- The document describes a project to design an acoustic modem system to allow students in a classroom to communicate without WiFi when the internet is down. It would use students' laptop sound cards and microphones. - An objective tree was created identifying key needs of the system: being easy to use, high quality audio, and low cost. Engineering requirements were identified and tradeoff matrices were made. - Two design options were considered: using .wav or .txt files. Simulations showed signals could be sent and received at 9600 baud without WiFi, but the received message could not be decoded. The project deadline was not met as decoding was not achieved.

1. Design and Project Management 3180
Lab One (Acoustic Modem)
October 6th 2014
Chris Franklin 100400543
Philip Hetzel 100454395
Kaiser Li 100489409

2. Need:
To transmit data (message) at the highest baud rate possible without use of WiFi; a
system must be created in order to be able to send messages without WiFi in the class
room ua2140. This system will work when the WiFi is down using laptop sound cards
due to constant internet problems. It is estimated that 20 to 50 percent of students have
connectivity problems every class. Due to complaints from the class rep and the TA,
there needs to be a messaging system developed in order for students to maximize
their learning potential. The internet problems are projected to become a larger issue
due to the fact that there were over 10,000 first year university students registered at
UOIT in September.
Objective:
To achieve this goal the following needs must be met:
1. The customer wishes to send data in UA2140, the size of the room (and data
range) is approx. 50x25 ft. There are a maximum of 90 students per class.
2. The design process must be completed by Friday October 10th.
3. Marketing requirements:
(a) Each user must have access to a working sound card and microphone (for
transmission).
(b) Each user system must have high quality audio ( Realtek Audio Driver –
Lenovo Thinkpad).
(c) The system should be able to connect and transmit without WiFi.
(d) The system should be easy to connect and simple to use.
(e) The system should have a large scale interface (91 terminals – 90 students,
one teacher)
(f)The system should be built with a maximum baud rate.
(g) The system should be quick to install
(h) The system should be created/developed at lowest cost.

3. Hierarchy of needs: (Objective Tree)
[ Point to Point Modem ]
[1] – Easy to Use
i) Simple connection
ii) Simple messaging system
[2] – High Quality
i) Soundcard must be working and HD.
ii) Microphone must be working and HD.
iii) Maximum baud rate.
[3] – Lowest Cost (Min $2500)
i) Maximum room size 50x25 ft.
ii) Maximum 91 connections available for interface, minimum two.
Pairwise Comparison Matrix:
Easy to Use High Quality
Audio
Lowest Cost Weight
Easy to Use 1 1/3 2 0.24
High Quality
Audio
3 1 4 0.62
Lowest Cost 1/2 1/4 1 0.14
All information was reviewed by group members and deemed acceptable for given
project and restrictions.

4. Research Survey
What is the basic theory behind the concept?
A user/admin will create a message in program, that message will be transmitted to the
soundcard/speakers and the other user/admin laptop will receive the audio signal via
the microphone. The audio signal will then be converted to an electric signal and
processed with program. The signal will be decoded using program to display the
message for the user.
How is this currently being done?
This method is being utilised around the world on many different platforms and devices.
This method can be converted underwater or in extreme conditions. The basic concept/
principals remain constant through all varying methods of creating a point to point
modem. We are going to use program functions for our design.
What are the limitations?
The limitations to our design are the laptops which will be used by students and
professors. The laptops come with a high quality sound card and microphone, however,
they are not brand new or top-of-the line. We also are limited to creating our point to
point modem using built in program features.
What will the cost be?
The minimum cost for the system will be the yearly rental of the laptop and software by
the students. To prevent higher costs for students, our design will be based on the
practical baud rate for the point to point modem.
What will the baud rate be?
The maximum baud rate that we could transmit with our laptops is 230400 bits per
seconds, which runs at 3.34 microseconds. Our realistic goal to keep costs low will be
9600 bits/second. If a higher rate can be achieved the consumer will benefit from it at no
additional cost.

