ZigBee Wireless Headphones
Final Report Submission
I pledge my Honor that I have abided by the Stevens Honor System
John Ziegler
Richard Wismer
Ryan Ramdehol
Wojciech Gajda
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Table of Contents
Section 1: Introduction…………………………………………………… 3
Section 1.1 Overall Description………………………………….. 3
Section 1.2 Benefits to Consumer………………………………… 3
Section 1.3 Sales Specifics…………………………………………. 3
Section 1.4 Initial Evaluation…………………………………….... 3
Section 2: Technical Information………………………………………….. 4
Section 2.1 Background Information…………………………….... 4
Section 2.2 Design Description……………………………………... 9
Section 2.3 Design and Ethical Constraints……………………….. 12
Section 3: Critical Evaluation of the Project……………………………… 14
Section 3.1 The Good………………………………………………. 14
Section 3.2 The Scary………………………………………………. 14
Section 3.3 The Fun………………………………………………… 15
Section 3.4 Funding the Project…………………………………… 15
Section 3.5 Other Researchers…………………………………….. 16
Section 4: Summary………………………………………………………..16
Section 4.1 Project Summary……………………………………… 16
Section 4.2 Further Research……………………………………… 16
Section 5: References………………………………………………………. 16
Section 6: Other URLs of Interest………………………………………… 16
Section 7: Team Vitas…………………………………………………….. 17
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Section 1: Introduction
Section 1.1 Overall Description
There are many sets of wireless headphones out on the market today. A quick search on Best Buy
returns over 50 different models. However, there are many design flaws that make them a burden to most
consumers. First, the majority of models are very bulky. This makes them useless for anyone with an
active life style. Additionally, those that are more compact have horrible battery life. Almost every review
mentions that the headphones are only useful for an hour or two. Most of these models utilize Bluetooth
to transmit the audio signal wirelessly to the earphones. My proposal is to modify the existing technology
to implement a ZigBee wireless transmitter and receiver on the wireless headphone platform. The end
goal would be to create a prototype that could transmit an audio signal from a standard headphone jack
found on any mp3 player to a set of headphones with an emphasis on keeping the size and required power
down, ideally being able to use simple AA batteries. This project would serve many purposes to the
project group as well as to consumers. It would help educate the group on the specifics of wireless
communications, specifically on the ZigBee platform. Also, it would expose the engineers to a complex
trade-off problem.
Section 1.2 Benefits to the Consumer
As a consumer product, these headphones would have many advantages over the current market.
They would require significantly less battery power than current models. Bluetooth is a notorious energy
drainer. Utilizing ZigBee would allow much smaller batteries to be used, lowering the end-cost for the
user. Aditionally, the battery life of the device could be significantly increased. Also, they wouldn’t be
very large. Most ZigBee chips are very small, approximately the size of a penny. This would allow the
engineers to develop a much sleeker end product that would address the need of an active user.
Section 1.3 Sales Specifics
The product would be marketed as music “with no strings attached,” with the goal of targeting the
active user. Athletes want a durable product that will last for the entirety of their athlete endeavor. They
want to be able to listen to music without fear of breaking their $300 music player or their $100
headphones. These headphones would ideally serve the user for the full battery life of the average mp3
player, and would be no larger than wrap-around ear buds. Cost should also be below $50. These
headphones could be sold with the intent of creating freedom - freedom to perform, move about, and
execute to the best of one’s ability without any restrictions from bulky electronics and wires.
Section 1.4 Initial Evaluation
The ZigBee Wireless Headphones are a fairly practical project. ZigBee wireless platforms are
relatively inexpensive, especially compared to competitors like Bluetooth. The circuitry could be
purchased COTS and then modified for this particular use. It would be a significant time investment to
develop a prototype. However, it is certainly within our means.
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There are many different components necessary to create a working prototype. First, a working
ZigBee transceiver will have to be modified and implemented. The current system can be used (i.e.
converters, circuitry) as a starting point. So there is the simplicity of a pre-established system, but there
are still many complexities for the team to tackle. Also, since this is a complex electronic prototype, the
team would be able to utilize the engineering design process from start to finish. Other disciplines like
engineering management and systems engineering could be used in the development of the product.
Requirements management and systems architecture and design would be just as important as the
technical details.
There are a variety of skills that will be key in the successful completion of this project. A keen
understanding of electronic circuits and basic circuit analysis will be necessary. Also, digital signal
processing and systems theory will be very important for understanding how the music signal can be
modified and transmitted most efficiently. Wireless communications knowledge is probably the most
important topic, since that is the main difference this project has over similar products.
The most basic component needed for this project would be a ZigBee wireless platform. The
project calls for a receiver on the headphones coupled with a transmitter device that would be hooked up
to the music device. On the transmitter side, there will need to be supporting circuitry present to make any
modifications to the signal to enhance its ability to be transmitted. On the receiver side, the signal will
have to be restored and played through the headphone unit. Both units will need a power source and some
sort of interface with the user to allow the units to be synchronized.
Section 2: Technical Information
Section 2.1 Pertinent Research and Background Information
ZigBee Wireless Technology
The Zigbee is a type of networking standard that is based around the IEEE 802.15.4 wireless
protocol and it is low-cost, low-power and used for combining mesh networks in LR-WPANs (Low-Rate
Wireless Personal Area Networks). The data is transmitted in RF (radio frequency) applications and
allows for low cost, low power consumption which in turn increases battery life but is only able to
transmit data at low rates. A mesh network is where all the nodes in the network receive, collect,
dissemble and transmit data to other nodes. Since all the nodes are connected together, there is always an
alternative path a data packet can take to get to a specific node. Any change in the network topology will
be updated by the current network and new paths will be formed. It is a dynamic network that can always
refresh itself and routing tables always change. This makes the transfer of data more secure because it
