Project Specification

Background
Users
Functional requirements
Non-functional requirements
Cost
Block diagram
Risks
Plan
Budget

Background

AGMC manufactures an acoustic guitar model aimed at the first-time buyer, primarily for children 10 to 16 years of age. A parent normally purchases the guitar. Corporate marketing studies show that children are unable to tune their guitars by ear and that many of the parents who purchase guitars for their children wonder how the child will keep the instrument tuned. The studies also indicate that if a tuning aid was bundled with the sale of the guitar, AGMC could increase the selling price of the guitar and, at the same time, realize a gain in market share. For such a device to have full impact, it must be user friendly. Sales personnel must be able to walk the customer's child through a tuning exercise in about five minutes.

The low manufacturing cost eliminates the need for product repair. Faulty units will simply be replaced.

AGMC expects to sell approximately 1500 units per month worldwide in the first three years following its introduction.

Users

Background Needs
Novice guitarist

Has fewer than a few months' experience in playing the guitar

Has little or no training in music theory

Understands the terms, sharp, flat, and natural

Quickly and easily tune an acoustic guitar

Sales person

Has extensive experience in playing acoustic guitars

Demonstrate the tuning aid to novice guitarists

Quickly train novice guitarists to use the tuning aid

Assembly technician

Has no experience in playing the guitar

Quickly perform pass/fail quality control tests on newly-assembled tuning aids

Figure: Tuning aid face plate

Functional requirements
Priority Name Measure Description
Must Close-range pick-up Between 1 and 3 feet;
Within 30 degrees of perpendicular		 The tuning aid must perform reliably with the input microphone placed between 1 to 3 feet of the guitar hole, and within 30 degrees of perpendicular.
Must Simple on/off operator control By design The tuning aid must require no user interaction beyond turning it on and off.
Must Six strings By design Indicate separate tuning state for each of six open strings.
Must Automatic detection 0.5s +/- 0.25s Automatically detect and indicate the tuning state of a single plucked open string
Must Sustained detection 3s +/- 0.5s Sustain indication of the tuning state for some observable period.
Must String-specific LED's Strings 6, 5, 4, 3, 2, 1;
Notes E, A, D, G, B, E 		The device must have a pair of LED indicators dedicated to each of the six strings of the guitar, where the strings are for the notes E, A, D, G, B, and E, in that order.
Must LED indicator pairs Sharp LED;
Flat LED		 The device must use a pair of LED's to indicate the tuning status. The single LED labelled sharp illuminates when the plucked string is sharp. The single LED labelled flat illuminates when the plucked string is flat. Both of thesharp and flat LED's illuminate when the plucked string is in tune.
Must LED on brightness 10-20 ma The LED's must sink a sufficient energizing current when illuminated.
Must LED off darkness <0.5 ma The LED's must not sink significant current when not illuminated.
Must Indicator response time 1 s +/-50% The appropriate LED indicator must automatically illuminate within a short period of plucking the string.
Must Indicator dwell time From 1 to 2 s The appropriate LED indicator must remain illuminated for a short period, allowing the user to easily read the indication.
Must Tuning precision See the Precision and Frequencies tables, below
(1 cent = 1/1200 octave)		 The tuning aid precision should be sufficient to provide satisfactory musical results for a novice player, but not be so precise as to be frustratingly difficult to tune correctly.
Should not String confusion Visual Only the LED indicator specific to the plucked string should illuminate. All other LED indicators should remain off.
Should String loudness 1st string: 70-74 db
6th string: 76-80 db		 The tuning aid should perform reliably for a reasonable range of plucking strength and loudness.
Should Background noise Up to 60 db long-term average broadband noise The tuning aid should perform reliably in the presence of broadband background noise.
Should Connectionless operation By design The tuning aid should require no connection with the guitar being tuned. All signals should be measured using an acoustic microphone mounted within the case of the tuning aid itself.
Table: Tuning precision
Input Silence Sharp 6+ cents Sharp 2-6 cents +/- 2 cents
of true		 Flat 2-6 cents Flat 6+ cents
Upper LED Off On On On Off or On Off
Lower LED Off Off Off or On On On On
Table: Tuning frequencies
String Note Fundamental (Hz) 6-cent deviation (Hz)
6E 82.410.286
5A110.000.382
4D146.830.510
3G196.000.680
2B246.940.857
1E329.631.144

Non-functional requirements

Priority Factor Requirement
Must Size Be smaller than 15 cm in its longest dimension, and smaller than 5 cm in each of its other two dimensions
Must Weight Weigh less than 2 kg
Should Power dissipation Dissipate less than 10 Watts
Should Power source Operate from a household 120V AC socket
Should Environment Operate in the temperature and humidity conditions found in most North American homes
Must not Cooling Require a cooling fan
Must Electronic assembly Assemble with a model PP456-01 pick-and-place machine
Should Mechanical assembly Assemble with ordinary tools
Should not Package fabrication Require custom metal or plastics mould tooling
Should not Calibration Require any external frequency reference, i.e., should not require calibration after leaving the factory
Might not Portability Be sufficiently small, light, or robust enough to be portable

Cost

Prototype Hand-assembled Mass-produced
Quantity 1 ~10 ~1,000
Estimate ~$200 ~$50 ~$25

Block diagram

Figure: Tuning aid system block diagram

The calibration functional requirement introduces the need for non-volatile storage for the calibration vector. Non-volatile storage (e.g., NVRAM) may be found as a built-in feature of some DSP's, or may need to be implemented through a separate device. These two options are not illustrated in the block diagram as they should have a neglible impact on the overall circuit design.

