525 results about "Satellite constellation" patented technology

A method and apparatus for mitigating communications interference between satellite communications systems in different orbits is disclosed. The method comprises the steps of evaluating a geometrical relationship between a second ground station and the satellites in the second satellite constellation, and directing communications between the second ground station and the second satellite according to the evaluated geometrical relationship. In one embodiment communications are handed over from a first satellite to another satellite when the first satellite is no longer at the highest elevation angle of visible satellites. In another embodiment, handover occurs when the first satellite drops below a minimum elevation angle.

A system and method for assisting an integrated GPS/wireless terminal unit in acquiring one or more GPS satellite signals from the GPS satellite constellation. The invention includes a method for narrowing the PN-code phase search. That is, by accounting for the variables in geographic location and time delay relative to GPS time, the systems and methods of the present invention generate a narrow code-phase search range that enables the terminal unit to more quickly acquire and track the necessary GPS satellites, and thereby more quickly provide accurate position information to a requesting entity.

Routing methods are provided for IP-based Iridium like LEO polar satellite constellation network for finding a Manhattan path between a source node and a destination node. The routing methods can include identification of congested inter satellite links (ISLs). By selecting and using uncongested alternative paths, an original routing process can be converted into sub-routing processes each in a small scale of a Manhattan path region. Quality of Service (QoS) requirements such as delays and jitters can be incorporated into the routing methods, which leads to efficient routing and enhanced QoS-performance over the satellite constellation network. The disclosed routing methods can be suitable for real-time routing/rerouting applications under dynamic network conditions.

A satellite network constellation employs a technique for multicasting packets through the network according to the present invention. The network comprises plural satellites in plural orbital planes with each satellite equipped with a plurality of high-speed point-to-point full duplex radio links for inter-satellite communications. A node intending to send a multicast packet to a multicast group or a set of destination satellite nodes initially sends the packet to the orbital planes that include the group members. Once reaching the plane, in-plane routing techniques are used to forward the packet to the intended group members. If there are broken or disabled links, an alternative path is taken to forward the packet without disrupting the functioning links.

A method and apparatus for monitoring a configuration of satellites to maintain integrity of LTO information in a GNSS receiver of a GNSS or other positioning system is described. The method may include obtaining broadcast ephemeris transmitted from at least one satellite of a constellation of satellites; comparing the broadcast ephemeris to long-term-orbit information available to a global-navigation-satellite receiver; and causing the global-navigation-satellite receiver to not use the long-term-orbit information when the long-term-orbit information does not correspond to the broadcast ephemeris.

<heading lvl="0">Abstract of Disclosure</heading> A method and apparatus for locating mobile device over a broad coverage area using a wireless communications link that may have large and unknown latency. The apparatus comprises at least one mobile device, a reference network, a position server, a wireless carrier, and a location requester. The mobile device is in communication with the wireless carrier and receives global positioning system (GPS) signals from a plurality of satellites in the GPS satellite constellation. The reference network is coupled to the position server and provides GPS data. The mobile receiver receives GPS signals, performs rudimentary signal processing and transmits the processed signals to the wireless carrier. The wireless carrier passes the signals on to the position server. The position server processes the mobile receiver's GPS data and the reference network ephemeris data to identify the location of the mobile receiver. The location is sent to the location requester.

An indoor GPS repeater unit comprising a directional receive aerial for receiving GPS signals from one or more satellites in a preselected area of the sky, a transmitting aerial for transmitting the received GPS signals; and, RF amplification means for enhancing the received GPS signals before transmitting into an indoor area is disclosed. One or more such GPS repeater units are used to reproduce the satellite constellation within buildings or underground to provide GPS coverage in these environments.

A global navigation system includes a first navigation receiver located in a rover and a second navigation receiver located in a base station. Single differences of measurements of satellite signals received at the two receivers are calculated and compared to single differences derived from an observation model. Anomalous measurements are detected and removed prior to performing computations for determining the output position of the rover and resolving integer ambiguities. Detection criteria are based on the residuals between the calculated and the derived single differences. For resolving integer ambiguities, computations based on Cholessky information Kalman filters and Householder transformations are advantageously applied. Changes in the state of the satellite constellation from one epoch to another are included in the computations.