would take many nodes to be turned off or shutdown for a data packet to be unable to reach its
destination. The Zigbee standard is used for devices that use radio frequencies, low data rate and secure
networking. Due to the low power consumption and low data rate standard set by Zigbee, this type of
technology can be used in various locations and small batteries can be implemented and in locations
where there is not as much resources for power.
The Zigbee standard has been setup around the IEEE 802.15.4 wireless protocol. This protocol is
the set of rules that specifies how data is transmitted, at what rates and at what frequencies and amount of
channels for those corresponding frequencies that the data can be transmitted. This IEEE standard has
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data rates of 250 kbps, 40 kbps and 20kbps. In addition to the rates that data is transmitted, the IEEE
802.15.4 wireless protocol has two types of addressing modes for the data that is being transmitted and to
what node. Another feature of this protocol is a power management system that regulates the amount of
power being consumed and keeps it low. The Zigbee standard operates under three unlicensed frequency
bands. In the region of the Americas, a 915MHz band is used with 10 channels while in Europe, Zigbee
operates under the 868MHz frequency band with only 1 channel. The third frequency band is the global
2.4GHz ISM (Industrial, Scientific, Medical) band. The IEEE 802.15.4-2006 wireless protocol also uses
IPv6 for the way data packets are sent and addressed. This protocol focuses mainly on the physical and
media access control layer. The physical layer is the most complex one because it is the base for all
layers. The Medium Access Control is a data service that manages the physical layer with a management
interface and controls how nodes talk to each other. The channels are selected in the physical layer by the
RF transceiver. In addition to the channels being selected, it also can manage the energy and signal
functions.
The Zigbee standard is an alternative to the previous and still current Bluetooth standard.
Bluetooth is a different kind of wireless standard one that can transmit up to much higher data rates but is
not as reliable because it is based on one device being the master, and all other devices that connect to it
it’s slaves. The Master is the base of all data that gets transmitted amongst the connected devices.
However, even though Bluetooth can transmit data at very high speeds, its power consumption is
significantly greater than Zigbees. The Zigbee standard has many uses and has been implemented in
medical data collection, industrial control, smoke and intruder alarms and in building automation. These
are some of the places where Zigbee has been used and it is greatly expanding.
Bluetooth Technologies
History
Bluetooth software was created by two researchers in Sweden who worked for Ericsson Mobile
Communications. Bluetooth is currently managed by the Bluetooth Special Interest Group (SIG Inc). The
SIG Inc was created in 1998 to handle research, development and licensing of any Bluetooth technology.
Bluetooth is not a separate company but is a privately held nonprofit organization that is supported by its
promoters, who are established companies that are monitored by SIG for the use of any Bluetooth
technology. In order for a company to use Bluetooth technologies they must go through a rigorous
screening process and maintain the Bluetooth trademark on all their products. Bluetooth currently has the
8th version as their latest version (SIG Inc).
“The word Bluetooth is an anglicised version of the Scandinavian Blåtand/Blåtann, the epithet of
the tenth-century king Harald I of Denmark and parts of Norway who united dissonant Danish tribes into
a single kingdom. The implication is that Bluetooth does the same with communications protocols,
uniting them into one universal standard. The Bluetooth logo is a bind rune merging the Younger
Futhark runes (Hagall) (ᚼ) and (Bjarkan) (ᛒ), Harald’s initials.”(Bluetomorrow.com & SIG
Corporation).
Coding
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From a coding standpoint, Bluetooth works on the basis of protocols to control the connection,
communication and data transfer between two devices. A protocol is a set of instructions, a language to
control the operation of an electrical device. Previously to Bluetooth different devices were working on
different protocols which limited the capability of them communicating with each other because they
were speaking in different languages. With Bluetooth though, they were trying to establish a universal
protocol, language, which would be understood by multiple electronic devices. By creating a universal
language that would be understood by multiple electronic devices, any two devices with the same
protocols could ensure that the message they sent between each other was 100 percent the same and
completely understood. However, this doesn’t mean that every Bluetooth capable device is allowed to
communicate with another Bluetooth capable device. These interactions are controlled by what are called
profiles.
So with every Bluetooth device there are a stack of protocols written to be used. What profiles do
is use different combinations of these protocols in the stack to complete a certain command. Protocols are
a set of rules in a language, words. A word cannot be changed or altered because it will then become a
new word. Restful has the same letters as fluster but they don’t mean the same thing. However you can
combine these protocols into different combinations to create different sets of commands. For example,
the File Transfer Profile (FTP) for transferring files (SIG Inc). So in order for devices to communicate
they must share the same profiles or protocol combinations. Currently, Bluetooth has 28 different
combinations of protocols, profiles (SIG Inc).
Technical
From a technical standpoint Bluetooth technology is based on the frequency hopping spread
spectrum (FHSS) technology (SIG Inc). This technology helps to reduce interference because it chooses
to operate on 79 different randomly chosen frequencies in an assigned range and changes 1600 times per
second (SIG Inc). This means that interference with another electronic device can only happen within
(1/1600) second intervals if and only if both devices happen to be operating on the exact same frequency
at that moment in time. They have gone further to reduce interference by now using Adaptive Frequency
Hopping (AFH) technology (SIG Inc). What this does is scan for interfering frequencies and adjusts the
sequence of hopping in the range to skip those bad frequencies.
The benefit to using Bluetooth is that it uses lower power. Compared to other electronic devices
operating in the same frequency, it uses 1000 thousand times less the power. This is because its
transmission distances are on the order of feet and not miles which allows for signals to be fairly weak yet
accomplish the necessary transfer of information. Due to its lower power requirements Bluetooth enabled
devices are cheap and very easy to produce.
Bluetooth Specifications (SIG Inc)

