The pursuit for higher performance at a lower cost is driving rapid progress in the field of packaged digital systems. As the complexity of interconnects and packages increases, and the rise and fall time of the signal decreases, the electromagnetic effects in distributed passive structures become an important factor in determining the system performance. Hence there is a need to accurately simulate these parasitic electromagnetic effects that are observed in the signal distribution network (SDN) and the power delivery network (PDN) of an electronic system. The accurate simulation of high-speed systems requires information on the high frequency transient currents that are injected into the power distribution network causing simultaneous switching noise. Existing techniques for determining these transient currents are not sufficiently accurate. Furthermore existing transient simulation techniques suffer from two major drawbacks: 1) they are not scalable and hence cannot be applied to large sized systems, and 2) the time domain simulations violate causality. This dissertation addresses the above-mentioned problems in the domain of high-speed packaging. It proposes a new technique to accurately extract the transient switching noise currents in high-speed digital systems. The extracted switching noise currents can be used in both the frequency domain and the time domain to accurately simulate simultaneous switching noise. The dissertation also proposes a methodology for the transient co-simulation of the SDN and the PDN in high-speed digital systems. The methodology enforces causality on the transient simulation and can be scaled to perform large sized simulations. The validity of the proposed techniques has been demonstrated by their application on a variety of real-world test cases.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / The necessity of supplying precise time information in large telemetry ground stations and astronomical observatories is very similar. Therefore the way of solving this problem as it is done in the Very Large Telescope of the European Southern Observatory can be easily adopted to telemetry stations and ranges, especially when fiber optics are used. The European Southern Observatory (ESO) is building a new observatory in Chile for the Very Large Telescope (VLT). This VLT consists of 4 telescopes, each of them has a primary mirror diameter of 8 meters. the control architecture is based on workstations and VMEbus computers. The VMEbus computers are distributed over the whole building and are using real time operating system. Since the availability of the Global Positioning System (GPS) the generation of highly accurate timing signals on remote locations without the use of expensive Cesium standards does not create problems any more. However, distribution of a timing signal to many computer with high accuracy is an issue. The accuracy of the commonly used IRIG B-code is not adequate if the requirements are in the 10 microseconds range. This paper presents the design of a timing system that is adopted to the VLT. An overview of the requirements of the Time Reference System (TRS) is given. These requirements have been defined on the basis of experiences with the timing system of the ESO NTT telescope. The hardware units are described. These are a Central Time Standard, a Time Distribution System and a VME Time Interface Module. The distribution is based on fiber optic transmission, using a simple digital modulation that outperforms the analog IRIG B modulation. The Time Interface Module in the computer does not only perform the timing signal decoding but contains also user-programmable timers that are synchronously clocked from the time source. Presently all units of the TRS have been tested and the series production of the distribution and the Time Interface Modules are in progress.

Η ερευνητική εργασία που ακολουθεί, έχει σαν στόχο, σε πρώτο επίπεδο, να μελετήσει τα διάφορα μοντέλα ηλεκτρομαγνητικής διάδοσης και σε δεύτερο πλάνο, να δωθεί μία εικόνα σχετικά με τις επιπτώσεις της μη ιονίζουσας ακτινοβολίας, που εκπέμπεται από κεραίες και ασύρματα δίκτυα, στον άνθρωπο και στον περιβάλλοντα χώρο. Στα πρώτα κεφάλαια γίνεται μία θεωρητική αναφορά στις βασικές έννοιες της ηλεκτρομαγνητικής ακτινοβολίας και στους μηχανισμούς διάδοσης της, αλλά και στις επιπτώσεις της ακτινοβολίας αυτής στον άνθρωπο. Ακολουθεί, εκτενής παρουσίαση των πιο σημαντικών θεωρητικών μοντέλων διάδοσης ραδιοσήματος εξωτερικών και εσωτερικών χώρων αντίστοιχα. Στη συνέχεια, δίνεται λεπτομερής περιγραφή των πεδιομέτρων που χρησιμοποιήθηκαν για την καταγραφή των μετρήσεων σε διάφορες περιοχές ενδιαφέροντος. Στο τελευταίο κεφάλαιο, γίνεται παρουσίαση των μετρήσεων με συγκριτικά διαγράμματα καθώς και αναφορά για το κατά πόσο οι μετρήσεις βρίσκονται εντός των ορίων ασφαλείας που τίθενται από διεθνείς οργανισμούς. / In the present work, were studied the models of the radio signal distribution at open and close area and the consequences of the non-ionized radiation, which emits from a wide variety of wirelesses systems, on human body. Initially, the basic significances of the electromagnetic radiation, the Maxwell’s equations and the mechanics of RF distribution, were shortly presented. Further emphasis at the models of the radio signal distribution, at open and close area, was given. The consequences of the electromagnetic radiation concerning basic factors of thermal and no-thermal effect were presented. An additional report of the RF safety limits, according to various international organizations, was given. For the experimental process, we used the Narda Broadband Field meter, which recorded all the frequencies of the electromagnetic spectrum and a laptop with a suitable software (NETSTUMBLER 0.40), which allows the operator of the laptop to know the exact received power coming from the specific router of the WLAN, excluding all other signals even if they belong to the same frequency of 2.4 GHz. The comparison of the experimental measurements with the theoretical, reveals the potential of each theoretical model. Furthermore, we came to the conclusion that the experiments are in the limits of RF safety.

