digital tuner project final presentation
Post on 27-Jun-2015
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Digital Tuner Project Team Haribo Jen, Mihir, Mike, Sami, and Zack
Overview • Project Overview • Hardware Building • Digital Measurement Chain Implementation • Digital Signal Processing • Digital Tuner Microcontroller Programming
Project Overview The 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
Project Overview
Hardware Building The 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
Hardware Building Functional 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)
Hardware Building Microcontroller
Microphone LED lights
USB to UART transmitter
Buttons
Digital Measurement Chain The Digital Measurement Chain (DMC)
consists of six stages: • Signal input • Signal conditioning • Anti-aliasing • Sample & Hold • Analog to Digital Conversion • Digital Signal Processing • Output
DMC Implementation
DMC Implementation Digital Tuner Board hardware already achieves: • Signal Input (Microphone) • Signal Conditioning (Op amp) • Anti-aliasing (Low-pass filter removes
erroneous artifacts from input signal)
DMC Implementation Digital 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
DMC Implementation Digital 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
Signal Sampling Signal sampling: taking measurement of a
signal at a specified rate and number of sample points
Signal Sampling Goal: reconstruct the original signal as
accurately as possible!
Signal Sampling What happens if we sample too slow?
ALIASING!
DMC Implementation Digital 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
Analog to Digital Converter Goal: convert analog signals to digital signals
Analog to Digital Converter Why? Simplified and faster signal processing!
Would you rather work with analog numbers (1.239454..., 8.323423...) or digital numbers? (1, 2, 3, 4, 5, ...)
Drawbacks: Quantization error
DMC Implementation Digital 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
Talked about in the
microcontroller coding section!
Where are we?
Digital Signal Processing Goal: Determine which guitar note and tune the
input signal corresponds to How? 1. Convert signal to frequency domain 2. Calculate signal's amplitude spectrum 3. Determine frequency of input signal 4. Match frequency of input signal to known
guitar string frequencies
Digital Signal Processing Goal: Determine which guitar note and tune the
input signal corresponds to How? 1. Convert signal to frequency domain 2. Calculate signal's amplitude spectrum 3. Determine frequency of input signal 4. Match frequency of input signal to known
guitar string frequencies
The Fourier Transform
The Fourier Transform Why? Easier to determine the frequency of the
input signal!
Digital Signal Processing Goal: Determine which guitar note and tune the
input signal corresponds to How? 1. Convert signal to frequency domain 2. Calculate signal's amplitude spectrum 3. Determine frequency of input signal 4. Match frequency of input signal to known
guitar string frequencies
The Amplitude Spectrum
Digital Signal Processing Goal: Determine which guitar note and tune the
input signal corresponds to How? 1. Convert signal to frequency domain 2. Calculate signal's amplitude spectrum 3. Determine frequency of input signal 4. Match frequency of input signal to known
guitar string frequencies
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
Matching Frequencies In tune? Frequencies falling in between these regions are considered flat or sharp notes Digital Tuner Accuracy?
Due to low precision in the ADC and hardware limitations, frequency calculations are approximate
Frequency (Hz) Guitar Note
82.41 Low E
110.0 A
146.8 D
196.0 G
246.9 B
329.6 High E
Microcontroller Programming
The aforementioned digital signal processing steps all take place in the microcontroller!
C programming!
User Interaction The Digital Tuner Board communicates the guitar
note and accuracy to the user, via LED lights.
Questions?
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