόριθμοι εκτίμησης και αφαίρεσης της ενδιάμεσης συχνότητας και αλγόριθμοι εκτίμησης και αφαίρεσης του θορύβου φάσης των laser.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This Master Thesis presents the development of a new dynamic model for the DC-DC Zero-Voltage-Switching Phase-Shift-Modulated Full-Bridge (ZVS-PSM-FB).At first, the ZVSPSM-FB converter is analyzed and the Steady-State equations are derived. Then, using the ac equivalent circuit modeling technique, it is derived two new ZVS-PSM-FB dynamical models, based on step operation of the converter and steady-state converter equations. These two new ZVS-PSM-FB dynamical models with two dynamical models previously presented in the literature are used to perform a frequency response and a transfer-function DC-gain comparison to verify the performance of the dynamical models. Comparison results shows that our second model here derived presents a better performance among other models, keeping the desirable characteristics as simple polynomial ratio transfer-functions, excellent theoretical accuracy of transfer-functions DC-gains, transfer-functions coefficients independency of circuit parasitics components, excepting the primary leakage inductance. Even in this work, it is shown frequency response experimental results of the ZVS-PSM-FB converter, designed following telecommunications rectifiers power supplies standards. / Esta Dissertação de Mestrado apresenta o desenvolvimento de um novo modelo dinâmico para o conversor CC-CC Ponte-Completa Modulado por Deslocamento de Fase e com Comutação em Zero de Tensão (ZVS-PSM-FB). Inicialmente, o conversor ZVS-PSM-FB é analisado, onde são derivadas as equações que definem a operação em regime-permanente do conversor. A seguir, utilizando-se da técnica de modelagem ca média de conversores estáticos, deriva-se dois novos modelos dinâmicos para o conversor, tendo por base as etapas de operação do conversor e as equações de regime-permanente. Feito isso, os dois modelos aqui derivados, são comparados com outros dois modelos dinâmicos já apresentados na literatura para verificar seus desempenhos quanto à resposta em freqüência e resposta do ganho-cc das funções de transferências à variações de carga do conversor, dos modelos dinâmicos. Resultados desta comparação mostram que o segundo modelo aqui derivado é o que apresenta melhor desempenho entre os modelos comparados, mantendo características desejáveis de simples formato de função de transferência como razão de polinômios, precisão teórica excelente para resposta de ganho-cc das funções de transferências e não-dependência dos coeficientes das funções de transferências de parâmetros parasitas do circuito, a menos da indutância de dispersão do transformador. Ainda neste trabalho, são mostrados resultados experimentais da resposta em freqüência do conversor ZVS-PSM-FB, projetado com especificações de normas para retificadores chaveados de alta-freqüência para equipamentos de telecomunicações.

This master’s thesis deals with the impact of atmospheric turbulence on phase changes of a free space optical signal. This problematic is investigated by the interferometric method. A part of the thesis is focused on the phenomenon of atmospheric turbulence. Then the physical effect of interference is discussed and optical interferometers are described. The experimental part of the thesis is focused on measurement of phase shift of optical signal by interferometric method. The result of the thesis is to determine how phase shift of an optical beam depends on the strength of turbulence.

This thesis deals with a power flow control in the electric power system. An overview of FACTS devices is introduced; their basic characteristics as well as examples of their application are discussed. A significant part of this thesis investigates phase shifting transformers (PST´s), which seem to be suitable for implementation in the transmission system of the Czech Republic. The PST´s are useful devices that control active power flows on cross-border lines and regulate unwanted and unexpected power flows. Basic types and characteristics of the PST´s are discussed. In chapter 7 is designed laboratory task that should validate the regulatory capabilities of the transformer PST. Designs of models of individual parts of this laboratory task are presented. In the last part of this thesis the regulation effect of the PST is validated in the GLF/AES program.

No description available.

By placing millions of space sunshades, of the order of 104 m2 at the sub-Lagrangian point L1',between the sun and Earth, solar radiation can be reduced enough to achieve the necessary temper-ature reduction to enable a slow down of the global warming. The vast amount of space sunshadesposes significant challenges on the communication system, as the probability of interference, whichcan distort information, increases with the number of simultaneously communicating units.This thesis aims to design a potential structure for the communication system that minimizesinterference as much as possible. To reduce the number of simultaneously communicating units, thesunshades are arranged in cell formation, where a mother is placed in the center with daughtersaround that only communicate with their specific cell mother. Direct communication betweenthe Earth and space sunshades is not possible as the interference from solar radiation can causesignificant distortion on the signals. Therefore, relay satellites are placed in orbit around thesub-Lagrangian point L1' at a sufficient distance to avoid the effects of solar radiation. Thus, thecommunication between the mothers and Earth is instead routed via the relay satellites. Sincecommunication between such a large number of entities in space has not been investigated before,this approach could provide a possible basic design framework for designing such infrastructure inthe future.

