Abstract: Systems and methods for commanding a satellite are provided. A system for commanding a satellite includes a data bus and a payload coupled to the data bus, the payload including a payload receiver. The system further includes a primary receiver coupled to the data bus and a processor coupled to the data bus. The processor configured to receive a first command from the primary receiver via the data bus, and to receive telemetry data from the payload via the data bus. The processor is further configured to detect a second command by processing the telemetry data received from the payload, and to execute the detected second command.

Abstract: A secondary payload interface for payload communications using a primary payload communications channel is provided. The secondary payload interface may include a plurality of input/output couplers which may connect the primary payload communications channel to a secondary payload. The plurality of input/output couplers may establish an isolated secondary payload communications channel within the primary payload communications channel. The secondary payload interface may be designed such that control and telemetry interactions with the operators of the communications satellite are limited.

Abstract: Systems and methods for commanding a satellite are provided. A system for commanding a satellite includes a data bus and a payload coupled to the data bus, the payload including a payload receiver. The system further includes a primary receiver coupled to the data bus and a processor coupled to the data bus. The processor configured to receive a first command from the primary receiver via the data bus, and to receive telemetry data from the payload via the data bus. The processor is further configured to detect a second command by processing the telemetry data received from the payload, and to execute the detected second command.

Abstract: A shock simulation test apparatus and method utilize a test plate and formed explosive charges to sever or penetrate one or more portions of a suspended test plate in order to subject any attached test item(s) to a realistic pyroshock stimulus. One or more shock measurement sensors, such as accelerometers, may be attached to the test plate or the test item(s) to measure the response to this shock stimulus. The apparatus and method is flexible in that many different scenarios can be simulated from different test plate materials, charge sizes and types. This method replicates actual end-use source shock environments typical in aerospace applications, but can be extended to any industry having a pyroshock environment and test requirement.

Abstract: A flexible, lightweight photovoltaic cell array includes one or more individual photovoltaic cell strings attached to a polyimide film substrate and covered with a polyvinyl fluoride film. Each photovoltaic cell string includes one or more photovoltaic cells attached to a flexible printed circuit board. The photovoltaic cell array may be manufactured by a method that includes bonding at least one photovoltaic cell to a flexible printed circuit board, mounting the flexible printed circuit board on a polyimide film substrate, and covering the flexible printed circuit board with a substantially transparent polyvinyl fluoride film.

Abstract: A solar-powered aircraft having a rotating tail assembly and/or a fore assembly is provided. The tail and fore assemblies have solar cells mounted on their upper surfaces and are rotated during flight to track the sun.

Abstract: A secondary payload interface for payload communications using a primary payload communications channel is provided. The secondary payload interface may include a plurality of input/output couplers which may connect the primary payload communications channel to a secondary payload. The plurality of input/output couplers may establish an isolated secondary payload communications channel within the primary payload communications channel. The secondary payload interface may be designed such that control and telemetry interactions with the operators of the communications satellite are limited.

Abstract: A system and method for broadcasting an audio signal in a turbo-coded satellite digital audio broadcasting system is provided that utilizes the combination of a turbo coding system having code combining and code diversity techniques to lower the power required for transmittal and to transmit at a higher code rate of 1/4 by utilizing the puncturing sequence and a pilot signal assisted orthogonal CDMA; the invention includes an improved receiver system that uses modified RAKE receivers in order to mitigate the Rayleigh multipath fading, shadowing, and temporal blockage and improve performance. The invention further uses a terrestrial gap filler network having a reduced amount of gap fillers.

Abstract: Communication systems, including, for example, cell-based mobile communication systems, multiple satellite communication systems, or multibeam satellite systems, require reliable handoff methods between cell-to-cell, beam-to-beam, or satellite-to-satellite respectively. Recent measurement of a CDMA cellular system indicates that the system is in handoff about 30% to 50% of an average call period. Therefore, system reliability during handoff is one of the major system performance parameters and eventually becomes a factor in the overall system capacity. The present invention advantageously relates to novel and improved techniques for handoff in cellular communications, multibeam and multisatellite systems. The present invention combines the soft handoff mechanism wvith a code diversity combining technique (i.e., combining signals from multiple sources), a packet combining technique (i.e., combining multiple signals), and an iterative decoding algorithm (e.g., Turbo Coding).

Abstract: A helical antenna structure is deformable and capable of being stowed in a small volume. At deployment, the helical antenna structure uses the stored strain energy in its resilient helices to revert to its original shape without the use of any outside force. Multiple antenna structures can be linked using a plurality of resilient lenticular shaped hinges.

Abstract: A system and method for broadcasting an audio signal in a turbo-coded satellite digital audio broadcasting system is provided that utilizes the combination of a turbo coding system having code combining and code diversity techniques to lower the power required for transmittal and to transmit at a higher code rate of 1/4 by utilizing the puncturing sequence and a pilot signal assisted orthogonal CDMA; the invention includes an improved receiver system that uses modified RAKE receivers in order to mitigate the Rayleigh multipath fading, shadowing, and temporal blockage and improve performance. The invention further uses a terrestrial gap filler network having a reduced amount of gap fillers.

