1. Accubeacon
Andrew Gans, Spencer Curran, Shreyank Amartya, Alex Fouss, John Bullock

2. Avalanche Hazards background
Winter backcountry recreation has become increasingly popular.
Thousands of skiers and sledders put themselves in dangerous avalanche zones each year
90% are caused by a victim or someone in their party.
Personal Account of Avalanche Video
Spencer

3. Avalanche Hazards
include data on life expectancy
Spencer

4. Spencer

5. Avalanche Rescue Methods
Probe line - A technique used with an abundance of searchers
K9 search team - Avalanche dogs are trained to sniff out buried victims
Proper Shoveling - There are several methods for fast and swift extractions
Air Bag - A backpack air bag that can be deployed when victim triggers an avalanche to prevent being buried.
Spencer

6. Spence

7. Other Innovations Use of sensors
1. Knowledge about the state of the victim; survival chances, urgency, vital signs.
2. Orientation of victim in snow
3. Depth of buried victim.
Multiple Buried victim markers

8. Accubeacon Avalanche Transceiver
System Overview
Accubeacon Avalanche Transceiver

9. Statement of Purpose
To design a set of avalanche transceivers that can communicate with each other to allow for more accurate pinpointing of buried victims and multiple burial detection
Spencer

10. Requirements-Primary
Level
Requirement
Dependencies
Primary P1
Triangulate relative location of buried
S1,S2,S3 P2
Display victim location in an easy to read format S4 P3
Supply enough power for extended use in the backcountry S5 P4
Meet all standard specifications and functionality of current transceivers
S7,S8 P5
Detect multiple burials S6
Spencer

11. Requirements-Secondary
Level
Requirement
Secondary S1
Calculate distance between user beacon and buried beacon using 457kHz wireless signal S2
Calculate distance between user beacon and other searching beacons using other wireless protocol S3
Receive distance data from other searching beacons S4
Place relative location of buried victim onto visual display S5
Provide a sufficiently sized battery pack to meet power requirements S6
Determine the event of multipal burials S7
Transmit at standard 457kHz frequency S8
Incorporate standard signal strength indicator search functionality
Spencer

12. Subsystems
kHz RF
Transmits/receives standard 457kHz frequency signal and processes associated RSSI signal
2. ZigBee Wireless
Transmits in the ISM band and uses RSSI or RTOF (round trip time of flight) to get triangulation information
4.User Interface/Data Processing
Provides clear and concise information about the location of burial
Alex

14. Processing and User Interface Subsystem
Accubeacon Avalanche Transceivers

15. Processing and User Interface
Collects data from 457khz and zigbee subsystems
Uses data to run required algorithms for multiple burial detection, localization and trilateration

16. Algorithms
Trilateration
Localization
Multiple Burial Detection

17. Localization
Uses distances between three or more searching beacons to determine relative x,y positions of other searchers
Requires accurate distance measurement between searching beacons
x,y positions of other searchers allows for triangulation using 457khz signal

18. Trilateration Process
-Localization determines relative position of other searchers
-Trilateration uses localized distance vectors from other searchers to compute buried location
-Buried location presented to searcher via user interface
Shreyank

19. Trilateration Diagram
Shreyank

20. System Setup
Alex

21. Multiple Burial Detection
Use 457khz signal strength from multiple antenna and multiple beacons to determine distance from buried victim(s)

25. User Interface and Hardware
Requirements
Processor that can run all required algorithms
User interface that displays results of algorithms

26. Development Board Atmel xmega 256-A3 microcontroller Power Conversion
Serial Connectors
4.5V Battery Jack
Test Pads
USB connector
Power and Serial LED's
PDI interface for AVR ISP mkii

27. Microcontroller - ATxmega 256A3U
Past experience with Atmel microcontrollers and AVR Studio
Can easily switch to a different series of Atmel microcontroller
Easily accessible drivers and libraries for different peripherals and modules
Can be easily programmed through PDI using Atmel mkii In System Programmer

28. User Interface
Push Buttons to power on, switch between search and transmit mode
LCD module to display the grid and relative positions of the searchers and victims

