Abstract: A system for combining AM and FM transmissions. In-band, on-channel, FM Digital Audio Broadcast (IBOC FM-DAB) allows simultaneous transmission of DAB and FM over existing FM allocations without interfering with conventional analog FM signals. The utility of existing FM spectrum allocations is therefore enhanced.

Abstract: A pressure and temperature sensor includes a sealed insulating package and an elastic, piezoelectric substrate deformably supported within the package. At least three surface-acoustic-wave resonators are affixed to a bottom of the substrate. A first and a second resonator are positioned in parallel relation along the substrate. A third resonator has a long axis nonparallel to the long axes of the first and the second resonator. The temperature coefficients of the first and second resonators are substantially equivalent; that of the third is different from those of the first and the second resonator, for permitting a temperature change to be sensed. Electrical connectors extend between the resonators to the outside of the package. A sensing system also includes an antenna for sending and receiving electromagnetic signals to and from the device.

Abstract: A lanthanum gallium tantalate single crystal substrate, referred to as langatate, has a prescribed range of Euler angles for substrate and crystal orientation for improving signal processing for a surface acoustic wave (SAW) device. When a voltage is applied to an input interdigital transducer (IDT) of the SAW device, a surface acoustic wave is generated in the langatate piezoelectric substrate. The surface acoustic wave propagates in a direction generally perpendicular to electrodes of the IDT. The langatate crystal cut and wave propagation directions are defined which reduce insertion loss and frequency response distortion due to SAW transduction, diffraction, and beam steering, while achieving improved temperature stability SAW device as compared to other commonly used crystal substrates. A low power flow angle and reduced level of diffraction is also achieved.

Abstract: A lanthanum gallium niobate single crystal substrate, referred to as langanite, has a prescribed range of Euler angles for substrate and crystal orientation for improving signal processing for a surface acoustic wave (SAW) device. When a voltage is applied to an input interdigital transducer (IDT) of the SAW device, a surface acoustic wave is generated in the langanite piezoelectric substrate. The surface acoustic wave propagates in a direction generally perpendicular to electrodes of the IDT. The langanite crystal cut and wave propagation directions are defined which reduce insertion loss and frequency response distortion due to SAW transduction, diffraction, and beam steering, while achieving improved temperature stability SAW device as compared to other commonly used crystal substrates. A low power flow angle and reduced level of diffraction is also achieved.

Abstract: A lanthanum gallium niobate single crystal substrate, referred to as langanite, has a prescribed range of Euler angles for substrate and crystal orientation for improving signal processing for a surface acoustic wave (SAW) device. When a voltage is applied to an input interdigital transducer (IDT) of the SAW device, a surface acoustic wave is generated in the langanite piezoelectric substrate. The surface acoustic wave propagates in a direction generally perpendicular to electrodes of the IDT. The langanite crystal cut and wave propagation directions are defined which reduce insertion loss and frequency response distortion due to SAW transduction, diffraction, and beam steering, while achieving improved temperature stability SAW device as compared to other commonly used crystal substrates. A low power flow angle and reduced level of diffraction is also achieved.

Abstract: A system for combining AM and FM transmissions. In-band, On-channel, FM Digital Audio Broadcast (IBOC FM-DAB) allows simultaneous transmission of DAB and FM over existing FM allocations without interfering with conventional analog FM signals. The utility of existing FM spectrum allocations is therefore enhanced.

Abstract: Selected transducer geometries including unbalanced split electrode and three electrode per wavelength structures are employed for use in wide band tapered SAW devices. Combining geometries useful in narrow bandwidth SAW filters for canceling reflected waves leading to triple transit interference, and electrode tapering useful in wide bandwidth SAW filters for permitting transduction of a wide range of surface acoustic wavelengths has the unexpected result of significantly reducing insertion loss and improving triple transit suppression over wider bandwidths than can be achieved with SPUDT designs on non-tapered devices. The interdigitized electrode fingers of opposing bus bars in the transducer have a tapered alignment wherein a period of electrode finger portions along an acoustic wave propagation axis decreases along a transducer dimension.