Bluetooth devices in a piconet share a common communication data channel. The channel has a total
capacity of 1 megabit per second (Mbps). Headers and handshaking information consume about 20
percent of this capacity.
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
In the United States and Europe, the frequency range is 2,400 to 2,483.5 MHz, with 79 1-MHz radio
frequency (RF) channels. In practice, the range is 2,402 MHz to 2,480 MHz. In Japan, the frequency
range is 2,472 to 2,497 MHz with 23 1-MHz RF channels.

A data channel hops randomly 1,600 times per second between the 79 (or 23) RF channels.

Each channel is divided into time slots 625 microseconds long.

A piconet has a master and up to seven slaves. The master transmits in even time slots, slaves in odd time
slots.

Packets can be up to five time slots wide.

Data in a packet can be up to 2,745 bits in length.

There are currently two types of data transfer between devices: SCO (synchronous connection oriented)
and ACL (asynchronous connectionless).

In a piconet, there can be up to three SCO links of 64,000 bits per second each. To avoid timing and
collision problems, the SCO links use reserved slots set up by the master.

Masters can support up to three SCO links with one, two or three slaves.

Slots not reserved for SCO links can be used for ACL links.

One master and slave can have a single ACL link.

ACL is either point-to-point (master to one slave) or broadcast to all the slaves.

ACL slaves can only transmit when requested by the master.
Microelectronic Circuits
This research is on microelectronic amplifiers. These amplifiers will be utilized in ear buds which
will be receiving wireless signals. The signal will be generated through a small adapter. This adapter will
hopefully be comparable in size to that of a lead cable on earphones. The ear buds will receive and then
amplify these signals to hearable frequencies. As a member of this team it is my responsibility to research
these microelectronic amplifiers and analyze their relative sizes and sound quality.
Requirements for this project design:



