FM Transmitter

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FM Transmitter
Dec06-01
Team Grant Blythe Tony Hunziker Luke Erichsen
Advisors Dr. John W. Lamont Prof. Ralph E.
Patterson III
Client Iowa State University - Senior Design
Date December 5, 2006
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Presentation Outline

• Introduction
• Introductory Material
• Project Activities
• Design
• Implementation
• Resources and Schedules
• Conclusion

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Project Overview
Objective Design a portable short range FM
transmitter for use with MP3 players or satellite
radios
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Definitions
FCC FM LCD MP3 player PLL RF Transmis
sion frequency VCO
Federal Communications Commission frequency
modulation, a method of modulating an audio
signal for wireless transmission liquid crystal
display portable digital music player, (i.e.
ipod) phase-lock loop radio frequency the
frequency at which the device is transmitting the
FM modulated signal to the FM radio voltage
controlled oscillator
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Acknowledgement
The team would like to thank the following people
for their help and support.
Jason Boyd For showing us various
possibilities for prototyping surface mount
components. Dr. John W. Lamont and Prof. Ralph E.
Patterson III For your knowledge and guidance
in helping us with part selection and referring
us to expert advice when needed. Dr
Geiger For help understanding the phase lock
loop Fredo For a helpful reference.
Yesuratnam Thommandru For help uderstanding
programming PICs
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Problem Statement
General Problem Statement
Currently many people use MP3 players and
satellite radios, but do not have a way to
connect them to their other audio equipment. It
should be easily tunable to transmit on any
desired frequency in the FM band (88-108 MHz)
with the ability to preset four selectable
frequencies within this range. The minimum
transmission distance is to be at least twelve
feet.
General Solution Approach
Most of this existing equipment has FM radio
capabilities, so the solution approach was to
develop a portable FM transmitter to link MP3
players and satellite radios to any FM receiver.
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Operating Environment

• The finished device will operate within a
  personal vehicle or a household room that could
  be exposed to
• Moisture
• Dust/Dirt
• Impacts
• Temperatures from 32 - 100 F
• Normal humidity/pressure

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Intended Users/Uses
Intended Users
The intended user for this product is anyone
owning a MP3 player or satellite radio device.
Intended Uses
The FM transmitter is intended to make personal
music devices accessible through home and car
stereos.
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Assumptions

• The device will receive a 20 Hz to 20 kHz input
  audio signal from all varieties
• of personal music devices.
• The device will output to standard North
  American FM radio equipment.
• The transmitter will be subjected to a variety
  of environments including
• varying temperatures, humidity, vibration
  levels, and electromagnetic noise.
• The device will be operated in varying ambient
  light conditions.
• The user will have access to a steady power
  source.

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Limitations

• The cost to purchase this product shall not
  become uncompetitive.
• The transmitter must conform to FCC regulations.
• Part 15 concerning unlicensed FM broadcasting
• Broadcast strength 0.1W
• Broadcast band 88 -108 MHz
• The device shall be capable of obtaining power
  from readily available power
• sources.
• The size shall not exceed 6 in. by 6 in. by 3
  in.
• The weight shall not exceed 1 lb.

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Expected End Product

• The device case will be made
• of plastic
• The case will allow for easy
• hand manipulation and
• transportation
• The device will implement an
• LCD screen displaying the
• transmission frequency.
• The device will be
• accompanied by a user
• manual.

• The user input interface will consist of six
• buttons.
• up and a down button to adjust
• transmission frequency
• 4 buttons will each access a programmable
• preset frequency
• Transmit a minimum of 12 ft

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Present Accomplishments
Problem Defined Successfully completed
Research Completed Successfully completed
Technologies Selected Successfully completed
Design Completed Successfully completed
Design prototyped Completed Prototype
testing Partially completed Project
documented Successfully completed
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Approaches Considered
Logic Approach The logic for the transmitter
could be implemented either with a
microcontroller and software or with dedicated
hardware logic.
Microcontroller/Software Hardware Logic Advantage
Cost 7.00 7.00 none
Ease of Implementation Requires software to be written, compiled and loaded Requires detailed design and intricate implementation with more components Microcontroller
Weight/Size One large IC Several small components none
Expandability Modifiability Requires software to be changed and recompiled Requires full redesign of entire circuit Microcontroller
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Approaches Considered
Display Approach Due to self-imposed
assumptions, transflective LCDs were only
considered. Transflective LCDs allow data to be
viewed with and without a backlight.
VIM - 404 VI - 415 Advantage
Cost 5.00 10.00 VIM - 404
Ease of Implementation Controlled by three 1/3 duty cycle signals as common inputs. Controlled by multiple drivers which receive binary input. VI - 415
Number of Pins 20 40 VI - 404
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Approaches Considered
Programming Approach It was possible to program
the PIC in two different languages. The two
different languages were Assembly or C.
Assembly C Advantage
Ease of Implementation Closer to machine language. Requires writing to specific registers. Abstract language that is more user friendly. C
Memory Space Allows more control for memory use. The compiler yields less efficient memory use in translation. Assembly
Group Understanding Minimal practice, unfamiliar with commands. More familiar with commands. C
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Project Definition

• A successful project will result in a device
  that
• shall receive an input signal and broadcast it
  on the FM band
• shall receive its signal input from a 3.5mm
  input port
• shall accept power from a cigarette
  lighter/power socket of an automobile or
• a standard wall outlet
• shall be capable of storing 4 programmable
  transmission frequencies
• shall display the transmission frequency on a
  back-lit display

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Research Activities

• FM Radio Transmission
• Uses transmission band of 88-108 MHz
• Signal Modulated onto carrier frequency
• Backwards compatible with stereo/mono

