Abstract: A system for measuring range to an RFID tag including situations containing high clutter and multi-path signals is disclosed. The system includes an RFID reader; an RFID tag; and a coordinated signal compression radar system. The reader causes the tag to respond to received signals in a first backscatter state at a first time and a second backscatter state at a second time. The signal compression radar system transmits signals coordinated by the backscatter state of the tag and creates a differential signal comprised of the differences between radar signals obtained during the first and second states of the tag to obtain an uncorrupted measure of a round trip time of flight of said radar signals between the radar system and the RFID tag. The radar may use signals typical of pulse compression radar systems such as chirp modulation or Orthogonal Frequency Domain Modulation (OFDM), either pulsed or semi-continuous.

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 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 system for measuring the range to an RFID tag including situations containing high clutter and multi-path signals is disclosed. The system includes an RFID reader; an RFID tag; and a coordinated pulse compression radar system. In the system the RFID reader causes the tag to respond to received signals in a first backscatter state at a first time and a second backscatter state at a second time. The pulse compression radar system transmits short pulses coordinated by the backscatter state of the RFID tag and the system creates a differential signal comprised of the differences between radar signals obtained during the first and second states of the tag to obtain an uncorrupted measure of a round trip time of flight of said radar pulses between the pulse radar system and the RFID tag.

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; EGOTM RFID backscatter transponders, SEGOTM 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 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 system for measuring the range to an RFID tag including situations containing high clutter and multi-path signals is disclosed. The system includes an RFID reader; an RFID tag; and a coordinated pulse radar system. In the system the RFID reader causes the tag to respond to received signals in a first backscatter state at a first time and a second backscatter state at a second time. The pulsed radar system transmits short pulses coordinated by the backscatter state of the RFID tag and the system creates a differential signal comprised of the differences between radar signals obtained during the first and second states of the tag to obtain an uncorrupted measure of a round trip time of flight of said radar pulses between the pulse radar system and the RFID tag.

Abstract: An automated system for the processing of radio frequency identification (RFID) tags. The automated system allows for the simultaneous processing of multiple individual tags through the use of multiple processing stations. A table is provided that is capable of moving the individual tags from one processing station to the next. Tables are also provided for receiving unprocessed tags for input into the system and processed tags for packaging. Individual tags are moved between the tables by a transfer mechanism.

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: Systems 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 releasably securing a disabling device having a metallic portion at 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 device is at the operative position. The RFID circuitry is arranged to be automatically enabled upon removal of the disabling device from the operative position.

Abstract: An automated system and method are disclosed for reading license plate characters and associating the image with a vehicle by comparing to existing images and supplementing the automated system with manual review, comprising: capturing a first license plate image; processing the first image with optical character recognition equipment to produce an OCR result; associating the OCR result with a confidence level. If the confidence level is above a predetermined threshold, determining whether the OCR result matches a previously-obtained OCR result and if the confidence level is not above the predetermined threshold, presenting the first image for a manual review to produce a manual result.

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: An automated toll collection system based on visual recognition of a license plate with a supplemental enhancement to confirm the character recognition of the license plate is disclosed. In an embodiment, a supplemental graphic insignia encodes a check-sum for the license plate characters. The insignia is recorded at the same time as the license plate and the check sum is decoded to confirm the interpretation of the characters on the license plate. Other forms of confirmation devices are also disclosed, including RFID devices.

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. In an embodiment the tag has memory for storage of said tag status and the user input can be used to cause the tag to indicate a stored tag status.

Abstract: In railroad uses or the like, a transponder having a single key for transactions is accessible through a reader/programmer to multiple users or owners. The reader/programmer receives a transaction request and determines whether the user or owner is authorized for that transaction. If so, the reader/programmer generates the key on the fly and performs the transaction.

Abstract: An RFID tag includes a capacitor between the ASIC ground pin and the circuit ground. The value of the capacitor is selected so that in the case of electrostatic discharge (ESD), the potential drop is primarily across the capacitor rather than the ASIC. Thus, the ASIC is protected against ESD.

Abstract: RFID tags are disclosed having uniform electronics assemblies, but which fit into a variety of housings. This manufacturing technique allows for high volume production of tag electronics while keeping the mounting means adaptable to a variety of support structures. This ability to host a variety of support structures is important at least in the field of RFID tags for motorcycles, because motorcycles have varying configurations and no one tag would fit all motorcycles.

Abstract: Systems 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 releasably securing a disabling device having a metallic portion at 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 device is at the operative position. The RFID circuitry is arranged to be automatically enabled upon removal of the disabling device from the operative position.

Abstract: A radio frequency identification (RFID) tag is provided with a capability to adaptively initiate a floating RF threshold from the level of a raw RF signal detected during a communication session with a designated RFID reader, and to compare that threshold with the level of a baseband signal derived from the RF signal so as to reject RF interference including noise from other sources during the communication session. Preferably, the threshold is derived from the peak level of the detected RF signal on commencement of each communication from the reader during the session.

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.