Abstract: An electronic level includes both a numeric scale and a graphic scale having a "fan-like" configuration of a number of elongated wedge-shaped segments. The inclination of the device is shown numerically using a digital display and, at cardinal angles, graphically by illuminating various segments on either side of a central segment line. The numeric scale provides a numeric indication of the angle of the level from 0.degree. to 360.degree. with respect to a null position, thus satisfying the need to measure absolute angles or slopes. The graphic display provides high resolution at cardinal angles while the numeric display provides lower resolution over 360.degree..

Abstract: Additives have been developed that reduce the emission of volatile monomers, e.g. styrene in unsaturated polyester resin system as well as producing a hard, weather resistant gel coat at the surface. Upon reaction, the polymeric additive comes to the surface and reacts with air to form a hard, mar resistance film. The film also has some reactive double bond that will react with the unsaturated polyester portion. The result is a product that has reduced styrene emissions for static or sprayable unsaturated polyester resins, a hard and clean gel coated surface for low pressure architectural sheet application and a class A surface for Sheet Molded and Bulk Molded Parts. These additives exhibit excellent chemical and weathering properties as well as producing a hard mar resistant surface in peroxide or ultra-violet curable polyester systems.

Abstract: A device for locating the edges of wall studs includes a comparison circuit connected to each of three capacitive elements. As the device is moved along a wall, the comparison circuit monitors the relative charge time associated with each capacitive element, the charge times providing an indication of the relative capacitances of the three capacitive elements. Changes in the relative capacitances of the three elements as the device is moved along a wall are due to a change in the dielectric constant of the wall, which normally results from the presence of a wall stud behind the surface over which the device is moved. The comparison circuit uses differences in the measured relative capacitances of the first, second, and third capacitive elements to locate the edges of the stud.

Abstract: A cost-effective wideband radar system capable of locating objects, such as reinforcing steel rods, pipes, and air bubbles, objects located behind or within a volume of, e.g., concrete, soil, wood, or air. A sequence of wideband radar pulses are emitted without a carrier from each of two transmit antennas. The system includes a receiver that detects reflected pulse energy (echoes) that result when transmitted pulses encounter a change in material (e.g., an air to metal change or concrete to metal change). These amplitudes of the echoes are visually displayed along with the length of the transmit/echo path for each transmitter. The lengths of the displayed transmit/echo paths are compared to determine whether the system is centered over an object located within or behind a volume, the system being centered over the object when the transmit/echo paths for each transmitter/receiver combination are of equal length.

Abstract: A ground penetrating impulse radar system provides three-dimensional images of targets. A moving array of transmitting and receiving antennas provides narrow beamwidths and high gain by real and synthetic aperture beam processing. Narrow pulsewidth impulse signals are utilized to obtain high resolution. Round trip time is calculated for each three-dimensional pixel in a search volume, and is used to process three dimensional imagery. Analog to digital conversion can be utilized, so all signal processing is accomplished digitally. The radar system is applicable to detecting small objects near the surface by using very narrow pulses, and also can be applied to detect large, deep objects by wider pulses.

Abstract: A cost-effective ultra-wideband radar system capable of locating nearby buried objects such as reinforcing steel rods, pipes, and other objects buried in concrete, soil, behind walls, or in the air. A sequence of ultra-wideband radar pulses e.g. at a plurality of frequencies in a range of about 2 MHz to about 10 GHz are emitted without a carrier and the system detects deflected pulse energy caused by the transmitted pulse whenever encountering a change in the medium i.e. an air to metal change or concrete to metal change. This reflected energy is detected and visually displayed. The range gate delay of the receiver is continuously varied, thus changing the distance from the unit to where the reflected energy would be potentially detected from the target. By continuously sweeping the "depth" of the scan, the operator need only move the unit in two dimensions across the surface to detect objects buried or hidden at varying depths interior to or behind the surface.

