Abstract: A spacecraft (10) body (20) located in an external magnetic field (12) has a substantially unbalanced electrical power bus (18) that generates a composite local magnetic field The electrical power bus (18) substantially surrounds an external surface (22) of the spacecraft (10). Current in the electrical power bus (18) is solar panel (14and 16) and/or battery (34) generated and can flow in different directions through different current paths. Electrical loads (58) are coupled to power converters (56) and current path switches (54) to couple the power converters (56) to the various current paths. A controller (28) takes sensor data (82), determines a required attitude adjustment torque (84), translates that adjustment torque into a composite magnetic field (86), determines an unbalanced bus current profile (88) to generate that composite magnetic field, selects a current source (90) and regulates current path switches (92) to achieve a desired attitude adjustment torque for the spacecraft (10).

Abstract: A method and apparatus for efficient power amplification of a wideband signal with a correspondingly wide modulation bandwidth includes an envelope detector (220), an adaptive split band modulator (270), and a power amplifier (260). The adaptive split band modulator (270) amplifies the low frequency components using a class S modulator (760), and amplifies the high frequency components using a class B amplifier (750). The power supply of the class B amplifier (750) is adaptively modified as a function of the amplitude of the signal that it amplifies. In this manner, the class B amplifier (750) operates at a higher efficiency.

Abstract: A method (400, FIG. 4) for beam management in a satellite communication system (10) which simplifies cell-to-cell hand-offs within a footprint (90) of a satellite (20) and between two or more satellites (20) is disclosed. The method includes the steps of providing multiple beam stripes (130, FIG. 2) extending across the footprint (90) in a direction corresponding to the direction of flight (60) of the satellite, grouping the beam stripes (130) into one or more beam groups (150, FIG. 3), and selectively associating hardware groups (300) comprised of hardware resources to support beam groups (150). Method (400) also can include steps (450-470) for determining and compensating for undesirable system effects arising as a result of the relative motion of the Earth (50, FIG. 1) with respect to satellites (20) of system (10). A satellite (20, FIGS. 10 and 11) designed and configured to execute method (400) also is disclosed.

Abstract: A packet data communication system (10) where multiple users (87) can access the same channel (22) to maximize an efficiency of the communication system (10). Each channel (22) is divided into time slots. Each time slot is allocated to a user based on the user's request (303) for time slots and the availability of time slots. If time slots are available, then the system (10) will inform the user (87) and allocate the time slot to the user (87, 305). If there are no available time slots, then the system (10) will inform the user (87) that no time slots are available and access to the system's channel is denied. The user (87) will continue to request access (303) to the system (10) as long as the user has data packets to send.

Abstract: A communication network (20) includes a multiplicity of switching nodes (18), many of which are located in orbiting satellites (16). Communication links (30) interconnect the switching nodes (18). A control center (32) performs a request for connection process (40) which routes a new call request over a current internodal topology of links (35) if possible. If the new call request cannot be routed over the current internodal topology of links (35), the process (40) determines how to augment the network with the creation of new links (45) so that the new call can be routed. As calls terminate, unused links are taken out of service.

Abstract: A class-S modulator (5) receives an input signal (10) having envelope information and pulse-width modulates the input signal (10) using a reference waveform (26) from a waveform generator (25). The envelope becomes a pulse-width modulated signal is level-shifted and amplified through a pre-driver (40). A driver (50) controls switches (60, 70) which drive an output (80) into a low-pass filter (90) wherein the envelope is restored to the amplified signal for driving a power amplifier in a wide-band transceiver.

Abstract: A method and apparatus for controlling current flow in current sources includes a current source FET (18), a control FET (20), and a driver circuit which includes complementary logic (310). The use of complementary logic for control advantageausly allows commonly available logic functions to control the current flow in individual current sources while maintaining a substantially constant bias voltage on the gate of the current source FETs. A chip-wide bias generator can be maintained substantially constant while controlling individual current sources.

Abstract: A method and apparatus for efficiently interconnecting a large number of high frequency high bandwidth signals includes two interface plates (100, 200), each having two substantially coplanar faces, a mating face (110, 210) and a non-mating face (120, 220). Each interface plate has waveguides (116, 216) disposed between the coplanar faces such that when the mating faces of the interface plates are brought together, a plurality of waveguide connections are made. An energy absorbing gasket (300) having a hole pattern matching the waveguide pattern is disposed between the mating faces of the interface plates so that reflections caused by misalignment and non-coplanarity of faces can be reduced.