Electrical Noise Location System

Drew Compston

Richard Denney

Josh Gordon

223 October 2007

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

NoiseSource

Noise

Receiver

Computer:Displays GUI andCalculates AoA

323 October 2007

Motivation 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)

423 October 2007

Software Implementation

Connect Computer with QT-400 Handle QT-400 Output Design User-friendly GUI Calculate Angle of Arrival (AoA)

523 October 2007

Connecting With Computer

Communicate through 802.11b Wireless Network

Set QT-400 Frequency Remotely Listen for Broadcast UDP Packets

623 October 2007

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

723 October 2007

Graphical User Interface

Written in C# Waterfall Plot Calculate AoA Set Parameters

823 October 2007

GUI Parameters

QT-400 Frequency

Graph Start, Stop, Step Frequencies

Sweep Time Graph Refresh

Rate

923 October 2007

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)

1023 October 2007

Electrically Small Loop Antennas

1801

111

~ jeAA 2

22

~ jeAA

Complex Voltages on 2 Loops: Null

NullLobe Lobe

Radiation Pattern of Electrically Small Loop:

01 Antenna

1123 October 2007

Virtual Loop Antenna

sincos)(~

2121

jj eAeAA

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

sincoscoscos

sinsincossinarctan

~

2211

2211

AA

AAA

2sin)cos(sincos~

212122

222

1 AAAAAA

1223 October 2007

Angle of Arrival AlgorithmAssume Phase Difference between 2 Loops is either 0° or 180°. Result:

180,)sincos(

0,)sincos()(

~

2121

2121

2

1

j

j

eAA

eAAA

Minimize Magnitudes to Obtain Possible AoAs of:

180,2

arctan

0,2

arctan

212

1

212

1

A

A

A

A

Front-Back Ambiguity

1323 October 2007

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

1423 October 2007

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

1523 October 2007

1623 October 2007

1723 October 2007

Steps in Computing AoA

1. Find Principle Angle ψ’ (below) Based on Phase Comparison:

2. Add or Subtract 90° to ψ’ Based on Absolute Phases

180,arctan

0,arctan

BCABA

C

BCABA

C

R

R

R

R

1823 October 2007

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

Signal/Noise

Generator

Power Amplifier

Broadcast Antenna

1923 October 2007

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

2023 October 2007

Power Amplifier

1

3X1IRF510

RFC50u

2

C10.1u

RL250

R21k

R3200

5

C20.1u

4

SigGen

Rs50

12

VccVcc

2123 October 2007

CostLecture Attendance

Weekly Meetings

Writing Reports

Development Total

3 hours/week 2 hours/week 3 hours/week 6 hours/week 14 hours/week

  x$24/hour $336/week

  x16 weeks $5,376

  x3 engineers $16,128

  Subtotal $16,128

  Parts $100

  Total $16,228

2223 October 2007

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

2323 October 2007

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

2423 October 2007

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