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Ampérmetr s velkým rozlišením
Honek, Marek ; Roubal, Zdeněk (oponent) ; Steinbauer, Miloslav (vedoucí práce)
Transmisní elektronový mikroskop je zařízení pracující na podobném principu jako optický mikroskop. Pro dosažení obrovských zvětšení využívá faktu, že elektrony mají mnohem kratší vlnovou délku než fotony. Pro zaostření světla se používají skleněné čočky, které jsou v elektronovém mikroskopu nahrazeny cívkami generujícími magnetické pole. To je přímo úměrné velikosti proudu, který těmito cívkami prochází. Pro dosažení vysokého rozlišení je nezbytné, aby proud dodávaný do cívek byl co možná nejstabilnější. Tato práce rozebírá metody měření proudu a snaží se o návrh zařízení pro měření stability proudu s rozlišením 1 ppm.
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Software-defined radio OFDM frame generation according to IEEE 802.22
Honek, Marek ; Gazda, Juraj (oponent) ; Maršálek, Roman (vedoucí práce)
This thesis proposes a new radio transmission protocol AWRAN for access to the amateur radio network HAMNET that does not require LOS to the access point. Furthermore, the thesis documents and discusses the prototypical implementation of simplified frames of this protocol on SDR and the test apparatus used for this purpose. The first chapter introduces the IEEE 802.22 WRAN standard on which AWRAN is based. Terms such as OFDM and OFDMA are described, as well as their advantages and applications. There are described the modulation techniques PSK and QAM, channel coding for error detection and correction, and the sources of these errors. The second chapter gives a detailed description of the parameters of the proposed AWRAN protocol. OFDM parameters, frame and superframe structures are described. The method of co-existence of multiple AWRAN cells and the exact form of the fourteen control messages that allow efficient allocation of bandwidth resources among up to four base stations and up to 63 users connected to each of these stations are described. The third section describes the structure of the simplified frame that was implemented on the RPX-100 testbed. It also describes the apparatus itself and its basic hardware building blocks as well as the software library that was used to implement the simplified frame. This chapter also describes the prepared test link and the theoretical calculation of the attenuation of this link. The fourth chapter deals with the programs that were developed as part of this work. Two of them were done for a first introduction to the hardware and software libraries. Another program serves as a generator of the previously described simplified frames, which are sent using SDR. The same program could be used as well as the receiver of these frames. The last program prepared performs a simulation of the wireless transmission using a mathematical model of the channel. It calculates the dependence of BER on SNR for the simulated transmission. The last section lists the functions that were defined and used in programs from the previous section.
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Software-defined radio OFDM frame generation according to IEEE 802.22
Honek, Marek ; Gazda, Juraj (oponent) ; Maršálek, Roman (vedoucí práce)
This thesis proposes a new radio transmission protocol AWRAN for access to the amateur radio network HAMNET that does not require LOS to the access point. Furthermore, the thesis documents and discusses the prototypical implementation of simplified frames of this protocol on SDR and the test apparatus used for this purpose. The first chapter introduces the IEEE 802.22 WRAN standard on which AWRAN is based. Terms such as OFDM and OFDMA are described, as well as their advantages and applications. There are described the modulation techniques PSK and QAM, channel coding for error detection and correction, and the sources of these errors. The second chapter gives a detailed description of the parameters of the proposed AWRAN protocol. OFDM parameters, frame and superframe structures are described. The method of co-existence of multiple AWRAN cells and the exact form of the fourteen control messages that allow efficient allocation of bandwidth resources among up to four base stations and up to 63 users connected to each of these stations are described. The third section describes the structure of the simplified frame that was implemented on the RPX-100 testbed. It also describes the apparatus itself and its basic hardware building blocks as well as the software library that was used to implement the simplified frame. This chapter also describes the prepared test link and the theoretical calculation of the attenuation of this link. The fourth chapter deals with the programs that were developed as part of this work. Two of them were done for a first introduction to the hardware and software libraries. Another program serves as a generator of the previously described simplified frames, which are sent using SDR. The same program could be used as well as the receiver of these frames. The last program prepared performs a simulation of the wireless transmission using a mathematical model of the channel. It calculates the dependence of BER on SNR for the simulated transmission. The last section lists the functions that were defined and used in programs from the previous section.
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Ampérmetr s velkým rozlišením
Honek, Marek ; Roubal, Zdeněk (oponent) ; Steinbauer, Miloslav (vedoucí práce)
Transmisní elektronový mikroskop je zařízení pracující na podobném principu jako optický mikroskop. Pro dosažení obrovských zvětšení využívá faktu, že elektrony mají mnohem kratší vlnovou délku než fotony. Pro zaostření světla se používají skleněné čočky, které jsou v elektronovém mikroskopu nahrazeny cívkami generujícími magnetické pole. To je přímo úměrné velikosti proudu, který těmito cívkami prochází. Pro dosažení vysokého rozlišení je nezbytné, aby proud dodávaný do cívek byl co možná nejstabilnější. Tato práce rozebírá metody měření proudu a snaží se o návrh zařízení pro měření stability proudu s rozlišením 1 ppm.
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