Microelectronic Audio Amplifier small enough to fit inside a ear bud style headphone
Proper frequencies attained
Good sound quality amplification
(Chapter 10 Section 7 of Microelectronic Circuits.)
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Tuned Amplifiers:
Page 971:
“The basic principle underlying the design of tuned amplifiers is the application of series or
parallel LCR circuits as the load or at the input, of a BJT or a FET amplifier.”
Synchronous Tuning:
When dealing with audio signals frequency is a very important characteristic, especially in this
application. The audible range for the human ear is approximately 20Hz to 20kHz. This obviously calls
for a pass band style set up. It is important to note that multiple stages are needed for the final product.
The overall frequency response will be some function of the individually tuned circuits.
A High Performance Switching Audio Amplifier Using Sliding Mode Control: Page 305
Typically switching amplifiers are widely used as portable devices because of their high
efficiency. One drawback of the system is its inherent nonlinearity. However the above cited paper shows
that there actually can be a low power and high audio performance amplifier.
This amplifier has much potential for the group’s goals. A size analysis must be done in order to
ensure this class D amplifier is a serious candidate. Figure 6 on page 307 shows a 3.5 mm2 amplifier die.
This will probably be a good size to fit in ear buds. One thing that is really interesting here is the SM
TECHNIQUE. This is an efficiency control designed to minimize error. It seems that this amplifier could
be a great choice for our project.
Power and Efficiency:
Another important issue to this project is power. The ear buds are intended to be wireless. This
means they must be efficient and low power consuming. As stated earlier the amplifier considered above
is a low power amplifier. Amplifier efficiency is a ratio of the power developed to that drawn from dc.
This is the main reason to consider a class d amplifier as opposed to the class AB amplifiers. Power levels
of around 10 watts are required to cancel out background noise. If a class AB amplifier was used for this
application a heat sink would be required, thanks to lower ambient temperature.
Properties of Music/Audio Signals
Audio signals at their simplest form are sound pressures represented as variances in voltage and
current over time. The “loudness” of these signals is measured in decibels (dB). For the purposes of this
project, most signals will be between 50 and 100 decibels. However, the team may have to scale the
signal down for transmission and then amplify it back up for actual listening. If this is the case, then
distortion, or unwanted changes in the signal, could be an issue. Usually, distortion comes from driving a
circuit with a voltage that is too large for the power supply voltage of the circuit. However, it can also
come from feedback in amplifiers and transformers. The best measurement of this distortion is the SNR,
or signal to noise ratio. The higher the ratio, the better audio quality one perceives. In this case, the team
must develop a very high signal-to-noise ratio to stay competitive with other products currently out on the
market.
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There are two representations of audio signals – analog and digital. Analog signals are the most
basic, and are best described as time varying voltages. However, the more modern form digital is
composed of a stream of numbers, with each number representing a voltage at a specific time. Since both
forms are still utilized, it is imperative that the group understands both and is able to convert between the
two.
Section 2.2 Design Description
Headphones:
Plastic WrapAround Casing
In-Ear Speaker
(Left)
In-Ear Speaker
(Right)
Corded
Connection to
Headphone
Module
The headphones section of this device is by far the simplest. The basic plan is to have in-ear
headphones, similar to those seen in retailers like Bose, SkullCandy, and Sony. This will allow for
superior sound quality as well as excellent comfort. There will also be a plastic casing that will “wraparound” the ears to ensure that the headphones remain on the user regardless of the situation. The ear buds
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will be connected to the Headphone Module by a short cord, creating a necklace type design. A simple
clip may be added to this section to increase comfort.
Headphone Module:
Input from User
Interface to
Headphones
(Hardware)
Connect button
(Hardware)
Power Button
(Hardware)
Microcontroller
(Hardware/
Software)
Signal Amplifier
(Hardware)
Signal
Decompressor
(Hardware)
Power Source Battery
(Hardware)
ZigBee
Transceiver
(Hardware)
Interface to PMD
Module
(Hardware)
The headphone module essentially performs the entire signal processing functions for the
headphone unit. When the music signal is sent through the ZigBee transceiver the signal is modified from
its original form to allow for wireless transmission. This module decompresses the signal and amplifies it
before sending it to the user via headphones. The ZigBee transceiver is controlled by a microcontroller
that simple turns the unit on and off and controls the connection to the portable music device (PMD) unit.
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The whole unit is powered via a battery. The team believes a C-type battery will be appropriate for this
device. The unit will be encased in a sleek plastic unit connected to the headphones by a short cord, as
previously mentioned. The dotted line connection the PMD Module to the ZigBee Unit represents the
wireless connection between the two modules.
Portable Music Device (PMD) Module:
Interface with
Headphone
Module
Power Button
(Hardware)
Microcontroller
(Hardware/
Software)
User Inputs
ZigBee
Transceiver
(Hardware)
Connect Button
(Hardware)
Signal Attenuator
(Harware)
Signal
Compressor
(Hardware)
Interface with portable
music device
(Hardware, 3.5mm
audio jack)
The Portable Music Device Module interfaces to the music player via a standard 3.5 mm audio
jack. The signal is attenuated and compressed to allow for wireless transmission on the ZigBee platform.
This ZigBee transceiver is controlled in a similar manner to the one in the Headphone Module. There are
two functions the user can request, power on and connect. Both inputs a taken via push button on the
plastic casing.
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Section 2.3: Design and Ethical Constraints
As with all new and emerging technologies it is important to consider the responsibilities a company
has taken on. These come in the form of professional and ethical responsibilities. It must be ensured that
our group as a mock company considers all aspects of our system and the mechanism of creating our
products. It brings an interesting dynamic to the work experience to be so inexperienced and working
towards a real design. It must be conducted in a professional manor and proper documentation must be
kept at every step. It is the intention of this group to utilize existing technologies in a new and exciting
