Abstract: A system for achieving spacecraft camera (1, 2) image registration comprises a portion external to the spacecraft and an image motion compensation system (IMCS) portion onboard the spacecraft. Within the IMCS, a computer (38) calculates an image registration compensation signal (60) which is sent to the scan control loops (84, 88, 94, 98) of the onboard cameras (1, 2). At the location external to the spacecraft, the long-term orbital and attitude perturbations on the spacecraft are modeled. Coefficients (K, A) from this model are periodically sent to the onboard computer (38) by means of a command unit (39). The coefficients (K, A) take into account observations of stars and landmarks made by the spacecraft cameras (1, 2) themselves.

Abstract: A dynamically reconfigurable multiplexer (7) has applicability in a space diversity communications system or a polarization reuse communications system. Multiplexer (7) may be situated on board a communications satellite or at the control nexus of a terrestrial microwave communications system. Multiplexer (7) comprises a set of N series-connected field reversible circulators (51). Coupled to one of the three ports of each circulator (51) is a channelizing filter (53), followed by an output isolator (54) and a high power amplifier (55). The electromagnetic energy rotating within each circulator (51) is commanded to move in either a clockwise or counter-clockwise direction, depending upon whether it is desired to access the channel (52) corresponding to said circulator (51) via a first energy source (1) or second energy source (2). An input isolator (43, 44) associated with each antenna (1, 2) absorbs unwanted energy emanating from the opposing antenna (2, 1).

Abstract: A closed loop system reduces pointing errors in one or more spacecraft instruments. Associated with each instrument is a electronics package (3) for commanding motion in that instrument and a pointing control system (5) for imparting motion in that instrument in response to a command (4) from the commanding package (3). Spacecraft motion compensation logic (25) compensates for instrument pointing errors caused by instrument-motion-induced spacecraft motion. Any finite number of instruments can be so compensated, by providing each pointing control system (5) and each commanding package (3), for the instruments desired to be compensated, with a link to the spacecraft motion compensation logic (25). The spacecraft motion compensation logic (25) is an electronic manifestation of the algebraic negative of a model of the dynamics of motion of the spacecraft. An example of a suitable model, and computer-simulated results, are presented.

Abstract: A two-dimensional image (1) is converted into an electronic signal (7). Image line segments (11) into which the image (1) has been divided are selectively projected onto a cylindrical image lens (4) and focused onto a linear array (5) of N photodetectors (15). A light modulator (3), a linear array of electro-optic shutter elements (13) arranged orthogonally to the photodetector array (5), is positioned between the image (1) and the image lens (4), and permits one of the image line segments (11) to be so projected while blocking the other segments (11). An object lens (2), a second cylindrical lens, focuses the image line segments (11) onto the light modulator (3). An electronic control circuit (6) accepts the electronic outputs (42) of the photodetectors (15) in synchronism with the sequential opening of the electro-optic shutter elements (13) corresponding to the image line segment (11) being converted. Three parallel detector arrays (5) can be used in a color imaging system.

Abstract: A lock detector (12) used in conjunction with a bit synchronizer (14) for determining when a random binary input signal (2) is in lock with a clock (7) generated by the bit synchronizer (14). A window comparator (3, 5; or 23, 25, 27) determines whether the amplitude of the input signal (2) is within or without an amplitude window, and generates a signal (33) as a result of said determination. This signal (33) is sampled at periodic sampling points (X, Y). The set of X sampling points and set of Y sampling points are interleaved and usually separated by half a bit period. The X samples and Y samples are averaged and compared. Means (19) are provided for declaring a lock condition when the X average exceeds the Y average by a preselected threshold (V.sub.REF), which occurs when the X points are positioned near mid-points of data bits (35) and the Y points are positioned near data transitions (39). The circuit (12) will not lock on false sidebands and can operate at very low signal-to-noise ratios.

Abstract: A method and apparatus are provided for transmitting a microwave signal as a beam having a wavelength small as compared to the size of the reflecting surfaces, wherein a main reflector is stationary with respect to a sub-reflector and the main reflector is motional with respect to the feed. The invention comprises rotating the sub-reflector about a first rotational axis transverse and preferably orthogonal to the guide axis, the first rotational axis being on the vertex of a secondary reflector, thereby directing radiation from a fixed feed to the motional sub-reflector. The primary reflector and sub-reflector are disposed relative to one another to share a common focus or confocal point.

Abstract: A layer of HgCdTe (15) epitaxially grown onto a crystalline support (10), e.g., of sapphire of GaAs. A CdTe substrate (5) is epitaxially grown to a thickness of between 1 micron and 5 microns on the support (10). 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 together in a thermally insulating, reusable ampoule (17) within a growth temperature range of between 500.degree. C. and 625.degree. C. for a growth step having a duration of between 5 minutes and 4 hours. Then an interdiffusion step is performed, in which the source (3) and substrate (5) are cooled within a temperature range of between 400.degree. C. and 500.degree. C. for a time of between 1 hour and 16 hours. In a first growth step embodiment, the source (3) and substrate (5) are isothermal. In a second growth step embodiment, the source (3) and substrate (5) are non-isothermal.

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 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).