Abstract: An acousto optic diffractive device including a transducer for launching acoustic energy into a crystal so as to maximize overlap of the acoustic energy within the crystal, and a light source for illuminating the crystal so that the light is diffracted by the overlapping acoustic energy. By operating an acousto optic diffractive device in resonance, the amount of power required to drive the acousto optic diffractive device is significantly lowered, without adversely affecting the wavelength pass band of the device.

Abstract: A cyclic redundancy check generator for a high speed data bus is capable of outputting frames of data and cyclic redundancy check bits concatenated together without any additional space or time delay between frames while operating at a normal clock speed. Data to be transmitted is parallel loaded into series-connected registers via multiplexers connected between the registers. The multiplexers also provide parallel loading of the cyclic redundancy check bits for a frame of data from a look-ahead cyclic redundancy check logic circuit. The output of the logic circuit is also connected to a cyclic redundancy check register. The logic circuit has inputs connected to the final series-connected data register and the cyclic redundancy check register.

Abstract: A coherent radio frequency memory (CRFM) which employs a digital RF memory (DRFM) and a power limiter at its input for limiting the power of the RF input to a relatively constant level over a broad range of such inputs. In addition, a RF noise generating means is coupled to the input of the DRFM at the optimum level for providing random noise for decorrelating spurious outputs of the DRFM.

Abstract: A multiplexed multi-channel DRFM is disclosed including at least one input and output mixer, D/A and A/D conversion means and a random access memory for receiving digital representations of the incoming RF pulse. A channel detector responsive to the frequency of the incoming pulse and an N channel switch responsive to the channel detector selectively connects one of a plurality of local oscillators to the DRFM mixers as the frequency of the incoming RF pulse changes with time.

Abstract: Pseudorandom pulse code generators utilize XOR gates constructed of a pair of back to back parallel connected laser diodes, and fiber optic delay lines connecting the XOR gates to generate PN code sequences with tens of Gbits/s data rates. The single tap generator uses a fiber optic line of a length representing a selected number of delay stages connected to the optical output of the XOR gate and with optical splitters at the end of the delay line and at a selected delay stage feeding back optical signals to the optical inputs of the XOR gate to produce the PN sequence at the end of the delay line. Multi-tap generators utilize additional electro-optical XOR gates connected in serial-parallel, or preferably in a converging cascade arrangement to feed back pulses to the delay line.

Abstract: A high power amplifier combiner for improving the linearity of an output of an amplifier. At least two prelinearizers are used to suppress all distortion products by using feedforward cancelling techniques. The effects of compression associated with the operation of the high power amplifier are reduced.

Abstract: A monitor signal injection system for a feedforward cancellation amplifier having at least one stage in which monitor signals having a constant relatively large amplitude are injected into, for example, a main amplifier. The monitor signals are used to measure the status of all individual components of the amplifier and are useful for fault detection and isolation. In addition, the monitor signals are cancelled in the output to a very low level and as a result, on-line monitoring can be performed without significant radiation of power from a load antenna.

Abstract: A fabricated dielectric aperture assembly includes a first layer of electrically conductive material having an opening therethrough to define a first aperture, a second layer of electrically conductive material spaced from the first electrically conductive layer and having an opening therethrough to define a second aperture and a plurality of solid dielectric layers interposed between the first and second layers of electrically conductive material. The first and second layers of electrically conductive material with the multiple layers of dielectric material interposed therebetween form a generally laminar assembly. A grid-like structure is embedded in the laminar assembly and extends between the first and second electrically conductive layers. The grid-like structure has an inner wall, an outer wall portion, an interior bounded by the inner wall and a plurality of openings extending from the inner wall to the outer wall.

Abstract: The invention is a thermal coupling to promote heat transfer between a heat source and a heat sink with abutting surfaces using a deposition of a thermally conductive substance having a melting point temperature less than the temperature of the heat source such that the substance when heated will be in a liquid state capable of effectively transferring heat between the heat source and the heat sink. The deposition is situated between and contacts the abutting surfaces of the heat source and the heat sink. The substance is contained using a sealant to completely enclose the substance between the heat source and heat sink surface while an adhesive is used to secure the heat source to the heat sink.

Abstract: A gain compensating circuit for a feedforward cancellation amplifier which compensates inbalance (i.e., changes in gain of the power bank amplifier) due to changes in operating conditions or failures in various circuits in the amplifier. The gain compensating circuit compensates the gain variations and restores balance and fundamental cancellation to the circuit while retaining the highly linear characteristics of the amplifier.

Abstract: An photometric sampling apparatus for an object surface shape and reflectance extraction system includes an array of point light sources spaced apart from one another in an arcuate configuration about a common site at which an object is placed from inspection, an array of extended light sources spaced apart from one another in an arcuate configuration about and oriented in different directions toward the common site, and a viewing device for viewing the object from a single direction when placed at the common site in order to extract information corresponding to the image of the object viewed. The array of point light sources can be activated for emitting light therefrom along different orientation angles toward the object at the common site. The array of extended light sources are generated on the surface of a light-diffusing medium, such as a translucent globe, disposed between the array of point light sources and common site.

