Abstract: A system for the distribution of RFID signals to a remote antenna or a remote antenna network comprising: a central control module to generate signals and control the protocol operations; cable, in particular twisted pair cable, connecting the central module to one or more antenna subsystems carrying substantially baseband representations of the reader to tag modulation and tag to reader modulation.

Abstract: A system for the distribution of RFID signals to a remote antenna or a remote antenna network comprising: a central control module to generate signals and control the protocol operations; cable, in particular twisted pair cable, connecting the central module to one or more antenna subsystems carrying substantially baseband representations of the reader to tag modulation and tag to reader modulation.

Abstract: We describe an RFID tag reading system comprising a plurality of transmit/receive antennas to provide spatial transmit/receive signal diversity, and a tag signal decoder. The system combines received RF signals from the antennas, and the antennas are spaced apart from one another sufficiently for one said antenna not to be within the near field of another. The system performs a tag inventory cycle comprising a plurality of tag read rounds, each having a set of time slots during which a said tag is able to transmit tag data including a tag ID. The system is configured to perform, during a tag inventory cycle, one or both of: a change in a frequency of the tag interrogation signals transmitted simultaneously from the plurality of antennas, and a change in a relative phase of a the RF tag interrogation signal transmitted from one of the antennas with respect to another.

Abstract: We describe a methods of locating an RFID tag. One method transmits tag location signals at a plurality of different frequencies from a plurality of different antennas spaced apart by more than a near field limit distance. The processing determines a phase difference at the plurality of different frequencies by determining a phase difference between either i) two or more of the transmit signals resulting in a maxima in the returned signal RSSI or ii) a first transmit signal and its corresponding return signal. The range determining uses return signals weighted by signal strength. Further data which may be used for averaging may be generated by using the above techniques along with changes in the polarisation state of the transmit and receive antennas and/or physical reconfiguration of the antennas (e.g. switch the transmit and receive elements).

Abstract: We describe an RFID tag reading system comprising a plurality of transmit/receive antennas to provide spatial transmit/receive signal diversity, and a tag signal decoder. The system combines received RF signals from the antennas, and the antennas are spaced apart from one another sufficiently for one said antenna not to be within the near field of another. The system performs a tag inventory cycle comprising a plurality of tag read rounds, each having a set of time slots during which a said tag is able to transmit tag data including a tag ID. The system is configured to perform, during a tag inventory cycle, one or both of: a change in a frequency of the tag interrogation signals transmitted simultaneously from the plurality of antennas, and a change in a relative phase of a the RF tag interrogation signal transmitted from one of the antennas with respect to another.

Abstract: We describe a methods of locating an RFID tag. One method transmits tag location signals at a plurality of different frequencies from a plurality of different antennas spaced apart by more than a near field limit distance. The processing determines a phase difference at the plurality of different frequencies by determining a phase difference between either i) two or more of the transmit signals resulting in a maxima in the returned signal RSSI or ii) a first transmit signal and its corresponding return signal. The range determining uses return signals weighted by signal strength. Further data which may be used for averaging may be generated by using the above techniques along with changes in the polarisation state of the transmit and receive antennas and/or physical reconfiguration of the antennas (e.g. switch the transmit and receive elements).

Abstract: A duplex optical fiber link is provided that includes two bi-directional optical fiber links. Each of the bi-directional links includes a multimode optical fiber and an optical transceiver connected to each of the ends of each of the fibers. Each of the optical transceivers includes a bi-directional optical multiplexer (MUX) that is configured to simultaneously optically couple optical data signals produced by a laser diode of the transceiver into an end of one of the fibers and to optically couple an optical data signal passing out of the end of one of the fibers onto a photodiode of the transceiver. The laser diodes operate at a data rate of at least 10 Gb/s such that each optical transceiver transmits and receives optical data signals at an aggregate data rate of at least 20 Gb/s. Consequently, the bi-directional duplex optical link has an aggregate data rate of at least 40 Gb/s.

Abstract: A duplex optical fiber link is provided that includes two bi-directional optical fiber links. Each of the bi-directional links includes a multimode optical fiber and an optical transceiver connected to each of the ends of each of the fibers. Each of the optical transceivers includes a bi-directional optical multiplexer (MUX) that is configured to simultaneously optically couple optical data signals produced by a laser diode of the transceiver into an end of one of the fibers and to optically couple an optical data signal passing out of the end of one of the fibers onto a photodiode of the transceiver. The laser diodes operate at a data rate of at least 10 Gb/s such that each optical transceiver transmits and receives optical data signals at an aggregate data rate of at least 20 Gb/s. Consequently, the bi-directional duplex optical link has an aggregate data rate of at least 40 Gb/s.

