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.

24
Thank you for your attendance