Abstract: A low-cost rocket or thruster has a low-cost propellant injector, in which fluid fuel and oxidizer are injected into a combustion chamber. The walls of the combustion chamber are protected from the high temperatures of the combustion by a grain of solid propellant, the surface of which tends to melt andor vaporize in the presence of combustion temperatures, and thereby protects the walls of the chamber. The low-cost propellant injector may not mix the fluid fuel and oxidizer effectively, so that pockets of noncombusted gas may occur within the chamber. The ratio of fluid fuel and oxidizer is selected to be slightly oxidizer-rich, so that any pockets of unburned gas tend to be oxygen-rich. When the pockets come into contact with the solid fuel, the excess oxygen combusts with the gaseous solid fuel, and when the mixture is near stoichiometric, the fluid fuel combusts.

Abstract: A switching converter achieves improved regulation range by the use of a saturable reactor in series with a transformer primary. The saturable reactor uses a conventional magnetic pot core including a magnetic shell and center post. The location at which the post joins the shell is perforated to reduce the cross-section of magnetic material, so that, at low reactor currents, incremental inductance is established by the gap between post and lid, and at high reactor currents, the incremented inductance is established by saturation at the base of the post. Perforation at the base of the post also results in generation of heat at a location immediately adjacent the flat bottom of the pot core.

Abstract: An apparatus and method for radar detection of spectral moments and other spectral characteristics of echoes includes an agile antenna which directs an antenna beam in a direction for a dwell interval. A clutter filter reduces clutter. In order to eliminate the need for fill pulses to stabilize the clutter filter, the clutter filtering is accomplished by matrix multiplication of the echo signal in each range bin by the inverse of the covariance matrix for that range. This reduces the dwell at each range interval, and provides a stream of pulse-to-pulse information at each range interval. The pulse-to-pulse data in each range interval is spectrum analyzed to extract the desired spectral information, which is displayed.

Abstract: An arrangement for coordinating positional and angle information made on separate relatively moving platforms, such as aircraft, having independent coordinate systems, uses measurements of a common reference made on both platforms. The measurements are transmitted to a common location. Measurements made at a first time are processed to determine two of three coordinate transformation angles. After a period of time, a second set of measurements is used to determine the third coordinate transformation angle. In a particular embodiment of the invention, the direction of motion of one of the platforms is controlled to be orthogonal to a coordinate axis of the other platform. When the coordinate transformation is determined, it can be used to coordinate or align navigation instruments, weapons, or the like. In one embodiment of the invention, a missile is directed toward a target, in a situation in which the target is viewed from the missile and another moving vehicle.

Abstract: A spacecraft includes a plurality of solar panels interconnected with a power coupler and an electrically operated device to provide power to the device when the solar cells are insolated. The solar panels are subject to bending distortion when entering or leaving eclipse. Spacecraft attitude disturbances are reduced by mounting each of the solar panels to an elongated boom made from a material with a low coefficient of thermal expansion, so that the bending of one panel is not communicated to the next. The boom may be insulated to reduce its bending during changes in insolation. A particularly advantageous embodiment mounts each panel to the boom with a single mounting, which may be a hinge. The single mounting prevents transfer of bending moments from the panel to the boom.

Abstract: Improved throughput is provided in a spacecraft TDMA cellular communications system by in-call signalling without the need for flag bits, while still allowing the in-call signaling to be differentiated from other traffic. The terrestrial locations include mobile user terminals and gateways which provide connections to the land telephone line system. The spacecraft includes a transmitter and receiver, and an antenna which forms a plurality of spot beam footprints, in which the terrestrial terminals are located. Each of the terrestrial terminals transmits signals to, and receives signals from, the spacecraft. Each of the terrestrial terminals includes an encoder/decoder, for encoding at least call maintenance control signals, for temporarily interrupting the traffic signals to allow another action. The control signals may have bit content which exceeds the bit-carrying capability of the TDMA bursts, so transmission of the control signals must extended over a plurality of bursts.

Abstract: A communications system includes first and second ground stations and a spacecraft repeater. Data signals are transmitted between ground stations by way of the repeater, together with spread-spectrum ranging signals. Uplink rain attenuation is compensated for changing the transmitted power at the ground stations. The amount of downlink attenuation is determined by measuring the total carrier-to-noise ratio in three paths, station 1 to station 2, station 2 to station 1, and station 1 to station 1. With these three values of total attenuation, the two downlink attenuations and the number of active signals traversing the repeater can be determined. The downlink attenuations are converted to uplink attenuations, and used to control the transmitters.

