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Detection of Cellular Activity Within A Defined Space

Undergraduate Project – Final PresentationSpring 2008

Doron Brot Eyal Cimet Supervisor: Yossi Hipsh

!

Department of Electrical Engineering High-Speed Digital Systems Laboratory

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The Main Objective

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• Detection and Positioning of Cellular Phone Activity In a Defined Space Where Cellular Use is Unwanted

4m

6m

8m

4m

0.5m

0.5m

6m

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Main System Requirements

• Detection and Positioning of Transmitting Cellular Phone• Desired Spatial Resolution & Accuracy:• Required Temporal Resolution:• Compatibility with all Cellular Providers• Detection Regardless of Phone Orientation – Reception of

all Linear Polarizations• Ability to Handle Simultaneous Events• Ability to Distinguish Between Original Signal and Multi-path

Reflection

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0.5 m

1 ms

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Solution Overview• Coverage of the Defined Space:

4m

6m

Area Split to Lower the Required Dynamic Range

Antennas

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System Operation Process

Sampling

Angle Measurement

Multi-path Filtering

Filtering of Dummy Origins

Origin Estimation

Idle / Trigger

Triangulation

Positioning

Storage

Start

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Angle Measurement• Multi-beam Arrays – MBA:

– Antennas Sensitive to Many Spatial Directions Simultaneously, Ideal for Angle Measurement

– DifferentialAngle Measurement

– Distance From Source Determines SignalStrength

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Antenna 1 Antenna 2

x

y

,x y

Table

1 cot tan

cot cot

Lx

Ly

Hz

• Origin of Signal is Estimated Based on Angle of Incidence with 2 MBA Antennas and Table Height:

L

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Multi-path

• Reflections Received Simultaneously Must Be Filtered Out

Antenna 1 Antenna 2 x

y

,x y

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Final Design

90-Degree Hybrid

Frequency Multiplexer

Band 112 dB Amp BPF DCA Detector A/D

Band 2

Band 3

Band 9

Horizontal MBA

Vertical MBA

Omni-directional Antenna

12 dB Amp BPF Detector A/D

Digital Controller

(CPU)

Display

6 Beams

4 Antennas

A/D

Trigger

Front-End

Customized Filter to All 9 Bands

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Proof of Feasibility - System Strip-Down

Original DesignSimplificationFull Cellular SpectrumOne Frequency

All Linear PolarizationsOne Polarization

Original HardwareMBA, Amplifiers and Hardware Included in Digitizing Scope

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Feasibility Experiment

Pos 1 Pos 2

1 [m]

1.8 [m]

2.3 [m]

H=1.7 [m]

H=2 [m]

H=2.6 [m]

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Version Using Power Detectors

12 dB Amp

Horizontal MBA Antenna 1

Beam 1

Beam 2

Horizontal MBA Antenna 2

Beam 1

Beam 2

12 dB Amp

12 dB Amp

12 dB Amp

Power Detector

Power Detector

Power Detector

Power Detector

CH 1

CH 2

CH 3

CH 4

Scope

Regular Low-Frequency Scope

The Minimal System for Proof of Feasibility(2)

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Our Measurements: Antenna Measurement System

Protractor

Transmitting antenna

CH 1

CH 2

CH 3

CH 4Scope:

Rotating table Antenna

Pulse Generator

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Antenna Measurements

Beam 1

Beam 2

Spatial Response of MBA [ dB ]

3 dB

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2 1

oTheory

Ant

o1 2

51 20.5

20

D

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Power Amplifier Measurement• The system : The 2 Outputs will be compared to measure gain

• Results:

Conclusion

• In this project, a full system that is capable of positioning a cellular activity in a defined space was designed.

• The system was simplified on order to perform feasibility checks

• The separate components were measured but the full feasibility check was not completed

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