Iskanje po katalogu digitalne knjižnice

Opis: Air-coupled ground penetrating radar (GPR) systems are widely used for subsurface imaging in demining, geological surveys, and infrastructure assessment applications. However, strong surface reflections can introduce interference, leading to receiver saturation and reducing the clarity of subsurface features. This paper presents a novel surface reflection suppression algorithm for stepped-frequency continuous wave (SFCW) GPR systems. The proposed method estimates the surface reflection component and applies phase-compensated subtraction at the receiver site, effectively suppressing background reflections. A modular SFCW radar system was developed and tested in a laboratory setup simulating a low-altitude airborne deployment to validate the proposed approach. B-scan and time-domain analyses demonstrate significant suppression of surface reflections, improving the visibility of subsurface targets. Unlike previous static echo cancellation methods, the proposed method performs on-board pre-downconversion removal of surface clutter that compensates for varying ground distance, which is a unique contribution of this work.
Ključne besede: GPR systems, ground penetrating radar systems, surface reflection suppression, SFCW, surface echo, echo cancellation, receiver saturation
Objavljeno v DKUM: 12.05.2025; Ogledov: 0; Prenosov: 6
Celotno besedilo (5,21 MB)
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Opis: In the master’s thesis, the development and implementation of optimal control for direct conversion receiver is presented. A background overview of direct conversion receivers, in-phase and quadrature mixers, sampling theory, control theories, adaptive systems, and optimal control is given. The development of a system model which is later used in simulations is also presented. Optimal control is achieved through standard control techniques, such as feedback and feedforward control, with error functions giving restrictions. Information to feed the optimal control is acquired by the system through the analog converters to the digital converters, digital to analog converters, and received signal strength indicators. For the development and testing of optimal control, MATLAB environment was used. Simulations and presentation of the results were also done in MATLAB. Limitations, exact operation, and comments were given throughout the thesis
Ključne besede: optimal control, direct conversion receiver, radio frequency signal, simulation, MATLAB
Objavljeno v DKUM: 23.11.2023; Ogledov: 394; Prenosov: 0

Opis: This work presents an observation of the analog and digital architecture of the reception system of a radio-frequency identification (RFID) reader in the high frequency (HF) domain and the creation of near-field communication (NFC) Application, which is developed for Android and iOS users. This thesis includes a description of RFID and NFC technology, as well as a sufficient amount of information about the standards that define those technologies. The reception system of a given interrogator was thoroughly studied, beginning with the analog signal on the interrogator’s antenna and how it is interpreted in the analog domain for determining the presence of an object in its vicinity. The most emphasis in this thesis was given to the reader when it is in a Tag Detector mode. The Tag Detector mode of the reader is the mode in which the interrogator can detect changes on its antenna. Measurements were taken while testing the Tag Detector at various gain settings of the reception system. To improve the accuracy of those detections, the Tag Detector mode was switched to reader mode, allowing the detected tag’s acknowledgement message to be received. The detection range, as well as the reading range of the interrogator, are also discussed. An NFC application was developed that functions as an interrogator for both the iOS and Android operating systems. The goal of this application is to apply the knowledge we have gained from the study about RFID and NFC communications, as well as the comparison between the tag detection and read ranges of the two types of interrogators.
Ključne besede: Keywords: NFC, RFID, receiver, transmitter, Tag Detector, interrogator, read range, tag detection range
Objavljeno v DKUM: 28.06.2022; Ogledov: 790; Prenosov: 68
Celotno besedilo (1,92 MB)