Analysis of Doppler Effect on the Pulse Compression of Different Codes Emitted by an Ultrasonic LPS

This work analyses the effect of the receiver movement on the detection by pulse compression of different families of codes characterizing the emissions of an Ultrasonic Local Positioning System. Three families of codes have been compared: Kasami, Complementary Sets of Sequences and Loosely Synchronous, considering in all cases three different lengths close to 64, 256 and 1,024 bits. This comparison is first carried out by using a system model in order to obtain a set of results that are then experimentally validated with the help of an electric slider that provides radial speeds up to 2 m/s. The performance of the codes under analysis has been characterized by means of the auto-correlation and cross-correlation bounds. The results derived from this study should be of interest to anyone performing matched filtering of ultrasonic signals with a moving emitter/receiver

Smartphone application for accessible navigation

Διπλωματική εργασία--Πανεπιστήμιο Μακεδονίας, Θεσσαλονίκη, 2018.The main aim of this study is to investigate how the modern smartphone technology can assist people with visual impairments in indoor navigation tasks. We use the free and open indoor navigation service Anyplace, to design an indoor guidance system that is accessible, inexpensive, simple and user-friendly to different user groups disregarding their disabilities. The Android application that Anyplace offers, was extended and modified to serve also the needs of visually impaired users. The presented system works well with the assistive applications that Android platform offers and provides various ways for interaction between the user and the system. The system is communicating with Anyplace server to inform the user about the information of the surrounding environment and guide him/her to the desired place in the building with accessible messages. The application can process, specific pre-defined user commands and location information from existing QR labels in the building. This thesis is focusing on assisting the impaired users on indoor navigation tasks, but not on replacing the assistive means that the visually impaired user is already using. (e.g. long cane, guide dog) Experimental results show the ability of the system to effectively communicate with the user and assist him/her in way-finding tasks in the building of the University of Macedonia

Indoor positioning and tracking based on the received signal strength

Received Signal Strength Indicator (RSSI)-based indoor Location and Tracking (L&T) is a promising and challenging technology that enables mobile users/nodes to obtain their location information. This dissertation focuses on overcoming the challenges as well as improving the positioning accuracy for the RSSI-based L&T. In particular, the author considers 4 L&T solutions. In the first, the author develops a L&T solution by designing the Kalman Filter (KF) to work linearly within the positioning framework. To elaborate on this implementation, the equations of the KF are presented in a consistent manner with the implementation. In the second, the author designs a L&T solution based on the Iterated Extended Kalman Filter (IEKF) to improve the accuracy compared with the popular Extended Kalman Filter (EKF). In the third, the author overcomes the particular implementation challenges of the EKF by designing a L&T solution based on the implementation of the Scaled Unscented Transformation (SUT) to the KF. The author calls the resulting filter Scaled Unscented Kalman Filter (SUKF). In the forth, the author overcomes the implementation difficulties of the EKF by designing a L&T solution based on the implementation of the Spherical Simplex Unscented Transformation (SSUT) to the KF. The author calls the resulting filter the Spherical Simplex Unscented Kalman Filter (SSUKF). The proposed solutions with their corresponding achievements enhance the role of RSSI-based L&T in wireless positioning systems. The contributions led to significant improvement in the positioning accuracy, reliability and the ease of implementation

Navigation and Geolocation Within Urban and Semi-Urban Environments Using Low-Rate Wireless Personal Area Networks

IEEE 802.15.4 defines networks and hardware capable of low power, low data rate transmissions. The use of these networks for the “Internet of Things”, machine to machine communications, energy metering, control and automation etc is increasing. In an urban environment, these networks may well soon become so popular and widespread in their usage that their discoverability and coverage density is sufficient for aiding geolocation – in the same way that IEEE 802.11 WiFi networks are used today. This research shows that although possible, there are some current inherent weaknesses in the use of IEEE 802.15.4 networks for location purposes particularly with respect to multilateration