bluetooth draft sept 09

8/9/2019 Bluetooth Draft Sept 09

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Steve Goodridge, MSc Technology Education - Module 3

2. Product Analysis & Development Report - Bluetooth Headset - Page 1

Product Analysis and Development Report

Bluetrek Bluetooth Headset G2

Content:

3 Product Disassembly Activity

3 Product Description:

4 Communication System: Bluetooth4 HowBluetooth Works

5 Bluetrek Bluetooth Headset G2

5 Power Source

6 Bluetrek Bluetooth Headset G2 - Disassembly Photographs

7 PCB Design & Manufacture

7 Casing Design & Manufacture

8 Materials Summary & Environmental Impact

9 Teaching & Learning Impact

1. Design Principles2. Bluetooth Operation

3. PCB Design & Manufacture

4. Electronics & Sustainability

11 Appendices of Teaching & Learning Materials

1a Product Design Disassembly

1b Product Reviews

2 Bluetooth Activity Sheet

3 PCB Manufacturing Techniques

4 Electronics and Sustainability

16 References


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Product Analysis and Development Report - Bluetooth Headset

Abstract:

A familiar electronic product, the Bluetooth Bluetrek G2 headset, is chosen as the focus product for a

Product Analysis activity in KS4. It is a product that has credibility with a teenage market and one thatcontains sufficient content and technology for a product analysis and disassembly.

The product gives the opportunity for students to understand Bluetooth connectivity, an often used

description in the interconnection of communication devices. An appreciation of radio waves is dis-

cussed in the assignment and built upon through an activity sheet - one of a number of learning materi-

als included in the appendix.

The assignment illustrates the potential of the device to be described in block diagrammatic form and

also disassembly through photographs that illustrate the components that can relate directly to the

diagram. Technologies used within the headset are used to establish how components are made andwork. The PCB process is discussed and later through the learning materials, students would be encour-

aged to compare three different processes and how they may be suitable for a particular assignment.

An important aspect of the Electronic Products course is to ensure students are aware of the need for

recycling and appropriate disposal of electronic equipment. The impact of the materials chosen should

be considered at the start of the product life-cycle as opposed to a terminal activity, again learning ma-

terials encourage students to think about the consequences of chosen materials.

A good product analysis activity can be a very motivating assignment for students who are often able

to place learnt skill, knowledge and understanding into real contexts, these are particularly effectivewhen using a familiar or desirable product - one that has credibility amongst the students. Using the

headset as such an activity is shown to have much potential from a number of starting points including:

Design PrinciplesForm, Function, Ergonomics and Aesthetics,

Understanding of the Electronics Systems and Subsystems,

Properties and Processes of Materials and

Issues relating to Environmental Impact & Sustainability.


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Product Disassembly Activity:

Diagram 1 shows the product to be considered for

a Product Analysis Activity in a KS4 Electronic

Products GCSE course. The Bluetooth Headset is a

familiar product that encapsulates the four main

Design Principles (see page 8) commonly used in

Product Design activities to help and guide stu-

dents with further designing opportunities or un-

derstanding of the systems/components within. As

Bluetooth Technology is a relatively recent innova-

tion and found in so many Information and Com-

munication Technology products used today, par-

ticularly in the connected world of the 21st Cen-

tury teenager, it has great credibility for a special-

ist study focussing on the electronic system that

gives this product its individual characteristic.

Diagram 1 - Bluetooth Headset, Design PrinciplesStarting

Point for KS4 Product Design Activity, (PowerPoint Slide)

A reflective and evaluative product specification can be created from students considering the above

slide as a starting point. This specification can be formed by small group and then class discussion con-

sidering the characteristics and attributes in each of the Design Principles then looking for common,

crossover and holistic qualities to ensure a thorough understanding of the product. This will clearly help

predictive design activities and, as an important learning outcome, an awareness of the Bluetooth sys-

tem of interconnection. This in itself is an important issue and an area that can be explored within an

extended homework/project assignment.

The Bluetooth Headset can be analysed in the following areas to further student understanding and

give them a framework within which they can work to identify all the key areas of Product Analysis.

