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Detection2002

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Detection2002 Firas Faham AD Tag contents AD Tag Overview AD Tag examples - single and multiple tag code access Algorithms Smart Material Introduction to Microwave ... – PowerPoint PPT presentation

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Title: Detection2002

1
Detection2002

Firas Faham

2
AD Tag contents

AD Tag Overview
AD Tag examples - single and multiple tag code
access
Algorithms
Smart Material
Introduction to Microwave
Microstrip
Coplanar Microstrip
Smith Chart
Impedance Transformation
Detection
System issues and considerations
Conclusion

3
AD Tags

Addressable tags (Non deactivate-able no high
voltage)
Reusable
Low cost
Ease of mass production
Management, tracking, and detection algorithms

4
AD Tag overview

AD Tag is used to manage and track assets.
Two components Micro controller reader and
passive tag.
The micro controller reader transmits microwave.
Tag causes backscattering of microwave. Micro
controller then detect scattering (signal level
fluctuation.)
Microwave Strip fabrication process along with
Smart Material are used for frequency selective
backscattering.
Frequency selective scattering gives each tag
unique frequency code signature.
It is the dedicated AD Tag software algorithm
that establishes the identity of each tag through
the frequency code signature.

5
AD Tag overview - continue

Access method depends on application, Speed,
accuracy, and cost.
Single tag Simple and faster processing.
Multiple tag Problem with AD Tag is code
collision. Conventional multiple access methods
include FDMA, TDMA, CDMA, Frequency Reuse,
Carrier Sense, contention access method, and the
hybrid.
Challenge Accuracy in multiple access. Difficult
and time consuming to turn ON one tag at a time
and turn rest OFF.
Algorithm Solves the collision problem through
Time State and Zone State Analysis linked to
asset management data base and reduces processing
time. Code Recovery algorithm is used to
establish and verify tag identity.

6
AD Tag Example 1Single tag detection

Caps shift the phase (delay)
Addressing degree of freedom Number of Micro
Strips (ex. Filters), BW of each Strip, Delay
between each strip scan, and operating frequency
of each Strip. MS Frequencies cant be same.
Each Strip takes full range of frequency sweep at
a time.
Codes in red are incremented or decremented
only. Similar red codes in two strips of same tag
may confuse the Reader.

code correlation

1
10
10
10
5
5
5
2
4
7
...
f
f1
f2
f3 .
Software Algorithm (code is 247 )
7
AD Tag Example 1 - continuesoftware algorithm

Set max number of strips N DOF degree of
freedom
Set lower and upper sweeping frequency fN BW,
f12 MHz to fmax2.4 MHz
Set delta frequency BW/N
Set delay time Dt DOF
Set strip counter cs 1 to N
Set frequency counter cf 1 to N
Hop frequency to centers of strip frequency
response f(cf)
Monitor fN output
If output detected go to next strip counter cs
step
Delay for a period of Dt
Next frequency counter cf step
Next strip counter cs step

8
(No Transcript)
9
AD Tag Example 2Multiple tag detection
Tags are uniquely coded by a microwave signature.
Degree of freedom parameters to generate codes
are number of strips and bandwidth.
8 scans at once
10
AD Tag Example 2

Total number of tags the manufacturer produces
could be in billions.
Tags have Time State property. Time can be 1
second, 1 minute, 1 hour, week, month, or a year.
Tags have Zone State property. When tags change
Zone a new Time State is created.
A Zone Life Time is the time span the tag reside
in that specific Zone. A Zone Code Reuse is
analogous to Frequency Reuse. Different Zones may
use same tag codes simultaneously under the
control of the dedicated software package. Global
dedicated AD Tag software package manages and
tracks tags globally at different times and
zones.
When tags are scanned by the cashier they are
electronically registered in the Exit System
Verification Registers so they can be used by the
Verification Algorithm.
The Verification Algorithm uses only the
registered codes and ignores the rest of the
global codes for rapid verification process. Tags
that are detected but not verified will trigger
an alarm.

11
AD Tag Example 2 - continuesoftware algorithm

Connect to data base of present time and zone
state for Registered Codes in the Verification
Registers.
Initialize systems variables Number of strips N,
BW, start frequency of scanning each strip, and
frequency steps within each tuned strip.
Perform scan (simultaneous hopping) on all strip.
Collect all monitored outputs.
Divide the monitored outputs into N (number of
strips) groups. Each group has start and end
frequency.
Pull out one tag data from the Verification
Registers at a time.
Match the first (2nd, 3rd,) data of the picked
tag from Verification Register with the collected
data of the first group (2nd, 3rd,)
Repeat until all collected codes match with data
in Verification Registers.
Initialize peripherals upon recovery of recently
collected codes.
If no match found for one (or more codes) start
all over for re-verification.
If (X times) resulted in no match sound the
alarm.
End.

