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Perceptual Omnidirectional Image Quality: Subjective Ratings by Diverse User Aspects
Šimka, Marek ; Polak, Ladislav
This paper deals with an unconventional experiment of subjective quality assessment of omnidirectional images. Within the subjective tests with 36 volunteers, the study was carried out in terms of different aspects of each user. Based on the assessments of 100 images by each respondent, it offers a new source of results for further investigation and development of virtual reality (VR) content or quality of experience (QoE). It focuses on the subjective ratings of various types of users such as people using dioptric glasses, with VR experience, or users with vision impairments. The output is thus the results of the subjective scores, including an analysis of their correlations with several objective quality metrics. The initial results of this work suggest that, for example, subjects with corrected vision using dioptric glasses exhibit similar subjective perceptions of the quality of omnidirectional images as average respondents without visual impairment.
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Mapping and analyzing of signal coverage of 4G/5G mobile networks
Baránek, Michal ; Polák, Ladislav ; Kufa, Jan
This paper addresses the enhanced measurement of signal coverage, capacity, and reliability in mobile networks, particularly with the growing prevalence of 4G and 5G technologies. Given the escalating importance of these networks in everyday activities, there arises a demand for open-source solutions to evaluate and enhance their performance effectively. The objective of this research is to analyze gathered data to pinpoint areas necessitating network enhancements and to develop opensource software and hardware solutions for extracting essential performance metrics (KPIs) from 4G/5G networks. The proposed system offers an interface for assessing network performance and signal coverage, enabling cost-efficient measurements across diverse environments.
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Measurement of the DVB-T2-based MISO Signal influenced by I/Q-errors in the OFDM Modulator
Buchta, Simon ; Polák, Ladislav
The Second Generation Digital Video Broadcasting Terrestrial (DVB-T2) system stands out as the most advanced system among the second generation DVB standards. Among others, it supports the multiple-input single-output (MISO) transmission technique to enhance terrestrial TV broadcasting. This paper focuses on a performance study of the DVB-T2 system utilizing the MISO technique for various fixed transmission scenarios, which are modeled by different transmission channel models. Additionally, it considers imperfections of the transmitter, due to errors in the Orthogonal Frequency-Division Multiplexing (OFDM) modulator. To facilitate this study, a laboratory measurement workstation with an appropriate measurement methodology is established. The proposed concept enables the interchangeability of measurement equipment and set-top-boxes (STBs).
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Laboratorní úloha pro hodnocení vizuální kvality komprimovaných obrazů
Sedlák, Ondřej ; Kufa, Jan (oponent) ; Polák, Ladislav (vedoucí práce)
Tato bakalářská práce se zabývá hodnocením vizuální kvality komprimovaných statických obrazů. Teoretická část poskytuje přehled současných standardů pro kompresi obrazů a popisuje metody hodnocení kvality komprimovaného obrazu. Komprimační algoritmy jsou kategorizovány podle metod a zdůrazněny klíčové formáty, které budou použity v experimentální části. Důraz je také kladen na objektivní a subjektivní metody hodnocení, poskytující robustní rámec pro vyhodnocení výkonu kompresních kodeků. Praktická část se zaměřuje na aplikaci zvolených metodik komprimace a hodnocení kvality, porovnání jednotlivých výsledků a návrhu postupu pro zpracování laboratorní úlohy.
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Stereo ADC and DAC converter for audio
Koiš, Christopher ; Polák, Ladislav (oponent) ; Kratochvíl, Tomáš (vedoucí práce)
This bachelor's thesis deals with the problem of designing a programmable digital sound processor with its input connected to a device, such as a personal computer or a mobile phone, and an output intended for headphones. One segment of this thesis handles digital filters, specifically FIR and IIR filters. The MATLAB environment was used to design the filters shown in this thesis. Furthermore, the buses SPI, I2C and I2S that are used on the device are described. The parameters of individual functional blocks are summarized, and the designed circuit schematic are displayed in this thesis. In the practical part of this thesis a prototype printed ciruit board was designed and its' electrical parameters were measured and processed. Finally, the last part of this thesis describes the inner workings of the program that the microcontroller executes.