Abstract: A printed circuit board is described in which an electrically insulating laminate material (40) has first and second sides. An electrically conducting first circuit pattern (15) is embedded in the first side of the laminate material (40), and an electrically conducting second circuit pattern (20) is embedded in the second side of the laminate material (40) electrically insulated from the first circuit pattern (15) by the laminate material (40). A solid interconnection member (20) extends through the laminate material (40) and electrically contacts both the first and second circuit patterns (15,20) at selected locations thereof.The method for fabricating the board includes as a first step the fabrication of a first board panel (10) having a raised electrically conducting first circuit pattern (15) extending from a base layer (14) of conductive material and a raised electrically conducting second circuit pattern (20) extending from the first circuit pattern (15).

Abstract: A method and an apparatus for depositing solder onto component lead pads of a printed wiring board. Solder preforms which are multi-layer, solder containing members are positively biased against the pwb pad which is then introduced into a vapor phase environment defining a temperature gradient between approximately ambient and the temperature of a saturated vapor of a first selected fluid which defines a primary saturated vapor phase with a boiling point which is greater than the melting point of solder. A second fluid having a boiling point which is lower than the first fluid is utilized to generate a secondary vapor blanket in order to prevent excessive loss of the fluid defining the primary vapor phase. The pwb is heated according to a controlled process in which the temperature of the pwb is continuously monitored.

Abstract: An analog to digital converter system is disclosed as comprising a conversion circuit operative for developing a digital output corresponding to the magnitude of an input analog signal, a calibration port arranged for receiving digital calibration data from an external source, adjustable calibration circuitry associated with the conversion circuit, and an adjustment mechanism for adjusting the calibration circuitry in response to data applied to the calibration port.

Abstract: An analog-to-digital converter having error correction in the digital stages of the converter. A calibration microprocessor executes a correction value program prior to, or interspaced with, the normal operation of the converter. From either of two calibration programs, appropriate digital correction values are stored into a digital memory. The analog input signal is converted to a digital signal by a main range analog-to-digital converter, with the output of the converter addressing the memory containing the error correction values. The main range digital value is reconverted to an analog signal which is compared to the original input signal to determine the difference therebetween. This analog difference is converted to a digital signal and combined with the main range digital signal and the addressed correction values to produce the digital output signal of the conversion system.

Abstract: A device for positioning within the interior of a conduit for enhancing heat transfer between the conduit and an enclosed flowing coolant fluid comprised of a longitudinal member having a plurality of protuberances for generating turbulent flow within the conduit with the longitudinal member being resiliently secured within the conduit such that the force of the fluid flow will not displace the member.Design of the device is such that installation or removal from a tube may be easily accomplished by merely sliding the device in or out of the tube.

Abstract: A modulated single channel (as opposed to a quadrature channel) digital radio frequency memory (DRFM) system retrievably stores incoming radio frequency (RF) signals in a digital memory and replicates the RF signals at the output. The input RF signal to be stored is mixed with a local oscillator (LO) signal modulated with a waveform pattern to produce an intermediate frequency (IF) signal which is digitized and retrievably stored in the digital memory. The stored digital values are later retrieved from memory after the programmed delay time, and converted back to an analog IF signal and mixed with the local oscillator to produce the output RF signal. The LO signal is modulated with the same waveform used to produce the input IF signal. A controller for controlling the modulation of the LO signal and the memory includes a ROM for storing a pseudo random string of one bit words and an address counter to drive the ROM beginning at a starting address upon the occurrence of the input RF signal.

Abstract: The present invention provides a system that cancels second time around clutter in a multiple pulse repetition frequency radar system which uses three groups of differently spaced pulses. The system processes returns from a clutter cancellation group of eight pulses from three different concatenated pulse repetition frequency groups, using two pulses from one group, all pulses from a central group and two pulses from a third group. The pulse returns are each multiplied by a different weight and the eight weighted returns are added together and output as the filtered return signal. As the weights of the outer pairs of pulses increase, as compared to the weights of the inner four pulses, the second time around clutter cancellation effects increase and the first time around clutter cancellation effects decrease.

Abstract: A decorrelated spur digital radio frequency memory (DRFM) system stores incoming radio frequency (RF) signals in a digital memory and at some later time replicates these RF signals at the output. The input RF signal to be stored is mixed with a local oscillator (LO) signal, which is coded with a decorrelation waveform, to produce an intermediate frequency (IF) signal which is next digitized with a multibit analog-to-digital (A/D) converter. This data is stored in a digital memory and is later retrieved from the memory and converted back to an analog IF signal. The IF signal is then mixed with the coded LO to produce a replica of the original RF signal. The code on the LO is the same decorrelation waveform used to produce the input IF signal. The resultant RF output spectrum can be made to be spectrally clean, i.e., containing no spurious harmonic signals arising from the signal's quantization.

Abstract: The invention is an automated solder joint inspection system for determining the quality of a specular soldered joint through examination of the shape of the joint surface using a series of point light sources and the associated highlight reflections from the joint surface. The light from the point light sources, which is directed toward the solder joint, is reflected in a pattern from the solder joint to an array of light responsive transducers, such as a camera, at a fixed location. Utilizing the intensity values from the light responsive transducer array, a binary grid map is generated for the reflections from each point light source. Using known surface features of solder joints along with curve fitting techniques, a series of grid maps may be mathematically interpreted to reconstruct the solder joint surface. A rule-based system, through comparison with acceptable solder joint surface features, evaluates and classifies the joint for an acceptability determination.