5. Design Document
Marketing Requirements vs Engineering Requirements:
The engineering requirements were validated by all group members as the most
significant 5. Explanations for each requirement is displayed in the table below.
Marketing Requirements Engineering Requirements Justification
a-h 1. Production cost
must be less than
$2500
Based upon the average
cost of UOIT Lenovo
laptop rental.
a,b,c,f. 2. (Full) Message
delivery time rate
must be less than
10 seconds.
Based upon the average
time to walk from front of
classroom to student (the
messaging system would
be inefficient if time is
greater).
d,g. 3. System install time
must be less than 5
minutes
Based upon average time
a student has to prepare
while waiting for professor
to start lecture.
c,e,h. 4. System should stay
connected and
function for at least
2 hours.
Based upon the fact most
lectures are less than 2
hours long.
a,b,c,d,e,h. 5. System sound
levels should be
relatively low.
Based upon the fact that
the messaging system
can’t interrupt other
students’ abilities to learn.
Marketing-Engineering Trade-off Matrix:
The trade-off matrix below displays the polarities between each of the marketing and
engineering requirements. This table is valuable because the design decisions for our
modem are based off of how each of the requirements effect another.
Marketing
Req.
(a) (b) (c) (d) (e) (f) (g) (h)
Engineering
Req.
POLARITY + + - + + + - +
1.Cost + -- -- vv ^^ ^^ ^ ^ ^^
2.Rate + ^ ^ ^^ ^ ^ ^^ ^^ ^^
3.Install - -- -- ^ ^ vv -- ^^ v
4.Function + ^ ^ vv ^^ ^ -- -- ^^
5.Sound - ^^ ^ vv vv v v -- ^^

6. Engineering trade-off matrix for Acoustic Modem
The trade-off matrix below displays the correlation between each of the engineering
requirements. Information displayed in this table was used to choose the best design
option.
Function Rate Install Sound Cost
POLARITY + + + + -
Function + -- ^ v ^^
Rate + ^ ^^ ^^
Install + -- ^^
Sound - vv
Cost -
Concept Fan for Acoustic Modem
Design Options for Acoustic Modem
Design option #1 – Design option number one is an acoustic modem developed in the
Simulink library of Matlab, transferring a converted .wav file at a baud rate of 9600
bits/second. The received signal will be converted back into a .wav file at receiving end
for user to hear message. The method of data transmission used would consist of a
time-coded signal at a high frequency with a decimation of 0.001. The estimated cost for
this system is simply the UOIT laptop fee for each user in class (Min – $2500 to a max
of $112,500).

7. Design option #2 – Design option number one is an acoustic modem developed in the
Simulink library of Matlab, transferring a converted .text file at a baud rate of 9600
bits/second. The received signal will be converted back into a .text file at receiving end
for user to read message. The method of data transmission used would consist of an
coded array at a decimation of 0.001. The estimated cost for this system is simply the
UOIT laptop fee for each user in class (Min – $2500 to a max of $112,500).
Based on all previous calculations and consumer needs, our group decided that
design option 2 was the most efficient choice.
Receiver End – Simulink Library Transmitter End- Simulink Library
Results of Simulink Simulations for Acoustic Modem
Our group was successfully able to send and receive a signal using design
option two; however, we were not able to decode our original message on the receiving
end of the acoustic modem.
We successfully ran our simulation without WiFi for 10 seconds at a baud rate of
9600 bits per second, at a decimation of 0.001 (meeting requirements). We observed a
small beeping noise whilst the program was running, but we feel that the noise was
within our engineering requirements. Our program had the potential to successfully
function for an extended range of time >2hrs, surpassing our requirements. Also, install
time for our program was (successfully) under 5 minutes. We successfully met every
need with a working and HD soundcard, microphone operating at a maximum baud
rate. We achieved the lowest cost for a maximum room size of 50x25 feet. Our system
was easy to use with simple and quick installation and messaging. Our system was able
to operate at a maximum of 91 connections.
In conclusion, had our group been able to decode the received signal, we would
have met every need, engineering & marketing requirement before the deadline of Oct.
10th.