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Group Design Project – B202

Product design report



Utility/Universal
Imagine that you have a standard Bluetooth Music connector for you IPod. You have it set up and are perfectly happy with its use; however what happens when you wish to use the Bluetooth streaming with another device that you currently own? Obviously that might not be a problem since you will properly have all of your music upon your IPod as it is at the moment. However consider the situation later on down the line when you are going to be in the market for another Music player? What happens if you have decided that you want a device that actually plays the music at a good quality, not a reasonable quality but at a good, or even at a great quality of music. And you end up going ahead with this purchase. Once you have arrived back home and loaded your playlist upon this great new media device that you have, what now? You lack the ability to connect up to your speakers as you no longer have an IPod. Well that’s where our device comes in, with an amazing utility that is one of the best selling points about the Aural Delight. With the Aural Delight we now have a great way to which one can play their music around their house without the need of wires or endless connecters and adapters.
The same thing applies for whenever the user may well decide that he would like to have a party and the music is constantly being swapped out by other people’s music players with an ordinary Bluetooth adapter many players may not be able to show their stuff but the Aural Delight surfaces and blows the completion out of the water.

Connectivity/Ease of use
Obviously this won’t relate to everything such as logging on to a computer. However if you were trying to just play your music through your speakers you don’t want to constantly have to enter a code to connect, the same goes for using a Bluetooth headphone so you can talk in the car, especially since time is money in this hectic life.
Let’s talk about Ian. Ian is a man who doesn’t suffer fools. In this respect he also doesn’t like technology that doesn’t work as he would like. This is why Ian in immensely happy with this device Its ease of use is second to none, as all the buttons are just where you would imagine them to be, you could give this to a child or even to your grandparents and they would have no qualms with using this device, that’s why he is very happy with the aural delight. Ian has been using wireless music to stream his music for a while now but cannot understand why he has to enter a code every time to connect to the same device again and again. This is why he has fallen in love with the aural delight. After a hectic day at the office and on the commute home via the Underground, Train and car to get home. Ian just wants to relax whilst listening to his music once he enters through his front door. With the aural delight all he has to do is to ‘Pair’ once with each individual receiver then he knows that he will never need to do this again with the corresponding receiver and transmitter from now on.

Student
Many students like Mike use the Phone as an alarm. So Mike, who has just made an investment in ‘Aural Delight’, has made the right choice, after barely minutes of setting up he has been able to make his music work for him. Now when he gets up in the morning it is a dead certain that he won’t sleep through that alarm again as he has the transmitter on his phone connected to the receiver on his Hi-fi system. As such he has a considerably louder and better sounding music to get him up in the morning. Once Mike has aroused himself from his pit of despair of being ripped away from x-rated night tine recreation thrown on some clothes theirs a feeble groan of pain and excitement with the anticipation of a new day forming. Of course this groan is in fact a warning sign that Mike is hungry. As such he stumbles down stairs and into the Kitchen where he proceeds to make Breakfast and a quick cup of coffee all the while he has his Favourite music radiating from room to room, until he settles down in the living room to devour that which is on his plate as he music continues to surround him from the TV for his ‘Aural Delight’ has blistering speeds and fantastic functionality all the while all mike needs to do is walk around with his MP3 or Mobile phone connected to the ‘Product still to be named’ for blissful aural delight.

Business man
I would like to tell you a story about a good friend of mine whom we will call 'Norman Brunswick' for privacy reasons. This man is a good man, with a good job and a loving family. In his job is always on the move moving from building to building as 'company X' most valuable trouble-shooter. In his job, and life he will always have an amazing collection of music out and about for in his career he works as a marketing Executive and as such works on many TV and Radio adverts. Due to this his always has a collection of music on his person so that he can pick out 'PHAT TUNEAGE' that would be perfect for any such device. The reason why he likes to work without wires is that he is an energetic sales man and likes to move about and talk through his ideas with several different pieces of Music. And as such finds it utterly Contmetabul the ideas of having to remain in a fixed place to change from track to track. After a hectic day of travel and Tunes he likes to relax at his house with the ability to keep up to date with the latest music. One of the advantages that Norman is offered is the convenience of having his choice of Music for relaxing to until it’s time to cook the Sunday roast so he can just walk through and continue with his Aural Delight.

