Group Design Project – B202

Product design report

Design requirements

To best understand the design requirements of the product, each stage of the functional process must be carefully considered, and the key concepts highlighted. This section will outline the most important features of the product, without which it could not function correctly.

The first point that must be appraised would be the products ability to play music from the MP3 player. Any basic pair of headphones are capable of this task, yet several key factors must still be taken into thought regarding even this simple aspect. The most important function is that the correct music is transported correctly along the headphone wire, and output is clear at the earphones.

A clear output is defined by its adherence to several requirements. Firstly there must be no static or interference noise played through the headphones. There must be no sound quality deterioration during the process, so the audio levels will remain the same, as will any equalizer settings. This is achieved by having a tight and secure connection from the phono jack to the MP3 player, and using headphones and wiring of a good standard of quality.

The level at which the music is played is also an issue, it will vary along with the settings on the MP3 player, but a maximum audio output level is needed. The requirement being that the noise level must not damage the users hearing, therefore the maximum volume must not exceed an output of 90dB(A). This level can start to damage the ear after eight hours of exposure per day, so in the case that someone listens to an MP3 player that long at maximum volume, a warning will be placed on the packaging.

When there is an incoming call, the user must be able to answer it by pressing the button on the main hub casing of the product. This must relay the callers’ voice through the headphones to the user and activate the microphone so that the user can reply. For this information to be relayed back and forth correctly, a strong and reliable Bluetooth connection is required.

This Bluetooth signal is going to need to be strong and clear enough to reach from pocket height, up to chest height, covering a minimum safe distance of 1 metre. This would require the product to operate at Bluetooth class 3, meaning the Bluetooth would easily have a range of 1 metre. It could be upgraded to class 2, but that is 10 meters and would unnecessarily increase costs and complexity.

To maintain a clear connection, the version of Bluetooth used must also be taken into consideration. The product will use Bluetooth version 2.1, which is the newest, clearest and most reliable version to date. Also it is compatible with older phones as it’s backwards compatible. This is a very important design feature, as it doubles the potential market than if only the phones with the newest version of Bluetooth were compatible. This version also uses less power, meaning batteries will last longer.

The next stage in the required functionality of the product is that the music coming from the MP3 player is paused when an incoming call is received. The decision was made that the music should be paused and not simply stopped as it’s easier then to resume after the call has finished. This means that the music must resume from the very point it cut off, taking into account and countering any sleep features the MP3 player may have.

When the music is paused, the ringtone from the phone must be played through the headphones. The headphones must sound the phones ringtone for five seconds when an incoming call is received. This allows the user to acknowledge that they have received a call. In this time they have the choice of checking their phone to see who the call is from, giving them the option of pressing the answer button on the headphones, or ignoring the call. If they choose to ignore the call, the music must resume and the ringtone must stop in five seconds and the call will be allowed to just ring out silently. This will need to all happen automatically, meaning that the appropriate hardware and software will need to be in place to make the appropriate switches between what the user can hear, at the appropriate time.

The product will need to be reliably watertight. This is because it may often be worn on the outside of clothing, outdoors in rainy conditions. If the product does not have adequate protection, one drip of rainwater getting into the inside of the hub with the boards and circuitry could potentially destroy the entire system and render the product useless. So whilst it needs to be far from submersible, it does need to have protection. This involves making all seals tight, and leaving no wires / boards / gaps exposed.

The CE mark on a product asserts that the item meets all of the essential requirements of the relevant European Directive. Our product in particular will have to meet European standards on low-voltage equipment. UL is the American counterpart of European CE standards, so as our product is to be sold internationally in the USA, it will need to meet these standards also.

Other factors must be taken into account when designing the product, such as size and weight. Our headphones will have everything to a standard industry size. This will include optional soft pads that can be attached to the earphones for comfort. The only thing that will be develop from scratch by the development team is the encased Bluetooth hub with the button on. This hub will be a rectangular prism in shape, 5cm tall, and 1.5cm wide/deep. The weight will only be a few grams as this means that it will be small and light enough to dangle on the headphones and fall into place wherever it may without inconveniencing the user. As for appearance, it will be small and matt silver, with a shiny silver button just to make it slightly easier to see, with the two LED’s clearly visible on the side.

The button on the main case is important as it will need to be easy to press, as it may often be underneath clothing. The user needs to easily be able to find the button, meaning that it is going to be of a definitive cylindrical shape, and of a relevant size. Therefore the button will stick out 5mm from the casing itself, and will be relatively hardly pushed to compress fully. The buttons tightness is so that it cannot be accidentally pressed by the user, or inadvertently getting knocked. Therefore the button will require a concentrated amount of force to compress.

The product will have two LEDs on the main hub, all behind translucent plastic so that they are not too bright. These LEDs will be; green, to show that the device is functioning properly and has adequate power supply left in the battery and blue, to show that a Bluetooth connection with the mobile phone has been established. With this setup the user will always be able to tell when and why the device is not functioning properly. As if the blue light is not showing, there is a problem with the Bluetooth connection to the phone, possibly that the phone does not have its Bluetooth feature enabled. If the green light is faded or off, then it means that the batteries are running low / are flat respectively, and replacement is needed. All of this will be documented in the user’s guide manual.

