Abstract: A modem is described for transmitting digitally coded information between an information distribution network and a data processing unit, which modem is responsive to modem control instructions provided by the very same keyboard input providing data transmission. The modem is capable of distinguishing modem control instructions from data transmission and includes such control functions as automatic telephone answering, automatic redialing of busy numbers, and an automatic escape sequence for terminating data transmission.

Abstract: Component masks are described for preserving unoccupied holes in a printed circuit board when such board is subjected to wave soldering. Each mask is a body of plastic resistant to adherence to the solder and capable of withstanding the temperature of solder when the printed circuit board is subjected to wave soldering and includes a supporting block from which a plurality of parallel pins protrude for reception into the printed circuit board lead-holes to be preserved. The pins are spaced from one another by distances equal to the distances between lead-holes on a printed circuit board, and component masks are provided respectively having a single row and a double row of such pins. Each pin is tapered slightly toward its free end, and is connected to its associated supporting block by a conically shaped transition body.

Abstract: Disclosed herein is an escutcheon for concealing a relatively expensive electronic apparatus, particularly magnetic tape players disposed in automobiles and the like. The escutcheon includes a face plate having indicia disposed on a front face thereof suggestive of a relatively inexpensive AM radio. The escutcheon includes means insertable into a receptacle provided for receiving magnetic tape magazines for firmly anchoring the escutcheon onto the magnetic tape player. The escutcheon disguises the appearance of an expensive electronic apparatus as an inexpensive radio to conceal its identity so as to thwart thieves.

Abstract: Wood particles are distributed in selected patterns and bonded together by an adhesive to form a multilayer wood particleboard. The board has a central core of three layers of wood strands sandwiched between two outer surface-forming layers of fine wood particles. The wood strands forming the central core have a length which is several times greater than their width, with their fiber elements substantially parallel to their length. The fine wood particles are irregularly contoured wood particles having a width and thickness less than the average width of the strands forming the central core layers. Each of the three central core layers has its wood strands distributed in a parallel orientation pattern, with the strands in the outer two layers of the core parallel and the strands of the center layer perpendicular to those of the outer two layers to form a layer-to-layer cross-oriented strand pattern.

Abstract: The loudspeaker system utilizes an ellipsoidal reflector of substantially the same diameter as the low frequency (LF) driver, positioned on-axis of the LF driver, as a reflective dispersing means for increasing the angular dispersion of acoustical energy, especially in the upper range of the LF driver. The ellipsoidal reflector is also utilized as a means to mount the higher frequency (HF) drivers in such a way that their axes diverge generally uniformly away from a point near the center of the ellipsoid so that the sound field of the higher frequency drivers is also well dispersed. The result is that the ellipsoid causes acoustical energy both from the LF driver and the HF drivers to appear to emanate from a point near the center of the ellipsoid, simulating the sound field generated by a single wide frequency range point source of sound.

Abstract: A pivotally-mounted laser or other collimated light beam source is maintained in a level position by means of a thermal motor capable of precise small movements. Actuation of the motor is accomplished by a control amplifier whose inputs are responsive to the output of a level-sensitive transducer. Pre-selected grades may be established and maintained by means of a second thermal motor which is employed to change the angular relationship between the pivotally mounted laser or light source and the level-sensitive transducer.

Abstract: The laser is an internal mirror hermetically sealed design, utilizing an envelope made principally of glass. The effects of thermally produced distortion on mirror alignment are minimized by providing a thermally and electrically conductive liner in close contact with the envelope wall. Misalignment of the discharge-confining capillary tube is minimized by supporting its inner end by means of a concentric stiff but resilient spring, thus avoiding an unsupported cantilevered section of the capillary. Reliable starting even in environments where the ambient electromagnetic radiation is inadequate for gas ionization is secured by providing a radioactive source in the region of the anode electrode.

Abstract: An apparatus for constructing a molding form for a concrete deck structure is disclosed. U-shaped spring clips secure flexible form boards to vertically anchored support stakes, with a flat side of each form board positioned along a desired border of the concrete. Each spring clip has a pair of arms spaced apart, each of which has a slot for receiving an anchored stake. The slots in the two arms are in registration to receive the anchored stake simultaneously, and appendages extend from the free end of each arm to hook onto a concrete form board and secure it to the anchored stake. Each spring clip includes a generally S-shaped flat spring defining a resilient wedge structure near its free end which transmits a spring force that holds the gripped form board firmly against the anchored stake.