Risks

Level Description Response
High The team does not have sufficient expertise to develop a reliable frequency-identification technique in time required to develop a high-level design. Assign the team member with the most prior experience in signal processing to study the literature and consult with the mentor about approriate signal analysis algorithms.
Medium A low-cost DSP cannot deliver sufficient performance to provide the required response times. Simulate the signal analysis algorithm in MatLab, confirming that computation required is within the capacity of the selected DSP component.
Low The University machine shop cannot accomodate the faceplate fabrication work due to overbooking near the prototype due date. Identify an off-campus machine shop through connections with the team members or classmates.

Plan

ECE 492A Timeline
May June July Hours
Tasks 01020304 0506070809 10111213 SDEDLSRS
Analyse input signals ++............ .................... ................ 1010 20
Simulate DSP algorithms ++............ .................... ................ 101020
Verify block design ....+.......... .................... ................ 0505050520
Verification Analysis ......d........ .................... ................ 0505050520
Breadboard circuit ........++.... .................... ................ 1010 20
Write DSP boot code ........++.... .................... ................ 101020
Prepare circuit schematic ............++ .................... ................ 1010 20
Write DSP algorithm code ............++ .................... ................ 101020
Review detailed design ................ ++................ ................ 0505050520
Detailed Design ................ ..d................ ................ 0505050520
Review PCB layout ................ ....++............ ................ 1010 20
Build tuner case ................ ......+............ ................ 100515
Order PCB ................ ......+---^...... ................ 0505
Write midterm exams ................ ........---........ ................
Tasks 01020304 0506070809 10111213 SDEDLSRS
Assemble circuit ................ ............++.... ................ 1010 20
Assemble chassis ................ ............++.... ................ 101020
Integrate and run DSP code ................ ................++ ................ 1010101040
Prepare testing checklist ................ .................... +.............. 05 05
Test and debug prototype ................ .................... ..+++........ 10101030
Prototype Testing Checklist ................ .................... ......d........ 05 05
Debug final prototype ................ .................... ........+...... 1010101040
Prototype Demonstration ................ .................... ..........d.... 0202020208
Experience Report ................ .................... ..............d 0202020208
Journals & Logs ................ .................... ..............d 0101010104
Write draft final report ................ .................... ............+.. 0202020208
Totals 107107107107428
-Wait time SD Sarah Defoe
+Active time ED Emily Dixon
^Event LS Lynn Strum
dDeliverable RS Rob Sullivan

Budget
Item Description Source
Prototype material
PCB 4-layer printed circuit board
Approximately 2cm x 11cm 		Instant-Circuits Inc., Kitchener
"48-hour service, over the web"
$100 minimum order
DSP Acoustic Devices AD-254P Soltronics Supply, Waterloo
(Buy at least one spare.)
Mic Lectrit MC23-A Soltronics Supply, Waterloo
Misc. Passives, wire, solder, etc. Soltronics Supply, Waterloo
Power 5V, 10A, DC regulated supply E&CE project inventory
Confirmed and reserved Nov 12, 2004
Other material
Kit Breadboarding kit Team member, Emily Dixon
Book Acoustic Signal Analysis using MatLab University Bookstore
Guitar Six-stringed acoustic guitar Team member, Sarah Defoe
Tuner Professional-quality tuning aid AGMC Inc. (project sponsor)
Services
Poster Symposium poster Graffiti Graphics, Kitchener


Need Cash In-kind
ItemQty.@Total SponsorSPFTeam SponsorE&CETeam
 
Grand total $1,530 $1,530 $150$300 g$150l$30l$900
 
Prototype material $205 $205 $150$25 l$30
PCB10$100 $100 $100
DSP2$20$40 $40 $40
Mic2$5$10 $10 $10
Misc.$25 $25 $25
Power$30 l$30 l$30
 
Other material $1,125 $1,125 $75 g$150l$900
Kit$100 $100 l$100
Book$75 $75 $75
Guitar$800 $800 l$800
Tuner$150 $150 g$150
 
Services $200 $200 $200
Poster$200 $200 $200

Legend
$ Canadian dollars
Taxes included		 Sponsor Provided by an outside party
l$ In-kind loan of material
Estimated equivalent dollar value		 SPF Requested from E&CE Student Project Fund
g$ In-kind gift of material
Estimated equivalent dollar value		 E&CE Borrowed from E&CE projects parts inventory