Abstract: A hinge (5) having a first, relatively stationary yoke (8) and a second, relatively rotating yoke (10). A torquing means (17) fixed with respect to the first yoke (8) transmits torque to the second yoke (10) via a block (18) retained within a cavity (20) of an elongated hinge pin (15) that is aligned along the axis of rotation (z) of the two yokes (8, 10). The torquing means (17) is coupled to the hinge pin (15). The yokes (8, 10) self-align about two orthogonal axes (x, y) that are also orthogonal to the axis of rotation (z). The block (18) is free to pivot within the cavity (20) about the x axis, while the second yoke (10) is free to pivot about the y axis about the hinge pin (15) and block (18).

Abstract: A bit synchronizer for a BPSK input signal having a sinusoidal carrier frequency f that is much greater than the modulating signal bit rate. The synchronizer comprises means (29, 31) for repetitively sampling the amplitude of the input signal over a preselected sampling interval portion of each modulating signal bit period (T). For each sampling interval, three numbers are recorded: N1, the total number of samples; N2, the number of samples that do not change sign with respect to a reference sample; and N3, the number of samples that do change sign with respect to the reference sample. When the number of samples not changing sign exceeds a preselected threshold value, which takes into account noise corruption of the input signal, bit synchronization is declared, a synchronized output clock (39) is generated, and digital data having a 180.degree. ambiguity is sent to subsequent ambiguity resolution means.

Abstract: A layer of HgCdTe (15) is epitaxially grown onto a CdTe substrate (5). A HgTe source (3) is spaced from the CdTe substrate (5) a distance of between 0.1 mm and 10 mm. The substrate (5) and source (3) are heated within a temperature range of between 500.degree. C. and 625.degree. C. for a processing step having a duration of between 5 minutes and 4 hours. During at least 5 minutes of this processing step, the substrate (5) is made to have a greater temperature than the source (3). Preferably the substrate (5) is never at a lower temperature than the source (3). The source (3) and substrate (5) are heated together in a thermally insulating, reusable ampoule (17). The CdTe substrate (5) is preferably a thin film epitaxially grown on a support (10) e.g., of sapphire or GaAs. When support (10) is not used, the CdTe substrate (5) is polished; and sublimation and solid state diffusion growth mechanisms are present in the growth of the HgCdTe (15).

Abstract: A coil (21) mounted inside a spinning guided object (20) has an electrical current (i) induced therewithin by means of interaction with the earth's magnetic field (B). A similar coil (22) mounted on the launch platform spins at the same rate (W) as the object's coil (21), although these two coils (22, 21) are not necessarily in phase. Apparatus (35) associated with the launch platform generates a constant phase signal (P) having amplitude and sign representing the phase difference between the signal generated by the launch platform's coil (22) and the vertical direction. This phase information (P) is used to correct the guidance commands sent from the launch platform to the guided object (20), or, alternatively, is fed directly to the guided object (20) for correction by said object's on-board computer. A hold fire indicator (33) is provided to inform the operator when the output from the launch platform's coil (22) is above or below a predetermined level sufficient for adequate roll angle compensation.

Abstract: An electromagnetic power divider/combiner comprises N radial outputs (31) having equal powers and preferably equal phases, and a single axial output (20). A divider structure (1) and a preferably identical combiner structure (2) are broadside coupled across a dielectric substrate (30) containing on one side the network of N radial outputs (31) and on its other side a set of N equispaced stubs (42) which are capacitively coupled through the dielectric substrate (30) to the N radial outputs (31). The divider structure (1) and the combiner structure (2) each comprise a dielectric disk (12, 22, respectively) on which is mounted a set of N radial impedance transformers (14, 24, respectively). Gross axial coupling is determined by the thickness of the dielectric layer (30). Rotating the disks (12, 22) with respect to each other effectuates fine adjustment in the degree of axial coupling.

Abstract: A conformal coating protects electrical components used in a high voltage high vacuum evironment from flashovers caused by patch charging. The coating comprises a semiconductor powder, preferably elemental boron, having a low atomic number and uniformly dispersed throughout an organic binder such an an epoxy. The coating's surface resistivity is made to be high enough so that the coating acts as an electrical insulator. On the other hand, the coating's surface resistivity is sufficiently low that any patch charge is siphoned off to the nearest conductor. The surface resistivity is regulated by the proportion of semiconductor present. The coating's secondary electron emission coefficient is 1 or just under 1. The coating has the properties of adhesion, stability, elasticity, provision of mechanical support, and resistance to solvents and heat. An example is given in which the epoxy comprises resin, fine particles of elemental boron, and a polyamide hardener.

