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Spread spectrum modulator
Lejsková, Alena ; Kováč, Michal (referee) ; Maršálek, Roman (advisor)
This thesis deals with a method of spectrum-spreading of the data signals transmitted in the radio channel. There exist three different ways of spreading application, they uses pseudorandom sequences and also orthogonal sequences. In these systems we can find various kinds of modulations, one of them (Quadrature Phase Shift Keying) is shown at the end of the thesis. Spectrum spreading orthogonal multiplex OFDM is based on this method. The thesis wants to present the principle of the spectrum spreading method and the description of systems, transmitters and receivers that are using this method.
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Utilizing psychoacoustic model and Wavelet Packet Transform for purposes of audio signal watermarking
Heitel, Tomáš ; Schimmel, Jiří (referee) ; Rajmic, Pavel (advisor)
This Thesis deals with a method to enforce the intellectual property rights and protect digital media from tampering – Digital Audio Watermarking. The main aim of this work is implement an audio watermarking algorithm. The theoretical part defined basic terms, methods and processes, which are used in this area. The practical part shows a process of embedding the digital signature into a host signal and her backward extraction. The embedding rule used spread spectrum technique and a psychoacoustic model. The implemented psychoacoustic model involves two properties of the human auditory system which are frequency masking and representation the frequency scale on limited bands called critical bands. The model is relatively new and based on the DWPT. In terms of above model is then the digital watermark embedded in the wavelet domain. This algorithm is implemented in technical software MATLAB. One part of this work focuses on robustness tests of the algorithm. Common signal processing modifications are applied to the watermarked audio as follows: Cutting of the audio, re-sampling, lossy compression, filtering, equalization, modulation effects, noise addition. The last part of the thesis presents subjective and objective methods usable in order to judge the influence of watermarking embedding on the quality of audio tracks called transparency.
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Design of a laboratory exercise with frequency hops
Novák, David ; Číž, Radim (referee) ; Škorpil, Vladislav (advisor)
Novák, D. Brno: Department of Telecommunications, The Faculty of Electrical Engineering and Communication, Brno University of Technology, 2008, Design of a laboratory exercise with frequency hops. Bachelor’s thesis, supervisor: Doc. Ing. Vladislav Škorpil, CSc., 35 pages. Bachelor’s thesis consider about Design of a laboratory exercise with frequency hops. Theoretical part treat about technology of frequency hops. Below about types, properties, method about transfer and practical use of this technology. This event is maked from information acquired from practical part and from literature. Practical part serves such as extended manual to laboratory exercises into simulator system Emona TIMS. Exercises are concerned about measuring connection establishment between transmitter and receiver technology of frequency hops, speed and quality connection. Accent is set to detailed explanation objectives measuring. Bachelor’s thesis is complemented about measured out findings, these measurements.
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Systems with frequency hopping
Jelínek, Martin ; Říha, Kamil (referee) ; Pust, Radim (advisor)
This bachelor´s thesis deals the systems, which use the Frequency Hopping (FH). The brief history of frequency hopping and its development together with Adaptive Frequency Hopping technology (AFH) is introduced. The general function principle of AFH, which differs AFH from FH, is described. Advantages and disadvantages of frequency hopping and its division into fast (FFH) and slow (SFH) are described next. Some of military communication systems (e.g. SINCGARS, Eritac, MRR, Panther V-EDR and next) as well as some of commercial systems (e.g. worldwide-spread Bluetooth system) are introduced. Mentioned systems use digital modulations, three of basic digital modulations are demonstrated (ASK - Amplitude Shift Keying, FSK - Frequency Shift Keying and PSK - Phase Shift Keying). Basic types of used spectrum spreading (FHSS, DSSS, OFDM) are mentioned next. The FHSS type of spectrum spreading is described in more detail, because the spectrum spreading is done by frequency hopping. Particular systems contain error control of radio transmission of information, which is realized by FEC (Forward Error Correction) and ARQ (Automatic Repeat Query) techniques. Practical part of the bachelor´s thesis demonstrates, with usage of Matlab programme, adaptive frequency hopping function (AFH) during communication of Master-Slave devices, where more systems are active. This causes the interference of the communication. This interference is caused by static and dynamic jammers, that work in the same band as the Master-Slave devices.
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WLAN and Bluetooth Systems Coexistence
Mikulka, Jan ; Hanus, Stanislav (advisor)
The dissertation thesis deals with a WLAN and Bluetooth systems coexistence. A Bluetooth standard works in an unlicensed frequency band 2,402 – 2,480 GHz. This frequency band is also used by an IEEE 802.11b/g standard (Wi-Fi) which is the most extended representative of WLAN networks. Because Bluetooth and Wi-Fi systems operate in the same frequency band, a mutual signal degradation may appear, when devices are collocated in the same area. In the first part of the dissertation thesis there is a brief summary of 2,402 - 2,480 GHz frequency band regulations and its usage. There are described physical layers of Bluetooth and IEEE 802.11b/g standards and techniques used for a collision avoidance. The main part of the dissertation thesis deals with a development of a new Matlab Simulink model for investigations of the Bluetooth and Wi-Fi standards coexistence. Physical layer models and results of the coexistence simulations are verified by a measurement in real conditions with a help of a modern vector signal analyzer. The results are presented in a graphical form and a brief summary is attached at the end of each chapter. Corresponding tables of simulated and measured values are available in the enclosed CD.
