Cílem této diplomové práce je změřit a vyhodnotit parametry techniky slučování kanálů, která je momentálně implementována v součástce AD7606C firmy Analog Devices. Poté, na základě výsledků z měření, navrhnout a odsimulovat několik možností, pomocí kterých by tato technika mohla dosahovat vyšších hodnot dynamického rozsahu a celkového harmonického zkreslení. V průběhů práce bylo zjištěno, že pomocí zvýšení zesílení kanálu s nižším rozsahem společně se snížením mezní frekvence celého signálového řetězce může tato technika dosahovat až 118.6 dB dynamického rozsahu, což je o 3.6 dB více, než bylo změřeno na AD7606C. Dále také bylo zjištěno, že pomocí jednoduchého algoritmu implementovaného v logickém bloku, je možné dosáhnout imunity vůči hodnotě externího rezistoru, který zákazníci používají jako součást anti-aliasingového filtru.

This seminar work deals with the topic of evaluating the quality of ECG signals. The introductory chapters explain the basic characteristics of ECG signals - measurement, the form of the measured signal, methods of analysis. The cardiac physiology and pathology is presented. The most common types of noise that occur in ECG signals are also mentioned. Further, the reader is acquainted with the importance of the issue of evaluating the quality of ECG signals. In the practical part of the work, two own methods for ECG quality evaluation are presented. First, a brief theoretical introduction to the techniques used in the creation of methoda is given, followed by a description of the principle of algorithms. In order to compare the functionality of the proposed methods, three more methods from other authors are presented. Their principle is briefly described. In the final chapter, all methods are subjected to functionality testing. The results are examined and all methods are compared with each other.

This diploma thesis deals with pause identification with degraded speech signal. The speech characteristics and the conception of speech signal processing are described here. The work aim was to create the reliable recognizing method to establish speech and non-speech segments of speech signal with and without degraded speech signal. The five empty pause detectors were realized in computing environment MATLAB. There was the energetic detector in time domain, two-step detector in spectral domain, one-step integral detector, two-step integral detector and differential detector in cepstrum. The spectral detector makes use of energetic characteristics of speech signal in first step and statistic analysis in second step. Cepstral detectors make use of integral or differential algorithms. The detectors robustness was tested for different types of speech degradation and different values of Signal to Noise Ratio. The test of influence different speech degradation was conducted to compare non-speech detection for detectors by ROC (Receiver Operating Characteristic) Curves.

The thesis deals with the biological data averaging applied to a periodical and repetitive signal, specifically to an ECG signals. There were used signals from MIT-BIH Arrhythmia database and ÚBMI database. Averaging was realized with constant, floating and exponential Windows, where was used the method of addition of the filtered residue. This method is intended to capture the slow variations from the input to the output signal. The outcomes of these methods can be used as a basis for further work, or function as an example of principled methods. Methods and its outcomes were created in Matlab.

The diploma thesis „Analysis and prediction of data traffic in mobile Ad Hoc network“ focuses on the radio propagation models of services in MANET (Mobile Ad-hoc) networks. It describes MANET networks and covers the theoretical analysis of routing protocols, radio wave propagation and propagation models of simulation enviroment NS-3 (Network Simulator 3). Furthermore, there is processed the creation process of model MANET networks with the routing protocol AODV (Ad Hoc On Demand Distance Vector) in the simulation environment NS-3. For analysis purposes there were implemented new functions to capture value of SNR (Signal to Noise Ratio) and throughtput. For this reason a physical layer of one of NS-3 model was modified. As an result there is a simulation build that compared several number of propagaion models.

Abstract Purpose: To compare the frequency specific Cortical Auditory Evoked Potential (CAEP) and the chirp-evoked 40 Hz Auditory Steady State Response (ASSR) with equivalent residual noise levels for behavioural threshold prediction in adults with normal hearing and with SNHL. Method: The study tested 23 adults with normal hearing and 20 adults with SNHL. The participants were aged between 18–65 years. A repeated measures within- participant descriptive design was used to collect the quantitative data. The participants underwent behavioural pure tone, CAEP and ASSR testing on the same day. Results: Similar CAEP difference scores across frequencies for the participants with normal hearing (mean=12.32-14.40 dB) and with SNHL (mean=10.00-16.47 dB) were measured. However, for the ASSR difference scores across frequencies slightly smaller difference scores were measured for the participants with SNHL (mean=10.17-17.30 dB) than for the participants with normal hearing (mean=11.74- 17.14 dB). CAEP thresholds were significantly closer to the behavioural pure tone thresholds at 500 (p=0.028; mean absolute difference 14.40 dB) and 2000 (p=0.016; mean absolute difference 12.56 dB) Hz for participants with normal hearing. In participants with sensorineural hearing loss, CAEP and ASSR thresholds were measured at similar sensation levels and were not statistically different (p>0.05). Conclusion: For the purpose of threshold estimation, representing the auditory function to the level of the auditory cortex the CAEP was closer to the behavioural hearing thresholds than the 40 Hz ASSR at all frequencies except at 4000 Hz, regardless of the hearing sensitivity. Keywords: Auditory steady state response (ASSR), Cortical auditory evoked potential (CAEP), Auditory evoked potential (AEP), Residual noise, Signal to noise ratio (SNR), objective threshold estimation, awake adults. / Dissertation (MA (Audiology))--University of Pretoria, 2019. / Speech-Language Pathology and Audiology / MA Audiology / Unrestricted

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The angle of arrival estimation of multiple sources plays a vital role in the field of array signal processing as MIMO systems can be employed at both the transmitter and the receiver end and the system capacity, reliability and throughput can be significantly increased by using array signal processing. Almost all applications require accurate direction of arrival (DOA) estimation to localize the sources of the signals. Another important parameter of localization systems is the array geometry and sensor design which can be application specific and is used to estimate the DOA. In this work, various array geometries and arrival estimation algorithms are studied and then a new scheme for multiple source estimation is proposed and evaluated based on the performance of subspace and non-subspace decomposition methods. The proposed scheme has shown to outperform the conventional Multiple Signal Classification (MUSIC) estimation and Bartlett estimation techniques. The new scheme has a better performance advantage at low and high signal to noise ratio values (SNRs). The research work also studies different array geometries for both single and multiple incident sources and proposes a geometry which is cost effective and efficient for 3, 4, and 5 antenna array elements. This research also considers the shape of the ground plane and its effects on the angle of arrival estimation and in addition it shows how the mutual couplings between the elements effect the overall estimation and how this error can be minimised by using a decoupling matrix. At the end, a novel miniaturised multi element reconfigurable antenna to represent the receiver base station is designed and tested. The antenna radiation patterns in the azimuth angle are almost omni-directional with linear polarisation. The antenna geometry is uniplanar printed logspiral with striplines feeding network and biased components to improve the impedance bandwidth. The antenna provides the benefit of small size, and re-configurability and is very well suited for the asset tracking applications.

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