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Designing a Directional Acoustic Transmitter
Hladký David
In this paper the parametric transmission of sound through an amplitude-modulated ultrasonic wave, using automatic demodulation in a non-linear environment is discussed. Methods for the processing of the transmitted signal are presented; these techniques employ modified amplitude modulation to suppress the environmental effects, which otherwise distort the signal. A special emphasis is placed on the mathematical instruments describing the parametric sound beam transmission in a non-linear medium. Within our research, we fabricated a parametric speaker consisting of 50 ultrasonic acoustic transducers with the resonant frequency of 40 kHz. The functionality of the acoustic source was verified via measurement of the spatial radiation characteristics and through determination of the total harmonic distortion (THD). In order to control the parametric speaker, a digital element comprising a sampler, a transducer of the input transmitted signal, and a microcontroller to preprocess this signal and to facilitate the amplitude modulation of the ultrasonic carrier wave is designed. The applied algorithms were analyzed to establish their computational intensity; such an analysis enabled us to select a microprocessor basis suitable for the implementation of the signal processing algorithms.
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Implemetation of signal processing problems for teaching purposes
Ševčík, Zdeněk ; Rajmic, Pavel (referee) ; Mangová, Marie (advisor)
This thesis is focused on Fourier series, phasor diagram, signal resampling and amplitude modulation. All of there problems are analyzed in theoretical part of thesis. Here are derived all three form of Fourier series, described signal sampling, decimation and interpolation. Next thesis is focused on signal modulation and closer deal with amplitude modulation of harmonic and inharmonic signal. In practical part is example of calculation of Fourier siries for a specific signal, example of signal resampling and example of amplitude modulation for harmonic and inharmonic signal. Objective of practical part is creates programs focused on these problems. Programs should be interactive and their purpose is demonstrate the problem to students.
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Ultrasonic Directional Speaker
Sedlák, Jiří ; Michalec, Jaroslav (referee) ; Mikulka, Jan (advisor)
The master´s thesis deals with theoretical research and practical application of the principle of spreading acoustic waves through nonlinear medium. The theoretical part describes five different types of amplitude modulation and their mathematic representation, which were verified by the program Matlab. Next, the impedance characteristic of ultrasound PZT transducer was measured and the design of PWM modulator and class D amplifier was described. The practical part of the master´s thesis contains the realization of the parametric loudspeaker assembled from the class D amplifier and the PWM modulator. In conclusion, the designed parametric loudspeaker was measured and the individual types of amplitude modulation were compared with respect to the total harmonic distortion of transmitted useful signal.
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Implementation narrowly directed beeper
Hladký, David ; Drexler, Petr (referee) ; Mikulka, Jan (advisor)
The present final thesis discusses the transmission of a narrowly directional parametric sound beam through an amplitude-modulated ultrasonic wave, utilizing the effect of auto-demodulation in a nonlinear medium and ensuring the subsequent processing of the input signal for the parametric sound transmitter. Emphasis is placed on the mathematical tools that relate to parametric sound transmission in a nonlinear medium. The basic part of the thesis describes a parametric speaker and the associated amplitude modulation techniques, which constitute a major prerequisite for the processing of the transmitted signal. In the following section, the author then analyzes the computational intensity of these techniques, considering applicable hardware approaches. Finally, the fabrication and practical use of the proposed solution are discussed, including the measurement of typical parameters such as the spatial radiation characteristics, total harmonic distortion, and transmission channel bandwidth.
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Shortwave power amplifier
Fiala, Roman ; Vařacha, František (referee) ; Prokeš, Aleš (advisor)
This master’s thesis describes RF power amplifier design. The designed amplifier has been built. The first three chapters outline basics about radio frequency amplifiers. The basic theory needed for amplifier implementation is also described there. In the fourth chapter the power amplifier is designed. The design is based on the theoretical knowledge. Complete amplifier contains RF preamplifier, power amplifier and filters. The OrCAD PSpice, Ansoft Designer SV and EAGLE programs have been used for the design and verification of some sections of circuits. Measurement results of the built amplifier are in the fifth chapter. This thesis contains also the draft for laboratory exercise.
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A Virtual Instrument for Measurement of Flicker
Cabala, Ľuboš ; Bok, Jaromír (referee) ; Šlezingr, Jan (advisor)
This thesis deals with the voltage fluctuation, its causes, resourses and affections on light sources. Further the posibbilities of the voltage fluctuations limitation are mentioned. This thesis also contains the decriptions of construction of UIE/EIC flickermeter on which bases the virtual flickermeter is programmed in the LabVIEW.
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Shortwave power amplifier
Kufa, Jan ; Vařacha, František (referee) ; Prokeš, Aleš (advisor)
The aim of the master´s thesis is to create a high-frequency amplifier with switching power amplifier classes among classes A, B, C with output power of 10 W. The amplifier operates at frequency from 3.5 MHz to 14 MHz. Master´s thesis includes also theoretical analysis, design of lowpass filter and amplifiers and their simulation, mechanical realization and measured parameters of the amplifier.
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Optimization of telecommunication education environment
Jeřábek, Josef ; Minarčík, Martin (referee) ; Škorpil, Vladislav (advisor)
The intended goal within the scope of this master´s thesis is to get acquainted with the product of EMONA INSTRUMENTS Company. There are two main concepts: the software version TutorTIMS – Advanced and the hardware version TIMS-301. Both concepts were bought into the laboratory, where the following subjects are being lectured: “Access and transport networks” and “Telecommunication network services”. Three laboratory exercises were prepared for both software version and hardware version. Both versions are modular and all designed exercises support independent and creative approach of students. All exercises also consist of standard parts, which are the description of the exercise and exemplary protocol solution. The first exercise is called “amplitude modulation” and is designed as an introductory exercise. Next are a couple of exercises which are designed to be performed on one workplace at the same time. The first of them is focused on practical verification of facts from amplitude shift keying, the second one focuses on link codes. This couple of exercises is the best choice, considering the hardware version of TIMS-301 and at the present time available modules in the lab. Software version is not limited in such way, but it was required to allow performing all of prepared exercises on both versions. Lastly there is a comparison between the software and hardware version and several options for hardware TIMS optimization.
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