Design and Evaluation of a logging system in a power-constrained environment

Abstract: Logging plays a crucial role in debugging endeavors, assisting technicians in identifying errors and improving the overall sustainability of electrical systems. This thesis focuses on integrating local logging capabilities into the Balise Transmission Module (BTM), a legacy control system that lacks such features. The project also aims to incorporate real-time remote logging functionalities. It should be noted that the BTM does not have power output, necessitating the logging system to derive energy from existing signals while ensuring the safe operation of the control system. The thesis starts by introducing the project’s context, then explains the system architecture and relevant background information. Subsequently, it delves into the design aspects of a power supply that efficiently extracts energy from the control system. Additionally, the thesis explores wireless data transfer solutions and local data storage alternatives, addressing other pertinent details related to the logging system. Finally, it presents an evaluation of the design and an analysis of the results. The power supply design was developed to incorporate in-rush current limiting, a buck converter, and current limiting mechanisms to ensure the safe operation of the BTM. Through simulations, this thesis demonstrates that the power supply can operate within the safe boundaries of the BTM while efficiently harnessing sufficient current to power the system. The wireless transmission protocols investigated in this study were Bluetooth Low Energy (BLE) and WiFi. The thesis evaluates BLE as sufficiently power-efficient but identifies throughput limitations due to the raw data generated by the BTM exceeding the available throughput. On the other hand, WiFi exhibits no throughput issues but consumes excessive power, making it unsuitable for legacy versions of the BTM. Flash memory was designed and implemented as a feasible solution for local storage.