Abstract: A remote programmer connectable to a satellite television receiver prompts a user to enter commands representing a satellite or local television program to be recorded by a video tape recorder. The remote programmer issues programming commands to the satellite television receiver and the video tape recorder to cause the program to be provided at the output of the receiver and recorded by the video tape recorder at a specified time.

Abstract: A method and apparatus for autonomous acquisition of attitude in a stellar inertial spacecraft attitude system is disclosed. The present invention uses star trackers, an on-board star catalog, spacecraft steering and inertial sensors to determine spacecraft attitude. The present invention utilizes pattern match and pattern rejection methods and uses multiple stellar snap-shots in conjunction with spacecraft steering and spacecraft inertial measurements to acquire spacecraft attitude. Spacecraft inertial measurements are used to connect multiple stellar snap-shots to provide adequate star information that can be used to acquire spacecraft attitude. In an attitude determination system using star trackers, the star trackers may have a narrow field-of-view or few stars may be available for viewing. The present invention uses pattern matching and pattern rejection on different sets of stars, thereby allowing attitude acquisition when the number of stars in view is small.

Abstract: A method and apparatus for estimating attitude sensor bias in a satellite system uses attitude sensors and a spacecraft control processor. Attitude sensors provide output signals, which may contain bias. The present invention interprets the signals, determines the bias present in the signals, and generates an output signal to offset the bias in the signals from the attitude sensors, thereby leading to more accurate positioning of the satellite employing the present invention.

Abstract: A spacecraft control system having a spacecraft with a gimbaled thruster attached thereto. An actuator is operationally attached to the gimbaled thruster to control the angled position of the gimbaled thruster in two orthogonal directions. A position control system is provided which sends a control signal to the actuator which moves the gimbaled thruster to an angled position in response to the control signal, wherein the angled position of the gimbaled thruster controls the attitude and orbital velocity of the spacecraft.

Abstract: A system for distributing first and second television signals of diverse modulation formats to a number of locations in a multiple-dwelling unit includes first and second antennas for receiving, at the multiple-dwelling unit, respective first and second received television signals having respective first and second, different modulation formats. The system also includes first and second transmodulators for transmodulating the first and second received television signals, respectively, to develop first and second transmodulated signals, respectively. A combiner or diplexer combines the first and second transmodulated signals into a combined signal, and a distributing network distributes the combined signal to each of a plurality of locations. A diplexer at a particular location selected from the number of locations separates the combined signal to recover the first and second transmodulated signals.

Abstract: A capacitive coupler for a microwave circuit that has a first cavity and a second cavity separated by a wall. The separating wall has an aperture that, due to its shape, is capacitive. The aperture has a pair of elongated walls separated by a pair of side walls. The elongated walls and the side walls each have a thickness substantially thicker than what is now the industry standard. At least one of the elongated walls has a ridge. Because the distance between the first elongated wall and the second elongated wall is substantially greater than that previously known, the aperture may be easily manufactured.

Abstract: A process is provided for fabricating MODFET's in group III nitride compound semiconductors. The process precedes isolation of the MODFET structure with the use of e-beam lithography to define very narrow (e.g., .about.0.25 micrometer) gates which enhance transistor microwave cut-off frequency. Because these compound semiconductors resist chemical etchants, isolation is accomplished by etching with reactive ions to form an isolation mesa having a vertical mesa sidewall. To improve breakdown, the mesa sidewall is covered with a passivation layer prior to deposition of a gate feed that contacts the gate. To reduce parasitic gate capacitance, the gate feed is spaced from a narrow edge of the transistor's two-dimensional electron gas.

Abstract: A paint is a liquid or solid mixture of a plurality of particles and an inorganic binder such as a silicate. The particles have a composition A[xAl(1-x)Ga].sub.2 O.sub.4.+-..gamma. (.delta.In), wherein A is zinc, magnesium and/or cadmium, the value of x is from 0 to 1, the value of .delta. is from 0 to about 0.2, and the value of .gamma. is less than about 0.2. In the liquid mixture, a paint vehicle is also typically present to impart the desired fluidity to the mixture. The solid paint made using this material is white, has very low solar absorptance, and may be made electrically conductive by doping the particles with indium or other appropriate dopant.

Abstract: A method and apparatus are disclosed for controlling the operation of a synchronous rectifier used in power conversion circuitry. The disclosed method and apparatus senses the voltage across the synchronous rectifier, and turns the synchronous rectifier OFF when the voltage across the rectifier is about to change direction. Preferably, the synchronous rectifier is commanded OFF at the approximate instant when the voltage across the rectifier reaches approximately zero, which also corresponds to a current of approximately zero. Accordingly, currents are prevented from flowing in the reverse direction in the synchronous rectifier. This results in approximately zero voltage and zero current switching when the rectifier is turned OFF, thereby minimizing switching losses.

Abstract: An message handling system for handling the delivery of critical and time critical messages for a near-real-time or real-time simulation environment. A message delivery type (38) accompanies each message (34) to designate whether the message (34) is delivery critical (46) or time critical (42). A message receiver (50) receives the message (34). A message delivery selector (58) selects a protocol based on the message delivery type (38) as determined by a message type determinator (54). The selected protocol conforms to a message format which has a common header and a message component. The message (34) is then sent to the intended recipient computer via the selected protocol.