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WLAN and Bluetooth Systems Coexistence
Mikulka, Jan ; Hanus, Stanislav (advisor)
The dissertation thesis deals with a WLAN and Bluetooth systems coexistence. A Bluetooth standard works in an unlicensed frequency band 2,402 – 2,480 GHz. This frequency band is also used by an IEEE 802.11b/g standard (Wi-Fi) which is the most extended representative of WLAN networks. Because Bluetooth and Wi-Fi systems operate in the same frequency band, a mutual signal degradation may appear, when devices are collocated in the same area. In the first part of the dissertation thesis there is a brief summary of 2,402 - 2,480 GHz frequency band regulations and its usage. There are described physical layers of Bluetooth and IEEE 802.11b/g standards and techniques used for a collision avoidance. The main part of the dissertation thesis deals with a development of a new Matlab Simulink model for investigations of the Bluetooth and Wi-Fi standards coexistence. Physical layer models and results of the coexistence simulations are verified by a measurement in real conditions with a help of a modern vector signal analyzer. The results are presented in a graphical form and a brief summary is attached at the end of each chapter. Corresponding tables of simulated and measured values are available in the enclosed CD.
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Systems with frequency hopping
Jelínek, Martin ; Říha, Kamil (referee) ; Pust, Radim (advisor)
This bachelor´s thesis deals the systems, which use the Frequency Hopping (FH). The brief history of frequency hopping and its development together with Adaptive Frequency Hopping technology (AFH) is introduced. The general function principle of AFH, which differs AFH from FH, is described. Advantages and disadvantages of frequency hopping and its division into fast (FFH) and slow (SFH) are described next. Some of military communication systems (e.g. SINCGARS, Eritac, MRR, Panther V-EDR and next) as well as some of commercial systems (e.g. worldwide-spread Bluetooth system) are introduced. Mentioned systems use digital modulations, three of basic digital modulations are demonstrated (ASK - Amplitude Shift Keying, FSK - Frequency Shift Keying and PSK - Phase Shift Keying). Basic types of used spectrum spreading (FHSS, DSSS, OFDM) are mentioned next. The FHSS type of spectrum spreading is described in more detail, because the spectrum spreading is done by frequency hopping. Particular systems contain error control of radio transmission of information, which is realized by FEC (Forward Error Correction) and ARQ (Automatic Repeat Query) techniques. Practical part of the bachelor´s thesis demonstrates, with usage of Matlab programme, adaptive frequency hopping function (AFH) during communication of Master-Slave devices, where more systems are active. This causes the interference of the communication. This interference is caused by static and dynamic jammers, that work in the same band as the Master-Slave devices.
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Spread spectrum modulator
Lejsková, Alena ; Kováč, Michal (referee) ; Maršálek, Roman (advisor)
This thesis deals with a method of spectrum-spreading of the data signals transmitted in the radio channel. There exist three different ways of spreading application, they uses pseudorandom sequences and also orthogonal sequences. In these systems we can find various kinds of modulations, one of them (Quadrature Phase Shift Keying) is shown at the end of the thesis. Spectrum spreading orthogonal multiplex OFDM is based on this method. The thesis wants to present the principle of the spectrum spreading method and the description of systems, transmitters and receivers that are using this method.
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|
|
Utilizing psychoacoustic model and Wavelet Packet Transform for purposes of audio signal watermarking
Heitel, Tomáš ; Schimmel, Jiří (referee) ; Rajmic, Pavel (advisor)
This Thesis deals with a method to enforce the intellectual property rights and protect digital media from tampering – Digital Audio Watermarking. The main aim of this work is implement an audio watermarking algorithm. The theoretical part defined basic terms, methods and processes, which are used in this area. The practical part shows a process of embedding the digital signature into a host signal and her backward extraction. The embedding rule used spread spectrum technique and a psychoacoustic model. The implemented psychoacoustic model involves two properties of the human auditory system which are frequency masking and representation the frequency scale on limited bands called critical bands. The model is relatively new and based on the DWPT. In terms of above model is then the digital watermark embedded in the wavelet domain. This algorithm is implemented in technical software MATLAB. One part of this work focuses on robustness tests of the algorithm. Common signal processing modifications are applied to the watermarked audio as follows: Cutting of the audio, re-sampling, lossy compression, filtering, equalization, modulation effects, noise addition. The last part of the thesis presents subjective and objective methods usable in order to judge the influence of watermarking embedding on the quality of audio tracks called transparency.
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Design of a laboratory exercise with frequency hops
Novák, David ; Číž, Radim (referee) ; Škorpil, Vladislav (advisor)
Novák, D. Brno: Department of Telecommunications, The Faculty of Electrical Engineering and Communication, Brno University of Technology, 2008, Design of a laboratory exercise with frequency hops. Bachelor’s thesis, supervisor: Doc. Ing. Vladislav Škorpil, CSc., 35 pages. Bachelor’s thesis consider about Design of a laboratory exercise with frequency hops. Theoretical part treat about technology of frequency hops. Below about types, properties, method about transfer and practical use of this technology. This event is maked from information acquired from practical part and from literature. Practical part serves such as extended manual to laboratory exercises into simulator system Emona TIMS. Exercises are concerned about measuring connection establishment between transmitter and receiver technology of frequency hops, speed and quality connection. Accent is set to detailed explanation objectives measuring. Bachelor’s thesis is complemented about measured out findings, these measurements.
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