140 results about "Geosynchronous satellite" patented technology

A method and system for a plurality of airplanes in flight to receive from and send to a plurality of ground stations broadcast and communication signals through a single or a plurality of geostationary satellites, wherein at least the mobile link between said airplanes and said satellite, uplink or downlink, uses the high frequency radio waves at 17 GHz or higher, such as Ka-band. The fixed link between said satellite and said ground stations may use any radio frequencies below the frequencies used to communicate between the satellite and the aircraft. The lower frequencies tend to be less susceptible to rain attenuation and hence suitable for closing the fixed broadcast and communication link. Frequencies such as C-band or Ku-band, or even Ka-band, are applied between satellite and ground such that the available link margin is sufficient to overcome rain attenuation at said ground stations. Said satellite carries a plurality of transponders that may include a plurality of frequency converters to enable the conversion between different frequencies. Said satellite generates a plurality of spot beams, shaped or unshaped, which collectively cover the flight routes of said airplanes, preferably the geodesic path between two highly populated regions.

A practical orbit raising method and system wherein a satellite quickly escapes the Van Allen radiation belts and payload mass and mission life are maximized. A satellite is launched that contains high thrust chemical propulsion thrusters, high specific impulse electric propulsion thrusters and a solar array. The satellite quickly escapes the Van Allen radiation belts by firing the high thrust chemical propulsion thrusters at apogees of intermediate orbits, starting from the transfer orbit initiated by a launch vehicle, to successively raise the perigees until the perigee clears the Van Allen radiation belts. The payload mass and mission life are maximized by firing high specific impulse electric propulsion thrusters to raise the satellite to near synchronous orbit, while steering the thrust vector and solar array to maintain the sun's illumination on the solar array. The chemical and/or electric propulsion thrusters are then fired to achieve geosynchronous orbit.

In a broadcasting receiver, to quickly switch channels of the received multiplexed broadcasting signals at a high response speed to improve the convenience for a viewer, when broadcasting signals of a plurality of channels are to be code-division-multiplexed and broadcasted from a ground broadcasting station (BC1, BC2) to a broadcasting receiver (MS) in a service area via a geostationary satellite (SAT), the broadcasting signals are multiplexed and transmitted after matching the spreading code phase between the channels in the ground broadcasting station (BC1, BC2). Alternatively, the spreading code phase difference between the channels of a CDM broadcasting signal arriving from the ground broadcasting station (BC1, BC2) is detected in the geostationary satellite (SAT), and the broadcasting signal is transmitted to the broadcasting receiver (MS) after matching the spreading code phase between the channels on the basis of the detection result.

Methods and apparatuses for managing inter-satellite handovers are provided to allow a user terminal to reduce the frequency of handovers while maintaining a sufficiently high system capacity in a non-geosynchronous satellite communication system. The method and apparatus for managing inter-satellite handovers may be implemented in a gateway, in infrastructure connected to a gateway, in a user terminal, or in a satellite.

A satellite system includes a satellite operating in an orbit around the Earth and a satellite operating in another orbit around the Earth. The satellite points a fixed beam at least temporarily to a zone above the Earth's surface through which the satellite passes.

A method for shaping reflected radio frequency signals includes geometrically shaping a reflector surface of an antenna to focus the beam, and reflectively shaping the reflector surface with phasing elements that emulate geometric shaping to configure the beam to a predetermined shape. In the preferred embodiment, the antenna comprises a geosynchronous satellite antenna conveying signals from a wave guide horn to or from a predetermined geographic area on earth. The use of a parabolic-approaching surface of reflectarray phasing elements for shaping the beam substantially improves the beam pattern bandwidth over the performance of previously known shaped beam reflectarrays.

Method and apparatus for time or frequency synchronization of radio signals transmitted by user terminals in communication with a gateway through a satellite is provided. The satellite may be part of a non-synchronous satellite communication system, such as a low-earth orbit (LEO) satellite communication system for data, voice or video communications. Times of transmission of return link radio signals from the user terminals may be adjusted such that the signals arrive at the satellite or at the gateway without large time delay differentials. Carrier frequencies of return link radio signals transmitted from the user terminals may be adjusted such that the signals arrive at the satellite or at the gateway without large frequency offset differentials.

A non-geosynchronous satellite system, where each satellite has an antenna (perhaps a multi-element antenna) to form a beam pattern comprising a set of beams in the footprint of the satellite, where in one implementation each beam is substantially elliptical in shape having a minor axis and a major axis, where the minor axes are substantially collinear and the major axes are substantially oriented east to west. For a satellite, power is reduced or turned off for a subset of the set of beams, wherein each beam in the subset is reduced at or below a corresponding power level such that when a beam is powered above its corresponding power level an equivalent power flux-density (EPFD) exceeds a limit at some point on the Earth's surface.

A satellite communications system is described for increasing capacity through spectrum reuse by multiple satellites. The system includes a constellation of satellites traveling in a geosynchronous orbit, where the geosynchronous orbit defines a satellite track. The satellite track of the constellation overlaps a geostationary orbital location occupied by a legacy satellite traveling in a geostationary orbit. To prevent interference between the co-located constellation and legacy satellite, each of the constellation satellites operates in a silent mode when traveling within an interference beam width of a ground terminal in communication with the legacy satellite. Once outside of the interference beam width, the constellation satellites return to an active mode of operation.