Electronics, control systems and subsystems,

Materials used in the Design,

Manufacturing Processes,

Environmental Impact.

Product Description:

Bluetrek G2 headset, Sold by Orange, cost 24.99. Productcompatible with virtually all current mobile telephones

with Bluetooth capability. Device sold with instruction

manual, mains charger and car charger. Device complies

with the Bluetooth 1.1 protocol: this supports two profiles.

The Headset Profile and the Hands-free Protocol. The

Headset can be used with a qualified Bluetooth mobile

phone, PDA or another Bluetooth Device.

www.bluetrek.com

www.orange.co.uk


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Communication System: Bluetooth

Bluetooth is a short-range communications wireless

technology that is secure, low power, apparently safe

and very robust. It is a system that will interconnect a

very wide range of different peripheral devices, can handle speech and data, creating a flexibility of in-

terconnection that has produced opportunities designs for systems, devices and systems that are piv-otal on Bluetooths adaptability. Bluetooth technology has achieved global acceptance such that any

Bluetooth enabled device, almost everywhere in the world, can connect to other Bluetooth enabled

devices in proximity. http://www.bluetooth.com/Bluetooth/Learn.The success of Bluetooth has been

to make sure that Bluetooth stands alone and does not interfere with other devices and systems and

that it can achieve full connectability. It has many advantages over other wireless systems including

infra-red by being a radio system and not line of sight.

Bluetooth is essentially a networking standard that works at two levels: It provides agreement at the

physical level, Bluetooth is a radio-frequency standard. It also provides agreement at the protocol

level, where products have to agree on when bits are sent, how many will be sent at a time, and howthe parties in a conversation can be sure that the message received is the same as the message sent.

HowBluetooth Works

Bluetooth networking transmits data via low-power radio waves. It communicates in a frequency band

of 2.402 to 2.48 Ghz. This frequency band has been set aside by international agreement for the use of

industrial, scientific and medical devices (ISM). A number of devices already use this same radio-

frequency band, Baby monitors, garage-door openers and the newest generation of cordless phones all

make use of frequencies in the ISM band.

Diagram 2 - Bluetooth Frequency Spectrum

Bluetooth uses low power signals to communicate between devices. Up to eight Bluetooth devices can

be connected together giving potential to a wide range of control situations. A Bluetooth system will

avoid potential interference by using a Spread-Spectrum Frequency Hopping technique that, by using

79 predetermined frequencies changing randomly at 1600 times a second. Since every Bluetooth trans-

mitter uses spread-spectrum transmitting automatically, it will be unlikely that two transmitters will be

on the same frequency at the same time.

When Bluetooth devices come within range of one another, an electronic conversation takes place to

determine whether they have data to share or whether one needs to control the other. This may have

been initiated by the user, i.e., turning a headset to on. This electronic conversation happens auto-

matically. Once the conversation has occurred, the devices create a personal-area network (PAN), or

piconet. Once a piconet is established, the devices randomly hop frequencies in unison thus avoiding

interference, which could be other Bluetooth piconets.


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Bluetrek Bluetooth Headset G2

The Bluetrek Bluetooth Headset G2 can be repre-

sented as a block diagram, identifying the key

component elements that operate, along with an-

other Bluetooth device, to create a communication

system.

The user controls and indicators are shown down the left-hand side of the diagram, these connect tothe CODEC, a device that simple codes and decodes analogue signals to and from the digital format re-

quired by the device. A Lithium Polymer Battery provides the power source that can be recharged. The

Bluetooth IC, or Platform is connected to an Aerial to transmit and receive signals from other Blue-

tooth devices.

Diagram 3 - Bluetrek Bluetooth Headset G2 Block Diagram

Bluetoothcommunication with

other devices within

the piconet.

Power Source

The power source used in the headset is a Lithium Polymer Cell. This cell has ideal properties and quali-

ties that make it very suitable for use in personal, portable ICT equipment. The cells are very robust

and, as they have a solid polymer electrolyte and no metal casing is required, are very light. The cellscan be shaped virtually free of any design restrictions making them ideal for many of the applications

noted above including, mobile phones, headsets, PDA, ipods and mp3 players and GPS devices etc. The

rate of discharge is also slower than previously used nickel-cadmium and nickel metal hydride cells.

