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. f1 f2 f3 f4 f5 f6 f7 f8 antenna 0˚ 45˚ 90˚ 135˚ 180˚ 225˚ 270˚ 315˚ C1 C2 C3 C4 C5 C6 C7 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 can’t 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 2 5 10 4 5 10 5 10 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, f1=2 MHz to fmax=2.4 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

9. 1 2 3 4 5 6 7 8 Frequency Codes: 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. Strip Resistor Ground dielectric 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. S21 S11 Input Output S22 S12 Device 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. λ /4 2 Zo Xc = Zo Xl Xl 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. Output goes to load PW Input from source 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 can’t 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.

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