Abstract: Apparatus for reading an RFID tag includes an RF-blocking enclosure having a port and adapted to receive through the port a non-RFID-active object having an RFID tag affixed thereto. An RFID reader has a reader antenna located outside the enclosure. The antenna transmits an RF downlink signal in a particular direction. An RF grating is arranged between the reader antenna and the port so that, after the enclosure receives the object having the tag, the port is located in the transmit direction from the reader antenna, and RF energy transmitted from the reader antenna has a selected linear polarization after passing through the grating.

Abstract: A method of detecting an RFID tag includes transmitting a bait RFID read signal at a bait power level and a simulated response signal at a simulated-response power level. A selected reader frequency is monitored for a selected detection time. A skimmer is determined to be present if a skimmer RFID read signal is detected during that time. If a skimmer is not determined to be present, multiple read signals are transmitted sequentially, each signal at a respective read power level. At least one of the read power levels is lower than the bait power level, at least one of the read power levels is lower than the simulated-response power level, and at least two of the read power levels are different from each other. A selected response frequency for a tag is monitored for a response from an RFID tag.

Abstract: A method of selecting digital images includes using a processor to store the digital images in an electronic storage and retrieval system, forming a corresponding machine-readable code for each stored digital image, the machine-readable code encoding a reference to the storage location of the corresponding digital image in the electronic storage and retrieval system, providing a viewable image that includes a representative image of each digital image in the first collection of digital images in association with its associated machine-readable code, selecting one or more but not all of the digital images by receiving references or photographs of the machine-readable codes and extracting the references from the received photographs, and compiling the digital images corresponding to the received or extracted references into a second image collection.

Abstract: A method of verifying the identification of fluids to be supplied successively through a fluid-supply hose that selectively connects to successive movable, RFID-tagged fluid containers includes providing an RFID reading unit including an antenna. A sequence of reference container identification codes is received. A container-present indication indicating one of the containers is positioned so that its RFID tag is in the antenna range is received. In response, the RFID tag of that container is read using the RFID reading unit to determine an identification code of the container. A controller automatically verifies the determined container identification code against the first reference identification code in the sequence using a controller. The starting through verifying steps are repeated, using successive values from the sequence in the verifying step, until all values in the sequence have been verified against container identification codes read using the RFID reading unit.

Abstract: A classification of a container is identified using a mobile station including an image capture device and an RFID reader having a reader antenna. The container has two RFID tags affixed thereto at respective, different locations. Each tag has a directional antenna steered in a different direction, so that a reader location is defined in the intersection of the antenna propagation patterns. Using the image capture device, one or more images of the container are captured. A controller determines, using the captured image data, whether the mobile station is in a candidate reader location. When the mobile station is in the candidate reader location, the RFID reader attempts to read both tags. If both tags are read while the mobile station is in the candidate reader location, the controller determines the classification of the container is a classification corresponding to the candidate reader location.

Abstract: A method of reading an RFID tag using an RFID reader includes providing an RF-blocking enclosure having a port. The RFID reader has an antenna located within the enclosure. The enclosure is positioned so that the port is adjacent to a conductive surface and the RFID tag is within the enclosure. The RFID reader is activated at a selected read power level to read the tag in the enclosure.

Abstract: An RFID system has an active tag with one antenna inside, and one outside, an RF-blocking enclosure having a port with a selected shortest dimension. The RFID reader is located outside the enclosure and uses a selected RF read frequency range. The RFID tag simultaneously transmits on a plurality of frequencies corresponding to respective wavelengths smaller than the selected shortest dimension, so that a respective beat frequency is defined between two of the frequencies. The beat frequency is within the selected RF uplink frequency range. The tag transmits a first signal at a first one of the plurality of frequencies using the interior antenna and a second signal at a second, different one of the plurality of frequencies using the exterior antenna.

Abstract: An active RFID tag has an antenna inside RF-blocking enclosure having a port with a selected shortest dimension. An RFID reader located outside the enclosure at a reader position transmits a downlink RF signal through the port as a directional RF signal on a downlink carrier frequency corresponding to a downlink wavelength smaller than the selected shortest dimension. The port is selectively configured so that the directional downlink RF signal can pass through the port in an access mode during a selected access time interval and are attenuated by at least 60 dB in a restricted mode during a selected restricted time interval that does not overlap with the access time interval.

Abstract: An RFID system includes a reader with antenna, a first barrier, a tag with a link antenna, a second barrier, and two key antennas connected to the tag, mechanically arranged in that order. The first barrier has two or more apertures in it to produce an interference pattern of a security signal from the reader. The security signal interference pattern passes at least partly through the second barrier. One of the key antennas is at a peak of the pattern after passing through the second barrier, and one is not. The tag includes a controller responsive to a downlink signal from the reader to transmit an uplink signal using the link antenna, but only if the downlink signal is preceded by the security signal and the security signal is received more strongly by the key antenna at the peak than by the other key antenna.

Abstract: An RFID reader system has an RFID tag and an RFID reader. The tag authorizes the RFID reader by receiving a plurality of successively-transmitted initial RFID read signals and determining respective initial-read signal power levels of the received initial RFID read signals. Using the determined initial-read signal power levels, a controller automatically selects an authorization sequence. A plurality of successively-transmitted authorization RFID signals are received sequentially, and respective authorization-signal power levels of the received authorization RFID read signals are determined. The determined authorization-signal power levels are automatically compared to the authorization sequence using the controller, so that the RFID reader is authorized if the determined authorization-signal power levels correspond to the authorization sequence.