A configuration for a satellite constellation has a plurality of planes, each plane including a plurality of satellites therein, at least some of the planes situated at a different altitude than other of the planes. In some embodiments, all planes contain the same number of satellites; in some other embodiments, at least one plane includes a different number of satellites than the other planes in the constellation. In some embodiments, the satellites in each plane are evenly spaced.

A time reference system for generating a time reference from signals produced by a global navigation satellite constellation has a satellite signal receiver to receive and down-convert code-modulated signals from a plurality of satellites and a correlator to track and decode the down-converted signals to provide signals containing partial pseudo-range measurements for respective satellites. A data processing arrangement receives assistance data from an external source and performs data-bit synchronisation in which bit edges of a low frequency data bit stream carried by the received satellite signals are identified, to perform a preliminary position-velocity-time solution to provide an approximate time reference, and to perform auto-correlation of pre-selected data sequences in the data stream to resolve time ambiguities thereby to compute a precise time reference signal in weak received signal conditions. The pre-selected data sequences may be the repeated data preamble in the GPS navigation message constituted by the data stream.

A system for sensing aircraft and other objects uses bistatic radar with spread-spectrum signals transmitted from remotely located sources such as aircraft flying at very high altitudes or from a satellite constellation. A bistatic spread spectrum radar system using a satellite constellation can be integrated with a communications system and/or with a system using long baseline radar interferometry to validate the digital terrain elevation database. The reliability and safety of TCAS and ADS-B are improved by using the signals transmitted from a TCAS or ADS-B unit as a radar transmitter with a receiver used to receive reflections. Aircraft and other objects using spread spectrum radar are detected by using two separate receiving systems. Cross-Correlation between the outputs of the two receiving systems reveals whether a noise signal is produced by the receiving systems themselves or is coming from the outside.

A wireless tank monitoring system for remotely monitoring a plurality of storage tanks is provided. This tank monitoring system utilizes wireless communication from individual tank level monitors to a single SatComm Gateway. The SatComm Gateway then utilizes a low-Earth Orbit satellite constellation to transmit information to a central data collection center. The data collection center then provides access to this information to clients. These clients also have the capability of controlling individual monitors via the bi-directional communications path through the satellite link to the SatComm Gateway to the individual monitors. The SatComm Gateway packages the information from each of the monitors to optimize the communications through the satellite link to decrease the cost of transmission. Intrinsic safety is provided by each of the individual tank level monitors.

The invention discloses a low-orbit satellite constellation system cell switching method and device based on ephemeris information. The method comprises the steps of enabling a mobile terminal to receive the signal intensity of a service satellite; judging a switching triggering moment, then predicting a subsatellite point position of a low-orbit satellite according to a received satellite ephemeris parameter; calculating a coverage satellite set of the switching triggering moment according to the predicted subsatellite point position; and comparing a mobile terminal with a beam feature pointset of all beams of each satellite in the coverage satellite set to obtain an adjacent cell list. The mobile terminal calculates the visual time of each beam in the neighbor cell list, screens out thebeams of which the visual time is less than a beam visual time threshold, selects the beam with the maximum switching weight in the screened neighbor cell list as a target beam, and finally sends a request of switching to the target beam to a source beam. The method has the characteristics that the beam cell switching reliability is improved; the ping-pong switching probability is reduced; the number of system control signaling is reduced; and the network efficiency is improved.

A system for remotely tracking, monitoring and messaging vessels (14) utilizing a global positioning system satellite constellation, having a transceiver located on the vessel to be tracked and monitored, a monitoring center located remote from the vessel, a communications means allowing the bi-directional communication between the transceiver and the monitoring center, a communications means allowing the uni-directional communication from the global positioning system satellite constellation to the transceiver, sensors on the on-board systems of the vessel, a communications means allowing communication between the sensors and the transceiver, an input/output means for messaging, and a communications means allowing communication between the input/output means and the transceiver.

