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Detection of Cellular Activity Within A Defined Space

Undergraduate Project – Final PresentationSpring 2008

Doron Brot Eyal Cimet Supervisor: Yossi Hipsh

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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

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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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The Defined Space

4m

6m

8m

4m

0.5m

0.5m

6m

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General Design Aspects

System RequirementImplied Design AspectCapacity for Real-Time Detection and Positioning

Performance-based Design, Focus on Algorithm Speed

Compatibility With All Cellular Providers

Wide-band Architecture, Modular Channel Design

Cellular Detection Without Breech of Content

Detection Based on Power

Detection of Short or Long Events (SMS vs. Voice)

Need for Direct Memory Access (DMA) and Storage

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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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Preliminary Schematic

Front-End Overall Band

Receiver

Power Sensor

A/D Positioning Algorithm

Power SensorCircular-Polarized

Omni-Antenna

Display

CPUSampling

Circuit

CLK

Memory

Circular-Polarized Antenna(s)

A/D

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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

1 2

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Angle Measurement (Continued)

1 2

Differential Zone

EstMax 10dBP

MaxP

The Differential Measurements from two Consecutive Beams Yields an Estimate of the Angle of Incidence

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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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Possible Solution to Multi-path (1)

Antenna 1 Antenna 2 x

y

,x y

• Use of RF Absorbing Material

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Possible Solution to Multi-path (2)

• Development of Filtering Algorithm for Multi-path Reflections

Antenna 1 Antenna 2 x

y

,x y

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Solution Overview• Coverage of the Defined Space:

4m

6m

Area Split to Lower the Required Dynamic Range

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Solution Overview

• Antenna Setup –– 4 MBA’s, each with 6 directional beams– Each MBA is Comprised of 9 Narrow-Band Antennas

4m

6m

Beamo

Tot

o

oTotBeam

Ant

2arctan

2arctan 134

26.85

51

DH

L D

H

D

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Solution Overview• Cellular Spectrum

– Detection of all Cellular Providers Demands Reception of all Cellular Frequencies in Spectrum

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Solution Overview• Front-End Received Power

Trans Antenna Antenna2

min max minTrans Trans Antenna2max

40.1 W ;

8.56 W 20 dBm ; 9 10 dBm4r r r

P G A

P G AP P P

R

2Antenna Antenna Antenna 0.039 m2 2

cA D Df

4m

6m

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Solution Overview• Detection Regardless of Orientation of Cellular

Phone:– Circular-polarized Antennas Receive all

Linear Polarizations

• Layout of Circular-polarized Antenna– Two Linearly-polarized Antennas Coupled by a 90-

Degree Hybrid:

Coupler

o90 Circularly-Polarized Signal

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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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Component Survey

• IPP-2036 90-Degree Coupler– Frequency Range: 800-2000 MHz– Maximum Input: 150 W– Insertion Loss: < 0.25 dB

• Preferred Amplifier: ZJL-4G– Frequency Range: 20-4000 MHz– Typical Gain: 12.4 dB– IP3: 30.5 dB– Noise Figure: 5.5 dB– Maximum Input: 20 dBm

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Component Survey

• Power Detector – ZX47-40+ – Dynamic Range: -40 to 15 dBm– Response Time:– Output Range: 0.5 – 2.1 VDC

• Criteria in Choosing a Detector:– Dynamic Range Fits the System Requirements– Response Time Sufficiently Small compared to

Typical Event Period

0.4 s

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Component Survey

• Sampling Hardware:– Sampler + A/D: Analog Devices AD-7999

Resolution: 8 BitSampling Rate: 140 KSpSNo. of Channels: 4Reference: Peak to Peak

• DCA: Digitally Controlled AttenuatorNormalizes the Input Power to the Dynamic Range of the Power Detector Based on the Measurement from the Omni-directional Antenna

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Proof of Feasibility

• A Simplified Experiment Demonstrating the Basic Principles of the System, Which Proves that the Suggested Implementation Works

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Original Schematic

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

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System Strip-Down

• Number of Antennas –

4m

6m

Successful Detection in One Half of the Room Proves Feasibility

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System Strip-Down

• Number of Beams –

4m

6m

6 Original Beam Directions Simplified Down to 2

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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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The Minimal System for Proof of Feasibility(1)

Version Using HF Digitizing Scope

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

CH 1

CH 2

CH 3

CH 4

Scope/CPU:

Agilent Infiniium DSO80204B

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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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Antenna Measurement SystemProtractor

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

12

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Antenna Measurements

Beam 1

Beam 2

Spatial Response of MBA [ dB ]

oTheory

Ant

o1 2

51 20.5

20

D

2 1

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Power Amplifier Measurement System

• The 2 Outputs will be compared to measure gain

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Amplifier MeasurementsAmplifier Gain vs. Frequency [ dB ]

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A Special Thanks to:• Yossi Hifsch Supervisor and Mentor

• Eli Shoshan For all the Support

• Bruriya Zochar For all the Help and Supplies

• The Entire HS DSL Staff

Questions ?