Caution must be taken when

charging Lithium Polymer batter-

ies as overcharging can cause the

cells to ignite.

Diagram 4 -

Construction of Lithium Polymer Battery


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Bluetrek Bluetooth Headset G2 - Disassembly Photographs

Figure 1 - Complete Product Figure 2 - Component side of PCB

Figure 3 - Lithium Polymer Cell mounted below PCB Figure 4 - Cell removed to show PCB, note Mic & Speaker

Figure 5 - PCB, Cell Mic & Speaker Figure 6 - PCB Detail

Figure 7 - Casing Figure 8 - Complete Product disassembled


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PCB Design & Manufacture

The headset Printed Circuit Board, PCB, has connections made on

both sides of the Glass Reinforced Plastic, GRP board. (See Figures

4 and 5). The device has 2 PCBs fixed together, the smaller board

resting onto of the boat shaped PCB. Connections between the

boards are made by connectors at the edge of the board, similar in

style to a traditional integrated circuit. These appear to be spot-

soldered together. The components are surface mounted, (as

shown in Figure 9,) where components are fitted with small end-

tabs to be soldered onto the board. Provision is made on the PCB

for some through holes for interconnection between the two sur-

faces of the PCB.

The designing of the PCB will be done using software to maximise the space available and plan the

through holes and other interconnections and connections to external devices including the battery,

microphone and speaker. Manufacturing process used for the PCB board, or substrate, could be oneof three main subtractive methods although the second is more likely in this case.

i) Silk screen printing uses etch-resistant inks to protect the copper foil. Subsequent etching

removes the unwanted copper.

ii) Photoengraving uses a photomask and chemical etching to remove the copper foil from the

substrate. The photomask is prepared computer-aided manufacturing software. Laser im

aging techniques are now being employed high-resolution requirements

iii) PCB milling uses a two or three-axis mechanical milling system to mill away the copper foil

from the substrate. The PCB milling machine operates in a similar way to a plotter, receive

ing commands from the host software that control the position of the milling head.

Casing Design & Manufacture

The 3 dimensional design of the headset casing could potentially be developed initially using a stereo-

lithography system where a 3 dimensional model is created from a vat of resin and a solid article cre-

ated when a laser is focussed within the vat in layers to created a rapid prototype of a design created in

3D software. 3D Printing will create similar outcomes to stereo lithography and is developed using one

of two formats. Fused Deposition Modelling, FDM, a technology also used in traditional rapid prototyp-

ing, uses a nozzle to deposit molten polymer onto a support structure, layer by layer. The second varia-

tion of 3D printing consists of an inkjet printing system. Layers of a fine powder are bonded by adding

an adhesive from the inkjet printheads in the shape of each cross-section. Alternately, these machinesfeed liquids, such as photopolymer, through an inkjet-type printhead to form each layer of the model.

These Photopolymer Phase machines use an ultraviolet (UV) flood lamp mounted in the print head to

cure each layer as it is deposited. 3D printing, in either format, could be used to create a prototype or a

model from which mould is made for the final process, Injection Moulding.

Injection moulding is a process that lends itself easily to automation

and hence mass-production. Plastic, heated and under pressure, is

forced into a mould that will create the desired 3D piece. This is evi-

dent in the headset components, top and bottom casing, switch cov-

ers and shaped ear grip. (See Figures 7 & 8). The ear grip has an in-tegral wire so an ergonomic, individual, shape can be set for comfort

and ease of use.

Figure 9 - Surface Mounting Detail

Figure 10 - Injection Moulding Process


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Figure 11 - Headset Components



Materials Summary & Environmental Impact

The two areas noted in the title for this section are inextricably linked. Although this is a very small

product is still contains materials that need careful consideration with regard to a) the design and use-

ful life of the product and b) its disposal and recovery of component materials.

