Terrastar, Inc.

Leland Stanford Junior University

K C Corp.

Other

Mitsubishi Electric and Electronics U.s.a., Inc.

Mitsubishi Electronics America, Inc.

Bruce B Lusignan

Arthur Karp

Behruz Rezvani

Kazuo Hosono

Tohru Takagi

David H Shen

Chien-Meen Hwang

Hamid Najafi

Amr Badawi

James Sytwu

JameBond Kuo

Simos D Dadakarides

Bruce A Wooley

An antenna feed horn assembly includes a circular feed horn having an electrically conductive wall with an edge defining a circular aperture. The antenna feed horn assembly further includes a circular waveguide mounted to the base of the circular feed horn and including an endplate. An cylindrical rod extends from the center of the endplate towards the center of the feed horn aperture along a longitudinal axis of the antenna feed horn assembly to minimize undesired reflections produced by transitions between electrically conductive material and non-electrically conductive material or dielectric within the antenna feed horn assembly. An antenna feed horn assembly can also include a splash plate opposite the endplate, the center from which another cylindrical rod extends towards the center of the endplate along the longitudinal axis of the antenna feed horn assembly to further minimize undesired reflections.

Antenna feed having centerline conductor

A C-Band or Ku-Band satellite communication system uses a relatively small receiving antenna while operating within current FCC designated bandwidth and using existing satellite configurations. Aperture synthesis techniques create nulls in orbit locations from which potential interference is expected. Bandwidth inefficient modulation techniques reduce transmission power flux density. Video compression reduces the power necessary to transmit video information. These three features make possible a receiving antenna with a receiving area equivalent to that of a three foot diameter dish, at C-Band frequencies. Comparable reductions are possible for Ku-, Ka-, S- and L-Band systems. Compressing the data reduces the required transmitted power by a factor of ten. Spreading the bandwidth reduces the power density below the FCC limitation. However, reducing the antenna diameter increases the beam width of the antenna, hence, the smaller antenna can no longer discriminate between adjacent C-Band satellites in their current orbital configuration. By designing the receiving antenna with nulls in orbital locations where potentially interfering satellites would be located, the small antenna avoids this interference. The same general technique is possible for a Ku-Band Antenna system. The FCC power limits are higher at Ku-Band than C-Band, however, losses due to rain absorption and thermal noise are higher at Ku-Band frequencies. Nevertheless, equivalent size savings on Ku-Band antennas are possible with the combination of the above techniques, when tailored for the Ku-Band environment.

Method for receiving signals from a constellation of satellites in close

A receiving antenna includes a parabolic reflector and a feed horn. The feed horn includes an electrically conductive wall with an edge forming an aperture. The feed horn further includes a plurality of electrical conductors that extend from the edge to the center of the feed horn in a substantially coplanar relationship with the aperture. Each of the electrical conductors differentially affect a first polarized electrical field perpendicular to the edge adjacent the electrical conductor and a second polarized electrical field parallel to the edge adjacent the electrical conductor. In this manner, the electrical conductors can be configured to reduce the effective aperture of the feed horn in a plane, so that a first polarized horn radiation pattern produced by the feed horn can be circularized. The electrical conductors with respect to a vertical plane preferably match the electrical conductors with respect to a horizontal plane, so that first and second polarized horn radiation patterns produced by the feed horn can be simultaneously circularized. Another receiving antenna includes a splash plate and a feed horn that respectively include opposing edges that form an annular aperture. The feed horn further includes a plurality of electrical conductors that extend from the feed horn edge towards the splash plate edge in a coplanar relationship with the aperture. Again, the electrical conductors can be configured to reduce the effective width of the annular aperture in a plane, so that a first polarized horn radiation pattern produced by the feed horn can be circularized, while at the same time a second polarized horn radiation pattern produced by the feed horn can be circularized.

