P13323: Optoelectric Guitar Pickup/public/
Concept Development (generation, improvement, selection)
Customer Needs and Specifications
Customer NeedsCustomer Needs PDF
Needs vs. Specifications Relationship
Function-Level Pugh Evaluations
System-Level Pugh Evaluation
Phototransistor Component Selection
Microcomputer Component Selection
Systems Design Review
System Design Review Presentation
System Design Review Notes
I. Customer Needs and Specifications
- The detectable frequency range should be 70Hz - 20kHz, since low E is at 82Hz.
- How are you going to have headphone volume control? Make use of an amplitude cap.
- The customer is fine foregoing the headphone option to make the design simpler.
II. Concept Selection
- Why are you considering sensors at both the saddle and fret board? The customer believes that having sensors in more than one location is unnecessarily complicating the project.
- There are no customer needs taken into account for the Pugh evaluations.
- Once more data is collected, redo the Pugh evaluations.
- Why was the AVR32 chosen as the microprocessor? It was chosen because is has an extensive DSP library and it is more precise than the MSP430.
III. System Flowchart
- How will you handle the state of the filters (on/off, issues in filters, etc.)? Implementing built-in test circuitry is an option to address this potential problem.
- Will you test for saturation?
- Will the summation of the signals occur before or after the processing? The customer would prefer that the summation occurs after the processing.
- There are free software tools to configure analog filters.
IV. Data Collection
- How was the test signal acquired? The signals were collected in an impromptu sound room created by using white boards using the open source software Audacity.
- The impromptu sound room may have created a resonance box and sound may not have propagated properly. Tests should be completed in an environment such as the ones that the film majors have access to.
- The customer would like to stick with 20kHz as the maximum frequency detected, unless the detailed design shows a significant benefit from cutting it down, such as circuit size. The maximum sampling rate of the processor might also dictate what the maximum detected frequency will be.
- Power is not a high priority issue.
V. Risk Management
- How much will ambient light affect the measurements if the sensors are only detecting IR light? Case studies should be done to determine the effect.
- Environmental noise could be compensated for using double correlated sampling, but it will decrease the sampling rate.
- The customer is not worried about all kinds of guitars, only the current guitar.
- Will the mechanical design allow sensors and LEDs to adjust?
- Predicting where the nodes are on the strings will assure that the sensors aren't trying to sense on a node.