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Research Activities

• FCC Rules
• Part 15 concerning unlicensed FM broadcasting
• Broadcast strength 0.1 W
• Broadcast band 88 -108 MHz

• LCD Displays
• Reflective technology
• Transflective technology
• Backlights

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Design Activities

• Functional Diagram
• Inputs
• Processing
• Outputs

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Design Activities

• Microcontroller
• PIC 16F877
• 28 Pin DIP
• Non-Volatile Memory
• I/O
• Handles all device logic
• Controls user interface
• Data connection to signal processor, LCD display
• Controls backlighting

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Design Activities

• Signal Processor
• Rohm BH1415F
• SOP22
• Phase Locked Loop
• Stereo Capability
• Built in pilot tone
• Serial communication
• with microcontroller

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Design Activities
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Design Activities
Overall Schematic
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Design Activities

• Component Communication
• Serial Connection from microcontroller to signal
  processor

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Design Activities

• Component Communication
• For Example in the case of 99.7 MHz carrier
  frequency.
• 99.7 MHz / 100 kHz (fref) 997 ? 3E5 (HEX)

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Implementation Activities
Changes From Original Design

• LCD display
• Switched to VI 415 from VIM 404 because of
  ease of connecting to PIC.
• Clock
• Switched from a clock to a ceramic resonator.
• Serial connection
• Used output pin instead of serial connection.

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Implementation Activities
Problems

• PIC
• Problems getting compilers installed and working
  in senior design labs. Solved by downloading
  free compiler online and bugging the Computer
  Support Group.
• Problems getting PIC to work. Initial registers
  were not initialized. Once watchdog timer,
  code-protection, and low voltage program were
  disabled and the clock type was selected, PIC
  worked.
• Transmitter Circuit
• Problems getting the output signal. Solved by
  enabling the transmitter chip.

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Implementation Activities
How Implementation Process Can Be Improved

• Make sure all necessary programs were installed
  before needed.
• Read all documentation on device.
• Schedule extra time for delays

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Testing/Modification

• Device Subsystem Testing
• Testing of signal modulation
• Test composite signal generation
• Test RF oscillator
• Test output power
• Transmission occurs across frequency band
• Power system tested for reliability
• Control system tested for proper function

• Prototype Testing
• Integration of all subsystems
• Verifying prototype meets or exceeds all design
  requirements
• User testing
• Advisor/Client acceptance testing

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Testing/Modification Results

• Device Subsystem Testing Results
• Testing of signal modulation
• Composite signal generates successfully
• RF voltage controlled oscillator does not
  initialize
• Testing output power
• Output .085 W which is less than FCC broadcast
  strength of .1 W
• Control system tested for proper function
• I/O control works successfully

• Prototype Testing Results
• Integration of all subsystems
• Verifying prototype meets or exceeds all design
  requirements
• RF VCO failure causes transmission system
  failure
• Advisor/Client acceptance testing
• Not completed

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Resources

• Personnel Efforts
• 4 Team members first semester
• 3 Team members second semester
• Jacob Sloat studying abroad

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Item Description Cost
Parts 100
Printing Binding 12
Poster 23
Case 16
PCB 36
Labor at 12.50  
Grant Blythe 2,937
Luke Erichsen 2,750
Tony Hunziker 2,875
Jacob Sloat 1,375
Total 10,124
Resources
Project Finances
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Resources
Project Schedule
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Project Evaluation
Milestone Evaluation Criteria
Evaluation Result Numerical Score
Exceeded/Met 90
Partially Met 1 - 89
Did not Meet Standard 0
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Project Evaluation
  Milestones Relative Importance Evaluation Score Resultant Score
Problem definition 15 100  15 
Research 10 100  10 
Technology selection 10 100  10
End-product design 15 100  15 
Prototype implementation 10  70 7 
End-product testing 10  70 7 
End-product documentation 10 95  9.5
Project reviews 5 100  5 
Project reporting 10 100  10 
End-product demonstration 5 50  2.5 
Total 100   91
Previously defined passing score 80
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Commercialization / Additional Work

• Commercialization
• Product market already exists
• Several competitors established in market
• Will be difficult to establish in market
• Must provide unique features to compete

• Recommendations for Additional Work
• Commercialization of product
• Expanded functionality
• Auto-Seek frequency to broadcast on
• Multiple input sources
• HD radio output

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Lessons Learned

• What went well?
• Team member interaction
• Programming (after initial configuration error)
• Documentation

• What did not go well?
• Configuring PIC programmer
• Transmission circuit debugging
• Device implementation

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Lessons Learned

• Knowledge gained
• FM modulation process
• Microcontroller programming
• LCD display drivers
• Soldering skills

• What would we change?
• Make sure necessary programs were installed
  before needed
• Talk to someone with background in RF
• Have a computer engineer on the team
• Project schedule

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Risk Management
Anticipated Potential Risks Risk Loss of a
team member Management Increase remaining
members efforts Risk Component
Failure Management Ordered multiples of the
less common components Risk Delay Receiving
Parts Management Rescheduling of tasks
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Risk Management
Encountered Risk - Anticipated Loss of a team
member Successfully managed through increased
efforts Delay receiving parts Successfully
managed through task rescheduling Component
failure Ordered extra parts
Encountered Risk - Unanticipated Complexity of
technology Marginally managed with additional
research
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Summary
The FM Transmitter project was meant to create a
device that allowed the output of a personal
music device to be utilized by a car or home
stereo. While a fully functional device was not
sucessfullly implemented,  the groups technical
knowledge was expanded and its project management
skills refined.