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Jammer Acquisition with GPS Exploration and Reconnaissance
Adrien Perkins James Spicer, Louis Dressel, Mark James, and Yu-Hsuan Chen
S C P N T P R E S E N TAT I O N
JÄGER
2
NextGen Airspace • Increasing use of GPS •! Need reliable signal during landing
•!Motivation
3
Newark Int’l Airport Example • personal privacy device jamming
• Need to locate and disable jammer quickly
• Motivation
4
Requirements and Simplifications • Requirements
! Quickly determine location of jamming device ! Navigate in a GPS denied environment ! Use only a single vehicle ! Pinpoint location
• Initial Simplifications ! Stationary jammer ! Single jammer ! Constant jamming
• Motivation
5
Jammer Detection • Independent of GPS •! Bearing to jammer
!! Signal strength + heading !! Directional antenna + magnetometer
•! Multicopter vs. Plane !! Take measurements at fixed points
•!Methodology
strainsecuritysystems.squarespace.com
6
Path Planning • Represent problems as Partially Observable Markov
Decision Process (POMDP) !! Grid-based, offline solution to a probabilistic model of sensor and
vehicle motion !! Based on real-time signal measurements and current belief of
sensor location, take action that localizes the jammer in the shortest amount of time
•! Onboard computer actively communicating with flight computer
•!Methodology
Computer Flight Computer
7
Positioning •!Methodology
Hardened GPS
Signals of Opportunity
wifi
Digital TV
3G / 4G Cell Network
•! Alternate Position Navigation and Time (APNT)
•! Automatic Dependent Surveillance – Broadcast (ADS-B)
•! Universal Access Transceiver (UAT)
•! 1090 •! Distance Measuring Equipment
(DME)
•• Alternate Position Navigation and Alternate Position Navigation and Alternate Position Navigation and Alternate Position Navigation and Alternate Position Navigation and Alternate Position Navigation and Aviation Signals
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Aviation Signals • Possible Signals
!! Automatic Dependent Surveillance – Broadcast (ADS-B) ›! Universal Access Transceiver (UAT) and 1090
!! Distance Measuring Equipment (DME) •! Initial testing with UAT signals •! Leverage known altitude from barometer
•!Methodology
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System Diagram
•! All communication through autopilot •! Each system is completely
independent and modular !! Each has own power source
•!System Design
Weight: 2 kg Power: 12 W
Weight: 0.5 kg Power: 8 W
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Vehicle Selection •! Target Performance
!! 20 minute flight !! 4 kg payload
•! DJI S1000 “Spreading Wings” Octocopter !! Frame Weight: 4.2 kg !! Max Takeoff Weight: 11.0 kg
•! Power !! Max of 4000 W !! 1.5 kg battery payload
•!System Design
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Path Planning • Two way communication with Autopilot •! Hunt Mode for autopilot
!! Waits for commands from outside source !! Reports completion of maneuvers
•! Ground station for testing
•!System Integration
Computer Flight Computer
12
Path Planning •!System Integration
vehicle autopilot Path planning
Ground station
Safety pilot
Not Human
Position
Path planning to human
Command Command execution
1 – Path planning to human
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Path Planning •!System Integration
vehicle autopilot Path planning
Ground station
Safety pilot
Not Human
Path planning to human 1
Human generated commands
Command Command execution
2 – Human generated commands
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Path Planning •!System Integration
vehicle autopilot Path planning
Ground station
Safety pilot
Not Human
Path planning to human 1
2
Position
Command Command execution
Full integration and automation 3 – Full integration and automation
15
APNT Electromagnetic Interference (EMI) • 2 sources of interference onboard
!! Telemetry antenna at 915 MHz !! Computer at 1.575 GHz
•!System Integration
GPS signal before shielding (16 dB peak)
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APNT Electromagnetic Interference (EMI) • System Integration
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APNT Electromagnetic Interference (EMI) •!System Integration
Before shielding (16 dB peak)
After shielding (-2 dB peak)
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Flight Testing • Split series of flights by hardware being flown
Series 1: •! Pixhawk
Series 2: •! Pixhawk + APNT
Series 3: •! Pixhawk + Path Planning
Series 4: •! Pixhawk + APNT
+ Path Planning
•!Testing
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Autopilot Only • Test vehicle performance
! Stability
Weight simulation
• Testing
Tethered Testing
20
UAT Ground Test • Static and dynamic tests
•!Testing
12 km
40 km
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APNT Ranging • Results
0 100 200 300 400 500 600 700 min = 39656
+59
+118
+177
+235 Pseudorange from San Jose
Pseu
dora
nge(
m)
0 100 200 300 400 500 600 700 min = 11262
+73
+146
+219
+292 Pseudorange from Woodside
Pseu
dora
nge(
m)
UAT GPS
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Ranging • Results
20 40 60 80 100 120 10 -3
10 -2
Histo of Pseudorange from San Jose, mean=76.2575m, std=11.6779m
80 100 120 140 160 180 200 10 -3
10 -2
Histo of Pseudorange from Woodside, mean=138.5428m, std=12.6833m
Pseudorange Error Gaussian Fit
Pseudorange Error Gaussian Fit
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Static • Results
GPS
UAT
-122.183 -122.1825 -122.182 -122.1815 -122.181 37.4308
37.431
37.4312
37.4314
37.4316
37.4318
37.432
37.4322
37.4324
37.4326
longtitude(degree)
latti
tude
(deg
ree)
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Accuracy • Results
25
Dynamic • Results
GPS
UAT
-122.183 -122.1825 -122.182 -122.1815 -122.181
37.431
37.4315
37.432
37.4325
longtitude(degree)
latti
tude
(deg
ree)
26
Flight Testing •! APNT
!! Constant altitude !! Loiter at each vertex (static) !! Dynamic flight
•! Jammer Acquisition !! Wifi router to mimic jammer
•!Testing
Wifi
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Future Work • Flight testing of APNT at Camp Roberts
• Continued path planning Integration
• Jammer acquisition testing
• Hardened GPS vs various signals of opportunity ! Explore the options
• Future
Questions?