This thesis is focused on the analysis of fetal ECG records measured by indirect method from mother´s abdomen. The thesis consists of the theoretical part is focused on fetal, heart development and description of fetal ECG signal. This thesis also offers an overview of fECG signal processing methods used nowadays. The practical part of the thesis deals with the implementation of algorithms based on wavelet transformation and Least Mean Square LMS method in Matlab programming environment. The final part of the thesis consists of the analysis of achieved results.

Tato práce je psaná v angličtině a je zaměřená na problematiku ekvalizace v digitálních komunikačních systémech. Teoretická část zahrnuje stručné pozorování různých způsobů návrhu ekvalizérů. Praktická část se zabývá implementací nejčastěji používaných ekvalizérů a s jejich adaptačními algoritmy. Cílem praktické části je porovnat jejich charakteristiky a odhalit činitele, které ovlivňují kvalitu ekvalizace. V rámci problematiky ekvalizace jsou prozkoumány tři typy ekvalizérů. Lineární ekvalizér, ekvalizér se zpětnou vazbou a ML (Maximum likelihood) ekvalizér. Každý ekvalizér byl testován na modelu, který simuloval reálnou přenosovou soustavu s komplexním zkreslením, která je složena z útlumu, mezisymbolové interference a aditivního šumu. Na základě implenentace byli určeny charakteristiky ekvalizérů a stanoveno že optimální výkon má ML ekvalizér. Adaptační algoritmy hrají významnou roli ve výkonnosti všech zmíněných ekvalizérů. V práci je nastudována skupina stochastických algoritmů jako algoritmus nejmenších čtverců(LMS), Normalizovaný LMS, Variable step-size LMS a algoritmus RLS jako zástupce deterministického přístupu. Bylo zjištěno, že RLS konverguje mnohem rychleji, než algoritmy založené na LMS. Byly nastudovány činitele, které ovlivnili výkon popisovaných algoritmů. Jedním z důležitých činitelů, který ovlivňuje rychlost konvergence a stabilitu algoritmů LMS je parametr velikosti kroku. Dalším velmi důležitým faktorem je výběr trénovací sekvence. Bylo zjištěno, že velkou nevýhodou algoritmů založených na LMS v porovnání s RLS algoritmy je, že kvalita ekvalizace je velmi závislá na spektrální výkonové hustotě a a trénovací sekvenci.

This thesis examines the possibility to implement e­learning in the educational process at HOPE – E. S. , v.o.s. The thesis compared the competitive opportunities of LMS systems, and selected one particular solution. The chosen solution is further specified, including the possible implementation and description of the environment. The last part is a proposed structure of the courses and supplementary materials for ongoing full-time courses.

The thesis deals with a design of adaptive testing in educational systems, the aim of the designed adaptive test is to simulate an oral examination by a teacher. Tes-ted knowledge are represented in two new structures - study map and proposition map that also drive the test. The goal of the test is to create a connected graph depicting knowledge of the examinee that represents its non-scalar result. Methodology for creation the maps, design of a complex software solution and proposal for incorporation of the adaptive testing to existing LMS were created. The economic benefits of the solution are discussed in case of its utilisation at FBE MENDELU. The adaptive testing can be used on different levels of education, e.g. corporate education as is shown on a practical application. The main contribution of the thesis is complexity of the solution - the thesis deals all aspects of adaptive testing starting with creation of educational materials up final feedback after the test.