way. In terms of professional and ethical responsibilities we must give credit to all sources in APA
format. This will insure that we are being ethical in giving credit to all rightly deserving parties. In
addition any third party assistance in designing the system must be properly given their credit. Another
professional issue is compliance, applicable laws and respective patent laws. All aspects of our system
will comply with all standards for wireless RF and will respect all laws that govern this type of device. In
particular the FCC will be a main source of legislation which will regulate our groups product.As defined
by their mission statement they govern over interstate radio communications. The wireless ear buds are
intended to be initially sold in the United States. This means even though the headphones will not
transmit over State lines they will be shipped over State lines. This makes our product subject to their
rules. If the headphones take off and are a great selling success the next step would be to make them an
international product. At this point in the process it will be important to research international laws
regarding our product. In general this group is deeply concerned in matter of professional and ethical
responsibility and all appropriate measures will be taken.
The environmental constraints are at a minimum. The only thing that will impact the environment is
the improper disposal of the battery contained within the wireless headphones. To correct this design
constraint we will use EnerChip batteries that don’t contain lead, or any other materials hazardous to the
environment. These batteries are safe and reduce the opportunity cost of proper disposal techniques.
There are a few health and safety constraints however. The first health & safety constraint will be the use
of wireless signals in close proximity to vital human organs. We will need to check the medical effects of
the signals used before implementation. To deal with this design constraint the signals used must be low
power, human tolerable waves. We are able to meet that requirement effectively because ZigBee
technology is designed specifically to work with low power signals lower than existing Bluetooth
technology which is already very low and operates with human tolerable waves.
Next is how comfortable is the earphone design. If it is poorly designed then it can cause fatigue and
discomfort in the soft tissue of the ear which can lead to infections. So the earphones have to be
comfortable and adjustable to fit different ear canals. To correct the comfort design constraint we will use
synthetic rubber or soft polymer plastics that are elastic enough to easily form to the shape of the ear
canal but rigid enough to not be permanently deform when removed. The next constraint is how well
insulated are the earphones. If they are not properly insulated and overheat, they can cause severe burns to
sensitive ear cartilage. To correct this design constraint we will use material that has low heat and
electrical conductive properties like, injection molded plastic.
The manufacturing constraints are, ease of manufacturing, high cost of manufacturing, high quality of
the product and, price of product. The sustainability constraints are customer service, customer guarantee
and warranty services. To correct the manufacturing constraints we will subcontract out the
manufacturing to manufacturers with facilities built to produce this type of technology outside of the
United States. It will reduce our cost of manufacturing because we won’t have to pay the costs to operate
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and maintain a production facility. We only have to maintain and oversee the quality of our products and
pay the manufacturer fees. This allows us to bargain with multiple subcontractors in different countries
and get a competitive COGS (Cost of Goods Sold) price. In addition by lowering our manufacturing costs
we lower of COGS (Cost of Goods Sold) which allows us to competitively lower the price of our
products. To correct the sustainability constraint we will outsource our customer service to cheap highly
knowledgeable technicians overseas and provide a 100 % replacement guarantee if the the products
failure was due to fault of our own.
The zigbee wireless ear buds project inevitably involves other disciplines besides electrical.
The micro circuitry will need to be mechanically designed into the system. It will be the responsibility of
this team member to design, fabricate and test the mechanical structures of the wireless ear buds. The
mechanical job continues to designing the transmitter structure which will be attached to the actual mp3
player.
The wireless protocols will need to be programmed into the system. That is once the electrical engineers
complete the transceiver's electrical components they need to be tuned to the correct frequencies and
tested.
There will also need to be a biomedical analysis to determine the effects of the wireless exposure to the
user. This member of the team will be responsible for conducting experiments and research regarding the
radio frequencies which will be used and how or if they affect the human brain while exposed for
extended periods of time.
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Section 3: Critical Evaluation of the Project
Section 3.1 “The Good”
The largest strength of this idea is its marketability. There are many problems with current
wireless headphones that make them useless to the average user. Large, bulky headphones with limited
battery life do not satisfy the customer’s need, which is the main point of any product. The main need in
audio headphones is music on – the – go. Users obviously want good sound quality and clarity, but at the
end of the day only the most refined ear will actually notice a difference. Most people simply want the
ability to go about their busy lives and listen to music at the same time. This product satisfies that need
better than what’s currently out on the market. Also, headphones need to have a “cool” factor. Apple
almost created a cultural phenomenon with its creation of the ipod ear buds. Current wireless headphones
are disgusting at best. The “best” models are bulky and almost look antique. Apple ear buds caught on
because individual customers thought they were futuristic and trendy. Wireless headphones, on the other
hand, looks like they were produced 5 years ago, despite the new and innovative wireless technologies
contained in them. Because of this design fault, it is the belief of this team the current wireless
headphones will never catch on. The proposed model, however, does not have this issue, and would
represent the futuristic and trendy technology that Apple once boasted. A ZigBee wireless platform
allows for better battery life, lower cost, and a more compact design. ZigBee was originally designed for
sensors, and because of that it was designed to be extremely reliable and compact. Sensor networks are
typically at the heart of most complex systems, and also typically have millions of dollars of equipment
