Abstract: An antenna reflector having a parabolically curved reflecting surface is formed of a cellular ceramic material having ceramic fibers fused together in a rigid cellular structure. The body is formed by bonding or fusing a mass of silicon dioxide fibers together at their points of intersection with a fusing agent such as boron nitride in a sintering process, resulting in a fused array of fibers with cellular porosity intentionally distributed through the body to reduce its density. Other types of ceramic fibers can be used either alone or in combination with the silicon dioxide fibers. The antenna reflector finds particular utility in parabolic antennas for satellite microwave communications systems.

Abstract: An adaptive antenna comprising at least two sensors for receiving electromagnetic signals and for producing first signals; the antenna further including divider means for dividing each first signal into respective second and third signals; weighting means for modifying each respective second signal according to a quantized weighting function; summing means for summing the respective second signals to provide a fourth signal; means for producing a system feedback signal in response to the fourth signal; limiter means for limiting the dynamic range of the system feedback signal; correlator means for correlating the respective third signals with the limited system feedback signal to produce respective correlator output signals; means for determining the signal environment power level of the far field sensed by the at least two sensors and for providing a fifth signal substantially corresponding to 1/.sqroot.

Abstract: An improved clamping connection assembly for separable parts of spacecraft is provided and includes a tension belt for securing a plurality of retainers against camming surfaces on flange members on separable spacecraft component parts. The other peripheral edges of the flange members have detents to respectively receive a single shear pin mounted on each of the retainers. The shear pins receive any shear and torsional forces and transmits them between the structural parts of the spacecraft components without creating additional forces on the tension belt.

Abstract: A synchronizer (10) for frequency division multiple access signals (FDMA) permits synchronization on board a communications satellite without feedback to a multitude of ground-based user stations. Fourier transform processors (12, 13) sample the FDMA signal at half the FDMA baud rate and provide a series of pulses. Frequency translators (14, 15) frequency translate each pulse to frequency align across channels the content of one respective complete symbol segment to be isolated by bandpass filters (16, 17). A demodulator 18 provides a synchronized time division multiplexed output. Two channels alternately sample the FDMA signal to obtain full decoding.A synchronization processor (20) is provided to ensure that the pulses undergo appropriate frequency translations. The synchronization processor detects TDM pulse amplitudes (at 22) and compares them (at 24) to obtain a discriminate which sets a translation frequency (at 26) for each FDMA channel.

Abstract: This invention provides improved performance and reduced cost relative to conventional carrier phase tracking systems. The invention improves the performance of the communication system by rapidly acquiring and reliably tracking the carrier signal with substantially digital hardware. The invention has no reverse slope null characteristic and therefore does not suffer from hangup. As such, acquisition time is independent of phase error. These solutions are provided without the added expense and calibration problems of a crystal filter or the performance compromise of the dual phase detector phase locked loop.The invention includes circuitry which removes the carrier from the received data signal and converts the signal to a complex baseband signal. The baseband signal is subsequently sampled to provide a plurality of complex samples. The phase of each sample is extracted and compared to the phase of an adjacent sample to provide phase difference signals.

Abstract: Apparatus and a method for deploying a spacecraft into orbit from a launching vehicle is provided. The apparatus includes a pivot support assembly having a pivot seat member contacting the spacecraft on the opposite side of its center of mass relative to the application of an ejecting force. The pivot seat member is biased against the stop member with a directional force which is less than the maximum force capable of being exerted on the seat member during the takeoff of the launching vehicle from earth but greater than the force exerted on the seat member during deployment. The biasing member can be a form of spring such as a torsion bar.

Abstract: A pivotal joint for waveguides provides a low-loss interface between two rigid waveguides at which relative movement can occur. The pivotal joint has two waveguide sections which are terminated in conical surfaces containing concentric chokes to minimize RF energy leakage. A universal gimbal is utilized to position the joints so that the pivotal motion occurs about the apices of the chokes. The advantages of this RF joint include zero bending torque, absence of a fatigue failure mode, low insertion loss and a good impedance match at all angles of operation and over large bandwidths.

Abstract: An apparatus for transporting a spacecraft and fluid propellant from the earth to a substantially low gravity environment above the earth with substantially reduced loading of the spacecraft due to forces upon the fluid propellant during the transport, the apparatus including a vehicle for carrying the spacecraft and the fluid propellant from the earth to a substantially low gravity environment above the earth; a plurality of external tanks disposed within the vehicle, external to the spacecraft, for containing the fluid propellant as the vehicle carries the spacecraft and the fluid propellant from the earth to the substantially low gravity environment above the earth; a plurality of spacecraft tanks disposed within the spacecraft for receiving the fluid propellant and for containing the fluid propellant; and means for transferring the fluid propellant from the external tanks the spacecraft tanks in the substantially low gravity environment above the earth.

Abstract: A bi-directional current switch is provided which serves as a DC coupler mixer driver for PSK modulators. The invention includes a first switchable current source for selectively providing one of at least two current flow rates at an output node. A second current source acts as a sink and provides a steady state current flow rate out of said node. When the first current source is switched on, the output current is reversed. The invention thereby provides bi-directional current switching in response to a logical input signal.