Female Case Study
Vera is a Professional Athlete, An Endurance runner and Climber. And as such benefits from the use of 'No Wires', also due to the use of her Music player she can organize the best playlists to help her keep in time and Motivated. Of course the best reason for her to have the ability to move the transmission of music from receiver to receiver and terminal to terminal after she has returned home so that she can just sit down and relax after a long day a training. When competition comes around Vera has always preformed at her best when in a world of her own, and due to this the ability to go about competing without the risk of accidental knocking of wires and pulling out her earphones whilst on the move.


Design Specifications


Initial design specifications of product

Aural Delight must be capable of streaming high quality two channel stereo audio within a range of 10m from a single transmitter (Master device) to one of seven selectable receivers (Slave devices) in a safe and secure manner. It must be user friendly and simple to make it accessible to all generations.
The product transmissions must be robust against interference from other electronic devices in its surroundings to give maximum audio pleasure while not interfering with other electronic devices.
Aural Delight must have a safe, ergonomic and stylish design that will fit in with other modern devices audio visual and look at home next to them while being tough enough to stand up to the knock of everyday life.
It must be produced as cheaply as possible without affecting its stylish appearance, safety and quality so that it can be competitive against other available devices with in the market.

Communication and connection:

The Bluetooth Baseband is the part of the Bluetooth system that specifies or implements the medium access and physical layer procedures between Bluetooth devices.
Two or more devices share the same physical channel. One Bluetooth device acts as the master (SRC), whereas the other devices act as slaves (SNK). The master device can communicate with up to seven devices in a Wireless User Group. This network group of up to eight devices is called a piconet. An ACL link will be used to communicate between devices inside the piconet as the other link protocol SCO does not support multiple devices. The ACL link is created automatically when the devices discover each other and pair. ACL links are also automatically disconnected by the bluetooth stack if there are no logical links such as L2CAP open, after a timeout. In the Bluetooth stack, the HCI is the interface used by the baseband link for communication purposes. It is used to simplify the physical communication between the Bluetooth stack and the controller.

Bluetooth Clock:

Every Bluetooth device has a native clock that shall be derived from a free running system clock. For synchronization with other devices, offsets are used that, when added to the native clock, provide temporary Bluetooth clocks that are mutually synchronized. The internal Bluetooth clock also determines the timing as well as the hopping of the transceiver. The clock is a 28-bit counter with a clock rate of 3.2 kHz.

Security:

Bluetooth is extremely secure in that it employs several layers of data encryption and user authentication measures. Bluetooth devices use a combination of the Personal Identification Number (PIN) and a Bluetooth address to identify other Bluetooth devices. Data encryption (i.e., 128-bit) can be used to further enhance the degree of Bluetooth security. The transmission scheme (FHSS) provides another level of security in itself. Instead of transmitting over one frequency within the 2.4 GHz band, Bluetooth radios use a fast frequency-hopping spread spectrum (FHSS) technique, allowing only synchronized receivers to access the transmitted data. The Baseband layer is the physical layer of bluetooth it is part of the link management profile but also deals with error correction security and hopping selection. Baseband also handles the paging and enquiry to other bluetooth devices in the vicinity and performs frequency division multiplexing and time slotting. The Link Management profile defines the link setup and control between bluetooth devices. As it is part of link establishment it also has a large role to play in handling security procedures. GAP or generic access profile is a standard profile for device communication. Any device with this profile may communication to any other GAP device, the GAP controls how the baseband and LMP operate, for this reason it has an important role to play in security of transmission it also communicates with higher layers such as L2CAP, RFCOMM, and OBEX. An encryption key is another important security feature of bluetooth it is 8-128 bits long and has the benefit of being regenerated for each transmission.





Master

• Dimensions of master device: L 70mm, W 40mm, D 15mm.
• Input will in the form of standard male 3.5mm TRS connector (stereo phono jack).
• The master unit will house seven blue LED lights, each one corresponding to a slave unit. If and when a LED switches on, it will indicate which slave the master unit is currently transmitting to.
• The pairing between the master and slave unit will be by means of a long push on one button. This button shall also serve to select from one slave to another by a single push of the button.
• A second button will serve as the on/off power button, which will help conserve power when device is not in use.
• The master unit will house a Ni-MH rechargeable battery which will allow the device to constantly stream music for over 2 hours. Nominal voltage of the battery is 1.2V, and nominal capacity being around 2500mAh. The battery will be housed inside the unit and shielded with an aluminium foil jacket.
• The power to the master unit will be provided by a concealed 3mm power connector. This will allow charging the battery from a 12V transformer block, or by 12V supply from a car lighter socket.
• The transmission will be through with a 128-bit encryption key for security purposes.