relying on their operation. Since ZigBee was built for sensor networks it also carriers this dependability.
Bluetooth can have interference issues and simple problems stemming from its use as more of a luxury
over a necessity. ZigBee wireless headphones would be more reliable than their Bluetooth based
counterparts, resulting in another competitive advantage. Also, sensory devices are designed to be
compact, as a large senor is useless in most applications. The ZigBee platform is compact to accompany
this need. While Bluetooth may be small, it is not at the micro level that ZigBee can operate around. This
will result in an overall smaller design. In today’s world, that means everything. The push is to constantly
make everything smaller, lighter, and more efficient. The design detailed in this paper would accomplish
all of those tasks. This combination of improvements gives this product the opportunity to beat out the
competition and seize a significant portion of the current market.
Section 3.2 “The Scary”
Originally, the team believed the main weakness to this design was the lack of range from the
ZigBee wireless platform. ZigBee may be smaller and cheaper, but it is also weaker. Bluetooth models
allow much larger signals to be transmitted with a better range - some models allow up to 30 ft. ZigBee is
not as powerful, and as a result would not be able to offer a range of that magnitude. A more feasible
range would be 8 to 12 feet. However, after more research the team realizes that this is not where our
largest challenges lie. Other challenges include the team’s unfamiliarity with microelectronic circuitry
and the threat of noise. In order to transmit a music signal wirelessly, we are going to have to modify it.
ZigBee is simply not powerful enough to transmit an audio signal. This means that the signal must be
compressed before its transmission from the audio device to the headphones. Compression chips represent
a huge challenge to this system due to their size and cost. Inexpensive chips are typically larger, and
would result in an overall larger design. The team must be extremely careful in this engineering tradeoff
situation, as a chip that is too large will lead to a bulky design that no one wants. However, at the same
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time a chip that is too expensive will result in a product that is too costly for the end user to justify
purchasing it. Another issue with the compression chips is the power drain that they cause. Compressing a
signal requires very high level signal processing and systems theory. The microelectronic chips that
perform these functions are notorious power drainers because of the power-intensive functions they
perform. If these power draining functions result in poor battery life the work put into this design is
worthless. Poor battery life is one of the main faults of the current technology, and not improving upon it
would be a waste to both the team and the general market.
Overall, there are multiple threats to this project. The first is the limitations of the ZigBee
platform. If the signal quality must be sacrificed in order to utilize ZigBee wireless, then the headphones
could be rendered useless. A small sacrifice in sound quality may be a necessary engineering tradeoff, but
no one wants to listen to static. Also, the complexity of modifying the current set up to utilize ZigBee
may be more trouble than it’s worth. If the circuitry gets overly complex and complicated, the headphones
will have to be too bulky, eliminating the competitive advantage of our product. The last threat is the
barrier to entry in the market. This product would be competing against much bigger developers with
more resources and time. It is unrealistic to think that they would accept a new product cutting into their
market share without challenging it at some point. It will be very necessary to secure some sort of
intellectual property rights for this product.
Section 3.2 “The Fun”
The greatest opportunity present in this project is the potential to develop and create an
innovative product that could take over an under-developed market. Wireless technology is still relatively
new and constantly changing. This product aims to take advantage of that, and apply a common
technology to a not-so-common application. If we are able to develop a set of headphones that is cheaper,
smaller, and more efficient, then this product has the potential blow away the competition. Also, Zigbee
has yet to be applied to the consumer electronics industry. As mentioned previously, ZigBee was
developed for wireless sensor networks, so its use has been niche focused to those areas. By applying this
platform to existing wireless technologies, we would be researching a previously unknown topic, which is
an extremely exciting endeavor.
Also the opportunity to market this product would be a lot of fun. As engineers, it is not often that
we get to put our names on a piece of technology used every day by millions of users. It would be a very
fun experience to see the team’s design wore by a user on the street, and be able to say that we designed
that. The risk of starting a project that could ultimately end in complete failure is a daunting proposal, but
the rewards that come with being a technical entrepreneur would be a lot of fun, especially if this project
were to succeed.
Section 3.4 Funding the Project
The economic constraints of this project are all in the upfront capital needed to plan, design and build
a prototype. We will have to spend lots of money on market research, customer requirements surveys and
technical components. To correct our monetary constraints we will initially try to fund our research and
development stage through government grants and out of pocket. This will provide us with loan free
money to plan and design our device. Next we will look towards low interest loans and investors to
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provide us with the additional capital needed to build our prototype and pay for any additional contracted
labor, market research, customer requirements surveys, etc.
Next we will have to spend money on designing an initial working prototype. The costs here will
come from technical designers and professional graphics designers to model our prototypes. Finally the
highest cost will be building a working prototype because it will be the only one of its kind therefore is a
customized design. Customization equals higher costs. To correct this constraint we will function as the
technical design team, conduct as much design in-house as we can and not use over customized parts. In
addition we will design our plastic casing to fit multiple designs to decrease prototype component
redesign costs. Our prototype will consist of a Transceiver, amplifier, and custom plastic casing with an
estimated cost of $1500 total, parts & labor. We don’t know if it will be necessary to redesign our
prototype in the future so reserve funds will be set aside for alternative prototype designs.
Section 3.5 Other Researchers
The following is a list of other researchers and companies working in areas pertinent to the team’s work.



