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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
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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Refreshment
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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).
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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Our target space:A Classroom
Room area
4x8
3m
supervisor
Relevant area
6m
חזור
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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Block diagram
Antenna A
2 beams
Antenna B
2 beams
Direction 1
ראה כיתה
Direction 2
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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What have we done???
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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A beam in
direction θ1
A beam in
direction θ2
Energy Detector
The ongoing implementation:
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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Energy detector
R
C
Out (DC)
In (Wave)
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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)
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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 !
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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):
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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Amplifiers verification - results
All the amplifiers work perfectly.
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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What will we do??
25/6/2007 High Speed Digital Lab George Ghantous, Husam Khshaiboun
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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