Abstract: A high frequency mechanical scanning assembly which is capable of one or two dimensional scanning comprises an actuator assembly, a base assembly, a coil assembly and a sensor assembly. The actuator assembly includes an upper resonant system and a lower flexure. The upper resonant system has an upper mass, a reaction mass, and an upper flexure. The top surface of the upper mass is a mirrored surface which can be used to reflect a light beam. The actuator assembly is connected to the base assembly via the lower flexure. The lower flexure connects to the reaction mass at a point close to the center of mass of the reaction mass. Movement of the upper resonant system is caused by an excitation system which includes magnets securely mounted to at least the lower mass and the coil assembly which provides driving torques to the magnets. The lower flexure is less stiff than the upper flexure.

Abstract: An imaging system for achieving enhanced image detail includes a sensor subsystem, an electronic image processing subsystem, and an automatic gain control (AGC) unit. The sensor unit is operative for sensing an image received from an exterior environment and for converting the image to an electrical representation having a peak value that is related to the dynamic range of the image. The electrical representation is then processed in the electronic image processing subsystem using a unique multiple order, non-linear transfer function that processes the signal in a manner that is dependent upon the dynamic range of the input image. The output signal of the electronic image processing subsystem is then applied to the AGC unit which performs a conventional AGC function on the signal. Thus, the imaging system automatically adjusts to changing scene content in the input image in a dynamic manner.

Abstract: A phased array type antenna apparatus compensates for phase and time differences between signals received at different elements of the antenna. Each element within the antenna apparatus has an associated phase/time adjuster circuit. The signals from each element are divided, with the first output routed to a combining circuit. The second output of one element is used as a reference signal, with the second output from the remaining elements routed to a switch. One signal is selected at the switch, and is used as a non-reference signal. Phase difference between the reference signal and the non-reference signal is determined at a comparator circuit, and the phase/time adjuster circuit associated with the non-reference signal is adjusted to bring the two signals into phase alignment. Time difference between the reference and non-reference signal is determined using dual correlators and a comparator circuit.

Abstract: An antenna apparatus that includes a beam control system and a beam collimating system having a compound curve antenna structure is provided. The compound curve antenna structure can be two-dimensional or three-dimensional. In one embodiment, the curve is parabolic and the compound curve antenna structure includes first and second parabolic reflector sections that are spaced from each other. A feed array of the beam control system is disposed therebetween at the base ends of the two parabolic reflector sections. When the compound curve antenna structure is three-dimensional, the two parabolic reflector sections are part of a body of revolution. The control system also includes memory storage that stores predetermined data related to controlling activation of each of a plurality of feed elements of the feed array. The predetermined data is based on information obtained using a reference beam with the compound curve antenna structure.

Abstract: A method and system for testing a test object, such as a satellite, is disclosed. High energy acoustic testing is performed on the object by assembling an acoustical system about the test object rather than transporting the test object to a specially configured acoustic chamber. The acoustic system of the present invention preferably provides and directs acoustic energy directly to the surfaces of the test object rather than providing the test object in a high energy acoustic environment where a substantial amount of the acoustic energy is randomly directed within a chamber having the test object. Additionally, the present invention further provides for mechanical vibration tests concurrently or serially with acoustic testing, wherein the object is not required to be transported.

Abstract: A spacecraft includes an articulating sunshield assembly that is capable of simultaneously performing thermal control functions and solar torque balancing for the spacecraft. The sunshield assembly includes a pair of shield members that can be controllably positioned as the spacecraft orbits about a primary body. Control functionality is provided for periodically adjusting the positions of the shield members to maintain a neutral solar torque stability condition for the spacecraft. In one embodiment, solar torque balancing is performed in each of three independent rotational directions or planes (i.e., roll, pitch, and yaw) using the sunshield assembly. Functionality is also provided for performing momentum dumping tasks using the sunshield assembly in place of, or in conjunction with, on-board thrusters.