Avsikten med detta examensarbete har varit att undersöka om lärare på gymnasienivå ägnar enligt dem själva mycket tid åt att administrera anteckningar om elevbedömningar och om de anser detta vara tidsödande. En enkätundersökning har gjorts på detta område. Slutsatsen är att lärare ofta behandlar samma elevbedömning mer än en gång. Detta kan visa sig genom att en anteckning om en elevbedömning först skrivs ned i en lärarkalender för att sedan föras in på datorn och för att slutligen tas fram för en sammanställning vid till exempel ett utvecklingssamtal. Ett fåtal pedagoger i undersökningen använder sig av ett datoriserat system för att föra in bedömningar direkt, ett system där elever kan logga in och se sina bedömningar vilket gör att antalet behandlingar av bedömningar för läraren minskar.Vidare tar uppsatsen upp hur ett datoriserat system för att spara och administrera elevbedömningar enligt teori bör se ut. Här gås begrepp igenom för att allmänt skapa ett bra grafiskt gränssnitt och olika tekniker för att visa mycket information på liten yta behandlas. En sådan programvara har också utvecklats och redovisas. / The purpose of this essay has been to investigate if teachers spend much time to administrate assessment from students and if they consider this a time-consuming task. The conclusion is that teachers often handle these results more than one time. Sometimes teachers first manually write down the students result in paper and after that write it to the computer and then finally handle the result a third time when putting together a compilation of the results when for example it’s time for students to have performance appraisal with their mentor. Some teacher saves the result directly into a computer system where the student immediately can see the result and therefore the teacher saves time since the results only have been handled a single time. Further on this paper deals with how a system that administrates student results should look like according to theory and behave and finally software for this purpose has been developed.

No description available.

Passive radar is a technology for detection of targets using echoes of existing radio transmitter, such as FM-radio. Since only receivers are needed for operation, a passive radar system has the possibility of being implemented using low-cost hardware. Using lower cost implementations to cover blind-spots of other, more sophisticated systems, could be a viable solution for full radar coverage. To achieve this, an understanding of the effects such low-cost systems have on the performance of a radar is needed.  A prominent problem for passive radar is that the interference caused by the direct signal from the transmitter used and reflections from uninteresting terrain, called clutter, can drown out the echoes from targets. This thesis compares the direct signal interference (DSI) suppression algorithms: ECA, ECA-S, ECA-B, NLMS and FBNLMS when run on data from a low-cost receiver called KerberosSDR. It is found that the low ADC resolution of 8 bits is a limiting factor for KerberosSDR. Random noise in the receiver can also limit the performance. None of the tested algorithms are any more or less affected by the ADC resolution or the noise. The first difference appears when comparing the execution times, where FBNLMS is 10–20 times faster than the other algorithms. However, the slower rate of convergence for FBNLMS and NLMS causes them to lose performance in environments where the DSI and clutter are considerably stronger than the target echoes. The algorithms FBNLMS and NLMS also lose performance due to their inability to model frequency shifted echoes as unwanted. The main disadvantages of ECA, ECA-B and ECA-S are their long execution time. It is concluded that FBNLMS would be the best candidate in most cases for low-cost hardware, as it allows execution on slower hardware and the main disadvantages not being too prominent in the use case of covering blind-spots of other systems.

Adaptive Least Mean Square (LMS) equalizers are widely used in digital communication systems primarily for their ease of implementation and lack of dependence on a priori knowledge of input signal statistics. LMS equalizers exhibit non-Wiener characteristics in the presence of a strong narrowband interference and can outperform the optimal Wiener equalizer in terms of both mean square error (MSE) and bit error rate (BER). There has been significant work in the past related to the analysis of the non-Wiener characteristics of the LMS equalizer, which includes the discovery of the shift in the mean of the LMS weights from the corresponding Wiener weights and the modeling of steady state MSE performance. BER performance is ultimately a more practically relevant metric than MSE for characterizing system performance. The present work focuses on modeling the steady state BER performance of the normalized LMS (NLMS) equalizer operating in the presence of a strong narrowband interference. Initial observations showed that a 2 dB improvement in MSE may result in two orders of magnitude improvement in BER. However, some differences in the MSE and BER behavior of the NLMS equalizer were also seen, most notably the significant dependence (one order of magnitude variation) of the BER behavior on the interference frequency, a dependence not seen in MSE. Thus, MSE cannot be used as a predictor for the BER performance; the latter further motivates the pursuit of a separate BER model. The primary contribution of this work is the derivation of the probability density of the output of the NLMS equalizer conditioned on a particular symbol having been transmitted, which can then be leveraged to predict its BER performance. The analysis of the NLMS equalizer, operating in a strong narrowband interference environment, resulted in a conditional probability density function in the form of a Gaussian Sum Mixture (GSM). Simulation results verify the efficacy of the GSM expression for a wide range of system parameters, such as signal-to-noise ratio (SNR), interference-to-signal (ISR) ratio, interference frequency, and step-sizes over the range of mean-square stable operation of NLMS. Additionally, a low complexity approximate version of the GSM model is also derived and can be used to give a conservative lower bound on BER performance. A thorough analysis of the MSE and BER behavior of the Bi-scale NLMS equalizer (BNLMS), a variant of the NLMS equalizer, constitutes another important contribution of this work. Prior results indicated a 2 dB MSE improvement of BNLMS over NLMS in the presence of a strong narrowband interference. A closed form MSE model is derived for the BLMS algorithm. Additionally, BNLMS BER behavior was studied and showed the potential of two orders of magnitude improvement over NLMS. Analysis led to a BER model in the form of a GSM similar to the NLMS case but with different parameters. Simulation results verified that both models for MSE and BER provided accurate prediction of system performance for different combinations of SNR, ISR, interference frequency, and step-size. An enhanced GSM (EGSM) model to predict the BER performance for the NLMS equalizer is also introduced, specifically to address certain cases (low ISR cases) where the original GSM expression (derived for high ISR) was less accurate. Simulation results show that the EGSM model is more accurate in the low ISR region than the GSM expression. For the situations where the derived GSM expression was accurate, the BER estimates provided by the heuristic EGSM model coincided with those computed from the GSM expression. Finally, the two-interferer problem is introduced, where NLMS equalizer performance is studied in the presence of two narrowband interferers. Initial results show the presence of non-Wiener characteristics for the two-interferer case. Additionally, experimental results indicate that the BER performance of the NLMS equalizer operating in the presence of a single narrowband interferer may be improved by purposeful injection of a second narrowband interferer. / PHD

