166 results about "Geosynchronous orbit" patented technology

A satellite communication system includes a plurality of satellites, such as low earth orbit satellites, and a plurality of gateways. The satellite communication system is bidirectionally coupled to a terrestrial communication system through at least the plurality of gateways. The satellite communication system and the terrestrial communications system together form a data communication network having a plurality of nodes including source nodes, destination nodes and intermediate nodes. Multiple copies of a packet can coexist within the data communication network, and the packet and its one or more copies are routed, using at least in part satellite-resident routers and gateway-resident routers, over a plurality of different paths between a particular source node and a particular destination node. At least one duplicate copy of a given packet is simply not used during the execution of a packet reordering procedure in the destination node, or at an intermediate node. Certain of the paths are carried over satellite-to-satellite cross-links, while certain other ones of the paths are carried over satellite-to-gateway uplinks and downlinks, and at least one path exists between a user terminal and at least one satellite. In a preferred embodiment the packets are TCP / IP (or equivalent protocol) packets containing information for enabling the selective destruction of a duplicate packet to occur.

A system for providing attitude and antenna steering for a spacecraft is disclosed. The spacecraft has a number of reaction wheels and a number of antennas. The system includes control logic configured to: determine a beta angle, the beta angle being the angle between a sun vector and an orbit plane of the spacecraft, and alternately engage either a first mode or a second mode to provide attitude and antenna steering based on the beta angle.

A wireless communication system includes a satellite constellation consisting of a plurality of satellites. Each of the plurality of satellites is in an orbit whose eccentricity and inclination are perturbed relative to the same geosynchronous orbit. Each of the satellites in the constellation is capable of relaying signals in either direction between a central ground hub and a plurality of mobile user terminals. The plurality of satellites are configured such that the period of their geosynchronous orbit remains substantially constant at one sidereal day.

A method and apparatus for operating one or more satellites in a non-geosynchronous orbit (NGSO) satellite constellation are disclosed. In some aspects, a coverage area on Earth for a first beam transmitted from a first satellite in the NGSO satellite constellation may be determined, a cone may be projected onto a first region of the beam coverage area, a second region of the beam coverage area may be defined as including portions of the beam coverage area lying outside the first region, and a minimum arc angle for each of a plurality of points within the first region but not the second region of the beam coverage area may be determined.

The invention provides a Beidou space-based high-precision real-time positioning method. The method comprises the following steps: firstly, generating difference revised data, then generating a difference broadcast telegraph text, adopting two pseudorandom sequences to generate a short precise code, and conducting spectrum spread and carrier modulation on the difference broadcast telegraph text and the short precise code so as to generate a difference broadcast signal; a user positioning terminal combines difference broadcast data of the difference broadcast signal and Beidou navigation satellite observation data to conduct positioning calculation so as to realize high-precision real-time positioning. The method can effectively realize decimeter-degree high-precision real-time positioning in the coverage area of a geosynchronous orbit satellite, and quickly improves and enhances the positioning service performance of a Beidou satellite navigation system.

A hub terminal and remote client communicate via a target satellite in an inclined geosynchronous orbit. As the target satellite ascends or descends away from the geostationary arc, the signal strength of the uplink channel is increased without increasing the level of interference with adjacent geostationary satellites. The increased angular separation from adjacent satellites also decreases downlink interference. The resulting increase in signal to interference ratio permits adjustment of the modulation and coding parameters to increase spectral efficiency. The antenna gain pattern is modeled based on antenna characteristics and the model may be supplemented with measurements of a signal relayed by adjacent satellites. The method permits intermittent communication from locations where the geostationary arc is blocked or using disadvantaged antennas that would be impractical for use with geostationary satellites. In some circumstances, it is desirable to deliberately mis-steer the antenna slightly away from the target satellite.

A method and apparatus for operating one or more satellites in a non-geosynchronous orbit (NGSO) satellite constellation are disclosed. In some aspects, the satellite may allocate a first frequency band to a first beam, and may allocate a second frequency band to a second beam. Then, if the first beam is disabled, the satellite may re-map the first frequency band from the first beam to the second beam. In this manner, frequency resources initially allocated to a disabled beam may be re-mapping to another, non-disabled beam.

The invention relates to a staring-imaging-based in-orbit signal-to-noise ratio test method of a satellite. Repeated imaging of an earth surface uniform region is carried out by a satellite with an ultra-high time resolution and a high spatial resolution; on the premise that the illumination condition and the surface radiation characteristic are consistent basically, statistics of mean values of detector cells and standard differences of the imaging at the uniform region is carried out and ratios of the mean values and to standard differences are used as pixel signal to noise ratios; and then a mean value of a plurality of pixel signal to noise ratios is used as an image signal-to-noise ratio. With the method, an influence caused by inconsistency of the pixel response spaces can be eliminated. When statistics of the standard differences of imaging data of each pixel at multiple times is carried out, uncertainty of repeated sampling is mainly reflected; and thus the noises can be effectively retrained in terms of numerical value and the actual signal to noise ratio of the satellite image can be reflected, thereby evaluating the remote sensing satellite imaging capability of the geosynchronous orbit objectively. Therefore, the method has the practical application value in development of in-orbit testing and in-orbit operation state image quality evaluation in satellite ground system engineering.