Antenna feed having electrical conductors differentially affecting

A C-Band or Ku-Band satellite communication system uses a relatively small receiving antenna while operating within current FCC designated bandwidth and using existing satellite configurations. Aperture synthesis techniques create nulls in orbit locations from which potential interference is expected. Bandwidth inefficient modulation techniques reduce transmission power flux density. Video compression reduces the power necessary to transmit video information. These three features make possible a receiving antenna with a receiving area equivalent to that of a three foot diameter dish, at C-Band frequencies. Comparable reductions are possible for Ku-, Ka-, Sand L-Band systems. Compressing the data reduces the required transmitted power by a factor of ten. Spreading the bandwidth reduces the power density below the FCC limitation. However, reducing the antenna diameter increases the beam width of the antenna, hence, the smaller antenna can no longer discriminate between adjacent C-Band satellites in their current orbital configuration. By designing the receiving antenna with nulls in orbital locations where potentially interfering satellites would be located, the small antenna avoids this interference. The same general technique is possible for a Ku-Band Antenna system. The FCC power limits are higher at Ku-Band than C-Band, however, losses due to rain absorption and thermal noise are higher at Ku-Band frequencies. Nevertheless, equivalent size savings on Ku-Band antennas are possible with the combination of the above techniques, when tailored for the Ku-Band environment.

Method and system for transceiving signals using a constellation of

Small antenna for receiving signals from constellation of satellites in

Communication receiver for receiving satellite broadcasts

A data transmitting/receiving satellite terminal for transmitting to and receiving from a geosynchronous satellite employs an antenna having nulls in its antenna receiving pattern at a first frequency corresponding to satellites spaced at regular intervals from the satellite. In addition, a phase and amplitude compensation network adjusts a phase and amplitude of the transmitted signal to compensate for transmitting at a different frequency than for which the antenna is optimally designed. The antenna includes a main parabolic reflector, and two side parabolic reflectors offset from a plane parallel to the main parabolic reflector. Each of the reflectors uses a dual frequency feed horn to couple energy to and from the reflector to a dipole exciter to which the receiving electronics is coupled. The above terminal is particularly useful in C-Band applications.

Very small aperture terminal & antenna for use therein

An adapter for a direct broadcast television system enables owners of existing dish antennas to receive both current analog television broadcasts and new digital television broadcasts via C-Band satellites. The adapter includes a coaxial switch for switching between analog and digital television, a tuneable demodulator for selectively switching between transponders on the C-Band satellites, a channel selector unit for selecting the channel specified by the user from the bit stream output by the demodulator, a channel expander for decompressing the video signal, and a control unit for accepting user commands and controlling the polarization of the received signals, the steering of the TVRO antenna, the demodulated transponder frequency and the demultiplexed channel. The ability to select the user's channel from multiple channels available on different transponders and different satellites allows the dynamic reassignment of television channels based on system efficiency considerations. The adapter described herein permits a smooth transition from existing television service to a new digital C-Band television service, without requiring a new antenna or removal of the existing antenna. The device is able to simultaneously serve analog and digital TV to both cable and TVRO and C-Band small antennas and enables a smooth, seamless conversion to digital C-Band receivers with only one box. In addition, the system design minimizes satellite costs and equipment conversion costs. Rapid change to 8 channels per transponder for TVRO and cable is then followed by reduction to 3 and 4 channels to permit use of small C-Band antennas without interrupting service to existing customers.

Apparatus for converting an analog c-band broadcast receiver into a

An RF communications receiver permits greater integration on standard silicon chips and consumes less power than previous receivers. Sub-sampling and discrete-time signal processing techniques are used to frequency down-convert, filter, amplify, and select a desired analog RF channel. A sample-and-hold circuit sub-samples the desired analog RF channel of carrier frequency f.sub.c, thereby down-converting it to a discrete-time image signal of frequency f.sub.i. Successive down-sampling, anti-alias filtering, and amplification of the discrete-time image signal yield a low-frequency discrete-time signal containing a down-converted channel of frequency f.sub.k. The low-frequency discrete-time signal is then digitized, filtered, and demodulated to reveal its baseband information content.

