Abstract: One or more secondary data channels are added to existing RFID protocols within the existing bandwidth, data clock rate and message frame times of the protocols. An RFID system is described having at least one reader and at least one tag includes communication between the reader and the tag using a radio frequency carrier signal modulated by a modulation signal to provide a modulated carrier signal conveying digital data in either direction. The modulation signal includes a first encoded modulation signal perturbed by encoded perturbations, the first encoded modulation signal being produced from a first data string. The encoded perturbations are produced from a second data string. The modulation signal modulates the radio frequency signals to transfer data representative of the first and second data strings simultaneously between the reader and the tag. The modulation signal modulates the amplitude, phase, frequency or any combination of the radio frequency carrier signals.

Abstract: A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGO™ RFID backscatter transponders, SEGO™ RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

Abstract: A testing system and method for testing glass-mounted RFID tags such as tags mounted on vehicle windows. A testing carrier for use in a test chamber simulates the effect on the tag of the mounting glass. The test chamber and carrier are calibrated by first mounting the tag on the test carrier and making sensitivity measurements and then mounting the tag on glass that is representative of the actual production environment. Comparisons are made between the two measurements and calibration factors are derived to compensate for differences between the actual mounting glass and the test carrier. The test carrier is designed to provide uniform pressure against the tag to minimize any distortions that would alter the sensitivity of the tag.

Abstract: An RFID tag for use in a vehicle for use in an electronic toll collecting system. The tag is capable of transmitting data to a tag interrogator indicating the occupancy status of the vehicle. In an embodiment, the tag has a user input and a visual and audible tag status indicator. The user input is used to change the occupancy status of the tag, wherein the occupancy status is a portion of a message sent by radio frequency to the interrogator when the vehicle passes through a toll area.

Abstract: A multi-mode, preferably dual mode, radio frequency identification (RFID) tag is adapted for automatic detection of whether a RFID reader located within communication range of the RFID tag is transmitting a continuous wave (CW) or modulated wave types of RF signal, and accordingly, mandating a response from the tag in read-only (RO) mode or read/write (R/W) mode, respectively. The tag includes means for designating one of the RO and R/W operating modes as a default mode of the tag, and for switching the tag from its default mode to its other operating mode, and vice versa, according to a rule for determining the frequency of occurrence of a selected event related to signal type of the reader. A device-implemented method of this automatic detection, and a method of fabricating the tag, are also disclosed.

Abstract: A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGO™ RFID backscatter transponders, SEGO™ RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

Abstract: An RFID tag having a non-volatile memory and a piezoelectric sensor. The piezoelectric sensor produces an electrical charge that momentarily supplies electrical power to the RFID tag when subjected to a mechanical force and the electrical power is sufficient to record data in the non-volatile memory. The piezoelectric sensor is affixed to an article such that an attempt to tamper with the article produces sufficient mechanical force on the piezoelectric sensor to record data evidencing the tampering in the non-volatile memory.

Abstract: A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGO™ RFID backscatter transponders, SEGO™ RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

Abstract: When multiple readers for RF transponders have to be placed in close proximity, such as in adjacent lanes of a highway toll barrier, they can be set to operate at different frequencies. When signals from two adjacent ones of the readers interfere, the resulting signal includes interference terms whose frequencies equal the sum of the reader frequencies and the difference between the reader frequencies. To remove such interference terms while passing the desired terms, a tag includes a low-pass or other frequency-selective filter.

Abstract: Systems, tags and methods for disabling transponders used in electronic toll collection or other RFID systems, wherein the transponders include an antenna and RFID circuitry. The transponders can be selectively disabled by positioning (e.g., pivotably moving) a disabling member having a metallic portion to an operative position over the antenna of the RFID system, whereupon the metallic portion is coupled to the antenna in such a manner as to disable the RFID circuitry so long as the disabling member is at the operative position. The RFID circuitry is arranged to be automatically enabled upon removal of the disabling member from the operative position (e.g., pivoting the disabling member back to an inoperative position).

Abstract: A multi-mode, preferably dual mode, radio frequency identification (RFID) tag is adapted for automatic detection of whether a RFID reader located within communication range of the RFID tag is transmitting a continuous wave (CW) or modulated wave types of RF signal, and accordingly, mandating a response from the tag in read-only (RO) mode or read/write (R/W) mode, respectively. The tag includes means for designating one of the RO and R/W operating modes as a default mode of the tag, and for switching the tag from its default mode to its other operating mode, and vice versa, according to a rule for determining the frequency of occurrence of a selected event related to signal type of the reader. A device-implemented method of this automatic detection, and a method of fabricating the tag, are also disclosed.

Abstract: Distance to a modulated backscatter tag is measured with a RFID reader that measures changes in phase with frequency of modulated backscattered RF signals. Measured distances are linked to a specific tag. The effects of other sources of reflected and interfering signals are mitigated. The techniques eliminate the need for high RF bandwidth used in time-of-flight methods, and may be used with linear, limiting or other types of amplifiers in the reader receiver. Unambiguous distance to a tag may be found using the derivative of phase with RF frequency of the modulated signal backscattered by a tag. The distance to a tag can be measured with an accuracy on the order of a centimeter. The techniques utilize the characteristics of cooperative backscatter tags (transponders, labels, etc.). New readers implement the techniques which may use unmodified tags.

Abstract: In a protocol for preserving the privacy of communications between a RFID reader and a RFID tag, two distinct actions are taken. First, the reader and the tag must be mutually authenticated as being authorized participants in the communications. After that process is successfully completed, the authenticity of each authorized participant must be validated prior to each subsequent communication between reader and tag.