Abstract: An actuator is configured to reliably provide fine and coarse positioning or adjusting for objects such as a telescope or other technical or scientific instrument or communication components, preferably at cryogenic as well as higher temperatures. The actuator includes a fine positioning system and a selectively engageable coarse positioning system. The fine positioning system includes a flexure structure constructed to provide support and strength, preferably in all axes, such as may be needed to withstand launch forces. Preferably flexure axes are defined at upper and lower edges of sidewalls and at intermediate positions of sidewalls. A cam or other suitable device adjusts distance between sidewall intermediate flexures and, by operation of sidewall flexures, adjusts the distance between upper and lower surfaces.

Abstract: A dual circularly polarized broadband array antenna includes two arrays of spiral-like antenna elements. The arrays of spiral-like antenna elements are oppositely oriented and located on opposite sides of a substrate member. The spiral-like antenna elements have a loop portion with a free end, and a tail portion. The tail portion of adjacent antenna elements are connected to one another. The antenna elements have feed points, located at the free end, with the feed points of the first array being offset from the feed points of the second array. Each feed point is connected to a balun. The offset of the feed points is adjusted to achieve enhanced isolation between the signals from the two arrays. The antenna can have tuning elements adjacent to the substrate member.

Abstract: A radio frequency connector for coupling radio frequency energy into or out of an antenna apparatus includes a ground portion that is both capacitively and conductively coupled to a ground structure within the antenna apparatus. The connector is designed so that radio frequency (RF) signals within the operative frequency range of the antenna apparatus flow predominantly through the capacitive ground connection of the connector, rather than through the conductive ground connection of the connector. Direct current signals and other low frequency signals within the antenna apparatus, on the other hand, have a direct path to ground through the conductive ground connection. Because the RF signals flow predominantly through the capacitive ground connection, the likelihood that passive inter-modulation (PIM) products will be generated within the metal-to-metal junctions of the conductive ground connection is significantly reduced.

Abstract: The present invention is directed to a connector for terminating a plurality of shielded conductors. The connector includes a conductive backshell housing, a connecting structure, one or more ground structures for grounding each of a plurality of conductive shields, and a strain relief structure. The ground structures are located inside the conductive backshell housing between the plurality of connecting elements and the passage in the housing for the cable. The connector is particularly useful in terminating a cable that includes a plurality of conductive shields surrounding one or more of the plurality of conductors.

Abstract: A deployable reflector for an electronically scanned reflector antenna is provided. The deployable reflector may be confined to a relatively small volume for transportation of the reflector to a deployment site. Upon deployment, the reflector of the present invention forms a relatively large reflector surface, having a precisely controlled surface geometry. The reflector generally includes a plurality of panel members interconnected to a plurality of ribs interconnected to an extendable boom. The antenna reflector of the present invention is particularly well suited for a space-based antenna, where a reflector that can be collapsed into a small volume for transport and deployed to form a large reflector surface having high gain is desirable.

Abstract: A multi-frequency radome includes a material-tuned radome portion for generating a low frequency passband of the radome and an integrated low pass frequency selective surface (FSS) portion for tuning a high frequency passband of the radome. The FSS portion provides a reactance necessary to move an upper passband of the material-tuned radome to a desired spectral location. Because the FSS portion is a low pass structure relative to the low frequency passband of the material-tuned radome portion, it does not substantially affect the low frequency passband when the FSS portion is applied to the material-tuned radome. In one embodiment, the FSS portion is designed to take advantage of various well known properties of FSS structures, such as the ability to tune for angle of arrival and polarization properties.

Abstract: A method an apparatus for calibrating an electronically scanned reflector (ESR) antenna to compensate for mechanical distortions in a reflector and feed thereof first determines displacement values for a multitude of points on the reflector and the feed. The displacement values are then analyzed to determine the types of distortion, if any, that are present within the ESR antenna system. Compensation values are then determined for each of a plurality of beam positions based on the type(s) of distortion identified. The compensation values are stored in a lookup table for later use in generating antenna beams in the corresponding beam position.