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Jay Kadis of Stanford University – Teaches class in the basics of audio electronics and sends a
considerable amount of time as a researcher developing new audio technologies. Email:
jay@ccrma.stanford.edu
ZigBee Alliance – The ZigBee Alliance is a group of companies that promotes the application of
ZigBee wireless standards and maintains the standards of their use. The Alliance’s main office
may be reached at +1 (925) 275-6607 (telephone) or +1 (925) 886-3850 (fax).
IEEE – IEEE has access to hundreds of researchers in the wireless technology field. It’s
collection of articles and journals is second to none. Their main email is
contactcenter@ieee.org .
Sony Electronics – Sony represents our largest competition, and their R&D department works
extensively in developing new technologies like this. http://www.sony.com/SCA/index.shtml
Section 4: Summary
4.1 Project Summary
The project proposed represents the opportunity for innovation in the wireless consumer
electronic industry. Wireless headphones designed through the ZigBee platform are a realistic and
plausible goal, a goal this team would like to see pursued. The design detailed contains many advantages
over the current technologies. The first and most obvious is cost. ZigBee is a relatively inexpensive
alternative to the current platform. It is also a more compact and efficient platform. This will result in
more ergonomic and attractive headphones, as well as a far greater battery life. Apple revolutionized
headphones with its earbud design; a relatively minor improvement considering it was merely ergonomic.
ZigBee wireless headphones are set to revolutionize through multiple channels, including but not limited
to simple ergonomics.
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4.2 Further Research
First, the group would like to build a working prototype made mostly off of commercial off-theshelf products. However, once that is accomplished, the team would like to construct multiple models
with varying compression chip sizes and performance levels. If a proper filter, amplifier, and compression
chip combination cannot be found, the group plans to attempt to develop their own technologies
specifically for that use. Overall, the prototyping of this technology will prove very challenging. However
the engineering team is poised to tackle those challenges and bring this exciting new technology to
market.
Section 5: References
1) About Bluetooth (2010). In SIG Inc BlueTomorrow.com. Retrieved February 25,
2011, from http://www.bluetomorrow.com/
2) Franklin, Curt, and Julia Layton. "How Bluetooth Works" 28 June 2000.
HowStuffWorks.com. <http://www.howstuffworks.com/bluetooth.htm> 24
February 2011.
3) (n.d.). In ZigBee Wireless Standard. Retrieved February 25, 2011, from
http://www.zigbee.org
4) (n.d.). In ZigBee. Retrieved February 25, 2011, from
http://en.wikipedia.org/wiki/ZigBee
5) (n.d.). In IEEE_802.15.4-2003 Standard. Retrieved February 25, 2011, from
http://en.wikipedia.org/wiki/IEEE_802.15.4-2003
6) Wireless ZigBee. (n.d.). Retrieved February 25, 2011, from
http://www.digi.com/technology/rf-articles/wireless-zigbee.jsp
7) What is ZigBee?. (n.d.). Retrieved February 25, 2011, from
http://www.wisegeek.com/what-is-zigbee.htm
8) Kadis, J. (2006). Basics of Audio Electronics. Retrieved February 25, 2011, from
https://ccrma.stanford.edu/courses/192a/1-Basic_Electronics.pdf
Section 6: Additional URL’s of Interest
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1445794
http://www.electronicsmanufacturers.com/Microelectronics/Signal_processors/Signal_amplifiers/
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http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4606382
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=964155
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=854703
http://www.cwc.com/past-present/corporate-responsibility.html
http://www.ethicapublishing.com/ethical/3CH10.pdf
http://responsibility.verizon.com/home/approach/ethics-and-governance/
Section 7: Team Vitas
Section 7.1 John Ziegler
John is a junior electrical engineer and systems engineer double major at Stevens Institute of
Technology. He is originally from Glen Burnie, MD, but now calls Hoboken his home. Before coming to
Stevens, John attended Glen Burnie High School. There, his interest in engineering was sparked by his
participation in the National Botball Robotics competition. His team went to the national tournament his
freshman year, and he was hooked after that. John learned about Stevens after receiving a letter from the
Head Golf Coach about playing for the college. John is also an avid golfer, and spends most of his free
time working on his game. When John came to Stevens, he joined Sigma Nu fraternity with Rich and
Wojciech. He now serves on the executive board of that organization as President.
John’s hobbies include golfing, sailing, cars, and boats. When he gets the chance, he goes to
Maryland to sail with his family. He plays in golf tournaments all over the northeast over the summer,
and looks forward to that now that his junior year. He also enjoys traveling, and hopes to go on a tour of
Europe later next year.
John will be graduating next spring, and hopes to get into the financial industry as a systems
analyst on the IT side. He currently works for UBS, and hopes that will pan out into a full time offer in
the fall. He has enjoyed his time working with Rich, Wojciech, and Ryan over the past few years, and
looks forward to working with them again his senior year.
Section 7.2 Richard Wismer
Richard is a Junior at Stevens Institute of Technology perusing and undergraduate degree in
Electrical Engineering with a minor in mathematics. Recently he decided to begin work on a Masters
degree in Systems Engineering and will now be staying for a 5th year to accomplish this. Originally
recruited by the Swim Coach to swim for Stevens he swam for the ducks for two out of the past three
