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Automatic Classification of Digital Modulations
Kubánková, Anna ; Novotný, Vít (advisor)
This dissertation thesis deals with a new method for digital modulation recognition. The history and present state of the topic is summarized in the introduction. Present methods together with their characteristic properties are described. The recognition by means of artificial neural is presented in more detail. After setting the objective of the dissertation thesis, the digital modulations that were chosen for recognition are described theoretically. The modulations FSK, MSK, BPSK, QPSK, and QAM-16 are concerned. These modulations are mostly used in modern communication systems. The method designed is based on the analysis of module and phase spectrograms of the modulated signals. Their histograms are used for the examination of the spectrogram properties. They provide information on the count of carrier frequencies in the signal, which is used for the FSK and MSK recognition, and on the count of phase states on which the BPSK, QPSK, and QAM-16 are classified. The spectrograms in that the characteristic attributes of the modulations are visible are obtained with the segment length equal to the symbol length. It was found that it is possible to correctly recognize the modulation with the known symbol length at the signal-to-noise ratio at least 0 dB. That is why it is necessary to detect the symbol length prior to the spectrogram calculation. Four methods were designed for this purpose: autocorrelation function, cepstrum analysis, wavelet transform, and LPC coefficients. These methods were algorithmized and analyzed with signals disturbed by the white Gaussian noise, phase noise and with signals passed through a multipass fading channel. The method of detection by means of cepstrum analysis proved the most suitable and reliable. Finally the new method for digital modulation recognition was verified with signals passed through a channel with properties close to the real one.
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Demonstration set for basic keying techniques
Žlebek, Lukáš ; Šilhavý, Pavel (referee) ; Číž, Radim (advisor)
This thesis concerns itself with construction of a set of laboratory products, used for demonstrating the basic methods of digital modulation. The primary product, is a generator of carrier and keying signals, which generates cyclically repeated data, and a carrier signal. Another two products are ASK and BPSK modulators. The theoretical part of this thesis describes a basic summary of different kinds of modulation and the design of all the product prototypes themselves. The practical part proves the functionality of individual components of the generator and the functionality of the modulators. In the last part of this thesis, there is a proposal of the laboratory task and its sample solution.
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Analysis of digital modulation robustness at various types of interference
Uher, Tomáš ; Šilhavý, Pavel (referee) ; Kubánková, Anna (advisor)
This bachelor thesis concisely describes essential type of modulation technique for transmission of binary signal. In first part there are summarized advantages and disadvantages for each described modulation technique. There are described proceeding of modulation and demodulation too. Selected digital modulations are tested for Gaussian, Rice and Rayleigh transmission channels. In final part there are compared theoretical and measured values and summarized analysis.
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Communication Systems with Digital Modulations
Spáčil, Jan ; Kubánek, David (referee) ; Číž, Radim (advisor)
The purpose of this semestral project is to explain the basic issues of simple digital modulations through the creation of simple digital modulations using direct digital synthesis. It begins with a short review of digital modulation theory and the theory about direct digital synthesis. All the technical documentation is attached, including schematics and boards of functional modulator.
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Power line data transfer
Ryška, Aleš ; Janík, Lukáš (referee) ; Dobesch, Aleš (advisor)
This thesis deals with powerline communication and application its use in headlamp. In thesis are compared various commercial available solutions, especially the Qualcomm QCA7000 modem. Furthermore, the work deals with the design and the prototype for exploring the applicability of the existing wiring in automobile. The aim of the thesis is to construct a prototype that allows the communication with the front lamp of the car via the power line.
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Simulation of the DVB-T digital modulation in Matlab
Málek, Pavel ; Říčný, Václav (referee) ; Kratochvíl, Tomáš (advisor)
Digital Video Broadcasting (standard DVB) is a system for transmission of the television signals in the digital form. There are used a various types of modulations in this system as QPSK modulation is used in the systems of satellite video broadcasting DVB-S (Satellite) and M-QAM modulations in the cable transmitting DVB-C (Cable). This paper mainly deals with system of the terrestrial digital video broadcasting DVB-T (Terrestrial), where OFDM modulation is used. This type of signal processing is more resistant to the distortions caused by multipath transmitting, which is main problem in the DVB-T. Matlab application, which can simulate digital modulation and demodulation of the transmission signals in the DVB-T, is created in this thesis. The models of the transmission channel is inserted between structures of modulator and demodulator. The user of this application can set the parameters of the broadcasting (e.g. constellation, OFDM mode, guard interval insertion) and the type of distortions (additive noise, reflected and delayed signals). By calculation of the channel bit error rate (BER) user can study influences of broadcasting parameters to the quality of transmission.
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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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Automatic classification of digital modulations using neural networks
Sinyanskiy, Alexander ; Uher, Václav (referee) ; Kubánková, Anna (advisor)
This master’s thesis is about automatic digital modulation recognition using artificial neural networks. The paper briefly describes the issue and existing algorithms for solving the problem of modulation recognition. It was found that the best results are achieved when using the feature-recognition methods and artificial neural networks. The digital modulations that were chosen for recognition are described theoretically and they are ASK, FSK, BPSK, QPSK and 16QAM. These modulations are most commonly used today. Later was briefly described theory of neural networks. In another part was given to the characteristic features of modulation for modulation recognition using artificial neural networks. The penultimate part describes the parameters for signal simulation in Matlab, how to create the key features in Matlab and results after experimental simulation. The last part contains neural network optimization experiments.
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Power line data transfer
Ryška, Aleš ; Janík, Lukáš (referee) ; Dobesch, Aleš (advisor)
This thesis deals with powerline communication and application its use in headlamp. In thesis are compared various commercial available solutions, especially the Qualcomm QCA7000 modem. Furthermore, the work deals with the design and the prototype for exploring the applicability of the existing wiring in automobile. The aim of the thesis is to construct a prototype that allows the communication with the front lamp of the car via the power line.
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Analysis of digital modulation robustness at various types of interference
Uher, Tomáš ; Šilhavý, Pavel (referee) ; Kubánková, Anna (advisor)
This bachelor thesis concisely describes essential type of modulation technique for transmission of binary signal. In first part there are summarized advantages and disadvantages for each described modulation technique. There are described proceeding of modulation and demodulation too. Selected digital modulations are tested for Gaussian, Rice and Rayleigh transmission channels. In final part there are compared theoretical and measured values and summarized analysis.
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