EMR Detection and Mitigation on the LSV2

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    Team Name
Team Echo
    Duration
Spring 2017 - Fall 2017
    Sponsor
US Navy Acoustic Research Detachment
    Current Members
Kristen Wells

and Jared Mahoney

    Advisor
Dr. Herb Hess
    Special Thanks
James Klein, ARD

and Dr. Ata Zadehgol

    Former Member
Jacob Bechler


Our goal is to investigate, develop, and improve EMR detection and mitigation techniques in order to assist the advancement of US Navy stealth technology.


Problem Definition[edit]

Problem Statement

The US Navy Acoustic Research Detachment in Bayview, ID on the southern shores of Lake Pend Oreille, is experiencing electromagnetic interference(EMI) issues with their acoustic data collection. They have asked us to locate the sources of electromagnetic radiation(EMR) and to figure out how to mitigate these sources to reduce interference.

Design Goals and Deliverables

Establish primary sources of EMI

Measure radiation and plot electromagnetic spectrum

Analyze and determine best mitigation techniques

Create and test mitigation scheme in lab

Specifications

Measurements

Frequency: 25 kHz

Time: 3 minutes

Measurement Distance: 1 inch

Design Goal

Attenuate by 20dB at 11.6kHz


Project Learning[edit]

Summary

We researched electromagnetic wave interactions with materials, use of spectrum analyzer and antennas (loop and stub) to measure emissions, and industry and military standards for electromagnetic compatibility in order to provide the Navy ARD with a successful EMI mitigation solution. Details of our research include learning about various techniques for mitigation of both radiated and conducted emissions and the complexities that accompany these solutions. For more information, please refer to our Final Report, linked at the bottom of our Wiki.

Characterization of the Problem

The plots below show a clear correlation between the measured electromagnetic radiation and the acoustic measurements taken by the ARD on the LSV-2.

Inverter Mod Plot
Measured Acoustic Spectrum
Inverter Measurement
Measured Emissions from Inverter

Equipment

Photos of the inverter and electromagnetic spectrum analyzer provided to us by the US Navy ARD:

Inverter - Front
Inverter Front View
Antennas
Various Antennas
Inverter - Rear
Inverter Rear View
Spectrum Anazlyzer
R&S FSV3 Spectrum Analyzer

Test Setup

The Electrical Engineering department's power laboratory is capable of supplying the 320VDC - 440VDC required to power the inverter. Two induction motor / DC generator combination machines are connected in series to supply a total of 365VDC. Resistor banks, each section capable of safely drawing 2kW of power, are connected in parallel to draw 27A, applying a load of 79% of the full-load capability of the inverter. The inverter is connected through a panel in a separate room at the back of the laboratory. This isolates it from the generation environment, which provides a less electrically noisy environment in which to measure EMR.

Test Setup
A picture of the test setup used to energize the system


Design[edit]

Process Flowcharts

Phase 1 Flow Chart
Phase 1 Flow Chart
Phases 2 & 3 Flow Chart
Phases 2 & 3 Flow Chart
Phase 4 Flow Chart
Phase 4 Flow Chart


Selection of Materials

Determination of Expected Attenuation

We used an absorbtion nomogram to determine the expected attenuation for MuMETAL and Conetic cable shielding foil. The expected values determined from this can be see in the table below:


Frequency (Hz) MuMETAL (dB) Conetic (dB)
10 1.0 2.5
100 3.4 8.0
1000 10 25
11600 34 75
25000 50 150


Absorption Nomogram
Taylor, R. E. (Ed.). (1971). NASA SP-3067 Radio Frequency Interference Handbook.

Attenuation Results[edit]

Absorption Nomogram
Absorption Nomogram

We successfully attenuated the J6/J7 cable by nearly 50dB in some areas. For more details, please refer to our Final Report.

Team Information[edit]

Kristen.png
Kristen Wells
Electrical Engineering
Email: well5734@vandals.uidaho.edu
Specialties
Electromagnetics
Acoustics
Jared.png
Jared Mahoney
Electrical Engineering
Email: maho1488@vandals.uidaho.edu
Specialties
Electromagnetics
Remote Sensing
JacobLSV.png
Jacob Bechler
Computer Engineering
Former Member
Specialty
Programming


Document Archive[edit]

Minutes

File:Feb 07.pdf

File:Feb 16.pdf

File:Mar 21.pdf

File:Mar 28.pdf

File:Apr 25.pdf

File:Aug 24.pdf

File:Aug 31.pdf

File:Sep 14.pdf

File:Sep 21.pdf

File:Sep 28.pdf

File:10-12-17 mm.pdf

File:10-26-17 mm.pdf

File:11-16-17-mm.pdf