An RFID system and method for communicating between a host computer, one or more interrogators connected to the host computer, and a large body of transponders distributed within an area covered by the interrogators. Each transponder originally has a common identification code, and upon initialization by the host computer internally generates a unique identification code based upon an internally generated random number. The host, through the interrogators, reads each of the identification codes associated with each transponder by iteratively transmitting a read identification code command along with a controlled variable. Each transponder compares the received controlled variable to an internally generated random number, and selectively transmits its identification code based upon the outcome of this comparison. After the completion of each read identification code iteration, the host adjusts the controlled variable based upon the responses received in the previous iteration. Preferably, communications between the interrogators and the transponders are DSSS signals in TDMA format, and the transponders use the random number generator to assign a time slot for transmission of their response. Each interrogator includes an antenna system utilizing a switch matrix to connect multiple antennas having different polarizations, which ensures that all transponders within the range of the interrogator receive the signals from the interrogator. In a further aspect, the interrogators are arranged in groups, each group in nearest neighbor format, to reduce the time for reading the transponders and the emissions generated when more than one interrogator is active at the same time.

Method and system for communicating with and tracking RFID transponders

An interrogator, methods of discerning the presence of an object, and interrogation systems employing the same. In one embodiment, the interrogation systems include multiple interrogators that communicate with a base command unit to track a location of an object. In another embodiment wherein the object is an RFID object (e.g., an object with an RFID tag), the interrogators employ signal processing techniques such as precharging the RFID object, and correlating a reference code with a reply code from the RFID object using selected techniques to increase a sensitivity of the interrogator, especially for adverse environments. In other embodiments, the interrogation systems include variations of metal instruments and sponges employed therewith. In yet another embodiment, the interrogation system includes metal interrogators capable of discerning the presence of a metal object, especially in a presence of another metal object.

Interrogator and Interrogation System Employing the Same

An RFID webstock containing a relatively high pitch-density array of semiconductive chips is provided and joined to a web bearing relatively widely spaced antennas in a continuous process. The RFID webstock is separated or cut into individual chip sections, with the spacing of the chips being increased as the RFID webstock is die cut. The individual chips on the sections are then joined to corresponding antennas to form an RFID inlay stock. This process is conducive to high speed roll-to-roll production of RFID tag and label roll stock.

Rfid label technique

A container and contents monitoring system includes a device, a reader, a server, and a software backbone. The device communicates with the reader in order to determine the security and/or location of the container to which the device is attached. The reader transmits the information from the device to the server. The device determines if a security condition has occurred based on at least one sensor located on or in the container.

Method and system for monitoring containers to maintain the security thereof

The invention relates to a method for the operation of a near field communication multifunction device in environments where interaction is desired between near field communication capable devices using multiple data formats, compromising the operations of performing a first initiation procedure for a first data format according to a protocol of a certain standard; performing a second initiation procedure for a second data format according to a protocol of a certain standard; performing a delay, and repeating these operations in a repetitive process.

Electronic near field communication enabled multifunctional device and method of its operation

Arbitration of multiple transponders, such as RFID tags, occurs in an interrogation field. The arbitration process is custom-tailored for individual applications, under software control, by the transponder reader or tag reader. Different wake-up slots are calculated for each tag during successive transmission cycles based upon the tag ID and the transmission cycle number. The tag reader may also send a special command to a tag to read its data and cause the tag to become decoupled from the environment. The tags may be selectively placed in either a tag-talk-first mode or a reader-talk-first mode. Furthermore, the tag reader may send a special fast read command to the tag which includes a read request and at least one parameter of the read request.

Anticollision protocol with fast read request and additional schemes for reading multiple transponders in an rfid system

A radio frequency identification (RFID) tag on a single layer substrate comprises a semiconductor integrated circuit RFID tag device and antenna circuit. A connection jumper may be used to bridge over the antenna circuit coil turns. The RFID tag device is located on the same side as an inductor coil and capacitor which forms a parallel resonant antenna circuit. The inductor coil has an inner end and an outer end. The inner or outer end may be connected directly to the RFID tag device and the outer or inner end be may connected to the RFID tag device with a jumper over the inductor coil turns, or the RFID tag device may bridge the inductor coil turns when being connected to both the inner and outer ends. An encapsulation (glop top) may be used to seal the RFID tag device and jumper, and an insulated coating may be used to cover the entire surface of the substrate to create an inexpensive “chip-on-tag.” The encapsulation may be epoxy, plastic or any protective material known to one of ordinary skill in the art of electronic circuit encapsulation. The insulated coating may be of any type suitable for the application of use of the RFID tag.

Radio frequency identification tag on a single layer substrate

A Radio Frequency Identification (RFID) tag device is configured as an electronic key. The electronic key disables the RFID Input/Output (I/O) by shorting or breaking the conductor between the RFID tag device and its resonant circuit or antenna whenever the electronic key is not inserted into a lock. This is a security measure which prevents unauthorized individuals from reading the electronic key code via a covert/concealed reading device. The circuit is completed by closing the key contacts with a matching shorting bar (normally open application), or spreading the shorted spring contacts with a nonconductive spacer (normally closed application) when the electronic key is inserted inside an electronic locking mechanism. Once the circuit is completed, the wireless transmission of data from the electronic key to the electronic locking mechanism is enabled.

A radio frequency identification (rfid) security device

A microcontroller-based passive keyless entry (PKE) transponder can be used for smart bi-directional communications. The transponder can detect low-frequency signals as low as 1 mVpp, and respond to the base station unit (reader) by using its internal backscattering modulators for proximity range or via an external high-frequency transmitter for long-range applications. This transponder device has three input channels to detect signals from x, y and z directions. The device's versatile low frequency front-end functions are dynamically controlled by the microcontroller firmware. The device can be used for smart keyless-entry systems in high volume low cost security and automotive applications. This paper describes the feasibility of the smart transponder for various hands-free access control applications.

Low frequency bidirectional communication transponder for security and automotive applications

Arbitration of multiple transponders, such as RFID tags, occurs in an interrogation field. The arbitration process is custom-tailored for individual applications, under software control, by the transponder reader or tag reader. Different wake-up slots are calculated for each tag during successive transmission cycles based upon the tag ID and the transmission cycle number.

Youbok Lee

Papers

Anticollision protocol with fast read request and additional schemes for reading multiple transponders in an rfid system

Radio frequency identification tag on a single layer substrate

A radio frequency identification (rfid) security device

Low frequency bidirectional communication transponder for security and automotive applications

Method for reading multiple transponders in an rfid system