Abstract: A plurality of steerable beam feed devices are used in combination with a single stationary toroidal antenna which permits simultaneous communication with several geosynchronous satellites. Each feed device is movably mounted on a flat elevation plate having linear bearings which mate with rails on a flat azimuth plate to allow the feed to be positioned vertically or at some angle with respect to the vertical depending upon the orientation of the antenna. The flat azimuth plate is mounted for movement on two curved rails which follow the focal arc of the toroidal antenna. Linear actuator devices are provided for moving each plate within a limited range to provide fine positioning of the feed relative to the antenna.

Abstract: An improvement in a fine geometry solar cell having a top surface contact comprising substantially more and finer metallic fingers spaced close together for collecting photo current is disclosed. The improvement comprises a reduction in the ohmic contact area of the fine metallic fingers with the light-incident surface of the solar cell. The improved solar cell is constructed by etching a fine line pattern into the anti-reflective coating of the solar cell and then depositing a fine line electrode onto the surface of the solar cell but oriented perpendicular to the etched fine line pattern in the anti-reflective coating. Due to the 90.degree. rotation between the etched fine line pattern in the anti-reflective coating and the fine line electrode, only point contacts are made between the fine line electrode and the exposed light-incident surface of the solar cell.

Abstract: A non-recursive digital filter is disclosed, composed of a cascaded plurality of basic sections, each of which is characterized by coefficient values of integer powers of two's. No hardware multipliers are required in the filter and the operating speed is several times faster than other filters which utilize multipliers.

Abstract: A niobium pentoxide (Nb.sub.2 O.sub.5) anti-reflective coating for use on a solar cell responsive to light in the short wavelength region.

Abstract: A method of testing both digital and analog color television systems is disclosed. The method includes the generation of a unique test signal enables the measurement of differential-phase and differential-gain at continuously variable average pictures levels (APL) anywhere between ten per cent and ninety per cent. Because of the particular test signal employed, the method of testing color television systems may be used with either full-frame or single-line (including vertical interval testing) format.

Abstract: A waveguide structure composed of circular waveguide cavities resonant in the TE.sub.011 mode is capable of realizing the most general bandpass filter characteristics with significant decreases in filter loss and gain slope. In addition to the commonly used Tchebychev and Butterworth functions, the structure can realize general transfer functions including the elliptic function. In its simplest form, the structure is composed of four cylindrical cavities which form a building block for more complex filters. The first and second cavities and the third and fourth cavities each have their side walls in contact and their end walls in common planes. The third and fourth cavities are superposed to the first and second cavities with their adjacent end walls in a common plane, but the second and third cavities are offset so that they overlap at one-half diameters. The first and second cavities are coupled by means of a centrally located side wall slot, as are the third and fourth cavities.

Abstract: An interference reduction circuit to provide isolation in frequency reuse systems operates on two or more non-isolated signals by cross-coupling the signals such that the interfering signals are cancelled on each channel. In a dual-polarized frequency reuse system, cancellation is effected by adding a sample of an oppositely polarized channel of equal amplitude, but of opposite phase, to the interference. Practical implementation includes closed-loop, digital feedback control to permit dynamic signal-to-interference improvement involving no a priori knowledge of the nature of the incoming signals. The circuit has applications in satellites and earth stations in a communications satellite system.

Abstract: A new sealed rechargeable electric fuel cell of the type using a metal oxide, metal hydroxide or oxygen as the positive electrode reactant and hydrogen as the negative electrode reactant. The cell uses a hexagonal nickel - rare earth metal hydride compound for storage of hydrogen gas which causes the cell to be maintained at a low gas pressure during charging and discharging.

Abstract: A planar microwave integrated circuit, including features of slot lines and coplanar lines, for use as a magic tee and a power divider.

Abstract: A method of applying an anti-reflective coating, particularly a metal oxide coating to a solar cell during the manufacture of such cell.

Abstract: A stuff decision code word of multiple bit length is transmitted over a number of frames equal to the number of bits per stuff decision code word. Advantage is made of a unique word used for burst synchronization wherein a common code word is used for both stuff decision and burst synchronization. A hierarchy of bursts is established to identify the particular channel of information to which the stuff decision is associated.