The invention provides a double-deck satellite load balancing method based on link cost conversion. According to the method, on the basis of the virtual topology strategy of a satellite, low earth orbit (LEO) layer link cost conversion and layered flow division are conducted on a topology snapshoot. Thus, by means of predictability and periodicity of constellation running of the satellite, system running time is divided into a plurality of same time periods, each time period is divided into n gaps tp, and link overload judgment is conducted on an inter-satellite link in each time gap. Congestion grading is conducted on a global coverage area, cost regulation and route optimization are conducted in cooperation with the real-time flow of the LEO satellite link when the link is congested, and therefore flow of the whole network is balanced. On this basis, reasonable route selection is conducted on transmission service with different qualities of service (QoS) in cooperation with the MEO layer satellite network, and the throughput of the whole network is improved while the requirement for the high priority service time delay is met.

A satellite constellation has a plurality of satellites. Each of the satellites has an RF ground link for communicating with a ground station and an optical link for communication with at least one of the plurality of satellites. Each of the satellites has a reconfigurable optical transmitter for sending and receiving data streams. Each reconfigurable optical transmitter has a first optical carrier associated therewith and a reconfigurable optical receiver. The plurality of satellites is arranged to have a first subset of satellites. The first subset of satellites is configured to communicate. The plurality of satellites is reconfigured to have a second subset of satellites having at least one different satellites than that of said first subset. The second subset supercedes the first subset. The second subset of satellites is configured to communicate. Various subset around the globe may form local area networks. The local area networks are preferably optically coupled to form a wide area network.

The invention belongs to the field of satellite communication technologies and particularly relates to a ground station system and a method for avoiding collinear interference with a geostationary satellite. The system comprises a ground station located at one position of the earth and a non-geostationary satellite constellation connected to the ground station, wherein the ground station traces one satellite in the non-geostationary satellite constellation through controlling antenna beam and establishes a communication link with the satellite; when a connecting line between the ground station and one non-geostationary satellite points at the geostationary satellite, the ground station adjusts the beam direction and selects another non-geostationary satellite in the different direction in view to communicate, so that the collinear interference with the geostationary satellite is avoided. According to the ground station system and the method, the restriction that shutdown of the non-geostationary satellite is needed or the transmitting power of the non-geostationary satellite is greatly reduced when the collinear interference occurs is avoided, and the satellite communication of the ground station keeps continuous, so that the availability and the message capacity of the non-geostationary satellite constellation are improved and the same frequency coexistence of the non-geostationary satellite and the geostationary satellite is realized.

Systems and methods are provided to determine launch parameters of satellites of a satellite constellation that provides optimized performance of the satellite constellation over the service lifetime of the satellite constellation. The launch parameters may be determined by considering perturbing accelerations of one or more of the satellites for the purposes of optimizing the launch parameters of the satellites of the satellite constellation. The systems and methods may include heuristic optimization and high-fidelity astrodynamic modeling methodologies.

The invention discloses a combined scheduling method of satellite-ground measurement and control resources of a low-mid-orbit satellite constellation based on orbit determination constraint satisfaction, and belongs to the field of combined scheduling of the satellite-ground measurement and control resources. The method comprises the steps of (1) building a visible geometry model, (2) building a visible link model, (3) building the constraint condition of orbit determination, (4) carrying out preprocessing, (5) determining a resource distribution principle, (6) building a combined scheduling model of the satellite-ground measurement and control resources, and (7) carrying out algorithm solution. Compared with the prior art, the method has the advantages that the scheduling result is reasonable, the scheduling process is efficient, and the scheduling method is high in universality. The air-and-ground-based integrated scheduling of the measurement and control resources is achieved. The transition from ground-based measurement and control to air-and-ground-based combined measurement and control in China is achieved.