Abstract: A low profile, low cost receiver/transmitter system includes a planar waveguide-to-microstrip adapter, a dielectric loaded waveguide fed slot array antenna, and a downconverter all formed on a single dielectric substrate made of polytetrafluoroethylene. The waveguide antenna includes a set of slots disposed in a surface thereof to receive/transmit a microwave/millimeter wave signal. The waveguide-to-stripline adapter is connected to the waveguide antenna and includes a taper section attached to a microstrip line. The taper section, which may be linear or may follow some other more complex taper function such as a Chebyshev function, adapts a signal propagating within the waveguide antenna to the microstrip line or vise versa.

Abstract: A method and apparatus for performing fractional minimum shift key modulation for a very small aperture terminal. A signal with a fractional modulation which appears to be frequency shift key is generated in the indoor unit. The outdoor unit employs a novel multiplication method to translate this signal to a minimum shift key modulated signal for satellite transmission.

Abstract: A video broadcast system is provided with an apparatus for processing a plurality of program signals corresponding to, for example, movies or other prerecorded programs, to selectively reduce the bandwidth required to transmit or broadcast the program signals. The signal processing apparatus includes a rate controller for generating a rate reduction factor based upon the data rates of the first and second program signals, a first channel processor coupled to receive the first program signal, and a second channel processor coupled to receive the second program signal. Each of the channel processors includes a data path for selectively reducing the bit rate of the program signals based upon the rate reduction factor.

Abstract: A collector for collecting an electron beam in a traveling wave tube is disclosed. The collector has an input end for receiving the electron beam from the traveling wave tube. The collector also has a plurality of stages biased at given voltages and arranged along a common collector axis and positioned at a different axial position with respect to the input end. A stage is biased more negatively with a voltage than a successive stage positioned axially farther from the input end to generate an electrostatic focusing lens for focusing the electron beam toward successive stages thereby increasing the collection efficiency of the collector.

Abstract: A dual band omni directional antenna is disclosed. A dielectric cylinder supports a cone shaped reflector over a corrugated radio frequency horn. Orthogonal mode transducers produce and conduct circularly polarized radio frequency waves within the horn. The reflector, the horn, and the transducers are all coaxially disposed. The antenna produces a torodial radiation pattern in a plane that is substantially orthogonal to the axis of the antenna. Transmit and receive functions may be performed simultaneously using a single reflector and two orthogonal mode transducers.

Abstract: A structure includes an electronic device support, an electronic device, and a fastener for the electronic device support and the electronic device. There is a first dovetail slot in the electronic device support and a second dovetail slot in the electronic device. The first dovetail slot and the second dovetail slot are in a facing relationship. A bar of a shape-memory alloy in the recovered state is received into the first slot and the second slot and has a cross sectional shape with V-shaped grooves on its opposing lateral sides engaging the first dovetail slot and the second dovetail slot.

Abstract: A spacecraft with a reaction wheel system can be autonomously safed by setting the solar wings to continuous tracking, determining a slew rate vector based on the total angular momentum, and slewing the spacecraft using the slew rate vector until commanded to stop autonomous safing. In a typical application, the spacecraft has a reaction wheel assembly with four wheels arranged to form a right regular pyramid. Two reaction wheels on opposite edges of the pyramid form a first pair and the two remaining reaction wheels forming a second pair. The slew axis of rotation is found by determining as a selected pair the first pair if either reaction wheel in the second pair is inoperative, otherwise determining as the selected pair the second pair and determining as the slew axis of rotation the normalized projection of the axes of rotation of the selected pair onto the base. The slew direction is determined by the sign of the total angular momentum component along the slew axis of rotation.

Abstract: The new signal amplifiers dynamically adjust based on the signal's power level. When used on multi-beam satellites, increased signal power indicates an increase in traffic on the channel. The power level of the input signal is sensed and converted to a DC signal, which is applied to a control terminal of a power supply that regulates DC power supplied to the amplifier. During periods of increased traffic, an increase in system power is allocated to the channel. By monitoring traffic on a plurality of channels, available onboard power is allocated based upon the relative channel requirements. The sensed power of multiple channels is summed and scaled to determine the power requirement of the channel relative to the other channels. A command voltage received from a ground station may be switched in place of the summed voltage to allow amplification levels to be controlled from the ground station.

Abstract: A statistical multiplexing apparatus for permanently recording a plurality of video signals on a video generator so that video programs represented by the video signals can be repeatedly broadcast is provided with a video analyzer for analyzing a first video signal and a second video signal and generating a first compression signal and a second compression signal, a first video encoder for encoding the first video signal at a variable rate determined by the first compression signal to form a first encoded video signal, a second video encoder for encoding the second video signal at a variable rate determined by the second compression signal to form a second encoded video signal, and a video generator for permanently recording the first and second encoded video signals so that the first and second encoded video signals can be repeatedly broadcast from the video generator.

Abstract: Spacecraft maneuvers (e.g., orbit transferring, stationkeeping and attitude controlling) of a first spacecraft are realized with conventional force and torque generators (e.g., thrusters and momentum wheels). Spacecraft maneuvers of a second spacecraft are realized through magnetic interaction between the first and second spacecraft. In particular, a magnetic moment vector m.sub.1 of a magnetic system of the first spacecraft and a magnetic moment vector m.sub.2 of a magnetic system of the second spacecraft are adjusted to apply selected force vectors and torque vectors to the first and second spacecraft.