Abstract: An integrated circuit latch is provided for providing first and second output signals, each first output signal being a logical complement of a corresponding second output signal; the latch includes means for receiving a first clock signal; means for receiving a corresponding second clock signal, the second clock signal being a logical complement of the first clock signal; means for receiving N first data signals, where N is an integer and N<1; means for receiving N second data signals, where each second data signal corresponds to a first data signal and is the logical complement of a corresponding first data signal; NOR-OR logic function means for providing the first output signal characterized by the OR function of first and second logic inputs, the first logic input characterized by the NOR function of the second output and the second clock signal, the second logic input characterized by the NOR function of the first data signals and the first clock signal; and NAND-AND logic function means for providin

Abstract: A waveguide switch operable at microwave frequencies is formed of two waveguides of rectangular cross section with a longer wall and a shorter wall, the two waveguides sharing a common shorter wall. Two coupling windows are disposed within the common wall for coupling electromagnetic energy between the two waveguides, each coupling window introducing a 90.degree. phase shift. Each window couples one-half the power of an electromagnetic wave from a first of the guides to a second of the guides. The common wall is parallel to the electric field of the coupled wave, with each wave being a TE wave. A 90.degree. phase shift is introduced by each coupling with the result that utilization of both windows produces a summation of the two waves in the second of the waveguides and a cancellation of the two waves in the first of the waveguides.

Abstract: A process and apparatus for controlling the charging of pressurized gas-metal cells such as nickel-hydrogen cells, to prevent detrimental overcharging, wherein the time rate of change of a battery gas pressure index is monitored as a control parameter. When the time rate of change of the index falls below a preselected value, charging is discontinued. The cell gas pressure index can be gas pressure itself, or a quantity which is responsive to, and depends upon gas pressure, such as the deformation of a cell component.

Abstract: A waveguide hybrid coupler is formed with a pair of waveguides of rectangular cross section and sharing a common sidewall. An aperture in the sidewall provides for the coupling of electromagnetic energy between a first of the waveguides and a second of the waveguides. An input terminal is located at an end of the first waveguide. A pair of stepped, multi-tiered abutments are disposed on the outer sidewalls of the waveguides opposite the coupling aperture. The dimensions of the abutment steps are selected to stagger-tune the frequency response of the coupler to achieve wideband operation.

Abstract: A process for preventing electrical capacity loss during storage of a pressurized nickel-hydrogen electrical storage cell. An electrical precharge is applied to the positive electrode of the cell, so that discharge of the cell is negative electrode limited. In one approach, the cell is charged, while sealed, to a state of charge corresponding to a first gas pressure, and then the hydrogen pressure is reduced to a lower value, preferably about atmospheric. In another approach, a current is passed through the cell while the cell is unsealed and maintained at atmospheric gas pressure, until the cell reaches the desired state of charge.

Abstract: A system for surveying features of a planet includes a novel attitude determination subsystem. A satellite includes an earth imaging sensor (106). The sensor is alternately directed at the earth and a predetermined star field. The optical detections are converted to electronic signals by a sensor electronics module (332). The outputs of the sensor electronics module corresponding to the times when the sensor is directed toward earth are processed by a signal processor (336), the output of which is a data stream which permits image reconstruction by a ground station computer. The outputs of the sensor electronics module corresponding to the times when the sensor is directed toward the star field are directed through onboard star detection thresholding electronics. A programmable threshold device (342) selects detections of target stars within the star field. A star data buffer (344) stores these target star detections for transmission to earth at a convenient time.

Abstract: Apparatus for use in gyroscopically ejecting a spacecraft supported in the open end of a spacecraft supporting cradle. The invention comprises a separable ejection restraint mechanism attached between the cradle and the spacecraft. The mechanism restrains the thrust force applied to the spacecraft for a predetermined time period in order to dissipate undetermined forces acting upon the spacecraft prior to the ejection thereof. The mechanism comprises a separable resilient portion and a releasable clamp portion coupled thereto. The resilient portion comprises a spring loaded anchor rod arrangement while the releasable clamp portion comprises a spring loaded split ball clamp arrangement. The invention also contemplates the use of a flexible carrier coupled between the spacecraft and the cradle. The invention acts as a tether connected between the cradle and spacecraft which acts to establish a determinant state of force on the cargo and eliminate unwanted ejection-related problems prior to cargo deployment.

Abstract: A switch (11) for a square coaxial network includes a lower housing (13), a rotor assembly (21), alternative transmission lines (19), and an upper housing (15) with a main transmission line (17). The rotor assembly includes a rotor (23) for selectively coupling the main transmission line to a selected alternative transmission line. The rotor is coadapted with each transmission line for resonant coupling therewith. A conductive shield (29) rotates with the rotor and isolates it from the unselected alternative transmission lines. A low-friction dielectric guide (25) helps provide proper spacing and coupling of the rotor and the square center conductor (35) of the selected alternative transmission line. A low-friction dielectric bushing (27) serves a similar function for the rotor and the center conductor of the main transmission line.

Abstract: An ejection mechanism for imparting an ejection force to substantially constant locus of points on a payload ejected from a spacecraft is disclosed. The ejection mechanism includes a rod having a contact end for abutting contact with the locus of points. The rod is slideably mounted within a housing defining a first aperture from which the rod is driven toward the locus of points. Means are provided for driving the rod toward the payload to eject the payload, and means are provided for securing the housing to the spacecraft. The ejection mechanism also includes means for permitting the contact end of the rod to substantially maintain abutting contact with the locus of points as the rod is driven toward the locus and the payload is ejected from the spacecraft.