Abstract: A spacecraft includes heat-radiating panels. Heat-generating boxes such as TWTs are mounted on shelves which are inside the spacecraft, where they cannot radiate to space. The shelves are coupled by bent heat pipes to the exterior radiating panels.

Abstract: A spacecraft includes a three-axis attitude control system. When velocity change thrusters are fired, their plumes impinge on a solar array, at angles which vary with the solar array position. This causes disturbance torques which vary with the solar array position. Disturbance torque information signals or torque bias signals which depend upon the solar array angle are summed with the torque demand signals which control the attitude control system during firing of the velocity change thrusters, to modify the attitude correction torques. The bias torque signals are generated by a Fourier processor based upon stored Fourier coefficients together with signals from a solar array angular position sensor.

Abstract: A ranging system for a communications spacecraft (14) overlays a Gaussian noise signal over a broadband channel which also carries information or traffic signals. The noise is used to establish the range between a ground station (12) and the spacecraft (14). The range is determined by delaying the Gaussian noise in a controllable delay (32), and autocorrelating the delayed noise with the noise returned over the communications channel from the spacecraft. The ranging system (FIG. 4) reduces the bandwidth of the noise in a filter (18) during initial acquisition, to color the noise and broaden the autocorrelation peak (FIG. 3a). The broad peak shortens the initial search time. Once the peak is initially found, the noise bandwidth is progressively broadened to narrow the autocorrelation peak (FIG. 3c) and to give a more accurate indication of range.

Abstract: The loop filter of a sigma-delta analog-to-digital converter (ADC) includes a multistage loop filter coupled to the output port of an input summer stage, for receiving difference signals therefrom. The loop filter includes a plurality of cascaded stages. All but one of the cascaded stages includes first and second cascaded half-stages, and that one of the stages includes at least one half-stage. The last one of the cascaded half-stages in the loop filter is coupled to the input port of an ADC stage for coupling loop-filtered difference signals or resonated signals thereto. The ADC stage produces the desired output digital signals. A DAC is coupled to the output of the ADC stage, for generating an analog replica of the desired digital output signals, and for coupling the replica to the input summer stage for aiding in generating the difference signals.

Abstract: A half-wave brushless, four-phase DC motor includes sets of four stator windings fed at 90.degree. phase increments by four switches. The 0.degree. and 180.degree. windings are wound about their magnetic stator poles in bifilar conductor pairs, and the 90.degree. and 270.degree. windings are similarly wound. The bifilar windings are connected to generate the same directions of magnetic fields as the prior-art windings. As a result of the bifilar windings, the magnetic fields of the windings tend to be identical, and all the inductances of each winding tend to be transformer-coupled to the other winding of the bifilar pair. During sequential turn-off of the switches in normal operation, the coupled inductance causes a voltage kick which is poled so it can be damped, and the energy returned to the source, by a diode coupled across the other switch of the bifilar pair.

Abstract: A speech signal has its characteristics extracted and encoded (16), transmitted over a limited-data-rate path (18) and is decoded (20) and synthesized (22) at the receiving end. The characteristics include line spectral frequencies (LSF), pitch and jitter. The LSF are extracted by autoregression, and splitvector quantized (SVQ) in a single frame, and, in parallel, in blocks of two, three and four frames. The SVQ codes have equal length and are evaluated for distortion in conjunction with a threshold. The threshold is varied in such a manner as tend to select for transmission those codewords which maintain a constant data rate into a transmit buffer. A single-bit jitter bit, and encoded pitch value, are product coded with the selected LSF codeword, and all are transmitted over the data path (18) to the receiver. The receiver decodes the characteristics, and controls a pitch generated (1226) in response to the pitch value and a random pitch jitter in response to the jitter bit.

Abstract: A hydraulic pump (16) is driven by an induction motor (14) from a source of multiphase alternating current (10) of either fixed or variable frequency. The pressure is applied to a hydraulic load, which may vary, and change the pressure. A pressure sensor coupled to the pump produces pressure signals. The motor includes plural windings, typically three, associated with a number of poles. Each motor winding is driven by a different phase of controlled alternating current. A rectifier (46) coupled to the multiphase AC source generates direct current, which is filtered to minimize DC ripple voltage. A controllable multiphase inverter (54) is coupled to the rectifier and to the motor windings, for converting the direct voltage into multiphase alternating motor drive voltages of controllable amplitude and frequency.