The headsets material profile includes:ABS Main Casing

Rigid Polystyrene Switches

Silicon Plastic Earplug

Epoxy Resin/Glass Fibre GRP Board

Copper PCB Tracks/Pads

Solder Connections

Silicon Integrated Circuits

Various Discrete Components

Gold Wiring/Interconnection

Lithium Polymer Battery

The environmental impact of the materials used in the headset and other similar devices should be

seen as a consideration for the designer not purely for the technicians attempting to reduce environ-

mental harm. An illustration of the materials from the headset and similar technologies is presented

below:

Electronic waste is of concern largely due to the toxicity and carcinogenicity of some of the substances

if processed improperly. Toxic substances in electronic waste may include lead, mercury, cadmium. The

WEEE directive attempts to put in place appropriate measures to control the impact of these materials

and the potential exploitation of under-developed countries.

Diagram 5 - Sustainability information. (Source www.nokia.com)

The materials have been selected for their rela-tive capability, weight and structural properties

to form a complete product. The recovery of

these materials is not a straightforward proc-

ess and is a current issue, particularly with mo-

bile phone manufacturers as they face increas-

ing pressure to be responsible manufacturers,

a responsibility that has sustainability at its

core. Diagram 5 shows the various practices

that are necessary to consider within the prod-

uct life-cycle published by Nokia to illustrate

their attempts to address responsible design.

Material Impact Outcome

ABS Production of 1Kg of ABS takes approx 2Kg Oil/Flammable ABS can be recycled

Lithium Very reactive element/can be explosive Recycle under WEEE directive

Solder Lead basedToxic Lead-free Solder should be usedSolder can be

recovered from some items


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Teaching & Learning Impact

A good product analysis activity can be a very motivating assignment for students who are often able

to place learnt skill, knowledge and understanding into real contexts, these are particularly effective

when using a familiar or desirable product - one that has credibility amongst the students. Using the

headset as such an activity appears to have much potential from a number of starting points. From the

Design & Technology starting point product analysis can help to focus:

Design PrinciplesForm, Function, Ergonomics and Aesthetics,

Understanding of the Electronics Systems and Subsystems,

Properties and Processes of Materials and

Issues relating to Environmental Impact & Sustainability.

This section of the report will consider the potential of each of the above focii and, through a teaching

and learning activity reflect on the effectiveness, suitability and outcomes from the activities.

1. Design Principles

The understanding of the four basic principles of design, Form, Function, Ergonomics and Aesthetics,

can be developed through a product analysis activity. Product analysis activities in the workshop often

are based around a range of products due to the availability of a range of similar products. An evalua-

tion of suitability, effectiveness or any other appropriate criteria can then be sought. Product Pairs, an

activity from the D&T Framework Materials has as its objective to Formulate criteria to judge the qual-

ity of a product and the extent to which it meets the need, purpose and resource limits, and its impact

on society. For this first activity the needs of 5 different users from society are discussed within small

groups and a blueprint created for a potential product. This potential product is then offered to each

group for them to prepare an evaluation of how far the headset meets their users needs. A Power-

Point presentation, (Appendix 1a), is the starting point and guide for this activity.

The purpose of this first activity is to define the design terms succinctly and be able to use them

through an investigation/evaluation of users needs. This activity relies heavily on the students abilities

to work within a team, talk and listen to each other and to value another team members views and

opinions. Also it will help clarify the requirements, or specification, of a product. The recording sheet

will give the students a list of requirements for each design principles. Teacher intervention will be re-

quired to stimulate discussion, ask questions and clarify thinking.

Using the product specification from the manufacturer

to introduce the Headset, students can then makequantative value judgements about how much the

specification satisfies the users need. An attribute

analysis could potentially be used here. An overall per-

centage can be generated from each group for one of

the principles or as a whole. The results can be consid-

ered carefully in the context of the products target

market. Some extension activity here is to read some

product reviews (including internet style contributed

reviews and consider the views of others gaining a fur-

ther insight into the product and understanding usersneeds. (Appendix 1b.) This complete activity would be

seen as a lead in to a more technical evaluation and

investigation into product operation.