Made available in DSpace on 2016-04-18T21:39:49Z (GMT). No. of bitstreams: 2 Carolina Duca Novaes1.pdf: 3168515 bytes, checksum: 4bc2a4d21f8e08b61653940548fcd0d3 (MD5) Carolina Duca Novaes2.pdf: 2186508 bytes, checksum: 51278edae485082fdb365b9e34ad3fda (MD5) Previous issue date: 2010-02-10 / This dissertation presents details of a structure needed to create a Single Frequency Network (SFN) using low-power transmitters, and a comparison with a network composed of a single transmitter with high power. Among the difficulties to implement networks which distribute signals in SFN, has prioritized the synchronization issue and equalization techniques to achieve better performance of this system. Thus, there was a theoretical research comparing the different methods of timing of single frequency networks and simulations of coverage and performance in order to discuss the implementation of such a network system in the Brazilian digital TV (SBTVD). / Este trabalho apresenta um detalhamento da estrutura necessária para se criar uma rede Single Frequency Network (SFN) utilizando transmissores de baixa potência, bem como um comparativo com uma rede composta por um transmissor único de alta potência. Dentre as dificuldades de se implementar as redes de redistribuição de sinais em SFN foi priorizada a questão do sincronismo e técnicas de equalização que permitam um melhor desempenho desse sistema. Para isso foi realizada uma pesquisa teórica comparativa entre os diferentes métodos de sincronismo de redes de frequência única e simulações de cobertura e desempenho, visando discutir a implementação desse tipo de rede no sistema Brasileiro de TV digital (SBTVD).

Description of construction of analog-to-digital and digital-to-analog convertors for audio signal and distribution via wireless channel, are the objectives of my master's thesis. There are descriptions of DPS construction, design of panels and measurement of system parameters in the project, above all sampling and reconstruction of audio signal, power consumption and signal range of wireless modules. At the end is discussed real usage and suggestions for further developement.

Photonics and Optical techniques have advanced recently by a great extend to play an important role in Microwave and Radar applications. Antenna array of modern active phased array radars consist of multiple low power transmit and receive mod- ules. This demands distribution of the various Local Oscillator(LO) signals for up conversion of transmit signals and down conversion of receive signals during various modes of operation of a radar system. Additionally, these receivers require control and clock signals which are digital and low frequency analog, for the synchronization between receive modules. This is normally achieved through RF cables with complex distribution networks which add significantly higher additional weight to the arrays. During radar operations, radio frequency (RF) transmit signal needs to be distributed through the same modules which will in turn get distributed to all antenna elements of the array using RF cables. This makes the system bulky and these large number of cables are prone to Electromagnetic Interference (EMI) and need additional shielding. Therefore it is very desirable to distribute a combination of these RF, analog and digital signals using a distribution network that is less complex, light in weight and immune to EMI. Advancements in Optical and Microwave photonics area have enabled carrying of higher datarate signals on a single fiber due to its higher bandwidth capability including RF signals. This is achieved by employing Wavelength Division Multi- plexing (WDM) that combine high speed channels at different wavelengths. This work proposes, characterizes and evaluates an optical Wavelength Division Multiplexed(WDM) distribution network that will overcome the above mentioned problems in a phased array radar application. The work carries out a feasibility analysis supported with experimental measurements of various physical parameters like am- plitude, delay, frequency and phase variation for various radar waveforms over WDM links. Different configurations of optical distribution network are analyzed for multipoint distribution of both digital and RF signals. These network configurations are modeled and evaluated against various parameters that include power level, loss, cost and component count. A configuration which optimizes these parameters based on the application requirements is investigated. Considerable attention is paid to choose a configuration which does not provide excess loss, which is economically viable, compact and can be realized with minimum component count. After analysing the link configuration, multiplexing density of the WDM link is considered. In this work, since the number of signals to be distributed in radar systems are small, a coarse WDM(CWDM) scheme is considered for evaluation. A comparative study is also performed between coarse and dense WDM (DWDM) links for selection of a suitable multiplexing scheme. These configurations are modeled and evaluated with power budgeting. Even though CWDM scheme does not permit the utilisation of the available bandwidth to the fullest extent, these links have the advantage of having less hardware complexity and easiness of implementation. As the application requires signal distribution to thousands of transmit-receive modules, amplifiers are necessary to compensate for the reduction of signal level due to the high splitting ratio. Introduction of commonly available optical amplifiers like Erbium Doped Fiber Amplifier (EDFA), affect the CWDM channel output powers adversely due to their non-flat gain spectrum. Unlike DWDM systems, the channel separation of CWDM systems are much larger causing significantly high channel gain differences at the EDFA output. So