FM TransmitterDec06-01

Advisors: Dr. John W. Lamont

Prof. Ralph E. Patterson III

Client: Iowa State University - Senior Design

Team: Grant Blythe Tony Hunziker

Luke Erichsen

Date: December 5, 2006

Introduction

Introductory Material

Project Activities Design

Implementation

Resources and Schedules

Conclusion

Presentation Outline

Objective:Design a portable short range FM transmitter for use with MP3 players or satellite radios

Project Overview

Definitions

FCC:

FM:

LCD:

MP3 player:

PLL:

RF:

Transmission 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

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 PIC’s

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 Problem Statement:

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.

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

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.

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.

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.

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

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

Approaches Considered

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

Logic Approach

The logic for the transmitter could be implemented either with a microcontroller and software or with dedicated hardware logic.

Approaches Considered

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

Display Approach

Due to self-imposed assumptions, transflective LCD’s were only considered. Transflective LCD’s allow data to be viewed with and without a backlight.

Approaches Considered

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

Programming Approach

It was possible to program the PIC in two different languages. The two different languages were Assembly or C.

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

Research Activities

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

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

Design Activities

Functional Diagram

Inputs

Processing

Outputs

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

Design Activities

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

with microcontroller

Design Activities

Design Activities

Overall Schematic

Design Activities

Component Communication

Serial Connection from microcontroller to signal processor

Design Activities

Component Communication

For Example: in the case of 99.7 MHz carrier frequency.

99.7 MHz / 100 kHz (fref) = 997 3E5 (HEX)

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.

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.

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

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

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 subsystemsVerifying prototype meets or exceeds all design requirements

RF VCO failure causes transmission system failure Advisor/Client acceptance testing

Not completed

Resources

Personnel Efforts 4 Team members first semester 3 Team members second semester

Jacob Sloat studying abroad235

137

227 232

0

50

100

150

200

250

Grant Jacob Luke Tony

Personnel Ef f orts

Resources

Financial Requirements

$100

$12

$23

$15

$35

Parts

Printing &Binding

Poster

Case

PCB

`

Project Finances

Resources

J F M A M J J A S O N D

Final Documentation

Final Product Testing

Final Product Implementation

Prototype Testing

Prototype Implementation

Finalization of Design

Design Research

Problem Definition

Project Schedule

Project Evaluation

Milestone Evaluation Criteria

Evaluation Result Numerical Score

Exceeded/Met 90% +

Partially Met 1 - 89%

Did not Meet Standard 0%

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%

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

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

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

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

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

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.