Abstract: An array antenna especially adapted for spacecraft use includes a support frame made up of intersecting beams which form an "eggcrate" of square openings. A plurality of subarrays or radiating tiles are dimensioned to fit within the openings. Distortion of the support frame due to external forces, or due to expansion and contraction of the radiating tiles, is accommodated andor resisted by a four-point mounting arrangement for each tile. Each mounting is located on the center of the sides of the radiating tile, and the corresponding center of the side of the opening in which it fits. Each mounting consists of a thin, flexible mounting beam, extending parallel to the associated support beam, and fastened to the support beam at the ends of the mounting beam. The center of the side of the tile is fastened to the center of the flexible support beam, so expansion and contraction of the tile are compensated by bending of the flexible beam.

Abstract: A speech signal has its characteristics extracted and encoded (16), transmitted over a limited-data-rate path (18) and is decoded (20) and synthesized (22) at the receiving end. The characteristics include line spectral frequencies (LSF), pitch and jitter. The LSF are extracted by autoregression, and split-vector quantized (SVQ) in a single frame, and, in parallel, in blocks of two, three and four frames. The SVQ codes have equal length and are evaluated for distortion in conjunction with a threshold. The threshold is varied in such a manner as tend to select for transmission those codewords which maintain a constant data rate into a transmit buffer. A single-bit jitter bit, and encoded pitch value, are product coded with the selected LSF codeword, and all are transmitted over the data path (18) to the receiver. The receiver decodes the characteristics, and controls a pitch generated (1226) in response to the pitch value and a random pitch jitter in response to the jitter bit.

Abstract: A three-axis stabilized spacecraft includes a plurality of primary attitude control thrusters, the torque vectors of which lie in, or parallel to a primary plane. It also includes at least two more secondary attitude control thrusters, the torque vectors of which lie in a secondary plane which is not parallel to the primary plane. The control system produces attitude error signals, which are processed with a PID characteristic to produce impulse demand signals, all in known fashion. The impulse demand signals are transformed into an auxiliary coordinate system, in which two of the three auxiliary axes lie in the primary plane, and the third is orthogonal thereto. One of the secondary thrusters is selected, which has, along the third auxiliary axis, the largest torque magnitude and the same sign as the transformed impulse demand.

Abstract: An optical fiber cable includes one or more optical fibers surrounded by a dielectric longitudinal strength member such as an aramid braid. The cable penetrates a bulkhead at a connector which couples tensile forces acting on the strength member to the bulkhead, to prevent breakage of the fiber(s). The connector includes two mating annular conical members which surround the optical fibers, with the strength braid flared and extending between the mating conical surfaces. The two cones are forced together by a bulkhead connector with a first thread and a second connector with a mating thread, thereby captivating the strength member to the bulkhead to resist tension. Concentric or annular grooves are formed in at least one of the mating conical surfaces to aid in gripping the slippery strength member.

Abstract: A system for extracting a three-dimensional model of an object viewed in a selected scene, includes at least one camera for acquiring scene information, each from a different spatial-temporal aspect of the total scene. A digitizer converts the scene video and directional information to digital data, for at least temporary storage in a mass memory associated with a computer for data processing. An interactive display provides a means by which a human operator can view the stored scene information and select at least one scene object for which the computer will extract a 3D model, for subsequent use by a designated output device.

Abstract: A digital signal processor (24) includes a plurality of vector processors (212x), each of which is made up of a group of, for example, six signal processors (214x). Each signal processor includes Local 1 and Local 2 ports (201, 203), and the Local 1 port of one processor of a group is coupled by a path (218) to the Local 2 port of another processor, so the group forms a ring. Each signal processor (214) also includes a memory (234), an arithmetic processor (232), and a switcher (230) for making internal interconnections among the ports, and also includes a switcher control (364, 366). At least one of the signal processors (214) of each group is of a type including a further external port (206), by which data can be coupled by a path (105) to and from the group. The signal processors of each group can be interconnected for serial or parallel processing, all under the control of a group controller (216) associated with each vector processor.