Abstract: Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises scrambling a first header of the first signal using a first scrambling code, scrambling a second header of the second signal using a second scrambling code, and transmitting the first signal and the second signal with the scrambled first header and the scrambled second header over different channels of the communication system.

Abstract: Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises scrambling a first frame using a first scrambling code, attaching a first header to the first frame to create the first signal, scrambling a second frame using a second scrambling code, attaching a second header to the second frame to create the second signal, and transmitting the first signal and the second signal over different channels of the communication system.

Abstract: Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises shifting a characteristic of the first signal with respect to a like characteristic of the second signal to mitigate co-channel interference, and transmitting the first signal and the second signal over different channels of the communication system.

Abstract: A method and apparatus for receiving signals transmitted from a plurality of communications satellites. An apparatus in accordance with the present invention comprises a reflecting surface having a focal point, and a plurality of low noise block down converters with feedhorns (LNBFs), each LNBF having a boresight, wherein at least a first LNBF receives signals in a first frequency band transmitted from a first communication satellite location that are focused at a first focal point and at least a second LNBF receives signals in a second frequency band transmitted from a second satellite location that are focused at a second focal point, wherein the boresight of the first LNBF is closer to the first focal point than the boresight of the second LNBF is to the second focal point.

Abstract: A method and apparatus for optimizing a system for transmitting a layered modulated signal is disclosed. The method comprises the steps of defining the system in terms of a set of system parameters, including an optimal power separation S between a power of a first modulation layer and a power of a second modulation layer and a required system carrier-to-noise ratio (CNRS), determining an optimal power separation S to minimize the error rate of a lower layer modulated signal BERL, and selecting the remaining system parameters in the set of system parameters using the determined optimal power separation S.

Abstract: An apparatus for reducing earth station interference in a receiver antenna from non-GSO and terrestrial sources is disclosed. The apparatus comprises an absorber coupled to a receiver antenna feed assembly disposed between the non-GSO or terrestrial source and the feed assembly. Embodiments are disclosed in which the absorber is strategically placed where it minimally affects the receiver antenna mainlobe performance, while reducing interference from non-GSO and terrestrial sources.

Abstract: Improved magnetron oscillators that controllably form a plasma within each of its resonant cavities to rapidly change the resonant frequency of each cavity. The present invention also provides for frequency tuning methods for use with magnetron oscillators. The plasma is controllably formed in one or more subcells of each resonant cavity in a manner that alters the electromagnetic field within each cavity. Preferably, a magnetized collisional plasma is controlled to rapidly change the resonant frequency of each cavity. However, many types of plasmas may be used to implement the present invention. Controlling formation of the plasma within each cavity tunes the magnetron oscillator on a submillisecond time scale.

Abstract: A microwave switch selectively directs a microwave signal along first and second signal paths. The switch includes a microwave transmission member, a microwave chamber formed by the transmission member for containing an ionizable gas, input and output ports formed by the transmission member to communicate with the microwave chamber and a triggered plasma generator which is configured to generate, in response to a voltage trigger signal, a trigger electron density N.sub.t in the gas. The microwave signal increases the trigger electron density N.sub.t to a reflective electron density N.sub.r. Consequently, the microwave signal is reflected along a first path from the input port when the trigger electron density N.sub.t is present and is directed along a second path to the output port when the trigger electron density N.sub.t is absent. A plurality of these microwave switches is arranged to form a tunable microwave short.

Abstract: Plasma wave tubes are disclosed having waveguide injection systems configured for injection of an RF signal to prebunch the electron beam of the tube and thereby control the frequency of an RF output signal. Preferred embodiments of the injection system include a plurality of rectangular waveguides arranged radially about a cylindrical waveguide member and joined to it for communication with its interior. Plasma wave tubes (140) are also disclosed that utilize the injection system as a collector (44C) to couple an RF output signal from the tube.

Abstract: A plasma wave tube is described in which a pair of counterpropagating electron beams are injected into a waveguide housing in which a plasma is formed, prefeferably by an array of fine wire anodes. The electron beams couple with the plasma to produce electron plasma waves, which radiate electromagnetic energy for beam voltages and currents above established threshold levels. A rapid control over output frequency is achieved by controlling the plasma discharge current, while the output power can be controlled by controlling the voltage and/or current levels of the electron beams.

Abstract: A high-power microwave/mm-wave oscillator is filled with an ionizable gas at a pressure of about 1-20 mTorr, into which an electron beam is injected at a high current density of at least about 1 amp/cm.sup.2, but typically 50-100 A/cm.sup.2. A plasma is formed which inhibits space-charge blowup of the beam, thereby eliminating the prior requirement of a magnet system to control the beam. The system functions as a slow-wave tube to produce narrow-band microwaves for a gas pressure of about 1-5 mTorr, and as a plasma wave tube to produce broadband microwave/mm-wave radiation for a gas pressure of about 10-20 mTorr.