Abstract: Non-invasive and non-destructive apparatus and method for imaging, recording, and comparing the mass density distributions and thicknesses of test specimens (19F, 19B). A source of medium-to-high-energy photons (3) directs a photon beam (4) at an electron source (17) comprised of high atomic number material, which emits in response thereto electrons (9F, 9B), some of which are not absorbed and not widely scattered by the test specimens (19F, 19B), but are transmitted therethrough and captured on one or more photographic films (15F, 15B) in contact with said specimens (19F, 19B). Net recorded film (15F, 15B) densities are in inverse relation to the mass density distribution of the corresponding test specimen (19F, 19B). A filter (5) is interposed between the photon source (3) and the capture film (15B) when back emission imaging (B) is employed. The filter (5) is optional when forward emission imaging (F) is used.

Abstract: A system for controlling the velocity and attitude of an exoatmospheric projectile (10) that spins about a spin axis (z). Several thrusters (e.g., 1-7) are disposed along the outer surface (8, 9, 11) of the projectile (10) for performing three prescribed functions. The number of thrusters (e.g., 1-7) is minimized to save weight. As few as four thrusters (1-4) can be used to perform the three prescribed functions, which are: (A) reorienting the spin axis (z) in inertial space, by firing the axial thrusters (1, 2, 6, 7); (B) adding velocity to the projectile (10) in any direction, without a concomitant change in the orientation of the spin axis (z), by firing continually a combination comprising at least one of the thrusters (1-7); and (C) changing the projectile's spin rate (W), by firing one of the radial thrusters (3, 4). Nutation dampers, such as ball-in-tube nutation dampers (20), can be used to decrease the cone angle E and thereby improve the pointing accuracy of the spin axis (z).

Abstract: A waveguide coupler for quickly, easily, and reliably coupling and decoupling two waveguide sections (1A, 1B). The ends (17A, 17B) of the waveguide sections (1A, 1B) are translationally aligned by means of closely fitting coaxial cylindrical shells (41, 21) surrounding the waveguide ends (17A, 17B, respectively). The ends (17A, 17B) are recessed within the shells (41, 21, respectively). A freely rotatable cylindrical sleeve (31) is axially positioned around one of the waveguide ends (17B) by means of a retaining means (13). Less than one revolution of the sleeve (31) is sufficient to effectuate coupling or decoupling of the waveguide sections (1A, 1B), by means of a set of substantially identical helical grooves (34) within the inner surface of the sleeve (31) engaging pins (49) protruding from one of the shells (41).

Abstract: A log periodic antenna (1) comprising two substantially identical non-resonant elongated log periodic conductive zig zag structures (3,5). The structures (3, 5) lie side-by-side in close proximity to each other in substantially the same plane defined by a planar dielectric board (13). The zig zag structures (3, 5) are axisymmetric about a line of symmetry coinciding with the midline of an impedance matching feed line (18). The feed line (18) comprises two substantially identical elongated conductive members (7, 9), sandwiched around the dielectric (13). The first zig zag structure (3) and the first member (7) lie on one side of the dielectric board (13), while the second zig zag structure (5) and the second member (9) lie on the other side of the board (13). At microwave frequencies, the zig zag structures (3, 5) and the member (7, 9) are preferably mounted on the dielectric board (13) using printed circuit techniques.

Abstract: In a method for fabricating lightweight bipolar metal-gas battery cell stacks (1), a segmented frame (21, 23) for insulating and mechanically supporting the stack (1) is fabricated of dielectric materials. Each cell (3) has associated therewith first and second frame segments (21, 23) associated with negative and positive electrodes (5, 7, respectively). Weld tabs (25, 27) are welded to the negative and positive electrodes (5, 7, respectively), and are welded together external to the cell frame (21, 23). Electrolyte is added to each cell (3), preferably as it is fabricated within the enveloping cell frame segments (21, 23). Alignment rods (34) align the stack (1) components, and assist in compression-sealing adjacent frame segments (21, 23) by means of compressing mating tongues (43) and grooves (41).

Abstract: An antenna reflector structure of the offset-fed type which is suitable for use on spacecraft. The reflector structure includes a central boom, a number of spaced ribs on the boom, an RF reflective mesh layer adjacent to the outer, transverse peripheral edges of the ribs, and contoured angle members for securing the mesh layer to the ribs to provide a specific contour for the reflector surface defined by the mesh layer. The boom can be of one-piece construction or formed from telescoped segments. The reflector structure is deployable and furlable. Several embodiments of the reflector structure are disclosed.

Abstract: A soft digital limiter (2) for limiting an analog input signal (1) from a maximum expected range (61) to a useful range (60). The number (m) of desired levels of resolution in the limiter (2) is preselected to be any power of two. An analog-to-digital converter (9) converts the input analog signal (1) to a digital representation (20). The converter (9) has its input voltage rating matched to the maximum expected range (61) and its output resolution matched to the preselected degree (m) of resolution. In the preferred two's complement numbering system, the condition for the input signal (1) falling within the useful range (60) is that the most significant p+1 bits of the digital representation (20) are all identical, where p is the number of bits required by the converter (9) to delineate that portion of the maximum expected range (61) outside of the useful range (60). A network of comparators (e.g., 38, 39) implements this condition.