Slave

• Dimensions of slave unit: L 110mm, W 80mm, D 20mm.
• The signal received will be with a 128-bit encrypted key from the master device.
• The slave unit will too house 7 LED lights indicate the number of the pared device.
• It will have the ability to wait to pair with a master by means of a long push of a button.
• Power will be provided through a 5mm female power connector which will allow the unit to be charged from a 12V transformer block
• It will also have a 3mm female power connector which will allow docking of the master unit providing a charge or running the master straight.
• Output will be via a standard female 3.5mm phono socket to allow a variety of audio devices to be connectable.

Software and transmission requirements

Aural Delight shall use Bluetooth 2.1 transmission giving high quality transmission speed up to 2.1 Megabits per second using the A2DP protocol.
A2DP stands for Advanced Audio Distribution Profile which is a special technology where high quality audio can be streamed from one device (e.g. Aural Delight) to another (e.g. your stereo headset) via Bluetooth technology. A2DP is revolutionizing the way we listen to music by allowing you to hear CD quality stereo music from your A2DP enabled device without wires. It encodes the incoming audio to be transmitted in a Bluetooth channel, and then sends the signal wirelessly to a Bluetooth receiver and then decodes and plays the audio.
The product shall be capable of transmitting audio from Master to Slave within a range of 10 meters with a low power consumption of 0dBm (1mW). And there is a possibility of considering extra amplification to give a range of 100 meters.
Aural Delight uses Piconet to allow 7 Slave devices to be connected to a single master device at any one time. This technology will be discussed later on.
And the product also use SBC which is a codec responsible for audio encoding and decoding special designed for use with Bluetooth audio and video applications. This, when implemented with A2DP, will provide high quality audio transmission.

Further possible considerations dependant on cost constraints

Send the signal to audio headphones
Audio/Video Remote Control Profile (AVRCP)
- Used with A2DP/VDP
- Interface (eg remote control) for controlling the A/V equipment
- Capabilities: transfer status of the music and the track itself

Interference
One of the ways Bluetooth avoids interference is through the use of low power signals ( around 1mW ). Aural Delight will be using the Bluetooth Core Specification Version 1.1 or later in order to be able to avoid interference with other wireless devices because the signal is very weak.

Support of Codecs
The table shows supported Mandatory and Optional codecs.


Mandatory Codecs
The Advanced Audio Distribution Profile (A2DP) mandates low complexity subband codec (SBC) to ensure the interoperability. The device shall implement a SBC encoder when the device is the SRC, and a SBC decoder when the device is the SNK.

Optional Codecs
The device may also support Optional codecs to maximize its usability. When both SRC and SNK support the same Optional codec, this codec may be used instead of
Mandatory codec.

SDP (Service Discovery Protocol)
Used to allow devices to discover what services each other support, and what parameters to use to connect to them. For example, when connecting our transmitter device to an existing Bluetooth headset, SDP will be used to determine which Bluetooth profiles are supported by the headset and the protocol multiplexer settings needed to connect to each of them.

Certification
Two main sets of approvals requirements must be addressed before our product can legally be placed on the market using Bluetooth. These requirements are the Bluetooth Qualification Program and the Product Certification.

Design Requirements


Hardware details

Common hardware requirements of casing

The casing must be tough and scratch resistant hence shall be made of high quality thermoplastic material (can be molded by heating and pressure or vacuum forming).
Note that the size of the plate of plastic in this case does not correspond to the size of the transmitter and receiver boxes. It is a standard purchase size from the manufacturer.


Bluetooth 2.1

Piconet


Protocols


Security

  • Authentication
  • Pairing
  • Change Link Key
  • Change Current Link Key Type
  • Encryption
  • Request Supported Encryption Key Size
  • Secure Simple Pairing
  • SAFER+ (128 bit block cipher)
  • Generated by pairing process
  • Passkey (116alphanumeric characters)
  • Random number (from device internal clock)
  • BD_ADDR of piconet master
  • 79 1MHz frequency channels
  • 1600 hops per second
  • Hopping sequence defines the piconet Master defines the hopping sequence
  • Up to seven active slaves
  • Scatter net creation


