A Universal RF Communications Link

A Universal RF Communications Link

Project Plan

Client: Senior Design

Faculty Advisor: Dr. Yao Ma

Senior Design Dec07-06

Team Members:

REPORT DISCLAIMER NOTICE

DISCLAIMER: This document was developed as a part of the requirements of an electrical and computer engineering course at IowaStateUniversity, Ames, Iowa. This document does not constitute a professional engineering design or a professional land surveying document. Although the information is intended to be accurate, the associated students, faculty, and IowaStateUniversity make no claims, promises, or guarantees about the accuracy, completeness, quality, or adequacy of the information. The user of this document shall ensure that any such use does not violate any laws with regard to professional licensing and certification requirements. This use includes any work resulting from this student-prepared document that is required to be under the responsible charge of a licensed engineer or surveyor. This document is copyrighted by the students who produced this document and the associated faculty advisors. No part may be reproduced without the written permission of the senior design course coordinator.

Submitted February 27, 2007

1

Contents

Figuresiv

Tablesv

Definitionsvi

Section 1Introductory Materials1

1.1Executive Summary,1

1.2Acknowledgements,1

1.3Problem Statement,2

1.3.1General Problem Statement,2

1.3.2General Problem Solution,2

1.4Operating Environment,3

1.5Intended Users and Uses,3

1.5.1Intended Users,3

1.5.2Intended Uses,3

1.6Assumptions and Limitations,4

1.6.1Initial Assumptions List,4

1.6.2Initial Limitations List,4

1.7Expected End Product and Other Deliverables,5

Section 2Proposed Approach5

2.1Functional Requirements,5

2.2Constraint Considerations,5

2.3Technology Considerations,5

2.4Technical Approach Considerations,6

2.5Testing Requirements Considerations,6

2.6Security Considerations,6

2.7Safety Considerations,6

2.8Intellectual Property Considerations,7

2.9Commercialization Considerations,7

2.10Possible Risks and Risk Management,7

2.11Project Proposed Milestones and Evaluation Criteria,7

2.12Project Tracking Procedure,8

Section 3Statement of Work9

3.1Project Definition,9

3.1.1Problem Definition,9

3.1.2End-Users and End-Uses,9

3.1.3Limitation Identification,9

3.2Technology Considerations,10

3.2.1Technology Identification,10

3.2.2Criteria Identification,10

3.2.3Technology Research,10

3.2.4Technology Selection,11

3.3End-Product Design,11

3.3.1Identification Requirements,11

3.3.2Design Process,11

3.3.3Design Documentation,11

3.4End-Product Implementation,12

3.4.1Identification of Limitations,12

3.4.2Implementation of End-Product Design,12

3.5End-Product Testing,12

3.5.1Test Planning,12

3.5.2Test Development,13

3.5.3Test Evaluation,13

3.6End-Product Documentation,13

3.6.1Development of End-User Documentation,13

3.6.2Development of Maintenance Support Documents,14

3.7End-Product Demonstration,14

3.7.1Demonstration Planning,14

3.7.2Faculty Advisor Demonstration,14

3.7.3Client Demonstration,14

3.7.4Industrial Review Panel Demonstration,14

3.8End-Product Reporting,15

3.8.1Weekly Email,15

3.8.2Project Plan Development,15

3.8.3Project Poster Development,15

3.8.4End-Product Design Report,16

3.8.5Project Final Report,16

Section 4Estimated Resources17

4.1Personal Effort Requirements,17

4.2Financial Requirements,18

4.3Other Requirements ,18

Section 5Schedule20

5.1Project Schedule, 20

5.2Deliverable Schedule,21

Section 6Closure Materials22

6.1Closing Summary, 22

6.2Project Team Information, 23

6.2.1Client Information,23

6.2.2Faculty Advisor Information,23

6.2.3Team Members Information,23

6.3References,23

Figures

Figure 1- Projected Schedule,20

Figure 2- Project Deliverable Schedule, 21

Tables

Table 1- Project Milestones and Overall Importance,7

Table 2- Milestone Evaluation Criteria,8

Table 3- Personal Effort Requirements, 17

Table 4- Financial Requirements, 18

Table 5- Other Requirements, 19

Definitions

AAnalog-to-Digital Converter (ADC)

A device which converts an analog signal to a digital signal

BBit rate (bps)

A term which specifics the number of bits per second a digital signal operates at

C

DDec07-06

The unique identification code designated for the team working on the universal RF communications link project. The first alpha-numeric code indicates when the project will be completed. The second numeric code indicates the project number.