Abstract: The present invention provides an adaptive optic system for an earth-viewing telescope on board an orbiting spacecraft. The adaptive optic system includes a deformable mirror, a synthetic guide star laser, and a control module that corrects not only on-axis wavefront error but also off-axis wavefront error.

Abstract: A hydrogen generating apparatus that includes a reactant with a vapor phase at greater than atmospheric pressure. The apparatus includes a tank for housing the reactant, such as ammonia. Ammonia communicates with a reactor having a solid reactant, such as lithium aluminum tetrahydride. A check valve is located between the tank and the reactor and is used to control the flow of ammonia to the reactor. Heat generated by the reaction is useful in raising the temperature of the reactant in the tank. The reactor can also include a gas flow enhancing material that facilitates gas flow through the reactor. A filter and getters are employed downstream of the reactor to remove unwanted solids and impurities from the hydrogen gas stream.

Abstract: The present invention provides a method and apparatus for carrying signals having different frequencies in a space-deployed antenna system. When the antenna system is in a first mode, DC power, command information and RF signals (1) are multiplexed via a multiplexer, (2) propagate along a RF transmission line and (3) are appropriately demultiplexed by a demultiplexer associated with each T/R module. Similarly, when the antenna system is in a second mode, telemetry data and RF signals (1) are multiplexed via a multiplexer, (2) propagate along the RF transmission line and (3) are appropriately demultiplexed by a demultiplexer at a driver stage. By using the RF transmission lines associated with each T/R module to deliver (1) DC power, (2) command data and (3) RF signals in the first mode and to deliver (1) telemetry data and (2) RF signals in the second mode, the DC power and command/telemetry wire harnesses (and their respective conductors) may be eliminated.

Abstract: A tracker for stellar objects including stars is provided. The star tracker includes a charge coupled device having an image section and a memory section. The image section is useful in obtaining acquisition information related to determining the presence of one or more stars. The image section is also useful in obtaining location information useful in determining the position of each such star. The image section also obtains discardable information, such as information related to dark current and background star generated charge. The memory section receives the location or acquisition information from the image section. Such information is stored in significantly fewer lines and cells in the memory section than the number of lines from which such information was obtained in the image section. When storing location information in the memory section, at least one guard line can be provided intermediate the location information and the discardable information.

Abstract: A low profile or very low profile antenna having a finely tunable frequency response is provided. The antenna is easily tuned to have a precise frequency response while its protective radome is in place. The antenna generally includes a first antenna element, a second antenna element, a ground plane, and a tuning mechanism. The tuning mechanism may be accessed while the radome of the antenna is in place. The antenna is particularly well-suited for use in shipping applications, where a very low antenna profile is desirable.

Abstract: An imaging system having a CCD sensor varies the intensity of an input image presented to the sensor during an integration period of the sensor to enhance the intra-scene dynamic range of the imaging system. The sensor well depth of the CCD sensor is also varied during the integration period in a manner that complements the intensity variation to achieve the dynamic range improvement. In one approach, the intensity of the input image is progressively decreased during the integration period while the sensor well depth is correspondingly increased. In another approach, an intensifier unit is gated off during the integration period to provide the intensity variation. A closed loop control method is provided for controlling the image intensity and/or the well depth based upon the content of the present image.

Abstract: The present invention relates to a system for providing highly accurate position estimates for a vehicle in space, in substantially real time. The system includes a Mission Control Center (MCC) that calculates precise orbits for GPS satellites that are in view of the vehicle, using GPS tracking data from the worldwide network of tracking sites. Because the tracking data from the tracking sites is not current when received by the MCC, the precise GPS orbits are "propagated forward in time" by the MCC. The propagated orbit information is uploaded to the user satellite where it is processed in an extended Kalman filter, or similar device, along with the real time output of the on-board GPS receiver, to achieve highly accurate satellite location estimates in substantially real time.