Η πληθώρα των εφαρμογών που μπορεί να εξυπηρετήσει η τεχνολογία Υπερευρείας Ζώνης (UWB), από τα ασύρματα προσωπικά δίκτυα υψηλών ταχυτήτων, μέχρι τα ασύρματα δίκτυα αισθητήρων με δυνατότητες ακριβούς εντοπισμού θέσης, και τα ασύρματα δίκτυα ιατρικών αισθητήρων, έχει προκαλέσει έντονο ερευνητικό ενδιαφέρον γύρω από τις υλοποιήσεις UWB συστημάτων. Η ασυνήθιστα μεγάλη περιοχή συχνοτήτων που έχει ανατεθεί στο UWB, από τα 3.1-10.6 GHz, επιτρέπει την επίτευξη υψηλών ταχυτήτων με απλά σχήματα διαμόρφωσης, ωστόσο, λόγω της διαμοίρασης του φάσματος με τις υφιστάμενες τεχνολογίες ασύρματης δικτύωσης, οι UWB εκπομπές πρέπει να περιορίζονται σε ισχύ κάτω από το κατώφλι των -41.3 dBm/MHz, ικανοποιώντας πολύ αυστηρές μάσκες εκπομπής που εισάγουν έντονες προκλήσεις στη σχεδίαση των πομπών. Η υλοποίηση αναδιατάξιμων UWB πομπών σε σύγχρονες CMOS τεχνολογίες, με υψηλή φασματική ευελιξία, ταχύτητα και ποιότητα διαμόρφωσης, καθώς και με χαμηλή κατανάλωση, αποτέλεσε το αντικείμενο της συγκεκριμένης διατριβής. Υιοθετώντας την αρχιτεκτονική Multi-Band Impulse-Radio (MB-IR) σε συνδυασμό με την τεχνική Direct Sequence BPSK, η έρευνα προσανατολίστηκε προς την ανάπτυξη καινοτόμων μονάδων βασικής ζώνης, με στόχο την ενεργειακά αποδοτική αντιστροφή Γκαουσιανών μορφοποιημένων παλμών υψηλής ποιότητας φάσματος και διάρκειας μικρότερης ακόμα και από 1 nsec. Προς αυτή την κατεύθυνση, αναπτύχθηκε μια καινοτόμα γεννήτρια Γκαουσιανών παλμών με πολύ χαμηλούς πλευρικούς λοβούς στο φάσμα, τυπικά κάτω από -40 dB, ώστε να υποστηρίζονται οι αυστηρότερες μάσκες εκπομπής ή και μελλοντικές. Η σχεδίασης της προτεινόμενης γεννήτριας είχε ως κριτήριο την ευέλικτη ρύθμιση της διάρκειας των παραγόμενων παλμών, και αξιοποίησε τη χαρακτηριστική μεταφοράς τάσης ενός ωμικά φορτωμένου, ασύμμετρου CMOS αντιστροφέα. Η γεννήτρια βασίζεται κυρίως σε ψηφιακά κυκλώματα πολύ χαμηλής τάσης και, σε σύγκριση με τις υφιστάμενες υλοποιήσεις, παρουσιάζει σημαντικό προβάδισμα στον τομέα της ταχύτητας, καθώς και στο πλάτος εξόδου, η μεγάλη τιμή του οποίου χαλαρώνει σημαντικά τη σχεδίαση του RF front end. Η γεννήτρια μελετήθηκε διεξοδικά, διεξήχθη ανάλυση κλιμάκωσης, έγινε εξαγωγή σχεδιαστικών εξισώσεων και αναπτύχθηκαν εργαλεία λογισμικού για την αυτοματοποιημένη σχεδίασή της. Για περαιτέρω αύξηση της ταχύτητας των παλμικών σημάτων εφαρμόσθηκε ειδική σχεδίαση, η οποία αντιπραγματεύεται την ταχύτητα με το επίπεδο των λοβών του φάσματος. Για την αποδοτική BSPK διαμόρφωση των Γκαουσιανών παλμών αναπτύχθηκε ειδική τοπολογία “Μεταγωγής Σήματος Πυροδότησης Πλήρους Ισορροπίας με Up-Conversion”. Η τοπολογία αυτή, σε αντίθεση με τις ανταγωνιστικές τοπολογίες, αποφεύγει την αντιστροφή του παλμού με αναλογικά κυκλώματα υψηλής κατανάλωσης, αλλά και την αναλογική μεταγωγή, καθώς η διαμόρφωση λαμβάνει χώρα πριν από την παραγωγή των παλμών. Παράλληλα, επιτυγχάνονται υψηλοί ρυθμοί, καθώς και υψηλή ποιότητα διαμόρφωσης λόγω των ισορροπημένων μονοπατιών της τοπολογίας. Η γεννήτρια μαζί με το διαμορφωτή αποτελούν τις καινοτόμες παρεμβάσεις στη μονάδα Βασικής Ζώνης του προτεινόμενου πομπού. Για την ολοκλήρωση της λειτουργικότητας του πομπού, αναπτύχθηκε ένα RF front end, το οποίο αποτελείται από έναν διπλά ισορροπημένο μίκτη, έναν LO buffer, ένα μετατροπέα διαφορικού σήματος σε απλό, και έναν ενισχυτή ισχύος, ο οποίος είναι προσαρμοσμένος στα 50 Ohms, χωρίς να απαιτεί κανένα εξωτερικό στοιχείο. Το RF front end ολοκληρώθηκε μαζί με τη μονάδα βασικής ζώνης, και ο ολοκληρωμένος πομπός κατασκευάστηκε σε τεχνολογία CMOS 130 nm. Το ολοκληρωμένο προσαρτήθηκε στην RF πλακέτα συστήματος με την τεχνική Chip on Board. Για την επιτυχία του συστήματος με την πρώτη προσπάθεια έγινε συσχεδίαση σε επίπεδο IC-Package-PCB, δίνοντας ιδιαίτερη έμφαση στα ζητήματα Signal/Power Integrity. Ο πομπός παρουσίασε την υψηλότερη ταχύτητα από τις ανταγωνιστικές MB-IR UWB υλοποιήσεις, ίση με 1.5 Gbps, με αντίστοιχη ενεργειακή αποδοτικότητα 21 pJoule/bit και μέτρο διανυσματικού σφάλματος 5.5%. Ο πομπός βελτίωσε τους πλευρικούς λοβούς στο φάσμα περισσότερο από 10 dB, ενώ η διατριβή, εκμεταλλευόμενη την αναδιαταξιμότητα του πομπού, παρουσιάζει, επιπλέον, τις πρώτες μετρήσεις σε ταχύτητες εκατοντάδων Mbps για ικανοποίηση της χαμηλής ζώνης της πρόσφατα θεσμοθετημένης, και εξαιρετικά αυστηρής, ευρωπαϊκής