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Measurement of the SISO/MISO Signal in the DVB-T2 System
Buchta, Šimon ; Kratochvíl, Tomáš (oponent) ; Polák, Ladislav (vedoucí práce)
This thesis deals with a measurement-based study of the second-generation Digital Terrestrial Video broadcasting system (DVB-T2), examining various transmission techniques and imperfections within the orthogonal frequency division multiplexing (OFDM) modulator. For this study, a universal measurement setup was proposed and implemented. The first part of this work focuses on the measurement and evaluation of a real singleinput single-output (SISO) DVB-T2 signal broadcasted in the Czech Republic. The second part examines different DVB-T2 signal configurations, considering multiple-input single-output (MISO) transmission and imperfections in the OFDM modulator with combination of power imbalance between transmitters and in various channels for fixed and mobile reception. The results are evaluated using conventional objective metrics, such as bit and modualtion error ratio (BER and MER), as well as from the perspective of the measurement equipment and receivers (set-top boxes – STBs) used.
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Programovatelný atenuátor pro laboratorní měření
Husslik, Tomáš ; Šimka, Marek (oponent) ; Polák, Ladislav (vedoucí práce)
Práce se zabývá návrhem programovatelného atenuátoru s digitálním řízením. Cílem práce je návrh atenuátoru s impedancí 50 s útlumem v rozsahu 0 až 40 dB, pracujícího v pásmu 1 až 2 500 MHz. Navržený atenuátor je řízen mikrokontrolérem, který ovládá obvod integrovaného atenuátoru. Součástí atenuátoru je základní uživatelské rozhraní. Pro atenuátor byla navržena a posléze vyrobena DPS. Zařízení bylo následně sestaveno a změřeny jeho klíčové parametry.
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Testing the response of operating systems to different IPv6 flows
Ruiner, Michal ; Polák, Ladislav (oponent) ; Jeřábek, Jan (vedoucí práce)
The aim of the thesis is to create an array of virtual machines and research their response to the IPv6 protocol. Another significant part is to utilize the provided tool for generating and sniffing IPv6 traffic and verify its correct functionality. For such purpose, the GNS3 open-source software is selected. A~reader is familiarized with the concepts of virtualization, GNS3 functionality and various methods of software testing together with the implemented practical models. The IPv6 protocol is introduced in detail as well as the packet format, address types and several IPv6 protocols useful for the thesis. The practical part is discussed in the Numerical results chapter. The topology is established and connectivity verified using IPv4. Configuration of static IPv6 addresses is performed on the devices as well as configuration of router to distribute particular prefixes. 5 testing scenarios are proposed that increase the input load to the tool in sense of higher number of addresses for the 3 different modes - passive, active and aggressive. 3 scripts were developed. Performance testing script measures utilization of computational resources. The other 2 scripts perform packet capturing and further analysis to compare the results of proposed scripts with provided tool. The comparison is done utilizing passive and aggressive modes. Active mode is used to observe the response of various operating systems to different IPv6 flows. Specifically, multiple Windows 10 builds, Linux distributions, Windows XP, 7, 11, macOS and Android.
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AI-based classification of RF signals
Turák, Samuel ; Ulovec, Karel (oponent) ; Polák, Ladislav (vedoucí práce)
This thesis focuses on Deep learning-based radio frequency (RF) signal classification. For this purpose, three neural networks are selected and introduced: Convolutional Neural Network (CNN), Gated Recurrent Unit Network (GRU) and Convolutional Gated Deep Neural Network (CGDNN). All are trained and evaluated on multiple datasets, influenced by different RF impairments, for wireless standard classification. The waveforms in these datasets have been created by the Wireless Waveform Generator app in MATLAB. One publicly available modulation classification dataset is also being tested on the models. The performed approaches of data preprocessing, model training and model evaluation are implemented in the programming environment Python, utilizing libraries such as Scikit-learn and Keras. The obtained results are evaluated and discussed.
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Mapping and analyzing signal coverage in 4G/5G mobile networks
Baránek, Michal ; Jeřábek, Jan (oponent) ; Polák, Ladislav (vedoucí práce)
This thesis deals with the advanced measurement of signal coverage, capacity, and reliability in mobile networks, especially with the widespread adoption of 4G and 5G technologies. As these networks become increasingly integral to daily life, there is a need for cost-effective solutions to assess and optimize their performance. The primary objective of this work is to develop affordable software and hardware solutions capable of extracting fundamental Key Performance Indicators (KPIs) from 4G/5G mobile networks. The proposed system aims to provide users with an accessible tool to assess network performance, signal coverage in specific areas, and predictive models for future network capacity. These functionalities are presented through a user-friendly graphical interface (so-called GUI), allowing for straightforward and cost-effective measurements in both outdoor and indoor settings.
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