Abstract: The present invention provides a system for discriminating between coded responses from multiple SAW identification tags and a method of operating such system. In one embodiment the system provides for (1) a SAW tag reader subsystem that detects coded responses from the tags to an interrogation pulse; and (2) a coded response analyzing subsystem, coupled to the SAW tag reader subsystem, that employs signal processing techniques to separate portions of the coded responses and generates possibilities for remaining portions of the coded responses.

Abstract: The present invention provides a system for avoiding code collisions from multiple SAW identification tags and a method of operating such system. In one embodiment the invention provides for (1) focusing an interrogation pulse to within a defined space; and (2) discriminating between coded responses returned from tags located within such defined space.

Abstract: The present invention in one embodiment provides for a propagated signal of (1) a time period divided into a group of time slots each having a unique phase/time position; and (2) multiple pulses distributed among the time slots encoding a data element by such unique phase/time position.

Abstract: An object-naming network infrastructure and a method of responding to queries for object names. In one embodiment, the infrastructure includes: (1) a central object name server coupled to a computer network and constituting a first hierarchical level and (2) peripheral object name servers coupled to the computer network and constituting a second hierarchical level, the central object name server responding to an object name query received from a querying system by directing the querying system to query instead one of the peripheral object name servers in the second hierarchical level, the one of the peripheral object name servers either responding to the query with an object name or directing the querying system to query instead further peripheral object name servers constituting a third hierarchical level.

Abstract: The present invention provides for a propagated signal using multiple pulse per group keying and a method of using the same. In one embodiment the propagated signal includes: (1) an element of data contained within a time period of the propagated signal, the time period divided into a group of time slots; and (2) multiple pulses distributed in a predetermined manner among the time slots by pulse group keying to encode the data.

Abstract: The present invention provides for a surface acoustic wave (SAW) identification tag reader and for methods of operating and manufacturing the same. In one embodiment, the SAW identification tag reader includes: (1) a transmitter capable of sending an interrogation signal that excites a SAW transducer located on a piezoelectric substrate, the piezoelectric substrate having a group of slots arranged by both pulse position and phase position, and a number of reflectors distributed among the slots such that the reflectors return to the transducer a return signal containing a number encoded by both pulse position and phase position; and (2) a receiver for detecting the return signal and decoding the number.

Abstract: The present invention provides for a propagated signal modulated by phase and time shift keying and a method of using the same. In one embodiment the propagated signal includes: (1) a period of time spanned by a pulse, the period of time divided into a group of time slots, each of the time slots having a unique phase/time position; and (2) the pulse encoding a data element by the phase/time position.

Abstract: A surface acoustic wave (SAW) identification tag and methods of operating and manufacturing the tag. In one embodiment, the tag includes: (1) a piezoelectric substrate having a SAW transducer located thereon, (2) a group of slots arranged by both pulse position and phase position on said substrate; and (3) a number of reflectors distributed among the slots such that the reflectors encode a number by both pulse position and phase position.

Abstract: There is described an electro-acoustic device, comprising a piezo-electric substrate and a first transducer and second transducer supported by the substrate and each including a pair of interdigital transducer electrode arrays, the electrodes of the arrays being interleaved with each other. The first and second transducer are disposed opposing each other in a propagation direction of acoustic waves excited by the first and second transducers. The first transducer has a first electric signal associated with and existing across, and the second transducer has a second electrical signal associated with it which has a different phase from the first electrical signal. The first and second transducers are spaced apart such that substantially in-phase acoustic waves propagating in the substrate and incident on the first transducer in-phase with the first electric signal and on the second transducer in-phase with the second electrical signal.

Abstract: A SAW filter having an even number of tracks, each track comprising reflective input and output IDTs having a partially reflecting grating disposed between them. One of the IDTs of each pair of tracks has its electrodes connected in opposite polarity to those of the other IDTs of the pair of tracks and the separation of the input and output IDTs of respective tracks of each pair of tracks is substantially the same. The relative dispositions of the partially reflecting gratings are such that waves launched into respective tracks of a pair of tracks undergo at least one reflection from the partially reflecting grating prior to being coherently incident on the output IDTs. By virtue of the oppositely connected electrodes of one of the IDTs, direct coupling through the tracks is inhibited at substantially all frequencies.

Abstract: This invention relates to an electronic device having a frequency dependent signal transfer characteristic which is electrically coupled to at least one SAW transducer. The SAW transducer acts as a SAW impedance element since it exhibits frequency dependent electrical characteristics. Such characteristics are utilised so that the transmission loss of the SAW impedance element is high in a relatively low signal transfer region of the signal transfer characteristic of the electronic device, and low in a relatively high signal transfer region of the signal transfer characteristic of the electronic device. This has the advantage that signals outside of the passband of the electronic device can be attenuated without increasing the transmission loss of the electronic device in its passband.

