25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun 1 Cellular Activity Detection &...

25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun

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Cellular Activity Detection & Identification

MidTerm Presentation Supervised By: Yossi Hipsh

Introduced By: George Ghantous , Husam Khshaiboun

Project : D0426 - Spring semester 2007


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Refreshment


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Problem Definition

We want to build a system that detects a cellular phone activity and finds the coordinates of its source in a predefined space.

Different cellular companies use different frequency ranges. they also use different codes (for each phone), communication protocols and modulation methods. Thus, the cell phones we want do detect differs not only because the companies differ. We want to detect each and every kind of phone.

Cellular radio pulses can be transmitted in a small time periods. We want our system to be able to detect these pulses (example: SMS messages).


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Our target space:A Classroom

Room area

4x8

3m

supervisor

Relevant area

6m

חזור


5

Block diagram

Antenna A

2 beams

Antenna B

2 beams

Direction 1

ראה כיתה

Direction 2


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Our target space:A Classroom

חזור

1m

1mWe check the whole idea and its partial implementation on a 1x1

square.

If we succeed in the far corner we will succeed in the whole

system implementation (with an adjustment of the number of beams and their direction)

Area with overlapping

beams


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What have we done???


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A beam in

direction θ1

A beam in

direction θ2

Energy Detector

The ongoing implementation:


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Energy detector

R

C

Out (DC)

In (Wave)


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Our needs:

High frequency diode with fast switching Fast charge a small capacitor medium speed discharge

Wont interfere with the charging. When reading the capacitors voltage the

discharge can be slow because we are not in a rush after the capacitor is charged


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Choosing the parts

RC in charge ~ 10n seconds When charging RC=50C=10n C=200pF

RC in discharge ~ m seconds R1=500kΩ RC=0.1msec

The Diode: Hp Schottky Barrier Diodes for general purpose

applications: FARNELL ©, 5082-2835: Low turn on voltage; 0.34V at 1mA. Pico second switching speed (switches perfectly in our

working frequencies- less than 1 GHZ at IF)


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5082-2835

Energy Detector - Final Circuit

C=200pFR1=500kΩR2=1kΩ

R1=500kΩ

C1=100pF C2=100pF

Diode 5082-2835

R2=1kΩ

In

Out


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The Antenna

A minimum of two beams is needed to find a direction. Two ways to do that: Mechanical shift of two antennas Mono pulse antenna

Theoretical material - about mono pulse, starting from electromagnetic radiation going threw antennas, electrical field Fourier transform using for beam pattern synthesis, reaching mono pulse antenna, and beam design networks - was studied.

A slight summary in the next slides Yet a mechanical shift will be implemented !


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How radiation radiates ?? Example: Dipole Antenna: Electrical (EM) field is induced so that it follows the direction of the AC current.

When the frequency gets high, the field cannot collapse and follow, thus a closed loops of field is created. In the next period another loop is created when pushing the first one and so on:

When the length of the dipole is λ/2 (λ/4 from each side) a resonance is achieved because at this length, a complete half wave of current and voltage distribution is accommodated. This ensures maximum power efficiency (resistive impedance). In theory, there is zero ohms (72 ohm in reality) impedance at the centre and infinite at the ends of the Dipole. E

I


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Fourier transform

The following shows how a window function field is transformed into a sinc or a beam pattern:

0

A a x ay x

else

jxY y x e dx

a

jx

a

e dx

ajx

a

e

j

ja jae e

j

sinc aa

00( ) sinc a jxy x x Y a e FFor a shifted

window (x0):


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Mono Pulse Antenna

Antennas radiate (receive) an electrically shifted beams using a beam design network.

A simple way to look at this is the following:

An example for a 10 dipole antenna that radiates 5 beams using electrical shift is given in the next slide

Σ,Δ adder

ΣΔ

Antenna 1 Antenna 2


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Mono pulse antenna:5 beams using 10 dipoles

1

2

3

4

5

Beamdesign

network

Adder 51

Adder 51 D

ipol

es A

nten

na

x10x10


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Amplifiers verification

Coaxial Amplifiers from Mini-Circuits ©: ZJL-4G 50Ω medium power, 20-4000Mhz band Can work as a RF and IF amplifier in our circuits. Measurements were made in the communications lab for the gain

response as a function of the working frequency

See next slide for results


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Amplifiers verification - results

All the amplifiers work perfectly.


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VCO duplication

A duplication of a VCO already created was done. One will be used as an generator for mixing purposes. The other will be used as a cellular phone emulator.

LOf


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What will we do??


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What will we do ?? Test the mixers Test the new VCO Test the energy detector Connect the elements Emulate a cell phone and check the system Build the antennas Test the system with a real cell phone in a

room


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Time Schedule

Action Item Due Date Status

Test the mixers 01/07/2007

Test the new VCO 01/07/2007

Connect the elements 07/07/2007

Emulate a cell phone and check the partial system (without the antennas)

12/07/2007

Build the antenna (s) 19/07/2007

Test the system with a real cell phone

26/07/2007

Final presentation and Report

2/08/2007


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Thanks For Listening

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25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun 1 Cellular Activity Detection &...

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