an analysis is carried out for the selection of a suitable wavelength for CWDM channels to minimize the EDFA output power variation. If the gain difference is still significant, separate techniques needs to be implemented to flatten the output power at the antenna end. A CWDM configuration using C-band and L-band EDFAs is proposed and is supported with a feasibility analysis. As a part of evaluation of these links for radar applications, a mathematical model of the WDM link is developed by considering both the RF and digital sig- nals. A generic CWDM system consisting of transmitters, receivers, amplifiers, multiplexers/ demultiplexers and detectors are considered for the modeling. For RF signal transmission, the transmitters with external modulators are considered. Mod- eling is done based on a bottom-top approach where individual component models are initially modeled as a function of input current/power and later cascaded to obtain the link model. These models are then extended to obtain the wavelength dependent model ( spectral response) of the hybrid signal distribution link Further mathematical analysis of the developed link model revealed its variable separable nature in terms of the input power and wavelength. This led to significant reduction in the link equation complexity and development of some approximation techniques to easily represent the link behavior. The reduced form of the link spectral model was very essential as the initially developed wavelength model had a lot of parametric dependency on the component models. This mathematical reduction process led to simplification of the spectral model into a product of two independent functions, the input current and wavelength. It is also noticed that the total link power within specific wavelength range can be obtained by the integrating these functions over a specific link input power. After the mathematical modelling, an experimental prototype physical link is set up and characterized using various radar signals like continuous wave (CW) RF, pulsed RF, non linear frequency modulated signal (NLFM) etc. Additionally a proof of concept Radio-Over-Fiber (RoF) link is established to prove the superior transmission of microwave signal through an optical link. The analysis is supported with measurements on amplitude, delay, frequency and phase variations. The NLFM waveforms transmissions are further analysed using a matched _ltering process to confirm the side lobe requirement. Further a prototype WDM link is built to study the performance when digitally modulated channels are also multiplexed into the link. The link is again validated for signal levels, delay, frequency and phase parameters. Since amplitude and delay are deterministic, it is proposed that these parameter variations can be compensated by using suitable components either in the electrical or the optical domain. Radar systems use low frequency digital signals of different duty-cycles for synchronization and control across various transmit-receive modules. In the proposed link, these digital signals also modulate a WDM channel and hence the link is called a hybrid system. As the proposed link has EDFA to compensate for the splitting losses, there are chances of transient effects at the EDFA output for these low bitrate channels. Owing to the long carrier lifetime, low bitrate digital channels are prone to EDFA transient effects under specific signal and pump power conditions. Additionally, the synchronization signals used in radar application vary the duty-cycle over time, which is found to introduce variations in transient output. This practical challenge is further studied and the thesis for the first time, includes an analysis of EDFA transient e_ects for variable duty-cycle pulsed signals. The analysis is carried out for various parameters like bitrate, input power, pump power and duty-cycle. Investigations on EDFA transients on variable duty-cycle signals help in proposing a viable method to predict the lower duty-cycle transients from higher duty-cycle transients. The predicted transients were again validated against simulated transients and experimental results. As these transient effects are not desirable for radar signals, we propose a novel transient suppression techniques in optical and electrical domain which are validated with simulation and experimental measures. One suppression technique tries to avoid transient effect by keeping the optical input to EDFA always constant by feeding an inverted version of the original pulse into the EDFA along with the actual pulse. It is observed that as the wavelength of the inverted pulse is closer to the original input pulse, the transient effect settles faster. These EDFA transients are evaluated with WDM link configurations, where both high and low bitrate signals are co-propagated. Another challenging aspect of the link operation is the non-at gain spectrum of EDFA. i.e., EDFA provides unequal power level for various signals at WDM link output. This is especially true in the case of local oscillator signals, where it is preferable to have the same amplitude signals before feeding it to the mixer stages. But in the radar applications, this will require additional hardware circuits to equalize the signal level within a phased array antenna. This work also proposes some of the power equalization methods that can be used along with the WDM links. This part of the work is also supported with simulation model and experimental results. The analytical and experimental study of this thesis aids the evaluation process of a suitable optical Wavelength Division Multiplexed(WDM) distribution network that can be used for the distribution of both RF and digital signals. The optical WDM links being superior with its light weight, less loss and EMI/ EMC immunity provides a better solution to future class of radars.