μάσκας εκπομπής. / The multitude of applications that Ultra-Wideband (UWB) technology can serve, from high-speed Wireless Personal Area Networks, to Wireless Sensor Networks with precision Geolocation abilities, and Wireless Medical Networks, has attracted intense research interest in the implementation of UWB systems. The unusually wide range of frequencies assigned to UWB, from 3.1-10.6 GHz, allows UWB systems employing low order modulation schemes to enjoy high throughput at low power consumption. However, since UWB shares the spectrum with existing wireless networking technologies, UWB emissions must be limited to a power spectral density below the threshold of -41.3 dBm/MHz, satisfying very stringent emission masks and introducing great challenges in the design of UWB transmitters. The subject of this thesis is the design of low power, fully integrated, reconfigurable CMOS UWB transmitters, with high spectral flexibility, high speed and high modulation quality. Adopting the Multi-Band Impulse-Radio architecture, in conjunction with the Direct Sequence BPSK modulation, the research focused on the development of a baseband unit, able to precisely invert Gaussian shaped, subnanosecond pulses. The key contributions of this thesis are a CMOS Gaussian Pulse Generator and a BSPK modulation topology, which jointly constitute the proposed baseband unit. The Pulse Generator (PG) is based on non-linear shaping, so as to facilitate the configurability of the output pulse duration, and exploits the voltage transfer characteristic of a Resistive Loaded Asymmetrical CMOS Inverter, which results in spectral sidelobes typically better than -40 dB. The PG incorporates mostly-digital low voltage circuits, while the MOSFET devices that undertake the pulse shaping avoid exclusive operation in weak inversion, in contrast to previous implementations. Consequently, the proposed CMOS PG is able to support higher throughput, as well as higher output amplitude, which relaxes considerably the design of the RF front end. This thesis presents a systematic design procedure and a scaling analysis of the non-linear pulse shaper. Moreover, in order to further increase the speed, a special PRF boost technique is proposed, which trades off speed and spectral efficiency for the spectral sidelobes level. Regarding the BPSK modulator, this work introduces the “Trigger Switching Fully Balanced Up-Conversion” topology, which avoids the use of power-hungry and distortion-prone analog circuits for the accurate inversion of the subnanosecond shaped pulses, as well as avoids the application of analog waveform switching to the baseband pulses, since the baseband modulation takes place before the generation of the pulses. The digital nature of the switching lends itself to high data rates, while the balanced paths of the topology ensure high modulation quality with minimal design effort. Wafer probing measurements confirmed the high performance of the baseband unit. The functionality of the transmitter was completed by the development of an RF front end which consists of a double balanced mixer, an LO buffer, a differential to single-ended (DtoSE) converter, and a power amplifier which is ready to drive a 50 Ohms load without requiring any off-chip components. The integrated transmitter, which incorporates the proposed baseband unit and the RF front end, was fabricated in 130 nm CMOS technology. The transmitter RFIC was directly attached to the system RF PCB using the Chip-on-Board packaging option. The First-Pass success of the system was ensured by paying particular attention to Signal/Power Integrity issues and following an IC-Package-PCB co-design procedure. The transmitter was measured up to 1.5 Gbps, which, to the author’s knowledge, was the highest speed amongst the competitive Multi-Band Impulse-Radio UWB implementations in the literature. The corresponding energy efficiency was 21 pJoule/bit and the Error Vector Magnitude (EVM) 5.5%, while the proposed transmitter improved the spectral sidelobes by over 10 dB. Exploiting the reconfigurability of the transmitter, this thesis presents the first measurements at multi-Mbps speeds that completely meet the final version of the European spectrum emission mask.