Patents Assigned to Comsat
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Patent number: 3988674Abstract: Bit rate compression in a digital communications system is provided by transmitting voice information from n telephone circuits over the capacity conventionally allocated for transmission of voice information from n/2 circuits without appreciable degradation in quality. Alternatively, a doubling of the number of voice circuits may be provided with transmission at the same bit rate required for conventional digital transmission of voice information. Each frame period, at the transmitter, all n circuits are serviced and, utilizing a predictive encoding scheme, only unpredictable samples in the given frame are transmitted over the available channel capacity. A sample assignment word (SAW), which identifies the circuits corresponding to the unpredictable samples, is transmitted therewith.Type: GrantFiled: March 17, 1975Date of Patent: October 26, 1976Assignee: Communications Satellite Corporation (Comsat)Inventor: Joseph Albert Sciulli
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Patent number: 3988736Abstract: 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.Type: GrantFiled: November 29, 1974Date of Patent: October 26, 1976Assignee: Communications Satellite Corporation (Comsat)Inventors: Lewis V. Smith, Jr., Norman P. Miller
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Patent number: 3982964Abstract: 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.Type: GrantFiled: January 17, 1975Date of Patent: September 28, 1976Assignee: Communications Satellite Corporation (Comsat)Inventors: Joseph Lindmayer, James Frederick Allison
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Patent number: 3979701Abstract: 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.Type: GrantFiled: June 17, 1975Date of Patent: September 7, 1976Assignee: Communications Satellite Corporation (Comsat)Inventor: Atsushi Tomozawa
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Patent number: 3977905Abstract: 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.Type: GrantFiled: June 20, 1975Date of Patent: August 31, 1976Assignee: Communications Satellite Corporation (Comsat)Inventors: Akos G. Revesz, Joseph Lindmayer
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Patent number: 3975690Abstract: A planar transmission line comprising a Gunn effect semiconductor having an epitaxial portion as the propagating medium amplifies and switches r.f. signals and is not transit time limited in the direction of propagation. The spacing between the transmission line conductors and the dopant concentration of the Gunn effect semiconductor are selected to prevent the formation of domains and thereby prevent Gunn oscillations from occurring at E fields above the Gunn threshold.Type: GrantFiled: September 2, 1975Date of Patent: August 17, 1976Assignee: Communicatons Satellite Corporation (Comsat)Inventor: Paul L. Fleming
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Patent number: 3972065Abstract: 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.Type: GrantFiled: June 30, 1975Date of Patent: July 27, 1976Assignee: Communications Satellite Corporation (Comsat)Inventors: Melville Lynwood Heiges, Jr., Leonard Golding, Bela Banyasz
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Patent number: 3969692Abstract: 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.Type: GrantFiled: September 24, 1975Date of Patent: July 13, 1976Assignee: Communications Satellite Corporation (Comsat)Inventors: Albert Edward Williams, Ali Ezzeldin Atia
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Patent number: 3963990Abstract: 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.Type: GrantFiled: February 27, 1974Date of Patent: June 15, 1976Assignee: Communications Satellite Corporation (Comsat)Inventor: Daniel F. DiFonzo
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Patent number: 3955156Abstract: A planar microwave integrated circuit, including features of slot lines and coplanar lines, for use as a magic tee and a power divider.Type: GrantFiled: April 29, 1974Date of Patent: May 4, 1976Assignee: Communications Satellite Corporation (Comsat)Inventor: Paul Lawrence Fleming
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Patent number: 3949463Abstract: A method of applying an anti-reflective coating, particularly a metal oxide coating to a solar cell during the manufacture of such cell.Type: GrantFiled: February 13, 1973Date of Patent: April 13, 1976Assignee: Communications Satellite Corporation (Comsat)Inventors: Joseph Lindmayer, James F. Allison
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Patent number: 3942115Abstract: 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.Type: GrantFiled: October 31, 1973Date of Patent: March 2, 1976Assignee: Communications Satellite Corporation (COMSAT)Inventor: Chester Joseph Wolejsza, Jr.
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Patent number: 3940706Abstract: 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.Type: GrantFiled: May 13, 1974Date of Patent: February 24, 1976Assignee: Communications Satellite Corporation (Comsat)Inventor: Ronald E. Stegens
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Patent number: 3934208Abstract: 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.Type: GrantFiled: May 31, 1974Date of Patent: January 20, 1976Assignee: Communications Satellite Corporation (Comsat)Inventors: William J. Getsinger, Paul Koskos, Su Min Chou
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Patent number: 3931953Abstract: 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.Type: GrantFiled: May 9, 1974Date of Patent: January 13, 1976Assignee: Communications Satellite Corporation (Comsat)Inventor: William Arthur Allen