Figure 12 - Product Reviews - See Appendix 1b


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2. Bluetooth Operation

A resource has been created to support an extended homework task where students are given a brief

to investigate Bluetooth. In this assignment students work autonomously to produce an assignment

over a half-term. This assignment has three components, i) to illustrate how the Bluetooth System

works - i.e., the principles of operation, ii) Bluetooth in action - An example of a Bluetooth product in

use comparing it to either wired or radio connected devices and finally iii) a prediction of how Blue-

tooth may be used in the future by suggesting some potential applications for this system.

This extended homework is supported by information on the student extranet, accessible to students

at home or school, and by information notes, (Appendix 2)

3. PCB Design & Manufacture

Students following GCSE Electronic Products are guided through a variety of forms of Manufacture

when creating Printed Circuit Boards for their designs. The students are in initially introduced to the

copper clad GRP and the chemical process of immersion in Ferric Chloride. The resist qualities of per-

manent pen and particularly Vinyl tape are explored. For an early PCB students are encouraged to

model the pcb with strips of self-adhesive vinyl tape. The shortcomings of this method are considered

through post manufacture process evaluations and a subsequent design is created on the Vinyl cutter

using 2D Design V2. A kit of tracks/pads and IC pin-out has been developed as a palette for the stu-

dents to use. Again this manual method has shortcomings and is then considered against a commercial

PCB software such as Circuit Wizard.

Appendix 3 describes PCB manufacturing methods for students to create manufacturing flowcharts and

process evaluation matched to the type of PCB required - this could mean quick prototype, high qual-

ity individual PCB or mass produced board. Students are able to select a suitable form of PCB manufac-

ture that will ultimately include, Photo Resist techniques, Milling, copper side/component side fixing

methods. The Bluetooth PCB is a good example of multi-layered, intricate path PCB design and manu-

facture. Photographs and the disassembled device are invaluable learning tools.

4. Electronics and Sustainability

Presenting students with factual information can have a very positive impact. To use familiar devices

and illustrate the impact of that device, then the combined impact of the whole class using the device,

even the school is a powerful tool. As an introduction to using commercially available info. the Blue-tooth Headset is good. Its size, manufacture, materials and function can contribute towards develop-

ing the students ethical viewpoint and social awareness.

A presentation created from materials on the Nokia corporate website has been used when consider-

ing sustainability in KS3 electronics. (This is illustrated in Appendix 4.) The awareness from this activity

is built upon the presentation of data from the Bluetooth assignment later in KS4 with a rapidly devel-

oping, more mature outlook of Year 10 students.


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Appendix 1a

Product Design Disassembly

Suggested Activity

Students consider Design Principles and User Groups for the Bluetooth Device building a set of require-

ments that can ultimately be matched against the actual product technical specification.


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Appendix 1b

Product Reviews

Suggested Activity

Students complete a review of the magazine articles to consider the style of writing prior to writing

their own review of a (similar) product.

Reviews written in a blog style are also included for a comparison.


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Appendix 2

Bluetooth Activity sheet

Suggested Activity

Students use Bluetooth resource sheets to complete a number of brief activities that build into an

extended homework task- a parallel activity to enhance knowledge and understanding of electronic

products and systems.


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Appendix 3

PCB Manufacturing Techniques

Suggested Activity

Students use the comparison sheet to create process flowcharts illustrating how PCBs are made in each

method. These techniques/methods can be compared for suitability.

Quality Control checks can be incorporated into the process flowcharts.


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Appendix 4

Electronics and Sustainability

Suggested Activity

1. Students view the slide and consider the composition of the phone they have in their own pocket.The materials that can potentially be reclaimed from the disused phone is shown - this is a presen-

tation suitable for KS3 students.

2. Designing-In Recycling - An identification of the product life-cycle. A slide that can be used asstimulus for environmental and ethical design discussions.

3. Brief figures to show the level of phone recycling - stimulate environmental discussions

Two further resources, short movies from Nokia, (windows media files) are used in conjunction with thisresource.


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References

www.bluetrek.com

www.orange.co.uk

http://www.bluetooth.com/Bluetooth/Learn

D&T Framework

product reviews

http://www.doitpoms.ac.uk/tlplib/batteries/batteries_lithium.php

http://en.wikipedia.org/wiki/

Printed_circuit_board

To be completed...

bluetooth draft sept 09

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