Abstract: In a guided projectile such as a missile, it is often necessary to negate the lift force imparted by the wings (5) during early low velocity stages of flight. Thus, wings (5) can be flattened against the airframe (2) of the missile (1) by a passive constraint, e.g., a shrink tubing (35) which disintegrates due to aerodynamic heating at a higher velocity stage of the flight, allowing each wing (5) to deploy into a position generally orthogonal to the airframe (2). The deployment force can be provided by torsionally and compressionally preloaded springs (19).

Abstract: A digital system for controlling the attitude of a spacecraft (14), e.g., a satellite, with respect to three orthogonal axes. The system can control satellites (14) in parking orbit, transfer orbit, or final operational orbit, whether or not the satellite (14) employs one or more momentum wheels. A processor (2) converts weighted data from spacecraft sensors (12), representing angular orientation and angular velocities about each of the three axes, into thruster pulsetrain signatures to command the firing of each of six thrusters positioned about spacecraft (14), a positive and a negative thruster being positioned to impart both directions of angular momentum about each of the three axes. Each thruster pulsetrain signature is created once every processed error cycle period T1, and contains a varying number of pulses of varying widths. A negative feedback PWPF loop (2, 16, 20, 22, 24) is actuated for each of the three axes, preferably several times each T1 in order to achieve better thruster on/off resolution.

Abstract: A vacuum dewar for infrared detectors is disclosed, in which unitary Kovar leads are used to reduce heat load and improve reliability and ruggedness. The Kovar leads are encapsulated in the glass walls of the hollow stem which carries the sensor array and supplies cryogenic fluid for cooling the array. The Kovar leads extend throughout the entire length of the stem to form both the electrical feed-through and the contact points at each end of the stem for the attachment of wire leads or cables, and to form a reinforcing structure for the stem. A fabrication method is also disclosed, in which a unitary Kovar leadframe is held under tension while two concentric glass tubes, between which the leadframe is vacuum-sandwiched, are fused together to form a stem encapsulating continuous Kovar leads throughout its length, while preventing excessive oxidation of the Kovar leads.

Abstract: Apparatus for enhancing the stability of a spacecraft (2) about a sensing axis (4). The spacecraft (2) may be of the three axis stabilized or spin stabilized variety. An attitude sensor (3) determines the offset angle (A) formed between a face (8) of the spacecraft (2) and an astronomical body (6), such as the earth. The sensor (3) produces an attitude signal (14) which is processed by compensation electronics (21) and fed to a torquing means (25) to close the angle (A) to within a desired preselected deadband (24).

Abstract: A current balanced linear amplifier which does not contain a transformer. A differential transistor pair (22, 32) forms the amplifying element, with at least one transistor (22 or 32) having an input signal (71, 72) applied to its base. A current sink (52) sinking a fixed value of current (I) is coupled to the commonly-coupled emitters of the transistor pair (22, 32). Coupled to the collector of each amplifying transistor (22, 32) is a self-biasing constant current source (2, 12) which produces a fixed amount of current (I/2) equal to one half the current (I) sunk by the current sink (52). Each self-biasing constant current source (2, 12) comprises a field effect transistor (2, 12) having a capacitor (6, 16) connected between the gate G and source S of the FET (2, 12) in a positive feedback arrangement. The balanced current output (61, 62) is taken from the collectors of each of the two amplifying transistors (22, 32).

Abstract: A method and apparatus for demodulating quadrature phase shift keyed (QPSK) signals in a manner which reduces crosstalk between channels. The in phase (I) data is recovered first by recovering the carrier frequency and then multiplying the carrier frequency by the QPSK signal. The I channel is contemplated to require higher power and thus the crosstalk error in the recovered I channel data is relatively small. The QPSK signal is then modulated with the recovered I channel data. The resulting signal is multiplied by a carrier in quadrature to the recovered carrier to produce a second signal in which the crosstalk component has been eliminated and which contains the quadrature (Q) channel data with the I channel modulation. The I channel modulation is removed by modulating the signal again by the I channel data to produce a signal containing only the Q channel data.

Abstract: An active cooling system (40, 41) for cooling electrochemical cells (11) that are arranged in a stack (9) in a fuel cell or battery (3). The cooling system (40, 41) comprises cooling panels (15, 16) carrying a cooling fluid that flows adjacent to, and parallel to the plane of, each cell (11). The rate of cooling fluid flow past each cell (11) is made to be substantially equal, so that each cell (11) experiences substantially the same cooling environment, adding to the longevity of the fuel cell or battery (3). This can be accomplished by equalizing the resistance to cooling fluid flow for each cooling path (12), e.g., by using pressure equalizing, monotonically increasingly sized orifices (28) in an input manifold (25). Dual cooling panels (15, 16) are preferably employed, in a counterflow mode. The panels (15, 16) may be divided into parallel channels (33). Heat pipe panels (35) containing a two-phase fluid may be used in lieu of panels (15, 16) that contain cooling fluid in a single state.