Detektor kovin z digitalnim procesiranjem signalov

Kranjec, Erazem (author), Meža, Marko (mentor)

Cilj diplomske naloge je razvoj prototipa detektorja kovin, ki združuje analogni del vezja in digitalno procesiranje signalov, ter omogoča razširjeno uporabniško izkušnjo. Jedro sistema predstavlja mikrokrmilnik Teensy 4.1, na katerem je implementirana VLF metoda z oddajno in sprejemno tuljavo. Za zaznavo kovin se uporablja I/Q demodulacija in EMA filtriranje. Z namenom izboljšanja uporabniške izkušnje detektor združuje več modulov: prikazovalnik, zvočno signalizacijo, GPS, IMU, kamero, tipkovnico in zapis podatkov na pomnilniško kartico. Programska koda je razvita v jeziku C++ z jasno modularno razdelitvijo in podporo za različne komunikacijske protokole (SPI, UART, I2C, I2S, SDIO). Poleg strojne in programske zasnove je predstavljena tudi izdelava iskalnih tuljav ter spletna orodja za vizualizacijo zbranih podatkov. Sistem je bil uspešno preizkušen in omogoča zanesljivo zaznavo kovinskih predmetov ter osnovno ločevanje materialov na podlagi faznega zamika. V teoretičnem delu naloga zajema pregled osnovnega delovanja različnih vrst detektorjev kovin (BFO, TR/IB, VLF, PI, RF, GPR), oblik tuljav ter opisuje njihove prednosti in omejitve. Prav tako je podan zgodovinski pregled raziskav magnetizma in razvoja prvih detektorjev kovin, kar ustvarja celovit kontekst za razumevanje uporabljenih metod in tehnologij. Naloga se zaključi tako, da razviti prototip predstavlja ustrezno osnovo za nadaljnje raziskave in nadgradnje, kot so večfrekvenčno delovanje, optimizacija tuljav in uporaba naprednejših algoritmov za obdelavo signalov.

• Language: Slovenian
• Keywords: detektor kovin, VLF, I/Q demodulacija, DSP, Teensy 4.1, mikrokrmilnik, vgrajeni sistemi, uporabniška izkušnja
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FE - Faculty of Electrical Engineering
• Year: 2025
• PID: 20.500.12556/RUL-173070
• COBISS.SI-ID: 248955907
• Publication date in RUL: 12.09.2025

Secondary language

• Language: English
• Title: Metal detector with DSP

Abstract

The aim of this thesis is the development of a prototype metal detector that combines the analog circuit part with digital signal processing while providing an extended user experience. The core of the system is a Teensy 4.1 microcontroller, on which the VLF method with a transmit and receive coil is implemented. Metal detection is based on I/Q demodulation and EMA filtering. To enhance the user experience, the detector integrates several modules: display, audio signaling, GPS, IMU, camera, keypad, and data logging to a memory card. The software is developed in C++ with a clear modular structure and support for multiple communication protocols (SPI, UART, I2C, I2S, SDIO). In addition to the hardware and software design, the thesis also presents the construction of search coils and the development of web tools for visualizing collected data. The system was successfully tested, demonstrating reliable detection of metallic objects and basic material discrimination based on phase shift. The theoretical part provides an overview of the basic operating principles of different types of metal detectors (BFO, TR/IB, VLF, PI, RF, GPR), coil designs, and their respective advantages and limitations. A historical review of magnetism research and the development of the first metal detectors is also included, offering a comprehensive context for understanding the applied methods and technologies. The thesis concludes that the developed prototype provides a suitable foundation for further research and upgrades, such as multi-frequency operation, coil optimization, and the application of advanced signal processing algorithms.

• Keywords: metal detector, VLF, I/Q demodulation, DSP, Teensy 4.1, microcontroller, embedded systems, user experience