FPGA-based architectures for acoustic beamforming with microphone arrays : trends, challenges and research opportunities

Over the past decades, many systems composed of arrays of microphones have been developed to satisfy the quality demanded by acoustic applications. Such microphone arrays are sound acquisition systems composed of multiple microphones used to sample the sound field with spatial diversity. The relatively recent adoption of Field-Programmable Gate Arrays (FPGAs) to manage the audio data samples and to perform the signal processing operations such as filtering or beamforming has lead to customizable architectures able to satisfy the most demanding computational, power or performance acoustic applications. The presented work provides an overview of the current FPGA-based architectures and how FPGAs are exploited for different acoustic applications. Current trends on the use of this technology, pending challenges and open research opportunities on the use of FPGAs for acoustic applications using microphone arrays are presented and discussed

System integration of a remotely accessible satellite tracker.

Masters Degree. University of KwaZulu-Natal, Durban.The recent rise in space missions and satellite launches has piqued the interest of many. As a result, the growing number of objects in orbit has led to an increase in space monitoring. While large-scale tracking systems exist, many enthusiasts utilise rudimentary methods for satellite monitoring. Some have created do-it-yourself rotators or radio reception stations. Subsequently, a remotely accessible system was required to track satellites and receive transmissions. A small-scale system was designed to fulfil the requirements. Aluminium extrusions were used to create the frame, while microprocessors, sensors and other components were integrated to complete the rotator assembly. A circuit layout was drawn up to coordinate the flow of power and data between components. Low-powered electronics allow the system to run off-grid via a 12 V battery. Many features of the Raspberry Pi lent well to the required application, such as wireless network connectivity and a remote access service. Gpredict, an advanced satellite tracking software, was used to calculate the coordinates for rotation. The RTL-SDR, a software-controlled tuner, provided control to receive radio frequencies. Features such as a slow scan image decoder and frequency identification toolkit were also integrated. The user interface program called TrackGUI was coded, which allows easy access to tracking features. A login system was created with ‘admin’ and ‘user’ access levels. Initially, the presence of GlobalProtect on the UKZN network posed an issue, but methods were implemented to solve this problem. Various aspects of the system were tested and iterated until they met the required parameters. Test results showed that the system could operate within 5 degrees of the intended target. Radio transmissions and slow-scan images could be received and recorded. Therefore, the aim of integrating hardware and software components to create a remotely accessible satellite tracking system was achieved

Two-dimensional direction-of-arrival estimation with time-modulated arrays

Two-dimensional direction-of-arrival estimation with time-modulated array