Battery life is an important concern as the user will require a long battery lif but also the battery needs to be small enough to fit in the casing with the other components. Two watch batteries will be used to give the desired power and are also small enough to fit in the hub. A note will be added in the user manual on how to change the batteries.

- Chris


Use case scenarios


Products Principle Use Case Scenario

The user wishes to set up the headphones with their mobile phone for the first time

- Saleh

The user has the product connected to their MP3 player via the phono jack, and their phone by the Bluetooth connection.


The user is listening to music through the MP3 player and a phone call is received.

The user wishes to hang up a phone call.

The user wishes to make a phone call, with the product connected.

The user wishes to change or remove the MP3 player Device.

The user wishes to change or remove mobile phone.

A feature of the product does not work correctly.

- Chris
- Jason







- David


Design specifications


The main roots of the product derive from a basic need to combine the functionality of a mobile phone and of an MP3 player so that a user can enjoy listening to must, whilst being safe in the comfort that they will not miss a mobile phone call. When a call is received, the product will pause the music being fed to the headphones from the MP3 player, allowing the mobile phone to take main control until the call has ended or is cancelled. At this point the primary control switches back to the MP3 player, allowing music to resume playback through the headphones once again.

The product will implement this feature through software programmed logic, in which the device will only function if it is receiving an active feed from one of the inputs, with the mobile phone having priority. This will allow for the music to play continually up until the very point which the call is received. The microcontroller will register input from the mobile phone instantly, sending a pause signal to the MP3 player. The speed and accuracy to which this function operates would not vary with the MP3 player or mobile phone used, as it does not require them to perform any key actions.

The quintessential controller over primary functions is a single central button mounted on the exterior of the product. This button allows the user to answer a call, to cancel a call and to end it. The product will be tight and hard to press, preventing the user from accidentally pressing or activating the button by mistake. This button is the products entire user interface, other than the input required on a mobile phone to activate the Bluetooth function. A green light will represent the remaining power in the device, which will fade when power begins to get low, giving the user the ability to see when the battery requires replacing. The remaining LED is blue to represent an active Bluetooth signal and indicate to the user that the device has a successful Bluetooth connection functioning.

The system works on the basis that each programmed device that functions with our product will only perform if all prerequisites are met. As long as the Bluetooth sync with the phone is active, the devices should in turn easily be able to connect through the wiring sockets of the basic headphone port and allow for the data to be fed through to the headphones. The programming allowing the device to interact with the phone and MP3 player will be programmed onto the PCB chip, where it will allow for only one of the functions to actively operate. This will operate under the basis of the MP3 as a constant, but having the phone as the highest priority interrupt. The user interface of the button allows the user to operate the phone, allowing simple access to the passing of data to continue to the headset, whether that be from the phone or the MP3 player.

The mp3 player will be connected to the main hub via a hard wired phono jack, which is simple enough for any user to set up. The phone however will be connected by holding down the button to emit the Bluetooth signal and then connecting by using the phone to find the device and connect. The order these two actions are carried out in will have no difference on the ability to connect the two devices, as long as they are carried out in relatively close proximity to one another and in relatively quick succession. Once this has been achieved and the mp3 player is playing the music, a logic signal is sent to the main hub to the phone to check if a phone call is being received. If so, then the audio signal is fed through an amplifier restricting the noise level to 90dB. This then goes to the headphones which output the audio signal. When a phone call is received it sets a flag, causing the hub to send a signal to the MP3 player through the phono jack to pause the song. It then puts the phone call through with the ringtone output from the headphones. The user then has o decide to either leave it for five seconds, signalling the hub to send a signal to the MP3 player, un-pausing the song, or to press the button to answer the call. Either of these actions will reset the flag, so that the next call can be detected. When the call is finished, the user presses the button and the signal is sent for the MP3 player to resume audio playback. The user also has the option of double tapping the button to hang up the call. This requires no extra programming, as it is essentially just answering and hanging up the call in quick succession.

The MP3 player will interface with the product via a 3.5mm phono jack, connected to a GPH cable of length 65cm, leading to the main hub. The hub will contain the Bluetooth transmitter and receiver chip, all logic programmed on a microcontroller board, and the push button to facilitate the required functionality, it will be powered by 2 LR44 cells as they are long lasting, small and with two of them produce a voltage of 3V which is the running voltage of the Bluetooth chip. The logic will be built with this voltage specification in mind. The “hub” that is continually mentioned is a plastic containment shell, 5cm long, 2cm wide and 1cm deep, containing a double-sided PCB board with the chips mounted. Another length of GPH cable of length 30cm will come out of the main hub and then be split to the two headphones. All parts will be manufactured by outside companies for mass production needs and for quality assurance.