Adaptive LMS equalizers are widely used in digital communication systems for their simplicity in implementation. Conventional adaptive filtering theory suggests the upper bound of the performance of such equalizer is determined by the performance of a Wiener filter of the same structure. However, in the presence of a narrowband interferer the performance of the LMS equalizer is better than that of its Wiener counterpart. This phenomenon, termed a non-Wiener effect, has been observed before and substantial work has been done in explaining the underlying reasons. In this work, we focus on the Bit Error Rate (BER) performance of LMS equalizers. At first a model “the Gaussian Mixture (GM) model“ is presented to estimate the BER performance of a Wiener filter operating in an environment dominated by a narrowband interferer. Simulation results show that the model predicts BER accurately for a wide range of SNR, ISR, and equalizer length. Next, a model similar to GM termed the Gaussian Mixture using Steady State Weights (GMSSW) model is proposed to model the BER behavior of the adaptive NLMS equalizer. Simulation results show unsatisfactory performance of the model. A detailed discussion is presented that points out the limitations of the GMSSW model, thereby providing some insight into the non-Wiener behavior of (N)LMS equalizers. An improved model, the Gaussian with Mean Square Error (GMSE), is then proposed. Simulation results show that the GMSE model is able to model the non-Wiener characteristics of the NLMS equalizer when the normalized step size is between 0 and 0.4. A brief discussion is provided on why the model is inaccurate for larger step sizes. / Master of Science

Active suspension technologies are well known for improving ride comfort and handling of ground vehicles relative to passive suspensions. They are ideally suited for mitigating single-event road obstacles. The work presented in this thesis aims to develop a structured approach for finding the peak force and bandwidth requirements of actuators for active suspensions, to mitigate single-event road obstacles. The approach is kept general to allow for application to different vehicle models, ride conditions and performance objectives. The current state-of-art in active suspensions was first evaluated. Based on these findings, the objectives of the simulation models and approach was defined. A quarter-car model was developed in Matlab to simulate the behavior of active suspensions over unilateral boundary conditions due to different road obstacle profiles. The obstacle profiles were obtained from existing standards and literature and then processed to replicate the interaction of tires on road. A least-mean-squares (LMS) algorithm for adaptive filtering, with the help of look-ahead preview was used to determine the ideal control force profile to achieve the performance objective of the active suspension. A case study was conducted to determine the requirements of the actuator in terms of bandwidth and peak force for different single-event road obstacle profiles, vehicle speeds and look-ahead preview distances. The results of the study show that the vehicle velocity and type of road obstacle have a strong influence on the required peak force and bandwidth of the actuator, while look-ahead preview will be much more important for real time controller implementation. / Master of Science