Abstract: Non-RFID-active units in a space are marked by affixing RFID tags. Two tags are affixed to each unit, each tag having a directional antenna. The antennas are oriented to define a per-unit reader location. Units are arranged in the space so the per-unit reader locations at least partially overlap to define a reader location. The units in the space can also be detected by an RFID reader located in the overlapping per-unit reader locations. A controller can compare a received list of tag identities corresponding to units expected to be in the container to the identities of the tags read to determine whether the expected units are in the container and disposed at positions and with orientations that cause the respective per-unit reader locations to at least partially overlap with the reader location.

Abstract: An RFID system includes an RF-blocking enclosure having a port with a selected shortest dimension. An active RFID tag including a controller and an interior antenna coupled to the controller is located in the enclosure. The tag responds to a selected RF downlink frequency range. An RFID reader located outside the enclosure simultaneously transmits directional RF signals on a plurality of frequencies corresponding to respective wavelengths smaller than the selected shortest dimension, the plurality including a carrier frequency and an interference frequency. A beat frequency is thus defined between the carrier frequency and the interference frequency and the beat frequency is within the selected RF downlink frequency range, so that the transmitted signals pass through the port and the tag responds to the beat frequency.

Abstract: Apparatus for reading an RFID tag includes an RF-blocking enclosure having a port and adapted to receive through the port a non-RFID-active object having an RFID tag affixed thereto. An RFID reader has a reader antenna located outside the enclosure. The antenna transmits an RF downlink signal in a particular direction. An RF grating is arranged between the reader antenna and the port so that, after the enclosure receives the object having the tag, the port is located in the transmit direction from the reader antenna, and RF energy transmitted from the reader antenna has a selected linear polarization after passing through the grating.

Abstract: A method of reading an RFID tag using an RFID reader includes providing an RF-blocking enclosure having a port. The RFID reader has an antenna located within the enclosure. The enclosure is positioned so that the port is adjacent to a conductive surface and the RFID tag is within the enclosure. The RFID reader is activated at a selected read power level to read the tag in the enclosure.

Abstract: An RFID system includes an RFID reader with a tag antenna located at a reader location. An RFID tag includes a controller and an antenna. An RF-blocking enclosure spaced apart from the RFID reader includes a port having first and second spaced-apart apertures. The enclosure is positioned with respect to the reader location to define a tag-antenna location at which an interference pattern of a downlink signal from the reader passing through the port provides a selected downlink power at the tag-antenna location, and an interference pattern of an uplink signal from the tag passing through the port provides a selected uplink power at the reader location. The tag antenna is located in the enclosure at the tag-antenna location.

Abstract: An RFID system has an active tag with one antenna inside, and one outside, an RF-blocking enclosure having a port with a selected shortest dimension. The RFID reader is located outside the enclosure and uses a selected RF read frequency range. The RFID tag simultaneously transmits on a plurality of frequencies corresponding to respective wavelengths smaller than the selected shortest dimension, so that a respective beat frequency is defined between two of the frequencies. The beat frequency is within the selected RF uplink frequency range. The tag transmits a first signal at a first one of the plurality of frequencies using the interior antenna and a second signal at a second, different one of the plurality of frequencies using the exterior antenna.

Abstract: An active RFID tag has an antenna inside RF-blocking enclosure having a port with a selected shortest dimension. An RFID reader located outside the enclosure at a reader position transmits a downlink RF signal through the port as a directional RF signal on a downlink carrier frequency corresponding to a downlink wavelength smaller than the selected shortest dimension. The port is selectively configured so that the directional downlink RF signal can pass through the port in an access mode during a selected access time interval and are attenuated by at least 60 dB in a restricted mode during a selected restricted time interval that does not overlap with the access time interval.

Abstract: An RFID system includes a reader with antenna, a first barrier, a tag with a link antenna, a second barrier, and two key antennas connected to the tag, mechanically arranged in that order. The first barrier has two or more apertures in it to produce an interference pattern of a security signal from the reader. The security signal interference pattern passes at least partly through the second barrier. One of the key antennas is at a peak of the pattern after passing through the second barrier, and one is not. The tag includes a controller responsive to a downlink signal from the reader to transmit an uplink signal using the link antenna, but only if the downlink signal is preceded by the security signal and the security signal is received more strongly by the key antenna at the peak than by the other key antenna.

Abstract: An RFID system includes an RF-blocking enclosure having a port with a selected shortest dimension. An active RFID tag including a controller and an interior antenna coupled to the controller is located in the enclosure. The tag responds to a selected RF downlink frequency range. An RFID reader located outside the enclosure simultaneously transmits directional RF signals on a plurality of frequencies corresponding to respective wavelengths smaller than the selected shortest dimension, the plurality including a carrier frequency and an interference frequency. A beat frequency is thus defined between the carrier frequency and the interference frequency and the beat frequency is within the selected RF downlink frequency range, so that the transmitted signals pass through the port and the tag responds to the beat frequency.

Abstract: A viewable image for selecting one or more digital images from a collection of digital images includes a plurality of representative images representing corresponding digital images in the collection, each corresponding digital image stored in an electronic storage and retrieval system and a plurality of machine-readable codes, each machine-readable code associated with one of the representative images so that a viewer can readily identify a desired digital image and a corresponding machine-readable code in the viewable image, wherein each machine-readable code can be photographed to select its corresponding digital image, and wherein the machine-readable code encodes a reference to the corresponding digital image stored in the electronic storage and retrieval system.