Development of a low-power-signal acquisition device for signals lower than 25 Hz

Inhaltsverzeichnis (Table of Contents)

• Assignment
• Concepts
  • Using the sound board of a personal computer
  • Using the USB-Interface
• Low-pass-filter
  • Motivation to use a low-pass-filter before digitizing
  • Kinds of low-pass-filters
  • Development of Butterworth-low-pass filters in general
  • Designing a Butterworth low-pass filter of 6th order
    • Measurement results
• Digitising and preparation of the signal
  • Sampling
  • Quantization
  • Coding
  • Requirements for digitising ELF-signals
    • Anti-aliasing filter
    • Sample frequency
    • Resolution
  • Microcontroller and adapting circuits
    • Sigma-Delta-ADC
• Data exchange
  • The SPI-Bus in general
  • Initialization of SPI with the MSP430F2013 microcontroller
• USB-Interface
  • Requirements to transfer the data into the compute
  • The IO-Warrior56 (IOW56)
    • Normal mode function
    • Special mode function
• Interaction
• Power supply
• Software
• Appendix
  • Circuit diagram
  • Board, layout and bill of material
  • Used formulaic symbols
  • Used equipment
  • List of sources

Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)

This diploma thesis aims to develop a low-power signal acquisition device for weak signals with frequencies up to 25 Hz. This device should be capable of digitizing and transmitting the data to a personal computer via a USB interface. The device is intended for use in various applications, including the measurement of extremely low-frequency (ELF) signals. The focus is on creating a cost-effective and user-friendly device that is easy to build and operate.

• Design and development of a low-power signal acquisition device for frequencies up to 25 Hz
• Digitization and transmission of acquired data to a personal computer via a USB interface
• Implementation of a low-pass filter to ensure accurate signal processing
• Selection and application of appropriate hardware components, including a microcontroller and an analog-to-digital converter
• Development of software for data acquisition and processing

Zusammenfassung der Kapitel (Chapter Summaries)

• Assignment: This chapter outlines the task of designing and developing a signal acquisition device for detecting and digitizing signals within the extremely low-frequency (ELF) range (0 Hz
• Concepts: This chapter explores various methods for capturing and transmitting the signals. It discusses the use of personal computer sound boards and USB interfaces as potential options for data transfer.
• Low-pass-filter: This chapter focuses on the importance of using a low-pass filter before digitizing signals. It explores different types of low-pass filters and details the development and design of a sixth-order Butterworth low-pass filter. Measurement results from the filter implementation are also presented.
• Digitising and preparation of the signal: This chapter delves into the processes involved in digitizing the acquired signal, including sampling, quantization, and coding. It examines the specific requirements for digitizing ELF-signals, addressing aspects like anti-aliasing filtering, sample frequency, and resolution. The role of the microcontroller and associated circuits, including the Sigma-Delta-ADC, in the digitization process is also discussed.
• Data exchange: This chapter covers the use of the SPI-Bus for data exchange. It explains the general functionality of the SPI-Bus and details the initialization process of the SPI interface with the MSP430F2013 microcontroller.
• USB-Interface: This chapter focuses on the requirements for transferring data into the computer. It introduces the IO-Warrior56 (IOW56) as a potential USB interface solution. The normal and special mode functions of the IOW56 are explored.

Schlüsselwörter (Keywords)

The thesis revolves around the design and development of a low-power signal acquisition device for frequencies up to 25 Hz, focusing on the acquisition and digitization of weak signals. Key aspects include signal processing using low-pass filters, specifically the Butterworth filter, and the application of a microcontroller (MSP430F2013) and a Sigma-Delta-ADC. Data exchange via the SPI-Bus and the use of a USB interface (IO-Warrior56) are also crucial components.