Abstract: A spacecraft data acquisition system comprises a telemetry and command controller, a payload unit, and a bi-directional interface that couples the telemetry and command controller to the payload unit. The interface is a single bi-directional interface that is used to reduce the complexity of the spacecraft. The transmission of information over the interface has a predetermined protocol so that the telemetry and command controller and payload unit may effectively use the single interface.

Abstract: A diffused junction semiconductor (12) for detecting light (48) at a predetermined wavelength is provided including a base (30) and an epitaxial structure (32) electrically coupled to the base (30). The epitaxial structure (32) forms a p-n junction (38) in the base (30). The epitaxial structure (32) includes at least one diffusion layer (50) electrically coupled to the base (30). At least one of the diffusion layers (50) contributes impurities in at least a portion of the base (30) to form the p-n junction (38) during growth of the epitaxial structure (32). A method for performing the same is also provided.

Abstract: A traveling wave tube assembly has a traveling wave tube and a predistortion network RF coupled and physically coupled to the traveling wave tube. The traveling wave tube and the predistortion network may be located in a high temperature zone. An amplifier located in a low temperature zone, is coupled to the predistortion network by an RF connecting cable.

Abstract: A method for operating a satellite (10, 34) so that a predetermined amount of fuel is left to perform end-of-life maneuvers is provided. A first pressure differential is established between a first propellant tank (74) and a second propellant tank (76). Propellant is transferred from the first tank (74) to the second tank (76). The second tank is used for orbit maintenance. The first tank is used for end-of-life maneuvers. Propellant may be transferred between the tanks using a latching process so that a predetermined amount of fuel may be transferred from a non-empty tank to a full tank. Another way in which the propellant may be measured is to equalize the amount of propellant in each tank and using one tank to completion so the amount remaining is known.

Abstract: An electrical system has a battery circuit that includes a plurality of battery blocks. Each of the battery blocks has a plurality of parallel strings of battery cells connected thereto. A plurality of virtual cells is formed during charging by parallel coupling one cell from each string in parallel using diode.

Abstract: A tunnel diode has a quantum well having at least one layer of semiconductor material. The tunnel diode also has a pair of injection layers on either side of the quantum well. The injection layers comprise a collector layer and an emitter layer. A barrier layer is positioned between each of the injection layers and the quantum well. The quantum well has an epitaxial relationship with the emitter layer. An amount of one element of the well layer is increased to increase the lattice constant a predetermined amount. The lattice constant may have a reduction in the conduction band energy. A second element is added to the well layer to increase the conduction band energy but not to change the lattice constant. By controlling the composition in this matter, the negative resistance, and thus the effective mass, may be controlled for various diode constructions.

Abstract: A circuit assembly has a heat sink assembly and a chip scale package assembly. The chip scale package assembly has an integrated circuit die coupled to a first printed wiring board. The heat sink assembly has an integrated circuit die coupled to a second printed wiring board. Preferably, the heat sink assembly and the chip scale package assembly are assembled separately then assembled together. The circuit pads on the first printed wiring board correspond with circuit pads on the second printed wiring board. The circuit pads may be coupled together by solder or adhesive bonding. The circuit pads on the first printed wiring board may have solder balls formed of high temperature solder that do not melt when the heat sink assembly is assembled with chip scale package assembly. The solder balls allow chip scale package assembly to maintain a predetermined distance from the circuit pads on the second printed wiring board.

Abstract: A charging circuit (28) particularly suited for use in a satellite (20) has a battery cell (32). A voltage sensor (36) is coupled to the battery for generating a cell voltage signal. A current sensor (34) is coupled to the battery cell (32) and generates a cell charge current signal. A controller (38) is coupled to the voltage sensor (36) and the current sensor (34). The controller (38) determines a compensated voltage in response to the cell voltage signal and the charge current signal and controls the charging of the battery cell (32) in response to the compensated voltage.

Abstract: A hybrid reflector antenna particularly suited for reflecting a frequency band in a satellite includes a central portion fully reflective to the frequency band. A first annular band is disposed directly adjacent to the central portion. The first annular band is partially reflective to the frequency band. The reflector may include several annular bands having various degrees of reflectivity and thus attenuation. The present invention may be implemented using two such reflectors, one for transmitting and one for receiving in a satellite, for either single or multiple beam applications. This invention offers more compact and lower mass/cost antenna configurations compared to conventional antennas from multiple beam satellite payloads.

Abstract: An equalizing apparatus includes an equalizer which has a plurality of adjustable tap weights that equalizes a received signal based on values of the adjustable tap weights, a tap weight update calculation unit coupled to the equalizer and which determines tap weight updates for use in adjusting the tap weights during operation of the equalizer, an offset memory that stores one or more tap weight update offset values and a summer coupled to the tap weight update calculation unit and to the offset memory. The summer combines each of the tap weight updates with one of the tap weight update offset values to produce modified tap weight updates which, in turn, are provided to the equalizer to adjust the tap weights.

Abstract: A fault detection system for a satellite communication system includes a satellite positioned above earth. Satellite has a payload that communicates with a network control center on earth. System ground stations generate diagnostic messages and transmits the diagnostic messages to the payload. Each diagnostic message has a predetermined path characteristic so that the diagnostic message takes a predetermined path through the payload, or part of the payload, if the payload is operating properly. Parts of the payload, if any, which do not permit deterministic path tracing using externally applied diagnostic messages may be probed by using internal signal or data injection points. In response to the externally applied or internally injected diagnostic message, a response signal is generated at the payload. The response signal is transmitted to the network control center where it is compared with a predetermined response.

