Directional SDR-based Local Positioning System Development Team - PowerPoint PPT Presentation

Directional SDR-based Local Positioning System

Development Team Crystal Eskander - Project Lead, System Design, Data Collection Jerry Liu - Hardware Development, Triangulation Algorithm Lillian Liu - Software Development, Triangulation Algorithm Lekha Adari - System Design, Data Collection

What is Bermuda? ● Goal: To provide an alternative location tracking system to GPS, potentially to plan against GPS loss (such as jamming or in locations with poor GPS signal). ● GPS uses satellites; Bermuda is a proof of concept that a device’s coordinates can be located using radio emitters and directional antennas.

Applications ● Defense ● Space Exploration ● Precision Landing ● Warehouse Navigation ● Surgery

System Architecture ● KerberosSDR ● Raspberry Pi 3B+ ● WitMotion IMU ● Adafruit Radio Emitters

System Architecture

KerberosSDR

Uniform Linear Array (ULA) Lysignal Antenna Freq Range ● 700 MHz - 2700 MHz Interelement Spacing ● 0.1095 meters Direction of Arrival Estimation ● Time Difference Of Arrival (TDOA)

Beamforming

WitMotion IMU (Inertial Measurement Unit) ● Orientation/Bearing Calculations ● Acceleration ● UART

Raspberry Pi 3B+ ● Ubuntu OS ● Interfaces with KerberosSDR via USB ● Interfaces with IMU via UART

Adafruit Feather M0 RFM69 Packet Radio, 900 MHz ● Software Programmable: ○ Frequency, Power, Modulation, Bandwidth, & Data Rate ● Three Emitters at Differing Frequencies: ○ 912.44 MHz ○ 912.50 MHz ○ 912.575 MHz

Direction Finding Emitter Emitter Emitter 1 2 3

Antenna Quadrants

Frequency Filtering High Frequency Center Frequency Low Frequency 912.575 MHz 912.50 MHz 912.44 MHz

Triangulation Algorithm

IMU Location Tracking Not Very Accurate Due To: ● Wind ● Drift (error accumulation)

Bermuda’s Triangulation Requires: ● Radio Emitters ● Radio Emitters’ locations and frequencies ● Bermuda’s starting location

Bermuda’s Triangulation 1. Plot the three known emitter locations.

Bermuda’s Triangulation 2. Get the angle the emitter is coming from.

Bermuda’s Triangulation 3. Bermuda can’t distinguish front from back...

Bermuda’s Triangulation 3. ...so use the IMU to estimate Bermuda’s location and bearing.

Bermuda’s Triangulation 3. ...so use the IMU to estimate Bermuda’s location and bearing.

Bermuda’s Triangulation 4. Incident Angle = slope . Emitter = point . Combine into a line.

Bermuda’s Triangulation 5. Repeat for the other emitters.

Bermuda’s Triangulation 6. The estimated location is the averaged intersection.

Triangulation Accuracy The accuracy of the estimate depends on a lot… ● Signal Multipath ● Angle Estimation ● Emitter Closeness

Triangulation Filtering Possible Data Filtering Methods: ● Outlier Filtering ● Moving Average ● Weighted Moving Average ● Kalman Filtering

Demo Video

THANK YOU!! ● Phil Tokumaru, AeroVironment Project Advisor ● AeroVironment Inc, Project Sponsor ● Yogananda Isukapalli, Capstone Instructor ● Kyle Douglas, TA ● Aditya Wadaskar, TA

Questions?