rfid technology

Radio frequency identification

about rfid technology

Identification, Classification and Registration

These processes play an important role in every aspect of economic activity, from commerce and transportation to manufacturing. The Trovan® electronic identification system provides: • reliable operation in harsh environment (wet, dusty, dirty conditions; in high impact areas where vibration and shocks are considerations) • speed • contact-free identification of objects • freedom from line-on-sight constraints The system is also cost effective and can therefore be utilized beneficially in many areas to optimize labor efficiency. A broad product palette has been designed to meet the demands of a wide range of applications.

Principe of Operation

The system consists of two main components: The transponder (code carrier) is attached to the object to be identified. The transponder contains no batteries and is hermetically sealed in a housing designed to tolerate harsh environment conditions. It is completely maintenance free and in principle has an unlimited life span. The permanently programmed code is unique, counterfeit-proof and cannot be modified or deleted. Transponders are available in many forms and configurations to suit different applications. The reader energizes the transponder by means of an electromagnetic field, which is emitted by the antenna. It then receives the code signal returned by the transponder and processes it. Compact, portable readers, which incorporate a battery pack, a two line LCD and memory, and stationary readers, with all the components (i.e. antenna) necessary for expanded layouts, are available. Contact-free communication between the transponder and the reader occurs inductively by means of a polarized low frequency magnetic field. Reliable, interference-free rapid code transmission is assured through phase modulation and an integrated process for error checking and correction. (PSK-Phase Shift Keying 180 degrees each for logic one and logic zero)

Advantages of the Trovan® Passive Transponder Technology

Non-contact, counterfeit-proof identification, free of duplicates, no line-of-sight requirement. The principle of the electromagnetic transmission in conjunction with special data transfer technology makes possible fast and accurate reading each unique code. The reading rate of the hand-reader device, for instance, is 24 ms. Depending on the reader and transponder type the system can operate at distances of up to 1 m, penetrating non metallic solids and liquids. Even non-ferrous metals, up to a certain thickness do not pose an insurmountable hindrance to the transmission. A unique aspect of the Trovan® system is that even transponders mounted on steel parts or countersunk metal with only one surface exposed, can still be read.

Code security and Uniqueness

The transponder has 39 bit of memory which are reserved for the code. That translates into a total of: 239 = more than 500 billion unique codes. If one were to assign all these codes to transponders with the smallest dimensions known today, specifically a diameter of 2.15 mm and length of 11.5mm, and then line these transponders up end-to-end, the resulting string would measure 6,5 million kilometers in length, which is about 160 times the circumference of the earth.

The secure Programming

The programming of the microchips is done centrally. During manufacturing of the microchips, respectively during the programming, a complex LASER BURNING PROCEDURE is used, so that a later falsification of the code, of on purpose or by error, is completely excluded. The 10 digit hex code is stored in a diode matrix on the microchip. For the reason of data security and to exclude an alteration to the code, the corresponding diode connections are not disturbed electrically but are burned out by laser. Through this way of programming the code, it is not possible to alter or disturb the code by electrical influences. The only way to destroy the Trovan® transponder is by mechanical force from the outside on to the microchip. Furthermore, through this programming system the security is given, that every code is only produced once, world-wide. Complex automatic test methods ensure that no code exists in duplicate in any of the transponder types and that the codes are programmed correctly in readable manner

Small but efficient: Micro-electronics

Broad applications of the system in a maximum range of uses, such as implantation in live animals, requires miniaturized code carriers (transponders). Thanks to micro-electronics, all necessary functional electronic groups, except the antenna, are accommodated on a small silicone chip measuring approximately only 1 x 1 mm

Micro mechanics: The transponder Antenna

For optimum effect, the antenna must be in resonance at the transmission frequency. Long-wave transmission frequencies require high inductivity, i.e. thousand of coil windings, which can only be achieved by using the very finest wires. Wires the thickness of a hair would still be too thick. A diameter of 1/17000 of a millimeter- one fifth the thickness of a human hair- will just do the job. To give a better understanding of the small dimension involved: one could thread 2.800 of these wires simultaneously through the eye of a needle. Exact winding of the antenna coil using such fine wires and subsequently establishing the contact between the wire ends and the chip are extremely difficult procedures, particularly in view of the fact that cost-effective mass production is essential. Customer-designed machines have developed specifically to accomplish this task.