Abstract: A surface acoustic wave (SAW) transducer comprises a piezoelectric substr, a pair of metal bus bars positioned on the substrate parallel to and separated from each other a preselected distance and a plurality of interdigital electrode fingers extending from each of the metal bus bars. A plurality of slots are positioned along each metal bus bar so that the bus bar metallization is reduced and the acoustic wave velocity is increased in the metal bus bar region.

Abstract: A method of descrambling received video program signals with transmitted synchronization signals for use in a video receiver comprising the steps of providing first terminals for receiving the scrambled video signal and second terminals coupled to the video receiver and connecting an electronic ticket containing descrambling circuitry to the first terminals for receiving and descrambling the received video signal and coupling the descrambled video signal from the electronic ticket to the second terminals for transfer to the video receiver.

Abstract: An electronic ticket for descrambling transmitted video program and synchronization signals for use in a video receiver comprising first terminals for receiving the scrambled video signals, a descrambling circuit having its input coupled to the first terminals and producing at least a partially descrambled signal at its output, second terminals for coupling the descrambled signal to the video receiver and enclosing portions of the first and second terminals, and the descrambling circuit in a unitary package whereby the ticket can be used as a plug-in unit.

Abstract: An impedance element formed from a single-port, surface acoustic wave transucer which generates a conductance versus frequency response characteristic having first and second peaks separated by a valley at a predetermined frequency and which generates a susceptance versus frequency response characteristic having a substantially constant portion over a finite bandwidth on both sides of said predetermined frequency.

Abstract: An improved notch filter having a single port, surface acoustic wave transducer in parallel with an inductor and forming a first circuit which primarily blocks the signal frequency at all frequencies except the notch frequency at which point the first circuit becomes essentially resistive and at that point is cancelled by a signal from a second circuit in parallel with said first circuit and which is 180.degree. out-of-phase thereby providing a notch filter.

Abstract: Disclosed is a unidirectional interdigitated surface wave transducer having at least three discrete arrays of conductive elements, each array comprising, in a comb-like structure, a plurality of electrodes electrically interconnected in parallel and having a periodicity corresponding to one acoustic wavelength of the resonance frequency of the transducer. The discrete arrays of electrodes are deposited upon a piezoelectric substrate in an interleaved pattern to define an interdigitated transducer. Respective electrodes of a given array are substantially equidistantly spaced apart from electrodes of the other arrays and are electrically insulated therefrom. The arrays of electrodes are positioned upon the substrate such that there are at least three electrodes per acoustic wavelength at the resonance frequency.

Abstract: A surface wave device (10) having substrate with at least a surface layer of piezoelectric material (12) and at least one pair of opposing electrically conducting pads (14 and 16) is disclosed. A first group of at least three electrodes (18, 20 and 22) in a distance (24) of one half wavelength of a preselected operating frequency is disposed on the piezoelectric surface between the opposing pads. At least one of the electrodes is electrically connected to one of the opposing pads and the remaining electrodes are electrically connected to the other opposing pad. The sequence of the three electrodes is unevenly distributed with respect to which of the pads the electrodes are connected to. At least two additional groups of at least three electrodes similar to the first group have sequences of electrodes within each group that is distinct from the other groups.

Abstract: A surface wave device includes a substrate (12 in FIG. 7) having a surface layer of piezoelectric material (14), at least one pair of opposing electrically conducting pads (16 and 18) and at least two electrodes (20 and 22) which generate surface waves that vary significantly in strength in a direction transverse to the opposing pads. An ungrounded pad (16) forms an electrode array of parallel segmented electrodes (24), joined by electrically conducting connecting bars (26), having more segmented electrodes near the center of the transverse distance than near the pads. A grounded electrode (22) forms a segmented electrode array having segmented electrodes (44) joined by electrically conducting connecting bars (46) having fewer segmented electrodes near the center of the transverse distance than near the pads.

Abstract: A surface wave resonator device (10) includes a substrate (12) having a surface layer of piezoelectric material (14), first and second reflective grating structures (16 and 18) and a middle grating structure (40). The middle grating structure includes an odd multiple of one-quarter wavelength for the resonant frequency of the first and second reflective grating structures. The surface acoustic wave transmission velocity of the middle grating structure is substantially equal to the surface acoustic wave transmission velocity of the first and second reflective grating structures. One arrangement includes a surface acoustic wave input transducer (52) and a surface acoustic wave output transducer (58).