12
AD Tag Example 2 Algorithm
13
Smart MaterialSensors

Principle Material provides a feed back
resulting from certain input. Smart material have
self adaptive capability (like human
intelligence.) Environmental inputs (changes)
include properties of elastics, thermal, optical,
magnetic, electric, and/or chemical.
Examples Active Surface Material enclosed by a
Radar-Absorbing Material. Will control flow of
energy.
Electro Magnetic Applications Include magnetic
and high frequency shielding, RaDAR absorbing
shields, Active surfaces, Adaptive scattering/
Radiation control.
Acoustical Applications Include Active
absorption/ Reflection of SoNAR radiation and
adaptive anechoic chambers.

14
Brief intro to Microwave

Security and Microwave
Hybrid Systems
Microwave
Analog
Digital
Algorithms
Smith Chart use
Lumped and distributed elements
Applications of Microwave
Micro Strip Lines
Passive or Active
Examples

15
Micro Strip

Advantages
Miniature in size
Easy to realize discrete elements
Disadvantages
Takes two sides
Requires ground plan opposite to substrate

16
Micro Strip LineDiscrete lumped elements
realization

Resistor or attenuator
Capacitor
Inductor

Copper foil or electrolysis deposit
17
Micro Strip Examples

Filters
Resonator
Delay Line

LPF
BPF
18
Coplanar Micro Strip

Advantages
Single side
Easier grounding
Lower dispersion and higher mm waves frequency
use
Less neighboring lines coupling
Easy diagnostic
Disadvantages
Reference ground compatibility
Higher losses

19
Smith Chart

Concept Graphical representation of complex
(real and imaginary) circuit parameters such as
impedance and scattering parameters Sij.
Use Rapid design and analysis of circuit
performance. Useful for design of microwave
filters, matching networks, stability analysis,
frequency response, and transmission lines.

20
Impedance transformation

Source to Load
Impedance changes with frequency. To compensate
for the change an LC network may be used. Looking
toward the load imply CCW movement.
Quarter wave

21
Detection

Continuous Wave Short term for power up.
Pulsed Wave Square pulses modulating a carrier.

22
DetectionIssues and considerations

Due to scattering the range is controlled by
power transmitted, antenna type, receiver
sensitivity, tag size, frequency, and amount of
energy reflected by tag.
Tags may be moving relative to each others a
challenge in detection of multiple passive coded
tags.
Reader must be able to listen to small signal
strength changes. It is important therefore to
allow a relatively longer periods of silence to
allow return of reflections and intelligence
recovery. In multiple Coded tags Access the
reader must be able to differentiate between
different reflections of various frequencies.
Resolution refers to the readers accuracy in
differentiating between multiple reflections from
multiple tags.
In Pulsed Wave operation it is vital to keep
pulse width small enough to establish balanced
resolution and long enough for noise separation
(design dilemma.)
Pulse Compression Systems allow high resolution
Multiple Coded Tags Access moving at high speed
from a distance by linearly increasing the
transmitted signal frequency along the period of
the pulse. Linear FM modulation with center
frequency at the intended operating frequency is
used to perform this task. Reflections of higher
frequencies will be received faster than the
lower frequencies therefore producing a
compressed pulse width at the receiver relative
to the transmitted pulse. Micro Strip filters may
introduce delays comparable to scan time and must
be carefully designed. Received pulse signal
(compressed) will have same intelligence as
transmitted signal and can be conditioned and
filtered for decision making. Compression Ratio
is BW x Pulse Period and is function of tag size,
operating frequencies, and tag speed (for high
speeds only.)

23
Conclusion

The use of Micro Strip and Smart Material
combined with the high speed processing
controllers and sophisticated software algorithms
provide powerful coding and detection of the AD
Tags.
Microwave AD Tags should be carefully designed as
a system composed of hardware, management and
detection software, and addressable tags. Tags
cant be deactivated. Solutions to design issues
must be mastered.
There is no best technology but there are
advantages and disadvantages.
Among the factors that determine the type of
technology to use are single or multi detection,
speed, compatibility, durability, reliability,
and cost.