Abstract: In a solar cell a pad of material is placed between the cell semiconductor surface and the portion of the top electrode which is bonded to an interconnector. The pad prevents destruction of the cell p-n junction during bonding. The pad may be the same as an anti-reflective coating and may be formed simultaneously with the formation of the anti-reflective coating.

Abstract: A pilot signal for implementing automatic frequency control in a satellite communications system is continuously transmitted by a designated ground station. Its frequency lies in the middle of the communications band so that it will undergo the same frequency shifts or distortions as the overall communications signal. A second ground station monitors the presence of the pilot signal, and if it is lost for a predetermined time, this second station then transmits the pilot signal to ensure the continuation of the AFC function throughout the system. If the pilot signal is lost at the second station, however, an uncertainty might exist as to whether the failure is in the designated ground station or the second ground station. To resolve this uncertainty a secondary pilot signal, having a frequency different from but in the same band as the primary pilot signal, is transmitted by a third ground station.

Abstract: A low noise, multistage microwave transistor amplifier constructed using microwave integrated circuit techniques is disclosed. The illustrated embodiment is a two-stage transistor amplifier which is the basic building block for broadband, high-gain cascades. This amplifier features an interstage network consisting of a very short transmission line which minimizes the size and frequency dependence of the amplifier. This is achieved in the satellite communications band of 3.7 to 4.2 GHz by constructing the amplifier on a suitably low dielectric constant substrate rather than the usual high dielectric constant substrates used in microwave amplifier applications.

Abstract: A low cost digital echo suppressor having break-in logic for overriding send-line interrupt operation. The send and receive signals are multiplexed and digitized. The digitized received signals are summed over a period of time to determine interrupt operation. The difference over a period of time of the receive and send line signals controls break in logic for overriding the interrupt operation.

Abstract: The low noise parametric amplifier disclosed is a non-cryogenic non-redundant plural stage unit with excess gain such that failure of any one stage results in only minor degradation of signal-to-noise ratio. While the amplifier is of general application, it is specifically intended for use in the receiver of an unattended earth terminal of a satellite communication system. In this environment, reliability is achieved by employing a plurality of cascaded, modular parametric amplifier stages. Each stage includes a varactor diode, a pump circuit with its oscillator, a bias circuit, and temperature stabilizing circuitry employing a Peltier junction. The stages are connected to a multi-port circulator by quick disconnect couplings which permit the modular amplifier stages to be removed and replaced without any interruption in the operation of the amplifier.

Abstract: The valve is comprised of a substantially oblong chamber having one end thereof extending transversely into a conduit having a semi-circular slot formed therein. The portion of the chamber extending into the conduit is provided with a through passage in alignment with the conduit and a valve disc is movably mounted in the chamber for transverse movement relative to the conduit between an operative position in alignment with the conduit and an inoperative position outside of said conduit. An inflatable tube is secured in a peripheral groove in the circumference of the disc and is disposed in fluid communication with the interior of a hollow valve stem secured to the disc and extending outwardly of the chamber. A piston is connected to the valve stem for reciprocating movement in a double acting fluid cylinder and the extreme end of the valve stem extends into a chamber connectable to a source of air under pressure by a suitable valve to control the inflation of the inflatable tube.

Abstract: A reliable earth terminal for satellite communications systems capable of unattended operation for extended periods of time is disclosed. The terminal includes an antenna with a single fixed reflector which can provide multiple beams, each of which can be positioned by small feed motion. The transmitter is of a modular construction, using a relatively low power traveling wave tube power amplifier for each increment in the operating band. The transmitting chains are designed to carry voice, data, or television signals to a satellite and include a modulator, IF amplifier, band-limiting filter, frequency converter, and power amplifier. Each amplifier is capable of operating over the full operating band; however, operation of each amplifier is limited to an assigned increment through the use of band-limiting filters. A single, redundant high power amplifier is provided and may be remotely switched into any one of the transmitting chains in the event of a failure.