    http://images.techtree.com/ttimages/story/75869_piconet.jpg


    • Connections

    Battery


    User Survey

    It should be noted that I did this survey both at Gunwharf Quays and at Commercial road as to enable me to get a better spread of results for our project. I didn’t set myself a target of Time or amount of people who were interviewed.
    Question 1,
    Do you own a device that plays music?
    e.g. MP3 Player, Phone, Computer ect.
    Question 2,
    If yes how many devices?
    Question 3,
    Do these devices ever connect to speakers around the places you may go?
    Such as Car, Living room ect
    Question 4,
    If yes how many Items?
    Question 5,
    Do you ever feel cluttered via all the cables in today’s world?
    Question 6,
    Would you ever consider a simple modular device that allowed easy connectivity without wires from nearly any device that can output music to your speakers/Home theatre/ Car sound system?
    Question 7,
    For this item how far away would you have you Music player from the Receiver whilst in use?
    Question 8,
    What level of security would you like on this item?
    Question 9,
    If Yes How much are comfortable to spend on an item like this?

    From the results collected I was able to knock up an excel document with this information. With this I went ahead and also created some pie charts showing the results in a much more graphical method. From the results we can see some very interesting information. One of the ones we expected was that there would be no one without a device that has the ability to play music. However there was some very useful information that has been able to back up what we were planning to do anyway, one being the distance of Transmission being up to 5 meters (the same as which the group had decided upon previously.
    This data must be remembered that all of this information must be read with a pinch of the proverbial salt, as I believe that we would be able to get some more accurate results if we were able to get a wider spread of people to input their opinions from a wider variety of locations.














    PROTOTYPE


    In general, “prototypes” fall into four basic categories:

    [1] Proof-of-Principle Prototype - Here we would test the audio streaming Bluetooth device without attempting to exactly simulate the visual appearance, choice of materials or proposed manufacturing process. This prototype would help us identify which design options would work, or where future development and testing would be needed.
    Several companies offer a wide range of PCB’s which would enable us after the schematics was done to quickly create a more solid circuit construction, such as www.pcb.co.uk/home, www.ProtoExpress.com and www.china-pcba.com for example.

    [2] Form Study Prototype - Next we would have to explore the basic size, look and feel of a product without simulating the products actual purpose or exact image. The outcome of this prototyping would be intended for internal decision making and are generally not strong enough or appropriate for consumers because of the materials used.

    Here we could use Cool Prototyping for example. This company offers a wide range of product design services such as:


    [3] Visual Prototype – Here we would produce the planned design aesthetic and simulate the appearance, colour and surface textures of the Audio Streaming Bluetooth device but will not actually have the functions of the final product. With this prototype we would be able to use it in market research and photo shoots for sales literature for example. This way we would get quick feedback from potential consumers/customers so that we could change the products specifications if needed before final development.

    Possible Interface

    Visual

    [4] Functional Prototype – This prototype would try to simulate the final design, aesthetics, materials and functionality of the Audio Streaming Bluetooth device. We could reduce size in this prototype in order to reduce costs, but because of its components it would probably be better to make it the intended final product size. At this stage it would be our last chance to find design flaws and would allow us last-minute improvements to be made before starting to produce the final product to go into markets.

    Simulations


    The idea for simulation of our product would be to use a mathematical tool such as MATLAB to simulate a Bluetooth piconet under a variety of conditions. For example when used in the home The Bluetooth frequency band is affected by Wi-Fi communications in the vicinity and also microwave ovens produce interference to the Bluetooth network. This requires heavy mathematical modelling although there is research papers available that have modelled our exact network which shows that simulation of our product could be performed using a tool like MATLAB before any production took place. This research would need to be performed before a product was produced to prevent a bad quality of service.
    One such research paper is posted in the link below. It is a very comprehensive look at maximising data transmission in particular audio transmission from a master device to up to seven slave devices at any one time. It looks at optimum packet lengths for maximum throughput. From their research it seems that the optimum packet size is a variable of the condition of the transmission line. Bearing this in mind they have produced algorithms that could be embedded into the Bluetooth protocols for sending and resending packets of data. For example if a data packet is sent from the master to the slave and is lost in transmission then the same packet could just be re sent. During the waiting period the conditions of the line may have altered and the algorithm would pick up on this and possibly change the length of the packet to be transmitted in order to keep optimum throughput.
    http://repository.upenn.edu/cgi/viewcontent.cgi?article=1160&context=ese_papers


    http://images.tomshardware.com/Reviews/images/scrnshots/belkin_f8t030_thruput_compare.jpg




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