Radio frequency signal reception using frequency shifting by

A digital solid state electric power usage meter for determining power usage by a load attached to an electric power network. The meter has a current sensor coupled to each phase of the electric power network for sensing current in each phase, a voltage divider coupled to each phase of the power network for detecting the voltage level on each phase, an analog to digital (A/D) converter coupled to the current sensors and voltage dividers receiving signals from the current sensors related to the current in each phase and signals from the voltage dividers related to the voltage on each phase. The A/D converter samples the current and voltage related signals at predetermined times at a rate which insures that samples of the current and voltage related signals do not repeat for a large number of cycles of the network frequency or never repeat and which rate is at least twice as fast as the rate of change of the current and voltage related signals and converts the samples to digital signals representing the voltage levels and current at the predetermined times. A processor calculates instantaneous values of power at the predetermined times from the digital signals and a memory accumulates the instantaneous values so as to form a value representative of electric power usage by the load attached to the network.

Solid state electric power usage meter and method for determining power

An electrical transmission line has improved signal transmission characteristics, low attenuation, constant phase and group velocity and constant and nearly ohmic characteristic impedance over a wide frequency band by providing low magnetic loss inductance along with the shunt capacitance of the insulation surrounding the conductors. The low loss inductance can be provided by particulate magnetic material, such as ferrites, homogeneously distributed in the insulating material or alternatively the inductance can be provided by ring(s) of magnetic material concentric with the conductor or by layer(s) of magnetic material when the conductor(s) are flat. A variety of radial or longitudinal profiles of the doping level is possible and can be used in combination with any of these basic loading designs. These concepts can be applied in twisted pair, coaxial or high voltage power transmission and distribution single or three phase cables or strip lines and other breadboard applications. A set of additional designs which incorporate the magnetic loading in the conductor occupied region is also proposed, with one application being the high voltage or large size cables. The so designed twisted pairs have performance comparable to existing coaxial cables. All lines have superior performance than the conventional ones at virtually the same cost. Magnetic loading of existing cables and overhead lines is also disclosed.

Electrical cable having improved signal transmission characteristics

An analog function generator useful in providing a variety of functions for analog signal processing applications includes a pulse width modulator and a switched capacitor operational amplifier. Capacitors in the input of the operational amplifier and in the feedback loop of the operational amplifier are selectively switched by the output of the modulator to create output voltages of the amplifier that are polynomial, logarithmic or exponential functions of the input voltages to the amplifier and pulse width modulator.

Switched capacitor function generator

A tone generator is disclosed comprising an LSI controller and read only memory to provide any one of a pre-established set of audio signals to a standard pulse code modulated data stream. This is accomplished utilizing the origination address and destination address that appear on the origination and destination buses in every cycle of data. The origination address designates any one of the pre-established signal patterns stored in the ROM. The designated signal is read onto the data bus by the disclosed signal generating system by reading out the elements of the signal tone stored in the ROM. The predefined tones are stored continuously and regenerated continuously by the controller; thus, each tone is available during each frame cycle to be read out when the origination address calls for the tone. The samples of the tones and signals are stored in the ROM in the digital form they will have on the PCM data bus. The destination address defines the point to which the designated tone signal will be transferred. It is only necessary to store enough data for each signal to complete one nonrepeating cycle; the first 64 words (2 bytes each) in the ROM designate the number of samples stored for each signal so that the controller knows where signal table starts in the ROM. Transmission of a complete tone is accomplished in the LSI controller's circuit by incorporating a counter therein which increments the address of each tone every frame, and stores it on the chip RAM to be retrieved in the next frame to read the next of the sample of the tone. As the controller senses the predefined end of each tone, the counter is reset to the starting address of that particular tone. The instantaneous value of each tone is stored in an output register in the controller to begin transmission of the tone immediately if an origination address or addresses request it. Several tones can be addressed simultaneously within the same time frame, and the tone addressed by the controller can be varied every 488 nanoseconds with the sample sent to a different destination.

Pulse code modulated digital telephony tone generator

A telephone line interface which performs the BORSHT functions employs pulse width modulation and eliminates dc in the transformer to reduce the size of the coupling transformer thereby reducing space and costs. The ring function is provided to the subscriber without use of mechanical relays. An automatic, dynamically adjusted hybrid network is provided for removing echo signals thereby providing major improvement in two-to-four wire conversion performance. The circuitry lends itself to large scale integration thereby reducing space and cost and improving reliability.

Growing community of inventors

Palo Alto, CA, United States of America

Bruce B Lusignan