Abstract: A cost-effective ultra-wideband band radar system capable of locating nearby buried objects such as reinforcing steel rods, pipes, and other objects buried in concrete, soil, behind walls, or in the air. A sequence of ultra-wideband band radar pulses are emitted without a carrier and the system detects deflected pulse energy caused by the transmitted pulse whenever encountering a change in the medium i.e. an air to metal change or concrete to metal change. This reflected energy is detected and visually displayed. The range gate delay of the transmitter is continuously varied, thus changing the distance from the unit to where the reflected energy would be potentially detected from the target. The receiver is driven by a fixed delay. By continuously sweeping the "depth" of the scan, the operator need only move the unit in two dimensions across the surface to detect objects buried or hidden at varying depths interior to or behind the surface.

Abstract: A sensor device and method for finding the location of a conductor such as a wire, having an alternating voltage and which is not readily visible, i.e. hidden in the wall of a structure or buried. The detector device has four plates in two balanced pairs and arranged in a quadrilateral with a central reference plate. This reference plate provides a common mode rejection of the background electric field typically present for instance on the wall, which is induced by the alternating voltage in the wire. A sharp signal peak is detectable immediately over the wire from a differential signal of a pair of the balanced plates, when the plates of the pair are located on either side of the wire. Also a determination based on the sum and difference of the signals from the two plates allows one to determine the relative phase induced in the two plates of each pair, which indicates the direction in which the sensor device should be moved in order for the plates to be immediately over the target wire.

Abstract: A pulse width modulation analog to digital converter can accommodate both wide band AC analog input signals and DC analog input signals. If the frequency of the input signal is much higher than the conversion rate of the PWM analog to digital converter, then the output digital pulse is of constant width versus the analog input signal amplitude. If the frequency of the analog input signal is lower than the conversion rate, then the output digital signal is a train of variable width pulses whose width tracks the amplitude of the analog input signal.

Abstract: A metal detector includes a receive coil and a transmit coil connected in an inductive bridge. To overcome imbalances in the bridge due for instance to misalignment of the coils or the presence of mineralization in the medium which is being examined, the metal detector automatically produces a nulling (bucking) signal to cancel out the effects of any unwanted receive coil signals detected during calibration. This nulling signal is a nulling current both in terms of level and phase, and its level and phase are determined during a calibration process prior to actual metal detection. By inclusion in the metal detector of a microprocessor (microcontroller) operating at a much higher frequency than the variations in the magnetic field used to detect metal, the nulling signal generation is performed with a high degree of time resolution, resulting a precision metal detector which adaptively ignores any unwanted signals.

Abstract: A pyramidal horn antenna that decreases ringing in radar systems that are placed against a solid volume of e.g. concrete or wood for finding an object in or behind the solid volume. The antenna includes a solid, pyramid-shaped dielectric, the pyramid shape including a rectangular base and four triangular sides that extend from the base to meet at the apex of the pyramid. Two conductive triangular plates overlay opposite ones of the four sides of the pyramid, each of the plates including an electrical connection for coupling the plate to a radar system. The pyramid-shaped dielectric has a dielectric constant that approximates the dielectric constant of the solid volume, and therefore provides an impedance match between the antenna and the solid volume.

Abstract: A dual sensitivity stud sensor senses studs through both thick and thin surfaces. Studs are sensed by detecting a change in the capacitive loading of plates as they are moved along a surface and into proximity with a stud. The sensor informs the operator when the sensor has (incorrectly) been calibrated over a stud. The sensor also informs the operator if the sensor is placed against a surface either too thick or too thin for stud detection. Through use of a digital register, the sensor remains calibrated indefinitely while the sensor is powered on.

Abstract: An electronic level includes a visual scale (similar to a ruler scale) having a number of parallel line segments. The inclination of the device is shown by illuminating various of the scale line segments on either side of a central line. When the device is at a null (typically level or plumb) only the central scale line is illuminated, indicating the inclination away from the null. Each scale line segment indicates a fraction of an inch of inclination per e.g. two feet of horizontal distance (the two feet being the level length in one version) which conforms to the normal use of such levels by building tradesmen. The level is calibrated by taking two readings with the level rotated 180.degree. between readings. The readings are averaged and negative feedback is provided to the level sensor itself to null out any system mechanical or electrical offsets.

