1 Capstone Design Project Silent Alarm System Students: Su Huang & Fenghua Chen Advisor: Professor...
-
Upload
theresa-harrington -
Category
Documents
-
view
216 -
download
0
Transcript of 1 Capstone Design Project Silent Alarm System Students: Su Huang & Fenghua Chen Advisor: Professor...
1
Capstone Design Project
Silent Alarm System
Students: Su Huang & Fenghua Chen
Advisor: Professor James Hedrick
March 03, 2007
2
Current Safety Alert System
Emergency phone booths
Surveillance cameras Wired together
(underground) Connect to Campus
Safety
3
Disadvantages of Current System
Slow notification of incident Surveillance cameras have blind spots Fixed in numbers and locations
4
What is a Silent Alarm System?
A personal safety alert system Mobile device Wireless transmission Easy, silent activation Instant alert to Campus Safety Better location tracking
5
Keychain (student)
Central Station(Campus Safety)
Signal
Signal Signal
Schematic Diagram
Sub.
Substation
Key Chain (Student,
faculty, etc)
6
The Big Picture
www.google.com
7
The Project
Idea by Nelson Rosario Originally based on Parallax Education Board Migration to C8051 MCU platform Develop a communication platform for software
engineers Develop basic communication protocol Built a standalone prototype on a PCB board
8
Design Specifications
Transmit Frequency: 433.92 MHz Transmit Range: 500ft Transmitter Output Power: -4 ~ 8 (dBm) Receiver Output Power: -4 ~ 4 (dBm) Baud Rate: 9600 bps Receiver Sensitivity: -106 ~ -118 (dBm) Meet all FCC and Public Safety regulations
9
Hardware Components Microcontroller (C8051) Parallax RF Transceiver Parallax Education Board Keychain
Key Chain 433MHz Transceiver by All Spectrum Electronics
10
Block Diagram
Transmitter Station Receiver Station
11
Communication Protocol
Transmitter• Check for button
press
• Synchronization Start character
• Message
• End character
• Back to checking
12
Communication Protocol (cont)
Receiver• Wait for start
character
• Getting message
• Wait for stop character
• Send alarm
• Back to wait
13
Communication Protocol (cont)
Start signal: character “!” Message: can take up to as much as 25
ASCII characters Test message: string “IRE” End signal: character “@”
14
Results
Spectrum Analyzer Antenna noise Receiver Sensitivity:
-106 ~ -118 dBm
15
Results
Oscilloscope Message Data (no
transmission) Noise only
16
State Diagram (Receiver#2)
17
LR Receiver and LS Decoder
Linx Technologies®
18
Progress Report
A prototype is built Signal/noise measurements using
Spectrum Analyzer Improving protocol to be more flexible
and noise resistant Building filter circuit
19
Results
Oscilloscope Message Received !,I,R,E,@
20
Results
Xmtrwide With Noise
21
Disadvantages
Wireless signal strength problem False Alarms
• Solutions are: fine, lock, save ID on keychain
Device Failure Inaccurate position detection
22
Future Thoughts
Open Shortest Path First More accurate position detection (i.e.
GPS) Vibration (feedback to user) Individual ID for each transmitter
23
Acknowledgements
Advisor: Professor Hedrick Nelson Rosario
24
Questions?