Digital-to-Analog Converter (DAC)

A device which converts a digital signal to an analog signal

EElectrical and Computer Engineering (ECE)

A department of IowaStateUniversity

FFederal Communications Commission (FCC)

An independent UnitedState government agency which regulates interstate and international communications by radio, television, wire, satellite and cable [1]

Frequency Shift Keying (FSK)

A common form of modulation used by communication systems

G – H – I – J – K

LLiquid Crystal Display (LCD)

A low power digital device which uses liquid crystals to display alphanumeric characters

MMicrocontroller (MCU)

A self-contained computer-on-a-chip consisting of a central processing unit, non-volatile program memory, random access memory for data storage, and various input-output capabilities [3]

N – O

PPrinted Circuit Board (PCB)

A structure which mechanically supports and electrically connects electrical devices

Q

RRestriction of Hazardous Substances (RoHS)

A directive which restricts the use of certain hazardous substances in electrical and electronic equipment.These substances include lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl, and polybrominated diphenyl ether flame retardants [2]

S – T – U – V – W – X – Y – Z

1

Section 1Introductory Materials

The following section contains the executive summary, acknowledgements, the problem statement, the operating environment the project will be subject to, the intended users and uses, the assumptions and limitations that were imparted upon this project, and the expected end product from the project team.

1.1 Executive Summary

Many times senior design projects require an embedded RF communications link to accomplish a certain task. This is often a problem for the project teams as they do not have the time or expertise to have one specifically designed. To facilitate teams’ needs this project will design and build a universal RF communications link. Two previous senior design teams have attempted this project but with limited success.

The basic functional requirements will include one input/output for both analog and digital signals. The analog will have a bandwidth of less than 4 kHz and the digital will have a bandwidth of less than5 kbps. The transceiver of the module will be controlled by an embedded microcontroller. The module mustfollow FCC regulations due to operation in the United States; however, this module will not meet new product industry design standardsbecause it will not be RoHS compliant. This product will utilize components which are available in RoHS compliant packages; therefore, this product could be made to meet RoHS if so desired.

The envisioned project is a device that has a physical size of 9cm by 13cm by 4cm(3”x5”x1.5”). This module will have “functional” full-duplex capability, meaning it can transmit and receive practically simultaneously. It shalloperate such that any analog or digital signal meeting the requirementswill pass to another module which will output the original signal. The input bandwidth will be about 4 kHz, and should work at a distance of 30m line-of-sight. Thebatteries should be rechargeable and capable of supporting the module for five hours.Individualmodulesshallnot exceed $100. For testing purposes there will be a need for two modules. Tests will include range, data integrity, battery life, reliability, and duplex functionality. Finally, moduleswillcome with a “cookbook” manual or a tutorial that allows quick and easy implementation into future projects.Since this module is being design for other senior design projects commercialization isn’t a factor; however, this product may support additional features thus making it better than available commercial units.

If time permits the module will have increased functionality which may include one or several of the following: frequency hopping, a LCD screen to indicate to the user the frequency and power/battery life of the module, a sleep/standby mode to save power, a remote on/off mode, multiple inputs/outputs, error checking, RF power regulation to adjust module’s range, master/slave operation, computer interface, and enclosed in a case. The specific detailswhich are still in consideration include frequency band, RF modulation, power/batteries, and individual components of the module.

1.2 Acknowledgements

The senior design team Dec07-06 would like to thank IowaStateUniversity for providing a positive learning community. The team would also like to thank Professor Lamont and Professor Patterson for providing us with a project which has the potential to greatly impact the success of future design projects. The team would also like to thank our faculty advisor Dr. Yao Ma, without a supportive advisor this project could not be successful.