Abstract: The circuit of the angle resolver compares a first angle to a second angle and produces an output voltage which is an analog representation of the angular difference between the two. One of the angles, which might be a controlled variable is represented by a pair of electrical signals from an electronic compass, for example, which are analog representations of the sine and cosine of the angle. Within the angle resolver circuitry, an analog switch and integrator form an output voltage which is accurately proportional to the sine of the angular difference between the two angles in accordance with: sine (A--B)=(sin A) (cos B)--(cos A) (sin B), where B might be the reference angle, and A, the unknown angle. For cases where A is nearly equal to B, A--B is a small angle, and sin (A--B)=A--B. The values of cos B and sin B are very simply linearly approximated in the present invention by the technique of sampling and integrating the sin A and cos A inputs.

Abstract: A demodulator for frequency shift keyed carrier signals is described. A conditioned F.S.K. signal is simultaneously fed to a pair of rising edge triggered single shot voltage generators, such carrier signal being inverted prior to being fed to one of such single shots. The single shots are each triggered upon receipt of a cycle edge to initiate an output pulse having a duration falling between the time intervals distinctive of the cycles of the two possible carrier signal frequencies. The next rising edge received by each causes the respective single shots to retrigger, and latches the previous output of each into the first element of an associated serial memory device. The successive elements of each of the serial memory devices, store the state output signals of adjacent cycles of the carrier signal, with the states in one of such devices being one-half cycle apart from the states in the other.

Abstract: A simulated volcanic rock is described, as well as a method for producing the same. The rock includes a central core encased within a concrete coating formed from a plaster which includes an aggregate of expanded polymer particles. During production of the rock, the polymer particles at the exterior surface of the coating are exposed and subsequently dissolved to leave such exterior surface with pocks simulating the gas-formed voids typically present on the surface of natural volcanic rock.

Abstract: The device consists of a pair of semicircular, transparent sheets of resilient plastic material, one of the sheets having molded on one surface a series of pegs which are insertable through the mesh of the screening. The other sheet has a corresponding pattern of holes to receive the pegs such that the two semicircular sheets can be secured together with a portion of screening between them in sandwich fashion. The device is used to reinforce and protect the mesh screening adjacent to the handle of a screen door so that bulging or accidental puncturing of the screening is avoided.

Abstract: A water stop for sealing the joint between a swimming pool wall and an overlying concrete deck is described, which water stop includes a flange useful in applying a finishing layer to the deck coping. The water stop includes a water barrier component that has a flat shelf adapted to seat generally horizontally on the upper end of a pool wall, and a skirt element extending transversely downward from the shelf to seat along the pool wall. A flange projects outwardly from the barrier component beyond its structure and inwardly of the pool, to present a finishing edge for the lower edge of a finishing layer applied to the deck coping surface.

Abstract: The limestone grits, formerly considered a waste product of the lime slaking process, become economically salvageable after successful fractionation to separate them into three parts: (1) caustic chemicals useful in the kraft pulping process; (2) under-, and over-calcined small limestone particles having an impurity level virtually identical to that of raw limestone; (3) caustic-free large particles containing the majority of residual impurities such as silicon, iron, magnesium, and chromium. The fractionation of limestone grits is economically carried out by a refluxive hydraulic washing system in which the untreated limestone grits from the slaker and first introduced into the open mouth of a vortex washer where they undergo an initial separation in which most of the smaller particles and caustic chemicals are recovered.

Abstract: The tool consists of a pair of forming blades made of stainless steel held at a slight dihedral angle of 10.degree., with a gap between them wide enough to accommodate the surface of an expansion joint or drain. The blades are rigidly held by a cast aluminum bridge which arches over the gap. A pair of rubber wipers project slightly into the gap for clearing wet concrete from the surface of the expansion joint. The wipers are removably supported in aluminum wiper holders. Compressive spring force is generated by a steel rod extending between the blocks and through the arch of the bridge. Removal of a spacer on the steel rod permits sliding the wiper assembly aside sufficiently to release it from the tool to permit changing rubber wipers. A small amount of adjustment of the gap width to accommodate different width joints is permitted by means of movement of the blades in slotted openings in the bridge. Larger variations can be accommodated by substituting differently dimensioned blades.