Abstract: An anti-reflective acoustic diffusion device is provided by a group of irregularly dimensioned diffusing elements positioned on an acoustic wave substrate end that diffuse the SAW and eliminate unwanted acoustic reflections from the end of the substrate. The irregularly dimensioned diffusing elements are substantially irregular in size, shape, composition, and location and provide the desired diffusion into a nearly uniform distributed acoustic energy with a random phase. The anti-reflective acoustic diffusion device can be used with SAW, BAW or multiple acoustic wave configurations. This invention also encompasses an anti-reflective acoustic diffusion system and methods for diffusing acoustic reflections with anti-reflective acoustic diffusing elements.

Abstract: RF programmable SAW filters achieve selectable filter performance by providing tunable input and output interdigital (IDTs) with different synchronous frequencies and substantially reduce electromagnetic interference (EMI) associated with RF signals not of interest. The RF programmable SAW filter includes tunable input and output IDT's, with the input and output IDT's having different input and output IDT synchronous frequencies. The input signal is divided into multiple output signals along multiple signal paths that are applied to an input tap weight network wherein the amplitude of each output signal may be varied individually. The individually weighted signal paths are then applied one each to individual IDT input electrode fingers in a means for IDT input, which is characterized by a synchronous frequency Fin. The IDT input means generates an acoustic wave that propagates to a means for IDT output, which is characterized by a synchronous frequency Fout, where Fin and Fout are not the same.

Abstract: Fiber Bragg gratings (FBG) seismic activity sensors coupled in sensor arrays provide increased sensitivity to seismic activities, lower strain values and an absence of EMI allowing detection of troop and vehicle movements based on ground vibrations generating seismic signals. The FBG sensor head features a spring-mass configuration with a head surface, fiber optic cable and the FBG sensor attached to a spring that stretches during the acceleration of the mass. Waves propagating inside the earth and along the ground arriving at the sensor locations cause movement of the seismic activity sensors embedded in the ground and this movement induces an acceleration-dependent change in the FBG gratings placed on the sensors. In multiple sensor configurations, the cable will be connected to the other sensors in the network. FBG sensors, sensor arrays and sensor methods are provided in several embodiments.

Abstract: The operational flexibility of programmable transversal filters is enhanced by incorporating switch arrays to permit passage for a plurality of tap voltages or signals to particular amplifiers in amplifier arrays. Fixed gain amplifiers may be incorporated to overcome the need to calibrate variable gain amplifiers and to reduced the number of amplifiers required.

Abstract: A programmable SAW transversal filter utilizing a finger array and phase shifters to implement unidirectional transducers for providing low insertion loss and reduced or suppressed triple transient echo. A piezoelectric substrate has an input unidirectional transducer and an output unidirectional transducer formed thereon. A surface acoustic wave is transmitted between the input unidirectional transducer and the output unidirectional transducer. Programmable gain devices and phase shifters are coupled to the respective input unidirectional transducer fingers and the output unidirectional transducer fingers forming multi-phase unidirectional transducers. The present invention may be utilized as a transversal filter in many communication devices, and in particular a multi format personal communication system.

Abstract: Bulk gallium arsenide having a high hold-off voltage is optically activated by a laser resulting in high power output. A high voltage input is applied to a semi-insulating gallium arsenide material. The gallium arsenide material is activated by laser light, thereby resulting in large current conduction. An external oscillating signal is superimposed on the high current resulting in a high power output.