29. Zigbee Wireless Subsystem
Accubeacon Avalanche Transceivers

30. Tasks and Responsibilities
Sends data between searching beacons
Detects RTOF/RSSI from received signal to calculate distance

31. ZigBee Display/Processing
-Received Signal Packer from Other Searchers
-Distance correlation (RTOF/RSSi)
Transmitted Signal Packet to Other Searchers
ZigBee Modem
Distance Data to Microcontroller
Display/Processing
Processing and Display
-Triangulates burial location
-Displays to screen
-Distances between searchers
-Distance/Angle to buried victim
-Mode information
Alex

32. Module
Zigbee Wireless Transceiver Level 2
Input
48 bit packets using TOA (Time of Arrival) or RTT (Round Trip Time)
Output
Functionality
Provide adequate signal to determine distance from other searchers and transmit own 457 kHz signal to aid in trilateration. As well as receive the distance of other searchers in order to locate them compared to own reference location. Determine their 457 signal of the buried victim to aid in trilateration.

33. Wireless Distance Measurement
RSSI(Received Signal Strength Indicator)
-RSSI is the measurement of power present in the received radio signal. RSSI is directly proportional the distance as follows
RSSI log (P/Pref)
Shreyank

34. Wireless Distance Measurement
Time of Arrival
- Using synchronized clocks and time stamps to record signal travel time
-Travel time can be correlated with distance
-More accurate than RSSI but requires precise timing
Shreyank

35. Wireless Packet
-Currently we are using XBee libraries to transmit packet arrays amongst other searcher.
-The packet contains the following data
1. Sender's XBee ID
2. 1st RF distance
3. 2nd Searchers RF distance
4. 3rd Searchers RF distance
5. Distance from 3 to 1
6. Distance from 3 to 2
7. Distance from 2 to 1
-Each individual XBee processes this data and extract all relevant data for their own array.

36. The backbone of avalanche transceivers
457 kHz RF Subsystem
The backbone of avalanche transceivers

37. Other marketed beacons only have this system.
The 457 kHz subsystem is the bare minimum needed for a working avalanche beacon
Other marketed beacons only have this system.
Some beacons use digital signal processing and 3 axis antennas to eliminate false readings
No current beacon uses communication with other searchers to correlate information and further eliminate error

38. 457 kHz Transmitter 457 kHz Receiver
Transmit on
(Oscillators / Filtering)
USER INPUT
(device power on)
Ferrite Rod Antenna (2x, orthogonal) Outputs Radiation Pattern
457 kHz Receiver
Ferrite Rod Antenna (2x, orthogonal) Determines Orientation
Analog Front End
(Filtering, Multiplexing, A/D)
Directional Information to Microcontroller
USER INPUT
(device switched to search mode)
Alex

39. 457 kHz Transmitter (Level 3)
Pulsed 457 kHz
457 kHz
Crystal
Oscillator RF
Filters
MUX RF
PWR
AMP
Demux
Buffer
AMP
Gnd
Antenna selection
Frequency
Divider
Frequency Divider
Counter
pulse
RF Choke
Power
Module
457 kHz Transmitter Level 3
Input
Power
Output
457 kHz pulsed RF power on either of two antennas
Functionality
Provide adequate radiation to allow for detection when buried ~50m away

40. Creates a DC voltage relative to received RF signal strength
457 kHz Receiver (Level 3)
Antenna selection
(sync with Tx)
Creates a DC voltage relative to received RF signal strength
457 kHz tunning
Pulsed 457 kHz
Mux
Band pass filter
Rectifier
Signal
Conditioning RF
AMP
Out to CPU
buffer
457 kHz tunning
RF Choke
Power
Module
457 kHz Receiver Level 3
Input
RF Radiation (tuned to 457 kHz), power
Output
Analog signal to be processed by microcontroller
Functionality
Provide a meaningful analog voltage that represents signal strength for each antenna orientation