Abstract: A bipolar transistor-based linearizer with programmable gain and phase response apparatus uses a splitter to separate an incoming RF signal into two equal components: in-phase (I) and quadrature (Q, ninety degrees delayed). The I signal then passes through a first bipolar variable gain amplifier (VGA) while the Q signal passes through a second bipolar VGA. After passing through the first and second VGAs, the amplified signals are combined at the output using a summer to produce a predistorted signal that drives a TWTA. The gains of each VGA are controlled using an RF power detector in conjunction with a bipolar gain/phase slope controller. Each gain can be adjusted separately to product a large range of linearization characteristics.

Abstract: A multilayer radio frequency interconnect apparatus includes a plurality of laminated printed wiring boards made of a dielectric material with low loss characteristics for radio frequency electromagnetic radiation. In operation, a RF signal launches from a first signal conductor 24. A vertical transition from the first signal conductor 24 to a second signal conductor 44 is realized by a 3-wire transmission line. The center conductor of the 3-wire transmission line is a RF via 30. The two outer conductors are RF ground vias 32 and connect the first RF ground conductor 22 to the second RF ground conductor 42. These two RF ground vias 32 are isolated from the ground planes 40, 46 which are located between RF signal layers 20, 38. The advantage of this ground isolation is to maintain the 3-wire transmission line characteristic impedance and to reduce disturbance to electromagnetic fields such that a broadband design may be achieved. The RF ground vias are terminated at signal layers 20, 38.

Abstract: A recessed p-type region cap layer avalanche photodiode (12) is provided. The photodiode (12) includes a semiconductor substrate (30) and a semiconductor stack (32), which is electrically coupled to the substrate (30). A cap layer (34) is electrically coupled to the stack (32) and includes a recessed p-type region (36). The recessed p-type region (36) forms a p-n junction (38) with the stack (32). A method of forming the photodiode (12) is also provided. The method includes forming the substrate (30), the stack (32), and the cap layer (34). The cap layer (34) is selectively etched to expose the stack (32) and form a cap layer opening (42). Dopant is diffused through the cap layer opening (42) into the stack (32) to form the p-n junction (38).

Abstract: A variable spacer includes a plate having a first surface and a second surface. At least one hole is integrally formed within the plate, extending from the first surface to the second surface. The hole receives a shaft of a separation bolt used for attaching a spacecraft to a launch vehicle. The plate increases a first load within the separation bolt to a second load during a turbulent stage. The second load reduces a gapping that occurs between the launch vehicle and the spacecraft. Thereafter, the plate reduces the second load within the separation bolt to a third load during a separation stage. The third load decreases a shock level experienced by the spacecraft and the launch vehicle.

Abstract: A launch vehicle assembly has a launch vehicle body (10) having a first slot (48a) therein. A first magnet (50a) is disposed within the first slot (43a). A fairing assembly (12) is positioned adjacent to the vehicle body (10). The fairing assembly (12) has a second slot (30a) therein positioned opposite the first slot (48a). A second magnet (40a) is disposed within the second slot (30a) so that the second magnet (40a) repels the first magnet (50a).

Abstract: A circuit assembly suitable for RF signals has an integration plate and an RF distribution layer disposed adjacent to the integration plate. The RF distribution layer has an RF conductive layer between a first dielectric layer and a second dielectric layer. A DC distribution layer is disposed adjacent to the RF distribution layer. An RF input is coupled to the RF conductive layer. A module assembly includes an integrated circuit coupled to the RF conductive layer and the DC distribution layer. An RF output is coupled to the RF conductive layer.

Abstract: The digital signal is provided to the digital-to-analog upconverter (40) such as through digital signal processing circuitry (70). A sample rate signal and a divided sample rate signal are provided by divider chain (96) using the clock input (44). The divided sample rate signal is used to drive the decode circuit (88). The digital outputs of the decoder circuit (88) is combined with the sample rate signal in a mixer (52) which in turn generates a digitally upconverted signal which drives a plurality of switches combined together to form the analog output (46).

Abstract: A TDMA beacon for satellite system synchronization includes a beacon signal generator and a time division multiplexed switch. The beacon signal generator generates a beacon signal. The TDM switch is coupled to the beacon signal generator and receives the beacon signal. The TDM switch embeds the beacon signal with a data signal into a TDMA signal. The TDMA signal is then broadcast to a ground station where the beacon signal may be extracted from the TDMA signal and used to synchronize a terminal with the satellite system.

Abstract: A switch matrix 10 is provided comprising a plurality of input modules X and a plurality of output modules P. Each input module 16 has a plurality of first input interconnections 14, a plurality of first interconnected switches 21, and a plurality of first output interconnections 20. Each output module 18 has a plurality of second input interconnections 23, a plurality of second interconnected switches 24, and a plurality of second output interconnections 20. The plurality of input modules X is electrically coupled to the plurality of output modules P, forming a plurality of signal paths 12 having a plurality of interconnected switches K per signal path 12. A method is also provided minimizing the total number of interconnected switches Z within the switch matrix 10 for a particular application. The method comprises determining switch matrix design requirements, calculating the values of X and P, and performing an integer partitioning process.