Abstract: An electronic level for leveling a fence post or other vertical member includes two inclination sensors mounted orthogonally. The sensors measure inclination in each of two orthogonal planes. The output of the sensors is displayed by two scales which intersect at a central point. Each scale includes a number of triangular shaped segments arranged along a line. Each of the two scales depicts inclination in a plane determined by its associated sensor; when the fence post is at the vertical position the display so indicates by illuminating a central display point at the intersection. Otherwise the illuminated triangular shaped arrowhead for each scale indicates in which direction the worker is to move the fence post in each of the two corresponding dimensions so as to achieve verticality.

Abstract: A cost-effective ultra-wideband radar system capable of locating nearby buried objects such as reinforcing steel rods, pipes, and other objects buried in concrete, soil, behind walls, or in the air. A sequence of ultra-wideband radar pulses are emitted without a carrier and the system detects deflected pulse energy caused by the transmitted pulse whenever encountering a change in the medium i.e. an air to metal change or concrete to metal change. This reflected energy is detected and visually displayed. The range gate delay is continuously varied, thus changing the distance from the unit to where the reflected energy would be potentially detected from the target. By continuously sweeping the "depth" of the scan, the operator need only move the unit in two dimensions across the surface to detect objects buried or hidden at varying depths interior to or behind the surface.

Abstract: A cost-effective ultra-wideband band radar system capable of locating nearby buried objects such as reinforcing steel rods, pipes, and other objects buried in concrete, soil, behind walls, or in the air. A sequence of ultra-wideband band radar pulses are emitted without a carrier and the system detects deflected pulse energy caused by the transmitted pulse whenever encountering a change in the medium i.e. an air to metal change or concrete to metal change. This reflected energy is detected and visually displayed. The range gate delay is continuously varied, thus changing the distance from the unit to where the reflected energy would be potentially detected from the target. By continuously sweeping the "depth" of the scan, the operator need only move the unit in two dimensions across the surface to detect objects buried or hidden at varying depths interior to or behind the surface.

Abstract: An electronic level includes two loudspeakers, one located at each end of the level housing (beam) and controlled in a stereo-like manner. Thus the volume balance between the two loudspeakers is controlled by the angular inclination of the level. The user hears the volume difference between the two loudspeakers and thus has an auditory cue in which direction to rotate the level to achieve exact level or plumb. The loudspeakers are located at the extreme ends of the level housing to achieve maximum stereo separation. The separation reinforces the user's natural binaural hearing capability in order to distinguish which loudspeaker is turned on or off. The loudspeakers are turned on or off so that at level or plumb both loudspeakers are on. For an out of level conditions one loudspeaker is on and the other is off; the end of the level which is high when out of level has its loudspeaker on, and the other loudspeaker is off.

Abstract: An electronic level includes a visual scale having a "fan-like" configuration of a number of elongated wedge-shaped segments. The inclination of the device is shown by graphically illuminating various of the segments on either side of a central segment line. When the device is at a null (typically level or plumb) only the central segment is illuminated. Each segment indicates a predetermined amount of inclination from the null.

Abstract: A framing layout tool includes two squares each with two legs or blades 90.degree. apart. The squares are pivotally attached at their vertices by a pivot pin including a knurled locking nut. One of the squares includes a longitudinally aligned electronic plumb and level indicator on one of the legs. The other leg of that square includes indicia on a leg reference edge for indicating rise-over-run integers representative of the angular separation of that other leg and a leg of the other square. Indicia indicating the actual angle between such legs is also contained on an opposite reference edge of that other leg. The layout tool has particular utility for accurately marking the location of a plumb cut, seat cuts and a ridge cut in roof rafters where the blade of the second square is placed on an inclined rafter and oriented with the electronic level in a vertical plumb position. When a visual and auditory indication of exact plumb is obtained the clamping nut is locked.

Abstract: A dual sensitivity stud sensor senses studs through both thick and thin surfaces. Studs are sensed by detecting a change in the capacitive loading of plates as they are moved along a surface and into proximity with a stud. The sensor informs the operator when the sensor has (incorrectly) been calibrated over a stud. The sensor also informs the operator if the sensor is placed against a surface either too thick or too thin for stud detection. Through use of a digital register, the sensor remains calibrated indefinitely while the sensor is powered on.