Abstract: A method of fabricating maps and other objects presenting multiple sets of spatially related information. Spatial alignment data, such as geographical boundaries is selected. First and second images are created by aligning or mapping first and second sets of information to the spatial alignment data. A lens sheet or lenticular material is fabricated, and based on the lens sheet configuration, the first and second images are combined to create an interlaced image including alternating strips from the first and second images. The interlaced image is printed on a substrate or the reverse side of the lens sheet, and the substrate is bonded to the lens sheet such that the interlaced image is sandwiched between the lens sheet and substrate. The first image is visible when the map or object is in a first position and the second image when the map or object is rotated to a second position.

Abstract: A computer-based method for creating a data structure for informal geographic spaces for use with geocoded databases. A set of data is stored in memory for a geographic region, and a plurality of neighborhoods is identified in the geographic region based on processing of the stored set of data. The method includes generating a boundary definition for each of the neighborhoods by processing neighborhood definition information. A data structure is created in the memory for containing neighborhood data content with at least one record for each of the neighborhoods. The data structure is populated by storing, for each neighborhood, the generated boundary definition along with a neighborhood name and identifier in the records of data structure. The boundary definition may be created by combining two or more definitions identified for a single neighborhood to provide a more inclusive geometry such as by aligning the geometries and performing an additive algorithm.

Abstract: A method of fabricating maps and other objects presenting multiple sets of spatially related information. Spatial alignment data, such as geographical boundaries is selected. First and second images are created by aligning or mapping first and second sets of information to the spatial alignment data. A lens sheet or lenticular material is fabricated, and based on the lens sheet configuration, the first and second images are combined to create an interlaced image including alternating strips from the first and second images. The interlaced image is printed on a substrate or the reverse side of the lens sheet, and the substrate is bonded to the lens sheet such that the interlaced image is sandwiched between the lens sheet and substrate. The first image is visible when the map or object is in a first position and the second image when the map or object is rotated to a second position.

Abstract: A method of fabricating maps and other objects presenting multiple sets of spatially related information. Spatial alignment data, such as geographical boundaries is selected. First and second images are created by aligning or mapping first and second sets of information to the spatial alignment data. A lens sheet or lenticular material is fabricated, and based on the lens sheet configuration, the first and second images are combined to create an interlaced image including alternating strips from the first and second images. The interlaced image is printed on a substrate or the reverse side of the lens sheet, and the substrate is bonded to the lens sheet such that the interlaced image is sandwiched between the lens sheet and substrate. The first image is visible when the map or object is in a first position and the second image when the map or object is rotated to a second position.

Abstract: A switchable multichannel external cavity injection laser incorporates a diffraction grating between a linear array of n reflectors and a common reflector to define a set of n optical cavities having different frequency bands. Each of the (n+1) reflectors is provided by the optically distal end of an associated semiconductor laser amplifier whose optically proximal end is arranged to be substantially non-reflective.

Abstract: The output polarization of a twin guide semiconductor laser is switched either by controlling the operating current of both guides or by injecting an optical signal. Twin-stripe and twin-ridge lasers of InGaAsP are described. True polarization bistability is reported for a range of devices: the effect is temperature insensitive.

Abstract: An opto-electronic switch which shows a good signal rejection ratio between modes is also of particularly small dimensions. The switch comprises a semiconductor laser 1 having four contacts 12, 12', 13, 13' which provide gain guiding under two stripe windows 18, 19. By varying the bias currents supplied to the individual contacts 12, 12', 13, 13', or inputting optical control signals to the waveguiding channels under the stripe windows 18, 19, different configurations of optical output from the laser 1 can be achieved. The two contacts, 12, 12' and 13, 13', associated with each stripe window 18, 19 are effectively a signal stripe contact with a discontinuity. It is thought that diffractive transverse coupling at the discontinuity allows the use of a shorter device than in known directional switches. With feedback, the switch operates as a memory device. The switch finds particular application in optical communications, for instance in signal routing.