- Jason
- Chris

Prototypes and Surveys

Team Alpha have prepared several prototypes and user surveys for this section. We felt that these four main key sections enabled us to test aesthetics, design, sizing, logic, power, as well as enabling us to get to grips with our market, how they felt about the product. These findings are represented in four different ways. Firstly there is a video of a prototype of the product, this aims to show the key concepts behind the product in a visual way, instead of just in words. The second section is a computer generated video and labelled diagram of the product. This is all to scale and shows realistic sizing, and placing of the shell, and all components within. The next section looks at power and logic connections that are essential within the system. It is this diagram which the 3D models wiring setup is derived from. Lastly is the user survey section. This section was useful to start looking beyong the product itself, and more at analysing and understanding the potential consumer market.

Product Prototype Video:

Below is a link to a video demonstrating a prototype model of the product.
http://www.youtube.com/watch?v=fS__PkyH3t4&feature=channel_page

-Bradley

Computer Generated Design Simulation of the Product in Action:

Please find in this section the newest video (old ones from coursework two) showing a 3D video of a model of the product.
http://www.youtube.com/user/ECETeamAlpha




- Chris

Diagram of the Products Internal Setup & Logic

Component List

• Power supply (battery)
• Blue LED, illuminated when Bluetooth signal is established
• Green LED, just set to on as it will naturally fade / go off when power is out
• Bluetooth chip, transmitting and receiving
• Some sort of logical PCB board to control everything
• Wiring carrying audio signal from jack to headphones
• Button, with the correct wiring to answer and hang up calls
• The plastic casing, how everything fits together



- Mike



- Chris

User Research and Surveys

User Survey - Posted on UoP ECE Forums & Taken into Portsmouth High Street

1. Do you own an MP3 player?

2. Do you own a mobile phone?

3. Have you ever / would you ever be concerned about missing a phone call because it was not heard, as you were listening to your MP3 player?

4. How much would you be willing to pay for a product that would integrate your mobile phone and MP3 player in the way this product does? (Description available here: http://mosaic.cnfolio.com/B202Coursework2009A108)

5. Are you more inclined to pay more for headphone quality, or buy the cheapest around?
Survey Feedback Results:

Below is the combined information taken from survey results from the University Online Forums and from in person surveys in local shopping area. Overall 12 people were questioned on the survey and here are there results:












- Jason



User Survey
These five graphs represent the results of a consumer survey carried out by the team. The survey was placed on the University of Portsmouths online forums. This was a suitable place as it targetted mainly males aged 19 - 22, which would be a great chunk of our key market. The survey was then also taken out into high streets around Portsmouth, specifically targetting those not coverred in our online survey. The questions coverred target market, potential customers, business oppertunities and technical specifications.

Question 1
The first question asked "Do you own an Mp3 Player?" Where this question would have been quite the opposite only a few years ago, it is plain to see that today it is in fact far more common to own an MP3 player than to not. It is also noteable that the only two results from people who did not have MP3 players were from the street survey, and not from the online results. This shows that our key demographic is showing us what we expected and what we need to sell our product. A staggering 91% of people asked owned MP3 players, meaning that 91% of the people asked fullfill at least half of the requirements to qualift as potential customers of our product.

Question 2
The second question that was asked was "Do you own a mobile phone?" The results of this proved very similar to those of the MP3 player ownership question. The results were in fact, exactly the same with 91% saying they did own a mobile phone and 9% not owning one. It should be noted that of the two people who did not own an MP3 player in the previous question, one was the same person, who owned neither. These results are also encouraging for our product.

Question 3
The third question really got to the heart of the purpose of our product as we asked people "Have you ever or would you ever be concerned about missing a call because it was not heard, as you were listening to an MP3 player?" Once again the reults were encouraging as we found 65% of people had missed a call as they were listening to a mobile phone, or at least thought that it was a concern. From this it can be estimated that at least 50% of people have been, or could be in this situation. This is a massive potential market sector, which will only continue to grow.

Question 4
The fourth question aimed more at the business side, focussing more on financial aspects, "How much would you be willing to pay for a product that would integrate your mobile phone and your MP3 player?" Apart from a few people at the low £0 to £9.99 and or at the £20+ section, the results were highly focussed around £10.00 to £19.99, with 70% of those saying £10.00 - £14.99. This is right about what we were expecting as £15 would be a good, profitable price to sell the product. It is good to know that people agreed with our assessment, and are not expecting to pick up something like this for £5 or £10.

Question 5
The final question we asked was "Are you inclined to pay more for quality, or go for the cheapest headphones around?" This question obviously focussed more on technical aspects of the product, as there is a fair amount of flexibility concerning how the product can be made. The preferences of people here was different than our expectations of quite a broad spectrum, with 83% of people preferring to pay a bit more for a product of superior quality, than to pay a bit less and have the quality suffer too. This clearly shows then that we should focus on quality over making the product as cheap as possible.

- Chris