Digital Tuner Project Final Presentation

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Presentation for our Digital Tuner Project at Technische Universität Berlin. We built the hardware for a music tuner board and programmed and tested the board to work as a guitar tuner board. See our project writeup for more specific details.

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Digital Tuner Project Final Presentation

  1. 1. Digital TunerProjectTeam HariboJen, Mihir, Mike, Sami, and Zack
  2. 2. Overview•  Project Overview•  Hardware Building•  Digital Measurement Chain Implementation•  Digital Signal Processing•  Digital Tuner Microcontroller Programming
  3. 3. Project OverviewThe Digital Tuner Project consists of:• Building a Digital Tuner Board• Sampling and conditioning input signals• Converting input analog signals to digital• Processing and analyzing digital signals• Determining guitar string note and tune• Relaying sensor data to the user via LEDs
  4. 4. Project Overview
  5. 5. Hardware BuildingThe Digital Tuner Board is constructed from soldering electronic components, including:•  Atmega1284P microcontroller o  Runs C code ("Brain" of the board)•  USB to UART transmitter o  Thing that connects to the computer and sends/ listens for messages•  Microphone o  Captures input sound signals
  6. 6. Hardware BuildingFunctional components of the Digital Tuner Board:• Microphone (input)• Operational amplifer• Low-pass filter• Analog-to-digital converter• Microcontroller• LEDs (output)• USB to UART transmitter (output)
  7. 7. Hardware Building MicrocontrollerUSB toUARTtransmitterLED lights MicrophoneButtons
  8. 8. Digital MeasurementChainThe Digital Measurement Chain (DMC) consists of six stages:•  Signal input•  Signal conditioning•  Anti-aliasing•  Sample & Hold•  Analog to Digital Conversion•  Digital Signal Processing•  Output
  9. 9. DMC Implementation
  10. 10. DMC ImplementationDigital Tuner Board hardware already achieves:• Signal Input (Microphone)• Signal Conditioning (Op amp)• Anti-aliasing (Low-pass filter removes erroneous artifacts from input signal)
  11. 11. DMC ImplementationDigital Tuner Board microcontroller accomplishes:• Signal sampling• Analog-to-digital conversion o  Converts analog signal to digital signal•  Digital signal processing o  Performs transformations and analyzes signal to determine guitar note and tune•  Output o  Transmits information to computer over bus line or blinks LEDs to communicate with the user
  12. 12. DMC ImplementationDigital Tuner Board microcontroller accomplishes:• Signal sampling• Analog-to-digital conversion o  Converts analog signal to digital signal•  Digital signal processing o  Performs transformations and analyzes signal to determine guitar note and tune•  Output o  Transmits information to computer over bus line or blinks LEDs to communicate with the user
  13. 13. Signal SamplingSignal sampling: taking measurement of a signal at a specified rate and number of sample points
  14. 14. Signal SamplingGoal: reconstruct the original signal as accurately as possible!
  15. 15. Signal SamplingWhat happens if we sample too slow? ALIASING!
  16. 16. DMC ImplementationDigital Tuner Board microcontroller accomplishes:• Signal sampling• Analog-to-digital conversion o  Converts analog signal to digital signal•  Digital signal processing o  Performs transformations and analyzes signal to determine guitar note and tune•  Output o  Transmits information to computer over bus line or blinks LEDs to communicate with the user
  17. 17. Analog to DigitalConverterGoal: convert analog signals to digital signals
  18. 18. Analog to DigitalConverterWhy? Simplified and faster signal processing!Would you rather work withanalog numbers(1.239454..., 8.323423...)or digital numbers?(1, 2, 3, 4, 5, ...)Drawbacks: Quantization error
  19. 19. DMC ImplementationDigital Tuner Board microcontroller accomplishes: Talked about in• Signal sampling the•  microcontroller Analog-to-digital conversion coding section! o  Converts analog signal to digital signal•  Digital signal processing o  Performs transformations and analyzes signal to determine guitar note and tune•  Output o  Transmits information to computer over bus line or blinks LEDs to communicate with the user
  20. 20. Where are we?
  21. 21. Digital Signal ProcessingGoal: Determine which guitar note and tune the input signal corresponds toHow?1.  Convert signal to frequency domain2.  Calculate signals amplitude spectrum3.  Determine frequency of input signal4.  Match frequency of input signal to known guitar string frequencies
  22. 22. Digital Signal ProcessingGoal: Determine which guitar note and tune the input signal corresponds toHow?1.  Convert signal to frequency domain2.  Calculate signals amplitude spectrum3.  Determine frequency of input signal4.  Match frequency of input signal to known guitar string frequencies
  23. 23. The Fourier Transform
  24. 24. The Fourier TransformWhy? Easier to determine the frequency of the input signal!
  25. 25. Digital Signal ProcessingGoal: Determine which guitar note and tune the input signal corresponds toHow?1.  Convert signal to frequency domain2.  Calculate signals amplitude spectrum3.  Determine frequency of input signal4.  Match frequency of input signal to known guitar string frequencies
  26. 26. The Amplitude Spectrum
  27. 27. Digital Signal ProcessingGoal: Determine which guitar note and tune the input signal corresponds toHow?1.  Convert signal to frequency domain2.  Calculate signals amplitude spectrum3.  Determine frequency of input signal4.  Match frequency of input signal to known guitar string frequencies
  28. 28. Matching Frequencies Frequency (Hz) Guitar Note 82.41 Low E 110.0 A 146.8 D 196.0 G 246.9 B 329.6 High E
  29. 29. Matching FrequenciesIn tune? Frequencies falling Frequency (Hz) Guitar Notein between these regions 82.41 Low Eare considered flat or sharp 110.0 Anotes 146.8 DDigital Tuner Accuracy? Due to low precision in 196.0 G the ADC and hardware 246.9 B limitations, frequency 329.6 High E calculations are
  30. 30. MicrocontrollerProgramming The aforementioned digital signal processing steps all take place in the microcontroller! C programming!
  31. 31. User InteractionThe Digital Tuner Board communicates the guitar note and accuracy to the user, via LED lights.
  32. 32. Questions?

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