years. Swimming was one of his main activities during his freshman year taking up a large majority of his
non school and sleep time. At the end of his first year he joined Sigma Nu where he gained a new
appreciation for campus involvement and leadership. This, along with personal reasons, led him to not
swim his Sophomore year. With his new interests, and time to take them up, he branched out into the
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Stevens community. This involvement first started in the fraternity by taking up two positions, namely
Member at Large and Judicial Chair. These allowed him to integrate more into the organization as well as
set the stage for moving into higher positions in the house. Over the Spring 2010 semester he ran and was
elected to the Student Government Association as a Junior Senator. Then Richard realized how many of
the people he knew liked to play golf but were not on the Stevens Golf Team. So Richard and his friend
Teddy Poppe spent a lot of that semester planning and eventually forming the Stevens Golf Club. His
junior year started off with the Stevens Orientation Program where he was a Orientation Leader for the
incoming freshman. Richard also returned to the pool in his junior year with one of the most successful
seasons of his swimming career. He also became a tutor for the academic support center his junior year
and tutors a variety of subjects to a verity of students. This semester Richard was elected Vice President
of Sigma Nu as well as IFC representative for the Fall 2011 semester. Also Richard has just accepted a
summer internship position at Schindler Elevator Corp. for his first engineering job experience to date. In
his spare time, Rich enjoys swimming, golfing, piano and guitar, and listening to music.
Section 7.3 Ryan Ramdehol
Ryan Ramdehol is 3/5 co op, electrical engineering undergraduate and systems engineering
graduate scholars student at Stevens Institute of Technology in Hoboken, New Jersey. He was born in
Mississauga, Canada on September 10th 1990. His family moved to New York when he was only 4
months old and has spent most of my life living in Brooklyn, but now is proud to call Queens Village and
Hoboken his homes. Ryan graduated Midwood high school in 2008 and has been attending Stevens
Institute of Technology ever since.
At Stevens Ryan has been involved in many clubs and organizations. He is currently a member of
IUA, FAST, IEEE, Formula SAE and the Stevens Golf Club. While at Stevens he has worked at the
Student service center and had an internship at L’Oreal cosmetics in Somerset, NJ. At L’Oreal he was in
charge of the total production quality of products for half of the factory. Ryan was in charge making all
quality completely autonomous and stream lining the process of quality inspections while maintaining
high quality standards throughout the manufacturing facility. Ryan worked there from August of 2010 to
January of 2011 and learned a lot about working in the real world.
Ryan’s interests and hobbies include automobiles, traveling, poker, electronics, food and video
games. Also, he has been to over 30 countries all around the world and loves experiencing new cultures
through their food and beer. In his spare time, he enjoys television shows like Dexter, Spartacus, House
Hunters international, Friends and Wheeler dealers. One of his other favorite things to do as well is
collect and watch movies.
Ryan has a mere three semesters before he graduates with his bachelors and masters in
engineering. He plans to work for a company for a few years, gain experience and connections, take my
GMAT’s and attend business school before branching out to pursue building his own corporation. He
does not want to work for someone for the rest of his life and make someone else rich. Ryan’s true
passion is to be that guy that signs the checks and calls the shots. He has big aspirations and looks
forward to pursuing them with the rest of this engineering team.
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Section 7.4 Wojciech Gajda
Wojciech Gajda is a 3/4 studying Electrical Engineering at Stevens Institute of Technology.
Wojciech was born in the borough of Manhattan and hails from Queens New York for the past twenty
years. His parents are both hard working Polish immigrants who entered the United States in 1988. As a
child he grew up playing with Lego's and going outside to play in the park. He has been very active in
sports throughout his life playing on a recreational basketball league, and then moving up to volleyball in
High School. All throughout his academic career he was in Honors classes and a member of the National
Honors Society. As a freshman in high school, he took and passed the Apple Hardware and Software test
to become a certified Apple technician. However, he ended up working for his high school to
troubleshoot and take apart Apple laptops from students and teachers alike. During his time in high
school Wojciech learned about many various aspects of computers such as learning how to program in
Java and C. In addition to that, he took a Cisco Networking course during his last year which exposed
him to the routing side of computing and broadened his knowledge. These various experiences in the
computer field made Stevens Institute of Technology his top choice when applying for colleges. Entering
Stevens Wojciech declared his major as Computer Engineering but then switched to Electrical
Engineering to pursue a major that was not as involved with programming. During his time at Stevens,
Wojciech has fulfilled his passion for volleyball by competing and playing for the Men's Club Volleyball
team and taking a leadership role as President during his junior year. He joined Sigma Nu Fraternity in
2009, where he met John Ziegler and Richard Wismer. In his spare time, Wojciech enjoys playing guitar,
listening to music, playing volleyball, and hanging out with friends.
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