1.3 Problem Statement

When a senior design team is provided with a project, the only details given about project are the name of the project and a one paragraph proposal. Listed below is the proposal receivedby the Dec07-06 team.

An embedded radio frequency (RF) link is often required in many electrical and computer engineering senior design projects.However, the design teams usually do not have the time and expertise to design such a link specifically for each project.To meet this need, several basic, microprocessor-controlled RF links have been designed and tested by two previous design teams but with limited success.This project team will review the previous teams’ results but will also conduct a comprehensive search for more recently developed technologies in order to produce an optimum RF link for use in future senior design projects. To enhance the usability of this link, a companion development board, similar to the microcontroller development board used in CprE 211, is also required.The project will involve the design, fabrication, testing, and documentation of the complete RF link package.This will include the selection and integration of the optimum component parts, the layout of the appropriate printed circuit board, the provision of various antenna systems, the addition of various data and signal processing capabilities such as analog-to-digital and digital-to-analog conversion, the addition of various output transducers and capabilities such as pulse-width modulation, the development of alternative power supplies and packaging, and comprehensive testing of the complete system.Full documentation will include tutorials and design guides for using the RF link. Multiple sets will be constructed for use by senior design teams in the future.

1.3.1 General Problem Statement

Previous senior design projects were unsuccessful due to insufficient time, money, or other resources they needed to build a short range 2-way wireless communications link.This project must provide a cost effective solution for error-free bi-directional transmission of analog and digital signals over a specified range. The module will be self supporting through use of onboard batteries and provide continuous transmission over a specified duration.

1.3.2 General Problem Solution

The solution is to build a universal RF link that can easily be integrated into senior design projects.For the given project, universal implies thatinput/output features must encompass analog and digital signal. This RF link will consist of standalone modules which will allow for a variety of signals to be transmitted and received amongst each other. A microcontroller will be necessary to buffer sampled data to the RF transceiver. In addition an LCD and control switches may be implemented to allow the user to set parameters such as frequency and range.

1.4 Operating Environment

This product will be designed to operate in an indoor and outdoor environment, depending upon the enclosure used. Without an enclosure the module must be kept in a relatively clean environment where the temperature can be maintained between -20to 60 degrees Celsius and humidity will be less than 90 percent. The product will perform under moderate vibration but will not be used in situations where a drop of more than 60 centimeters (case dependant) may occur. The module will be used in environments with little RF interference in the 2.4 GHz band.

1.5 Intended Users and Uses

This section has been divided into two separate sections. The first being discusses who the intended users will be and the second discusses how this product will be used.

1.5.1 Intended Users

The intended users will mainly consist of senior design students within the ECE department at IowaStateUniversity; however, it may also beused by anyone needing an analog or digital communications link.

1.5.2 Intended Uses

The device is expected to be used within a senior design project as a data communications link. It is intended to be used for relatively short range communication with relativelylow data rate transmissions within the user’s chosen application.

1.6 Assumptions and Limitations

As a project undergoes a transformation to an end product there are limitations and assumptions which must be made. Limitations include how the project is physically restricted, as requested by the client, while assumptions are what the project team defines as restrictions.

1.6.1 Initial Assumptions List

• Battery will be charged to a minimum of 75% of its rated capacity for module to meet the battery life requirement.
• A form of FSK modulation will provide adequate performance for operating in the 2.4GHz unlicensed band.
• The module will provide a means of error correction to maintain data integrity.
• A microcontroller will be used to provide error correction and radio control.
• A LCD panel will provide the user with channel and radio power configuration information.
• The final product will operate correctly when used in the specified environment.

1.6.2 Initial Limitations List

• The module will be used in the United States; therefore, FCC regulation will apply and it will operate in unlicensed frequency bands.
• The module will have a smallform-factor. The maximum size shall be 4cm by 9cm by 13cm, and weigh less than 0.5kg.
• The module must support full duplex communication at a minimum range of 30m (line-of-sight).
• The module will support a minimum of one analog and one digital input and output. The analog input/ output will have a minimum bandwidth of 4 kHz.
• The module must perform under battery power for a minimum of five hours.
• An individualmodule’s cost will not exceed $100 ($200 per pair).