Abstract: The asset monitoring system and associated method includes an asset monitor for providing a remotely located central station with information relating to a container, such as a trailer, both during tethered periods in which the energy storage reservoir of the asset monitor is electrically connected to an external power source, such as the electrical system of a tractor or truck, and during untethered periods in which the energy storage reservoir of the asset monitor is electrically untethered or disconnected from the external power source. As a result, the energy storage reservoir is recharged by energy received from the external power source during tethered periods and supplies energy to the asset monitor during both tethered and untethered periods. The asset monitor also includes a controller for controlling its operations. The controller includes tether status determining means for separately identifying tethered periods and untethered periods.

Abstract: A system and method for broadcasting an audio signal in a turbo-coded satellite digital audio broadcasting system is provided that utilizes the combination of a turbo coding system having code combining and code diversity techniques to lower the power required for transmittal and to transmit at a higher code rate of 1/4 by utilizing the puncturing sequence and a pilot signal assisted orthogonal CDMA; the invention includes an improved receiver system that uses modified RAKE receivers in order to mitigate the Rayleigh multipath fading, shadowing, and temporal blockage and improve performance. The invention further uses a terrestrial gap filler network having a reduced amount of gap fillers.

Abstract: A battery charge control method which relies upon the relationship between the battery state of charge and the charge efficiency. The battery charging efficiency is estimated by computing the amount of charge received by the battery as a function of input charge. Thermodynamic calculations are used to obtain an estimate of battery charge levels over a wide range of temperatures, and two stage filtering is used to obtain a useful slope from noisy charge level signals to determine charging efficiency and ultimately control the charge rate. The method is especially useful for recharging nickel-hydrogen batteries used aboard spacecraft. The battery charge in such a battery is estimated by computing the number of moles of hydrogen gas in a cell. The input charge is the integral of the charge current. Thus, the charge efficiency is proportional to the rate of change of the number of moles of gas with respect to the input charge.

Abstract: The present invention provides a method and system for formationkeeping between two or more orbiting spacecraft by controlling the surface area of the spacecraft facing the direction of perturbative forces acting on the spacecraft. The actual position of each spacecraft is sensed and the distance between the spacecraft is computed. If this separating distance exceeds acceptable tolerances, the affected spacecraft are commanded to change their orientation so that the total surface area facing the direction of motion is altered. Alternatively, the total surface area of the spacecraft facing the direction of solar pressure can be altered. As a result, the forces acting on the spacecraft are altered which alters spacecraft position and velocity. In accordance with another aspect of the invention, surface area variations of individual spacecraft are used to maintain the planar separation between adjacent constellations of orbiting spacecraft at desired distances.

Abstract: The invention provides an imaging spectrometer that provides a wide field-of-view camera and spectrometer for spectral imaging of a large two-dimensional area of the Earth's surface from an orbiting satellite or airplane. The wide field-of-view camera fore-optics includes spherical optical elements arranged monocentrically. The spectrometer includes an all-reflective coupling design that transfers the curved optical image to one or more compact imaging spectrometers. The spectrometers preferably comprise a spherical convex holographic grating and associated reflective optics for dispersing a collimated optical beam into its spectral components and focusing the spectral image onto a planar detector array. The instrument described herein is designed to operate in a "pushbroom" fashion, that is, the forward motion of the satellite or airplane generates the spatial dimension of the resulting image.

Abstract: The present invention comprises a method for injecting a heavier payload into orbit than is possible using a traditional method and the same rocket booster launch vehicle. The method of the present invention does not utilize a parking orbit and does not perform orbital injection at perigee or apogee of the desired orbit. Rather, in the present method the flight path angle is positive at the final lower stage booster burn so as to boost the perigee kick motor and payload into a suborbital trajectory having a low perigee, which may be below the surface of the Earth. In the preferred embodiment, the launch vehicle maintains a negative flight path angle during the PKM burn. The PKM burn does not occur at perigee, but perigee is at the desired location when the PKM burn is complete. Use of this method increases the payload capacity of some launch vehicles by up to fifty percent (50%).

Abstract: A flexible feed line is provided for use with a selectively deployable antenna system. The feed line is resilient and expandable so that it can maintain connections within antenna feed circuits while the antenna is being deformed or moved for stowage. An antenna system for use with the feed lines of the present invention may consist of a deployable quadrifilar helical antenna elements having four resilient conductive strips bonded thereto. Flexible feed lines are attached to each of the conductive helical strips. The feed lines expand to accommodate the shape of the antenna elements when compressed for stowing and return to their operating shape when deployed, thus providing identical feed paths to each of the antenna conductors when the antenna system is deployed.

Abstract: The present invention comprises an axially arrayed helical antenna system adapted for use in a variety of broadcasting or receiving stations including a low Earth orbiting communication satellite station. The helical antenna array comprises a plurality of antenna structures each including at least one helical antenna element coaxially mounted on a common mounting structure with a separating distance between them. Each element is electromagnetically coupled to a corresponding element of the subsequent antenna structure in the array to form a separate, isolated antenna. A feeding means is included for supplying appropriately phase shifted signals to the elements that comprise each antenna. In addition, in accordance with the invention, additional independent antennas or other equipment or payload can be deployed in the separating distance between the arrayed antenna structures.

Abstract: A shear viscous damped hinge uses a negator spring and a high viscosity fluid to provide a relatively slow and controlled deployment of the hinge. Shear damping of the fluid slows the angular velocity of the hinge. The invention reduces the end of travel impact loads thereby reducing the risk of damage to the hinge and the object rotated by the hinge. The hinge is particularly useful in, but not limited to, spacecraft applications.