Abstract: A method for detecting faults on a printed circuit board populated with semiconductor electronic components. To detect faults, signal pins on the components are taken in pairs. The an indication of the common mode resistance between those pins and ground is computed from a series of current measurements. An error is detected when the common mode resistance is outside of a predetermined range. A "learn mode" is also disclosed in which the pairs of leads used for the test are selected by taking measurements on a known good board without detailed knowledge of the semiconductor components on the board.

Abstract: Method and apparatus for digital sample rate conversion. A mixed signal tester employing digital sample rate conversion is also disclosed. According to the invention, variable phase jitter is introduced into an input digital signal to produce an intermediate signal at a second sampling rate. The intermediate signal is then low pass filtered to produce the output signal. This technique is used in a mixed signal tester where one period of a stimulus signal is stored in a digital memory. The frequency of the analog stimulus signal is dictated by the rate at which the digital signal is retrieved from the memory. Sample rate conversion is used to convert the signal retrieved from memory, regardless of the rate at which it was retrieved, to the sampling rate for which a digital to analog converter has been calibrated.

Abstract: Apparatus for heating a fiber using microwave energy. The apparatus has a source of microwave energy feeding and applicator. The applicator is configured to concentrate the microwave energy on a chamber holding a fiber. Fibers made or coated using chemical vapor deposition in the apparatus are also disclosed.

Abstract: A reinforcement system for mastic intumescent fire protection coatings. Free floating hybrid mesh embedded in the coating is used to reinforce the coating. The hybrid mesh is made from a combination of high temperature and low temperature yarns.

Abstract: The invention is directed to composite preforms which comprise reinforcing fiber deposited in grooves pre-formed in a metal or ceramic foil.

Abstract: Methods for and preforms for making fiber reinforced composites are disclosed. According to the invention, preforms which allow composites to be machined are provided. Also, preforms with a uniform debulking ratio are provided with non-uniform fiber placement. In addition, methods of forming composites have less material waste and allow more than one composite to be consolidated at one time.

Abstract: A system of fireproofing panels. The panels are light weight and easy to install. Lap joints are formed between the panels and simply secured with screws. No fireproofing material need be applied over the joints or the screws. In one embodiment, the panels are screwed to a corrugated underlayment. In an alternative embodiment, brackets are used to hold several panels in place around structural members. Also, the panels can be fabricated with a metal foil backing which acts as a radiation shield during a fire.

Abstract: In accordance with the invention there is provided a method of producing a densified carbon preform having interior a porous region of graded carbon-silicon carbide, carbon-silicon nitride or ceramic-ceramic composition.

Abstract: A porous preform is densified by heating while emersed in a precursor liquid. Heating is achieved by passing a current through the preform or by an induction coil immersed in the liquid. Ways to control the densification process are also described.

Abstract: Net shape composite articles are made by a molding process. The molded preform is densified in a process where the rate of temperature increase is controlled to prevent distortion. The densified composite objects are impregnated with a secondary material to provide desirable properties such as strength, stiffness, or oxidation resistance. Diverse parts such as golf clubs and engine parts can be made by the process.

Abstract: The tooling includes a central die member and an outer die member spaced thereabout to form an annular, draftless chamber for receiving a composite preform. An annular punch is received in the chamber for pressing the preform at an elevated temperature sufficient to consolidate and bond the preform into the desired composite. The tooling with the preform therein can be enclosed in a gas impermeable envelope (e.g., a steel can) and hot isostatically pressed at the elevated temperature to press the punch against the preform for purposes of consolidation. The coefficient of thermal expansion of the central die member is selected greater than that of the outer die member and the consolidated composite to facilitate removal of the composite from the draftless chamber.

Abstract: A method of forming a bipolar transistor. A base region is implanted into an epitaxial layer. An emitter and collector contact regions are formed of doped polysilicon on the epitaxial layer, the emitter being formed over the base region. The implant is below the surface of the epitaxial layer in all regions not covered by the collector region. Low resistance silicide contacts, such as titanium or cobalt, are formed on the structure in a self-aligned fashion. This method is well suited for forming BJTs as part of BiCMOS circuits.

Abstract: An improved ferroelectric, non-volatile memory comprises an array of ferroelectric capacitors with each capacitor connected to one row and one column select line through a network of diodes. The select lines are connected to a power supply or ground to access one of the cells. The diodes are configured to provide a conducting path between a power supply and ground including the accessed cell while isolating all other cells from the power supply and ground.

Abstract: Built in test circuitry for an array transmitter. The circuitry includes a directional coupler with directivity equal to the mutual coupling between adjacent antenna elements. The direct input port of the coupler is connected to the antenna element and the direct output port of the coupler is connected to the circuitry generating the signal transmitted by the antenna element. The coupled port of the coupler feeds a detector which in turn provides an input to a control circuit. This circuit can be controlled to test, for each antenna element, the RF power driving each antenna element, the effective power radiated from each element, and the operation of the phase shifter coupled to each antenna element.

Abstract: A method of aligning two images of the same scene by matching features in a first image to features in a second image is disclosed. The method comprises identifying edges of objects in the first image using two different processes. The edges identified using both processes are compared and combined into one image representing confirmed edges which are readily identified in other images of the same scene. A template is then formed from the confirmed edges which is matched to a subregion of the second image.

Abstract: A sensor for measuring the rate of angular acceleration of an object around an axis of rotation. The sensor is relatively easy to assemble. The sensor has a fixed coil and a rotating magnet mounted on bearings with a torsion spring providing a restoring torque.

Abstract: A beam steering module for rapidly applying control signals to a plurality of digital phase shifters in a phased array antenna system. The module can receive and store a plurality of phase shift commands for a plurality of phase shifters. The commands may be quickly applied to the phase shifters to rapidly steer the beam from the antenna array.

Abstract: A method of aligning two images of the same scene by matching features in a first image to features in a second image is disclosed. The method comprises identifying edges of objects in the first image using two different processes. The edges identified using both processes are compared and combined into one image representing confirmed edges which are readily identified in other images of the same scene. A template is then formed from the confirmed edges which is matched to a subregion of the second image.

Abstract: A method of processing in a two-channel monopulse receiver and processor is shown to include the steps of: (a) forming composite signals equal to [S+(p+jy)] and [S-(p+jy)] where S in a monopulse sum signal and p and y are, respectively, pitch and yaw error signals; (b) alternately passing the composite signals through a two-channel amplifier; and (c) separating the components in the resulting amplified composite signals for conventional monopulse processing and smoothing to eliminate the effects of any imbalance (in phase or amplitude) between the channels in the two-channel amplifier.

Abstract: A fast and inexpensive set-on oscillator is disclosed. According to the invention, the input signal is processed in two paths. In the first path, a coarse estimate of the input frequency is made. In the second path, the input signal is down converted to a baseband. The frequency of the relatively low frequency baseband signal is measured and a new signal at this frequency is synthesized. The synthesized signal is up converted in frequency. The down-conversion process is performed ambiguously and circuitry is included to resolve the ambiguity. The up conversion process is also performed ambiguously. The coarse estimate of the input frequency is used to resolve this ambiguity.