1.7 Expected End Product and Other Deliverables

The end product will include multiple inexpensive communications modules all of which will meet the minimal operation requirements. A user manual, service manual, and tutorials will accompany the fully functional communications link. These deliverables should be completed by December 2007. The tutorials will walk the user through connecting the communications link to their system and sending data. The user manual will include a more detailed description of the tutorials and will also include a troubleshooting section, so users know what to do if the communications link becomes unreliable. The service manual will include schematics, datasheets, and part replacement options for future service needs.

Section 2Proposed Approach

To ensure a high probability of project success a proposed approach is crucial. The proposed approach is broken down into several sections and defines not only what the end product will do but also includes how the team will accomplish this.

2.1 Functional Requirements

The following functions will be implemented into this project and are necessary to complete the primary requirements of the client.

• Transmit analog input to analog output via RF
• Each analog channel supports 4kHz bandwidth
• Transmit digital input to digital output via RF
• Each digital channel supports 5kbps
• Transmit and receive practically simultaneously (“functional” full-duplex)
• Transmit/receive range of 30m(line-of-sight)
• Self supporting for 5hours

NOTE: These are the primary goals of this project. Additional functionality may occur once the primary goals have been satisfied.

2.2 Constraint Considerations

The following constraints will be imposed upon this project. The constraints where formed from the assumptions and limitations.

• Size must not exceed 9cm by 13cm by 4cm
• Weight must not exceed 0.5 kg
• Batteries must be removable or rechargeable
• RF transmissions must be FCC compliant
• Cost must not exceed $100 per module ($200 per pair)
• Temperature range must not exceed -20 to 60°C
• Batteries must be charged to a state of greater than 75% capacity before use
• Only 1 operating communications link per channel
• Limited traffic on the 2.4GHz frequency
• Low power consumption

2.3 Technology Considerations

This project consists of several systems and requires additional research to determine which systems are best suited for this project. At minimum the project will need:

• Central processing unit- This converts sampled inputs into a format usable by RFtechnology, and converts RF technology data output to usable signal outputs.
• Signal processing- This may be necessary if the central processing unit is not sufficient
• RF technology- This is responsible for sending data from one unit to another. It may consist of a transceiver which combines transmit and receive into a single unit, an amplifier to increase output power, and an antenna to radiate the RF.
• Power technology- This is responsible for providing power to the other systems

NOTE: The central processing unit will most likely take the form of an embedded microcontrollerbecause of the low-current draw and sufficient data processing capabilities.

NOTE: The RF technologymay consist of a purchased module which encompasses all required necessary RF components.

2.4 Technical Approach Considerations

A major part of technical approach is to choose parts that contribute greatly to the overall success of the project. The project team will research RF links that previous senior design teams have worked on and will decide whether it more practical to revise one of the previous design projects or initiate a new design. If a new design is necessary, research of components will be necessary.The component research will emphasize price, power consumption, and features that make the module easily adaptable to any improvements added after basic system functions of the device have been met. Once the components have been researched, a side-by-side comparison will be formulated which will allow for an optimal design.

The development of the project will consist of the team choosing suitable components, then creatingschematics and software as soon as possible. In addition, once hardware and software are in place the approach will consist of testing, and once the basic link has been established, implementing additional features as time and resources permit. Oncethe prototypemodules are completely testedthe project team will produce2end product modules.

2.5 Testing Requirements Considerations

Testing for the device will include four main areas: range, data integrity, reliability, and duplex communication. To test the range,the project team plans to input signal from a function generator to the module and use an oscilloscope to check the output for various distances. Reliability will be tested by requiring a single 24 hour continuous operation of the module. Also, a mixed signal will be applied to the input to test the dependability of analog and digital data transmission. The strategy for testing the duplexfunctionality of the device is to use multiple function generators and oscilloscopes. This way the project team will visuallyconfirm data integrity while the module is transmitting and receiving simultaneously. A test will be considered a success if and only if the test meets the predefined specifications.