RNDr. Ing. Vladimír Smotlacha, Ph.D.

Although optical networks are primarily used for data transmissions, they currently provide a suitable and perspective platform for other applications, including the transmission of a highly stable frequency and accurate time from atomic clocks to distances of up to thousands of kilometers. The advantage of the optical line is that it allows simultaneous bidirectional transmission in the same fiber and thus the interfering effects can be compensated for, as they apply equally in both directions. The used methods of time and frequency transmission work on different network layers, the most accurate of them on the link and physical layer. The student will have to get acquainted in detail with existing methods, measure and evaluate their parameters. The research will be focused on the design of new protocols, methods of encoding transmitted information and carrier signal modulation with the goal to improve accuracy and reliability of the transmitted time and frequency. This is a complex topic that is interdisciplinary and includes computer networks and programming of FPGA circuits with a possible overlap in the design of electronic circuits and possibly opto-electronic circuits.

RNDr. Ing. Vladimír Smotlacha, Ph.D.

Ing. Jiří Dostál, Ph.D.

Department of Computer Systems

In my bachelor thesis I deal with the issue of monitoring of high-speed streaming video, detecting errors and providing statistics about this stream. Part of the thesis is the analysis of protocols used for video streaming, as well as previous solutions of this problem. The outcome of this thesis is an application written in C under the Linux operating system, which solves the above problem. For implementation of this application was used library pcap, which serves for the packet capture and analysis. For keeping statistics and as charting tool was used RRDtool. This application can be practiced to detect possible weak points in the network for video streaming and help in their possible subsequent elimination. On the enclosed CD you can find the source code of the resulting application and test results of its functionality.

Thesis on DSpace

RNDr. Ing. Vladimír Smotlacha, Ph.D.

Ing. Jiří Dostál, Ph.D.

Department of Computer Systems

This bachelor's thesis deals with the implementation of TSA server and client application using time-stamp protocol or TSP as specified by RFC 3161. Final solution aims to be least dependent on external services, such as web or data- base server, as possible. This goes step by step with lowering data overhead of application protocols and in the end simplifying and improving the speed of deployment. In comparison with existing open-source implementations (which use HTTP protocol for transport of data), transport layer protocol TCP is used instead. Implementation uses libraries from OpenSSL project and progra- mming language C. Testing of response time, according to number of requests being sent to TSA server, is part of the thesis as well. Correct functionality is verifyied in Linux operating system.

RNDr. Ing. Vladimír Smotlacha, Ph.D.

Ing. Jiří Dostál, Ph.D.

Department of Computer Systems

The aim of this thesis was to design and create a network monitoring tool, that would capture and report network traffic via the PTP protocol in real time, with emphasis on precision of the distributed time as well as possible errors in communication. Firstly, I go over the fundamentals of PTP and try to determine whether a universal monitoring tool, such as Wireshark would be suitable for this purpose. In the second part of this document I design my own monitoring tool for OS Linux and subsequently implement it using C++ programming language with the PCap library.

Thesis on DSpace

RNDr. Ing. Vladimír Smotlacha, Ph.D.

Ing. Jiří Dostál, Ph.D.

Department of Computer Systems

This thesis deals with the creation of a communication layer between time server and the Symetricom (Microsemi) 5071A atomic clock. The created system was installed in the CESNET network node. Subsequently, measurements were performed to evaluate the influence of the atomic clock on the frequency stability and time offset of the time server. The resulting data processing showed a significant increase in stability and a decrease in time deviation while using the atomic clock.

Thesis on DSpace

RNDr. Ing. Vladimír Smotlacha, Ph.D.

Ing. Alexandru Moucha, Ph.D.

Department of Computer Systems

This master's thesis deals with sensor localization in IoT based network calledLoRaWAN and presents (prepares) necessary infrastucture. Final solutionaims to be power efficient in a way that would not degrade sensor lifetime. Thatis reason for using passive localization which utilizes information gathered fromregular sensor operation - specifically using time difference of arrival. Solution,which is proposed and implemented, is compared to other localization techniques. Measurements are made by test sensor equipped with external sourceof position, i. e. GNSS module, which functions as a reference location. Properfunction was verified by field test conducted in Prague, utilizing LoRaWANgateways run by CESNET assocation of legal entities. Presented solution doesnot achieve accuracy of technologies like GPS, however, it can offer an interesting and power friendly alternative, in some use cases.

Thesis on DSpace

RNDr. Ing. Vladimír Smotlacha, Ph.D.

Ing. Jiří Dostál, Ph.D.

Department of Computer Systems

This master thesis focuses on network protocols for time transfer, namely Precision Time Protocol and White Rabbit. First, the protocols were studied and their capabilities and options explored. After that a group of PTP end devices PTP switches was evaluated based on their capabilities. This served as a basis for experimental testing, when the performance of said devices was measured and evaluated. Similar experiments were also conducted with White Rabbit devices. The option to calibrate White Rabbit devices was also explored and evaluated. Since the official calibration guide does not cover every use case, a new method to calibrate connections using unidirectional pairs of fibre was proposed. Finally a monitoring system for White Rabbit was developed, that is now used in CESNET network for monitoring deployed White Rabbit Switches.

Thesis on DSpace