Piscivorous Bird Deterrent Device Based on a Direct Digital Synthesis of Acoustic Signals

This paper addresses the development of an acoustic deterrent device for the protection of fishponds and other objects against the unwanted presence of birds. The objective of the paper is not only providing of a deep analysis of available technologies for waveform synthesis and generation, but also building a theoretical base for the design and implementation of acoustic bird deterrent solutions. The paper addresses the synthesis of bird songs and calls using technologies for music, speech, and other types of acoustic signal processing. The second part of the paper is devoted to the unique algorithms and implementation details of the intelligent acoustic deterrence device prototype. The practical applicability of algorithms for bird call record conversion into synthesizer sequences has been analysed and possible issues are highlighted. The effectiveness and ease of practical implementation of the given method in the hardware are briefly discussed.

The Development of a High Performance Digital RF Transmitter for NMR

<p>This Master’s thesis consists of the development of a Nuclear Magnetic Resonance (NMR) Radio Frequency (RF) transmitter, which is a core electronic subsystem of an NMR system. The main purpose of this research is to contribute to the application of NMR, which is a new sensing technology that has yet to be fully implemented into the everyday world. One of the barriers to adopting this technology is its complexity. However, the invention of high speed digital FPGAs (Field Programmable Gate Array) such as the Spartan series has made it easier to develop high performance NMR systems over recent years. The major contribution to this research is the development of faster digital signal processing hardware, and methodologies that have been implemented on a single chip. This has reduced the size and the cost of the electronic subsystem and contributed towards the evolution of NMR as a general tool. This thesis introduces the concept of implementing a high-speed NMR RF multi-frequency transmitter by using multiple Direct Digital Synthesis (DDS) cores to generate sine-waves, which range from 100 kHz to 750 MHz. The research required three stages to be achieved, beginning with conceptual design of a high-speed transmitter using MATLAB-Simulink, RTL-level (Register-Transfer Level) simulation and hardware implementation, which included hardware testing on a prototype board. This Master’s research is to seek a solution to building a multi-core DDS module in an FPGA device. In other words, the research work focuses on finding an alternative solution to constructing a DDS system. The project involves building up the VHSIC Hardware Description Language (VHDL) program to work beyond the hardware limitation of an FPGA device. Hence, the final solution does not consider any noise impact due to the structure of the developed system.</p>

The Development of a High Performance Digital RF Transmitter for NMR

<p>This Master’s thesis consists of the development of a Nuclear Magnetic Resonance (NMR) Radio Frequency (RF) transmitter, which is a core electronic subsystem of an NMR system. The main purpose of this research is to contribute to the application of NMR, which is a new sensing technology that has yet to be fully implemented into the everyday world. One of the barriers to adopting this technology is its complexity. However, the invention of high speed digital FPGAs (Field Programmable Gate Array) such as the Spartan series has made it easier to develop high performance NMR systems over recent years. The major contribution to this research is the development of faster digital signal processing hardware, and methodologies that have been implemented on a single chip. This has reduced the size and the cost of the electronic subsystem and contributed towards the evolution of NMR as a general tool. This thesis introduces the concept of implementing a high-speed NMR RF multi-frequency transmitter by using multiple Direct Digital Synthesis (DDS) cores to generate sine-waves, which range from 100 kHz to 750 MHz. The research required three stages to be achieved, beginning with conceptual design of a high-speed transmitter using MATLAB-Simulink, RTL-level (Register-Transfer Level) simulation and hardware implementation, which included hardware testing on a prototype board. This Master’s research is to seek a solution to building a multi-core DDS module in an FPGA device. In other words, the research work focuses on finding an alternative solution to constructing a DDS system. The project involves building up the VHSIC Hardware Description Language (VHDL) program to work beyond the hardware limitation of an FPGA device. Hence, the final solution does not consider any noise impact due to the structure of the developed system.</p>

Development of technology of high-speed digital-to-analogue converters to improve the efficiency of direct digital synthesis of radio-frequency signals

The importance of high-speed digital-to-analogue converters for the synthesis of high-frequency coherent signals is shown. A review of the main specialized modes of operation of high-speed digital-to-analogue converters is carried out, which make it possible to effectively use the side components of the spectrum that arose during the restoration of a signal from digital to analogue form. An RF2 reconstruction mode with a modified bipolar pulse sequence is proposed, which makes it possible to increase the amplitude of the images in the eighth and ninth Nyquist zones.

Research of metrological capabilities of digital (DDS- and Trueform-) generators

One of the fundamental improvements of the measurement standard of frequency deviation of frequency-modulated oscillations was the replacement of analog frequency-modulated generators used in DETU 09-03-95 with digital ones based on the principle of direct digital synthesis (DDS) and its next version of Trueform technology. These generators have wider ranges of frequency deviation and modulation frequencies than analog ones, but nonlinear distortion laws of the frequency modulation are not standardized. The subject of the article is the development of methods and research of these generators and frequency-modulated signals generated by them for nonlinear distortions, accompanying amplitude modulation, frequency noise. Three methods were used in the study: direct measurement; “combination frequencies” and “frequency shift”. The experiment was performed using several measurement methods, which allowed to estimate very small values of nonlinear distortion. Methods were developed and experimental estimations of concomitant amplitude modulation of DDS-generators (in frequency modulation mode), as well as their frequency noise level, were performed. An experimental evaluation of the capabilities of the analog-digital demodulator of the R&S FSL6 spectrum analyzer with the K7 option was performed, its high linearity was shown, its capabilities with respect to the frequency ranges of carrier oscillations and frequency deviation were evaluated. The research results provide a basis for the method of calibration of DDS-generators and demodulator of spectrum analyzers with the K7 option in those ranges where their parameters are not normalized (at direct current up to 8 MHz and F up to 500 kHz).

Function Generator Based on Personal Computer

This paper aims to generate the various waveforms commonly used in a laboratory. A computer is used to synthesize the waveforms. It makes use of software to synthesize the waveforms digitally and a Universal Serial Bus (USB) to parallel converter to transmit the digital version of the waveform to a digital to analog converter where it is converted to produce an analog waveform. A buffer is used to display the analog signal on an oscilloscope. Direct Digital Synthesis (DDS) is used to generate these waveforms. MATLAB simulation software is used to perform the DDS, and PROTEUS software is used for circuit design of the digital to analog converter.