A small antenna system for communications on-the-move (“COTM”) with a geostationary or geosynchronous satellite to and from a land mobile, maritime or airborne vehicle is disclosed. The antenna system provides a robust and simple means of establishing communications with a satellite or remote computer device. Further embodiments of systems and methods of the various aspects of the present invention mitigate RF losses customary in existing horn antennas. Embodiments also facilitate COTM by utilizing novel antenna configurations that tightly integrate RF electronics while dissipating generated heat via an antenna compartment that may be designed to function as or be used in conjunction with a heat sink.

A non-scanning radar system is installed on an aircraft to detect and avoid bird strikes or collisions with other airborne hazards. Target amplitude, range, and Doppler tracking versus time are used to qualify the collision threat. Avoidance is based on a quick minor altitude change by the pilot or autopilot to exit the imminent bird or other airborne hazard altitude window. In one embodiment, a bistatic passive radar receiver antenna is used in conjunction with an existing geostationary satellite signal. Range and Doppler information are obtained via cross correlation processing of the hazard reflection signal with a direct path reference signal from the satellite.

A method is provided for using at least two lunar flyby maneuvers to transfer a satellite from a quasi-geosynchronous transfer orbit having a high inclination to a final geosynchronous orbit having a low inclination. The invention may be used to take the inclination of a final geosynchronous orbit of a satellite to zero, through the use of a first leading-edge lunar flyby and subsequent successive leading or trailing edge lunar flybys resulting in a geostationary orbit.

A system for re-using GEO-allocated communications spectrum in a LEO satellite constellation based communications system, such that the LEO satellite originated signals will not appear in the beam-width of GEO-pointed earth station antennas, and satellites configured to provide communications by manipulating their respective beam transmissions, which may include a forward beam and rearward beam whose angles are controlled to project the beam and reduce or eliminate the potential for interference with GEO-pointed earth station antennas. The system and LEO satellites may provide substantially 100% coverage of an earth station located anywhere on the surface of the earth, without coordination with the GEO satellites or GEO-pointing ground stations. The system also may provide earth stations that are configured to enhance the isolation between the GEO communications system and the LEO communications system using the same spectrum to reduce the potential for GEO-pointed earth station antennas from picking up the LEO communication.

A method is provided for using a lunar flyby maneuver to transfer a satellite from a quasi-geosynchronous transfer orbit having a high inclination to a final geosynchronous orbit having a low inclination. The invention may be used to take the inclination of a final geosynchronous orbit of a satellite to zero, resulting in a geostationary orbit, provided that the satellite is launched in March or September.

The invention belongs to the technical field of synthetic aperture radar and particularly relates to a geosynchronous orbit circular track SAR imaging method using beam pointing control. By using such a method, a circular track geosynchronous satellite having a 8-shaped sub satellite point locus is taken as a radar platform, 12 hours corresponding to the half 8 shape where an object to be observed is arranged are regarded as an imaging period, the two-dimension antenna wave beam directional control is carried out in the imaging period by means of a stepping technique, so that the satellite can be in the corresponding movement process of the half 8-shaped sub satellite point locus, the antenna wave beam can always point to the imaged ground object to be observed, the 360-degree relative movement of radar relative to the object is formed, and the circular track SAR imaging based on the geosynchronous orbit satellite platform is realized.

The invention discloses an orbital uncertainty analysis method based on differential algebra technology. Based on Taylor expansion of multivariate functions and polynomial operation framework, and based on the dynamic model of geosynchronous satellite orbit element description, solar pressure to the kinetic model, the third gravitational perturbation and the three perturbation terms of the Earth'soblateness are added in the dynamic model , the right term of the dynamic model is expanded along the nominal orbit by Taylor expansion, the expansion polynomial with initial deviation as variable isobtained, Under the frame of differential algebra, the orbital state expressed by the polynomial with the initial deviation as variable at any time is obtained, and the concrete value of the initialdeviation is brought into the polynomial result to obtain the state of the final spacecraft. The invention analyzes the optimal expansion order, the balance calculation time and the calculation precision according to different perturbation forces. The method can be used to analyze the orbit evolution of geostationary satellites with initial state deviation and parameter uncertainty, and can also be used in other spacecraft orbit evolution and attitude evolution missions.

The invention relates to a method for sharing a radio frequency spectrum with a high-orbit communication satellite running in a near-equatorial orbit including an earth synchronous satellite based onbeam constant offset and a low-orbit communication satellite system. The method comprises the steps that low -orbit communication satellites complete conversion of a transmitting beam constant offsetstate near the North-South poles and the equator, the beam offset directions are opposite before and after each implementation, and the beam offset degree is a fixed constant; the low-orbit communication satellites close to the equator all deflect towards the equator; and during the beam offset conversion near the North and South poles, services are provided by the beams of other low-orbit communication satellites in two other orbits adjacent to each other on both sides of the current orbit. During implementation of beam offset conversion near the ascending node and the descending node, beam coverage services are provided by adjacent low-orbit communication satellites located on the other side of the ascending node or the descending node in the same orbit.

A conical region in space with a base at a geosynchronous distance from the earth and the apex of the cone at a point on the ground may be termed a space needle. A multiplicity of small satellites in elliptical orbits located within such a space needle may establish timing of their radio frequency (RF) transmissions forming what may be termed a needle beam downlink having an apparent origin that may be thousands of kilometers to the North or South of a Kepler geosynchronous satellite parking orbit. A noise-like RF signal may be transmitted synchronously from multiple transmitters in space forming a spatially distributed spread spectrum RF needle beam. Applying the method of space-based needle beams to a multiplicity of transmitters on the ground, a network of ground stations may form a ground-based needle beam uplink that may be pointed a given satellite at a given time.