Abstract: A dual track, low signal loss surface acoustic wave filter includes tapered transducers and tapered reflectors within an axis of propagation for each track to achieve an improved pass band response associated with tapered transducers. The bandwidth of the filter is achieved by adjusting the taper of periodicity normal to the propagation axis. Each track includes reflector gratings mounted on the filter substrate for reflecting a surface acoustic wave propagating from a transducer mounted within each track back to the transducer. Input and output transducers are positioned between the reflectors within each track for providing a direct surface acoustic wave propagation path within the track between the transducers. Alternate parallel tracks have the reflector with an input transducer, and a reflector with an output transducers mounted in an offset alignment with a corresponding adjacent track reflector and transducer for constructively adding surface acoustic wave signals detected within the adjacent track.

Abstract: Surface acoustic wave (SAW) filter performance is enhanced using series-block weighting and line-width weighting combined for providing a transducer having a finely adjusted uniform weighting across the beam profile. Such a transducer permits practical transducer pairing within a surface acoustic wave filter, as well as use with transducers requiring uniform weighting, such as transducers employing apodized weighting. A three electrode per wavelength transducer electrode finger geometry includes line-width weighting for providing a fine weighting control to complement the inherently coarse weighting control of the series-block weighted transducer. Selected transducer geometries including three electrode per wavelength structures are employed for use in wide band tapered electrode finger SAW devices.

Abstract: A system for combining AM and FM transmissions. In-band, On-channel, FM Digital Audio Broadcast (IBOC FM-DAB) allows simultaneous transmission of DAB and FM over existing FM allocations without interfering with conventional analog FM signals. The utility of existing FM spectrum allocations is therefore enhanced.

Abstract: A waveguide for surface acoustic waves comprises a substrate for supporting propagation of surface acoustic waves along a direction at a substrate velocity and a dielectric structure disposed above the substrate along the propagation direction of the surface acoustic waves. The structure includes a central portion disposed along the propagation direction, first and second intermediate portions respectively disposed along each opposed side of the central portion along the propagation direction, and first and second outer portions respectively disposed along each outer side of the first and second intermediate portions along the propagation direction. The central, intermediate and outer portions each has first, second and third intrinsic surface acoustic wave propagation velocities along the propagation direction of the surface acoustic waves, respectively and the first velocity is intermediate of the second and third velocities.

Abstract: A system for combining AM and FM transmissions. In-band, On-channel, FM Digital Audio Broadcast (IBOC FM-DAB) allows simultaneous transmission of DAB and FM over existing FM allocations without interfering with conventional analog FM signals. The utility of existing FM spectrum allocations is therefore enhanced.

Abstract: A Surface Wave Acoustic (SAW) is constructed with hyperbolically curved electrode fingers. The transducers consist of relatively narrower inner electrode fingers and relatively wider outer electrode fingers, and may also be divided into a plurality of tracks with each of the tracks being subdivided into a plurality of subtransducer elements which are capacitively coupled in electrical series.

Abstract: A surface acoustic wave (SAW) radar doppler shift detection system is provided by transmitting a modulation signal having an up-chirp component followed by a downchirp component from a dispersive array SAW assembly to a target, and then receiving the radar return from the target by a receiver which also employs a similar dispersive array assembly. Dispersive array assemblies are constructed with two in line dispersive arrays. The dispersive arrays of the transmitter is positioned relative to two input SAW transducers and two output SAW transducers such that a pulse signal supplied to the two input transducers results in an expanded signal of the output transducers. The expanded signal acts as a modulation signal which is multiplied by an RF and transmitted. The receiving array assembly detects the radar return signal, and, after it is multiplied down to the SAW frequency, compresses it.