41. Trilateration (Triangulation)
Using cross-searcher data communication reduces guesswork and ambiguity with ultimate goal of eliminating a coarse search
Trilateration (Triangulation)
Quick and precise pinpointing of multiple buried victims (even with unintended signal modulation - overlap)

42. Tasks
Transmit RF signal within margin of error up to current standards (457 kHz ± 80 Hz)
Differentiate signals of multiple buried victims
Relay analog information to microcontroller when in search mode

43. Features Backwards Compatibility
Receive RF signals within a large margin of error (457 kHz ± 200 Hz)
Covers range of frequencies for 1970's era beacons
If all else fails (one searcher, no xbee communication, etc) the transceiver will function as a regular ("digital”) beacon

44. Prototyping & Testing Multiple searcher tests done
Differences in signal waveform (BCA Tracker DTS) give signature characteristics based on buried beacon’s orientation
Use the differences in signal to communicate between beacons and determine instantaneous location of buried victim
This method can be extrapolated for multiple burials

45. Prototyping & Testing Digital signal processing
Differentiate between signal overlap and no signal overlap
Smooth out signal modulation when overlapping

46. Prototyping More information is needed to reduce degrees of freedom
Searcher inputs number of burials
Digital compass used to find magnetic north

48. Receiving Antennas Arrangement
Transmitting Antenna
(Buried Person)
Receiving Antennas Arrangement
(BCA Tracker DTS)

50. Two Transmitters Same Relative Distances

52. 1 Transmitter Closer to CH. 2

54. 90 Degree Triangle

58. In H-Plane Closer to CH. 2

62. In H-Plane Tx, RxCH.1,RxCH.2 Orientation

64. Same Configuration with RxCH.2 Rotated 90 Degrees

66. Both CH. 1 and CH. 2 90 Degree Offset

67. Development Plan (Multiple Burials)
Input data into microcontroller
Analog voltages converted to sampled digital signal
Signal processed using differential algorithms
Vectors assigned to signals and output to high-res matrix display

68. Design Approach Milestones 1. Proof of Theory
2. Rev A. - Proof Of Concept
3. Rev. B
4. Final Rev.
Wheeler

69. Design So Far
Completed required background research to show that the concept is feasible - Used existing beacon as test platform
Incorporated Zigbee wireless:
-data transmission
-distance measurement
Algorith Implementation on arduino
Wheeler

70. Current Setup Arduino Uno Xbee BCA Tracker Beacon
Point to Point network
RSSI -Distance Measurement
BCA Tracker Beacon
RSSI pulled from 7-Segment Display
Allows for easy implementation of algorithms

72. Revision B -First PCB Revision
-Atmel Microcontroller on “development board”
-Multiple Burial Algorithm Implemented
-Lower Level Input from Existing Beacon
-RTOF implementation
Wheeler

73. Revision C - Final Rev. -Integration of our own 457kHz Transceiver
-Finalized Zigbee System
-Finalized Multiple Burial Determination System
-Finalized Processing/Display
Wheeler

74. Team/Project Management
Wireless Communication
RF Communication
Multiple Burial Determination
User Interface/Data Processing
Spencer X
Wheeler
John
Alex
Shreyank
John

75. Scheduling Tasks
Along with our bi-weekly scheduled lab time, we have weekly "scrums" to discuss progress and updates on Monday nights.
We do our best to set up 2 week sprints, in which we set goals and task to accomplish in order to stay on track with our milestone goals.
John

76. Budget Applied for UROP and using Personal Funds. Estimated Costs
Research
$102
Rev A
$133
Rev B
$294
Rev C
Total
$823
Applied for UROP and using Personal Funds.
John

77. Risks and Contingencies
RSSI accuracy has not been proven, RTOF should prove to be more accurate, but we have been unsuccessful implementing
2. RF 457 kHz implementation
3. Expandability to function with N searching beacons
4. Multiple Burial Determination
John

78. Conclusion -Current beacon technology is decades old
-Accuracy is going to be our biggest concern and goal
-Through 2-way communication we project to minimize search time to save lives and hopefully carve out a spot in the market not yet realized
John

79. Questions & Comments