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Electrical Noise Location System

Electrical Noise Location System. Drew Compston Richard Denney Josh Gordon. Background of Project. Identify Angle of Arrival of AM RF Display Information about Incident RF in GUI Build Noise Sources to Test System Expect Total Cost to be $16,228. Noise Source. Computer:

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Electrical Noise Location System

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  1. Electrical Noise Location System Drew Compston Richard Denney Josh Gordon

  2. Background of Project • Identify Angle of Arrival of AM RF • Display Information about Incident RF in GUI • Build Noise Sources to Test System • Expect Total Cost to be $16,228 Noise Source Computer: Displays GUI and Calculates AoA Noise Receiver

  3. Q-Track Desires System for its QT-400 QT-400 is an RTLS using NFER Operates in AM Frequencies (Pictures from Q-Track User’s Guide Pamphlet, used with permission) Motivation

  4. Software Implementation • Connect Computer with QT-400 • Handle QT-400 Output • Design User-friendly GUI • Calculate Angle of Arrival (AoA)

  5. Connecting With Computer • Communicate through 802.11b Wireless Network • Set QT-400 Frequency Remotely • Listen for Broadcast UDP Packets

  6. Handling Information • Information in UDP Packets: • Magnitude of Received Voltage on Each Channel (RA, RB, RC) • Relative Phase Difference Between Channels A & B and Channels B & C • Save QT-400 Output Data in .dat File • Graph Using Open-source Software from the Code Project

  7. Graphical User Interface • Written in C# • Waterfall Plot • Calculate AoA • Set Parameters

  8. GUI Parameters • QT-400 Frequency • Graph Start, Stop, Step Frequencies • Sweep Time • Graph Refresh Rate

  9. Calculating Angle of Arrival QT-400 Has 3 Antennas: • 2 Electrically Small Orthogonal Magnetic Loop Antennas (Channels A & C) • 1 Electrically Small Electric Whip Antenna (Channel B)

  10. Electrically Small Loop Antennas Radiation Pattern of Electrically Small Loop: Complex Voltages on 2 Loops: Null Antenna Lobe Lobe Null

  11. Virtual Loop Antenna Combine 2 Loops’ Response in Weighted Sum to Create Virtual Loop Oriented in any Direction θ:

  12. Angle of Arrival Algorithm Assume Phase Difference between 2 Loops is either 0° or 180°. Result: Minimize Magnitudes to Obtain Possible AoAs of: Front-Back Ambiguity

  13. Resolving Front-Back Ambiguity • In General: Loop Antenna Has 180° Phase Flip Across Each Lobe • Result: Combining Loop Response with Whip Response Results in Cardiod Pattern • Not Possible with QT-400 Because of Arbitrary, Unknown Phase Offset in Measurements • Test to Determine which Phase Measurements Result in Correct AoA to Use

  14. Computer Simulations • 3 Antennas Modeled in NEC: • 2 Square Loop Antennas (side lengths = 0.01λ) • 1 Dipole (whip, length = 0.04λ) • Data Exported to MATLAB and Plotted

  15. Steps in Computing AoA • Find Principle Angle ψ’ (below) Based on Phase Comparison: • Add or Subtract 90° to ψ’ Based on Absolute Phases

  16. Design Testing • Create Sinusoids at 1MHz, 1.54MHz, and 1.84MHz with Signal Generator • Create Noise Signal with Broadband Random Noise Generator • Step Up Signal Strength with Power Amplifier • Broadcast Signals with Simple Antenna

  17. Broadband Noise Generator Different Capacitors for Different Frequencies From: J. Williams. A Broadband Random Noise Generator. [Online] http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1026,P1476,D4262

  18. Power Amplifier

  19. Cost

  20. Current Status • Unable to Connect to QT-400 • Software • Program Retrieving Data from QT-400 Completed but Untested • Plotting Software Obtained • AoA Algorithm Defined, not yet Implemented in Software • Noise Source Circuit Schematics Finalized, Parts yet to be Ordered

  21. Timeline/Future Work • 11/2 – Test Noise Source in Lab • 11/12 – Fully Functioning GUI and AoA Algorithm • 11/19 – Portable Noise Source Completed • 11/26 – Test Entire System with Noise Sources • 12/7 – Final Design Prototype Completed

  22. Pending Questions • Will Algorithm Work on Broadband Noise Source? • Can We Account for Multiple Noise Sources at the Same Frequency? • Any Others? THANKS FOR YOUR TIME

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