Abstract: An acoustic signal is launched as a surface acoustic wave (SAW) by a hyperbolically tapered transducer and then reflected into a bulk acoustic wave (BAW) by a tapered reflector. At each frequency the tapered reflector must satisfy the phase match conditions between the SAW and BAW as defined by their wave vectors. Let k.sub.B be the projection of the BAW wave vector on the surface, and let k.sub.S be the wave vector of the SAW. Then, if k.sub.G is defined to be the wave vector of the grid, i.e., k.sub.G =2.pi./d, where d is the periodicity of the reflecting strips at the frequency under consideration, the phase match condition is k.sub.G =k.sub.B -k.sub.S. A reflector designed to satisfy this condition will reflect the SAW into a BAW at any desired angle (as specified by k.sub.B). The laser beam is then Bragg scattered by the BAW in the usual manner. The advantage of this scheme is that the tapered transducer separates the acoustic signals spatially so no intermodulation products are formed.

Abstract: A delay line with multiple taps is provided in which a hyperbolically tapered input transducer directs a wave to a plurality of hyperbolically tapered partial reflectors. A plurality of hyperbolically tapered output transducer taps are aligned with each of the partial reflectors so that varying delays may be obtained over a wide frequency band.

Abstract: A simple compact, high performance SAW multiplexer is provided by utilizing an input transducer in which hyperbolic tapered electrode fingers are provided. These hyperbolic electrode fingers provide a low frequency output acoustic wave at locations where the spacing between the fingers is relatively large, and a higher frequency signal at points where the spacing is relatively closer. A series of pickup taps which are preferably located on both sides of the input transducer which are also constructed with hyperbolically tapered fingers, but these pickup elements are separated into segments, and isolated by ground straps so that each pickup finger pad will be responsive only to a portion of the frequencies launched by the input transducer. The frequency of the pickup pads varies from a low frequency to a high frequency in alternate manner from one side of the multiplexer to the other.

Abstract: A single mode waveguide dispersive surface acoustic wave (SAW) delay line is formed by aligning an elongated input transducer, which has a pattern of interdigital electrode fingers which launches a wideband SAW, with a beam compressor that feeds an input waveguide. The input SAW passes down the waveguide to a 3 dB coupler which extracts one-half of the power of the incoming SAW and feeds it in the direction opposite to the input wave. Both portions of the SAW are passed to dispersive reflective arrays along a folded path. A series of additional couplers and reflective dispersive arrays that form the folded path serve to further delay the SAW until it reaches a beam expander at the output end which feeds the SAW to an output transducer that is constructed in a manner similar or analogous to the input transducer.

Abstract: A dispersive Surface Wave Acoustic (SAW) filter is provided by a dispersive reflective array, and input and output transducers that we aligned with respect to the array so that the angle of incidence of a SAW from the input transducer is approximately equal to the angle of reflection from the reflective array over the entire range of the dispersive array, wherein the transducers are constructed to provide a frequency response which is matched to the periodicity of the dispersive array. Such design may be accomplished by forming the transducers with hyperbolically curved electrode fingers. The transducers may consist of relatively narrower inner electrode fingers and relatively wider outer electrode fingers. The transducers may also be divided into a plurality of tracks with each of the tracks being subdivided into a plurality of subtransducer elements which are capacitively coupled in electrical series.

Abstract: A surface acoustical wave (SAW) filter is provided by placing at least one pair resonator channels consisting of reflectors and input and output transducers on the surface of a suitable substrate, such as a piezo-electric crystal. One channel of the pair consists of an input transducer and an output transducer which are aligned in a path along which the SAW progresses. The two channels are identical except that the separation distance between the transducers and the reflectors, in one channel is slightly different than the corresponding distance in the other channel. This separation difference serves to broaden the passband for applications which require a broader passband than is obtainable with a single channel resonator filter. Differential detection of the SAW in one section with respect to the other channel is achieved by using a symetrically inverted output transducer, in one embodiment. In another embodiment an offset transducer is used to accomplish the differential sensing.