Transponders for Every Purpose: Robust and Hermetically Sealed

Harsh environments in industrial, commercial, agricultural and transportation applications make sturdy encapsulation of the electronic assembly a must. The functioning of the assembly, however, must be assured. To this end, the smallest transponders specifically those intended for animal identification, are sealed in a biocompatible glass capsule which is not vulnerable to body fluids. The transponder can be pre-packed in sterile injection needles. The electronic assemblies of industrial transponders are encapsulated in a robust, quartz-filled epoxy resin. This provides, in addition to the previously mentioned protection against dust, dirt, moisture and various chemicals, effective protection from shock and vibration and assures the functionality of the transponder in a broad temperature range: from minus 40°C to plus 180°C.

Transponder Activation: Operation in Full Duplex Mode

The reader supplies the transponder with energy, activating the transmission of the unique identification code. The process of energizing the transponder and the transponder’s subsequent transmission of the code takes place in the full duplex mode, meaning that transmission and reception occurs simultaneously. This makes a very short read time. When the reader ceases transmission, the transponder immediately returns to the inactive mode. By selecting from the complete reader systems an almost inexhaustible range of applications can be addressed.

Reader Operation Principle

The transmission process makes very complex technical demands on readers and transponders. In order to achieve the greatest possible reading distance, the transmitter has to supply the transponder antenna with sufficient energy. Likewise, the requirements for the receiver are high sensitivity, selectivity and resistance to electromagnetic interference (EMI). The comparison and timing frequencies for phase modulation and digital code signal processing are derived from the transmission frequency by means of dividing. This is important for the error- and interference-free operation of the reader system.

Difference between multiple and single coil

There are two kinds of antennas. Single and multiple coil systems. Which antenna type can be used in which situation? And with which decoder? Single coil: The single coil antenna is used to create the magnetic field and is also being used to receive the data that is transmitted from the transponder as the transponder is within the field of the antenna. These antennas are very simple, and therefore cheap. The reading distance of these antennas is less compared to the multiple coil antennas. The dimensions for these antennas are limited. The shape can vary from circular, rectangular, tubular etc. As long as the inductance is ca. 0,37mH the system will work. These kind of antennas are used to identify chickens/birds/trolleys etc. In all the applications the distance between transponder and antenna is limited. Single coil antennas can be mounted on metal although influences the reading distance. A single coil antenna can directly be used with the following decoders LID665 and LID608. If you want to use a single coil antenna with the LID650 you’ll need the single coil driver board TM613. Multiple coil: The advantage of the multiple coil antennas is the superior reading distance. A multiple coil system consists of an transmit antenna and one/two separated receiver coils. The receiver coil(s) are placed in such a way that the exciter field (128kHz) is eliminated in the receiver coil(s). This pre-filtering gives a very sensitive receiver circuit that is capable of detecting a transponder at a greater distance. With multiple coil antennas there’s always a so called hotspot and a cold spot, a hotspot is a location were the reading distance is optimal. This is because, due to position of the transponder towards the receiver coil, the data signal that is achieved. Besides this the magnetic field created by these antennas is stronger.

The multiple coil antennas are:

• Plate antenna ANT610 • Sensor antenna ANT611 • High performance antenna ANT612 Multiple coil antennas can be used in combination with the LID650 and LID608 stationary decoder for industrial or access-control applications. The multiple coil antennas have standard 4 meters cable, but can be limited.

Practical application is facilitated by:

User friendly design, simple operating procedures, robust design, standard electrical interfaces to facilitate transfer to external devices (PC’s, networks, printers etc.)

Characteristic data of the transmission process

Exciter frequency: 128 kHz Return frequency: 64 kHz Transfer rate: 8kbit/s Coding: Manchester code Modulation: 180°PSK Synchronization: 8 bit flag Error detection and correction: 17 bit Data telegram: 64 bit Time per reading: 24 ms