685results about "Satellite communication transmission" patented technology

There is provided a method for improving an allocation of resources, i.e., frequency and power, to terrestrial services and satellite services that use a same frequency band. The method includes determining a demand (DS) for a resource by users of a satellite system, determining a demand (DT) for the resource by users of a terrestrial system, and allocating the resource between the satellite system and the terrestrial system based on a ratio of DS to DT.

A technique for acquiring and tracking terminals in a free-space laser communication system involves exchanging beacon laser beams between the terminals to acquire and then track the terminals such that data laser beams exchanged by the terminals for communication are steered based on feedback from detection of the beacon laser beams. The beacon laser beams used for acquisition have a greater beam divergence than those used for tracking. Gimbals provide coarse steering of the data laser beams, and steering mirrors provide fine steering. GPS position data exchanged via an RF link can be used for initial pointing of the beacon laser beams for acquisition. The beacon laser beams can be chopped such that all terminals can use the same beacon wavelength and are distinguished by using different chopping frequencies. By detecting a chopped signal, the position sensor detector can be AC coupled to reduce sensitivity to solar radiation and glint.

A visible light communications transmitter combines a modulated carrier signal with a pulse from a pulse generator. The carrier signal is modulated according to data read from a buffer during the pulse.

For an information terminal to be operated by users for collecting predetermined pieces of information from remote information devices by free-space optical communication, the present invention provides a technique for suppressing the power consumption of the information terminal by minimizing the amount of calculation performed to collect the aforementioned information. According to the present invention, each information device emits ID light on which a low-frequency pilot signal is superimposed. The information terminal captures a series of frames of images including the ID light and locates the ID light within the images by the following steps: (1) creating multiple levels of binned images having different resolutions for each frame of the image; (2) calculating an evaluation index for each pixel within a target range of the binned images at each level, from the lowest to the highest resolution, where the target range is narrowed every time the process switches over to a lower level. In (2), the evaluation index is calculated by an evaluation function including fast Fourier transformation performed throughout the series of frames of images. The evaluation index thus calculated is compared with a threshold to determine whether the pixel concerned is receiving ID light. The present technique significantly reduces the number of pixel to be analyzed and evaluated, thereby decreasing the total number of arithmetic operations to be performed using the evaluation function. Thus, the power consumption is suppressed.

An optical communication system using a high altitude tethered balloon 10 that operates above most clouds and atmospheric turbulence. An optical communication system includes a balloon 10 with an optical communication payload 30, a fiber optic cable attached to the tether 12, an automated winch system 14, and a ground station 28. The balloon 10 is designed for sustained flight at, and recovery from, high altitude using the automated winch system 14. An acquisition, tracking and pointing (ATP) system 22 enables a balloon-based optical transceiver 24 to maintain line-of-sight optical communications with an overhead satellite 34. The optical link between the satellite 34 and the balloon 10 is an open channel. Data is transmitted to the ground station 28 from the balloon 10 through the secure fiber optic closed channel attached to the tether 12.

A free-space communication transceiver includes a telescope for transmitting and receiving laser beams, a tunable laser transmitter for generating a transmit laser beam modulated with data, a tunable optical receiver for processing a receive laser beam received from the telescope to recover data, and a tunable beamsplitter that directs the transmit laser beam to the telescope and directs the receive laser beam from the telescope to the optical receiver. Between the telescope and beamsplitter, the transmit and receive laser beams travel along a common optical axis as collinear collimated free-space beams. The transmit and receive laser beams operate at different wavelengths that can be interchanged, thereby support full-duplex operation. The beamsplitter employs a tunable etalon filter whose wavelength-dependent transmission characteristics are adjusted according to the transmit and receive wavelengths. Optionally, RF signals can additionally be couple to the common optical axis and transmitted and received by the telescope.

An illuminating light communication device, which is for establishing a communication system capable of controlling fluctuation in intensity of illuminating light when transmitting data using a power line and illuminating light, and satisfactorily carrying out communication using the power line and communication using the illuminating light, is provided. When data is transmitted through the power line, a signal component is extracted by a filter unit 12, and the demodulated by a power line modulator-demodulator 13, thereby retrieving the data. The retrieved data is temporarily stored in a protocol converter 14. Afterward, the data is converted to the optical communication protocol, and blinking or amount of light of a semiconductor light emitting element 16 is controlled according to the data transmitted from a light source control unit 15, thereby modulating the illuminating light. This allows transmission of data utilizing the illuminating light. Multiple-valued PPM, which defines that existing pulses correspond to OFF while no pulse corresponds to ON, may be used as a modulation system for optical communication.

A PLC modem performs communication via transmission lines made of a pair of cables as an example of a wired transmission line. Data displaying an operation state of the PLC modem is transmitted to a light emitting part via a modulator, and is converted into a high-speed flash signal for output.

A system and method of free-space optical satellite communications includes a ground station and transceiver for transmitting and receiving an optical communications signal. Adaptive optics at the ground station are operative with the transceiver for determining the shape of any distortions in the wavefront of the optical communications signal and compensating at the ground station for the distortions. A satellite includes a transceiver for transmitting and receiving the optical communications signal and includes adaptive optics for determining the shape of any distortions in the waveform of the optical communications signal and compensating at the satellite for the distortions.

For an information terminal to be operated by users for collecting predetermined pieces of information from remote information devices by free-space optical communication, the present invention provides a technique for suppressing the power consumption of the information terminal by minimizing the amount of calculation performed to collect the aforementioned information. According to the present invention, each information device emits ID light on which a low-frequency pilot signal is superimposed. The information terminal captures a series of frames of images including the ID light and locates the ID light within the images by the following steps: (1) creating multiple levels of binned images having different resolutions for each frame of the image; (2) calculating an evaluation index for each pixel within a target range of the binned images at each level, from the lowest to the highest resolution, where the target range is narrowed every time the process switches over to a lower level. In (2), the evaluation index is calculated by an evaluation function including fast Fourier transformation performed throughout the series of frames of images. The evaluation index thus calculated is compared with a threshold to determine whether the pixel concerned is receiving ID light. The present technique significantly reduces the number of pixel to be analyzed and evaluated, thereby decreasing the total number of arithmetic operations to be performed using the evaluation function. Thus, the power consumption is suppressed.

A visible light communication system, includes a data storage apparatus, a data transmitter and a data receiver, the data transmitter includes data receiving module for receiving data from the data storage apparatus, modulating module for modulating the data received by the data receiving module, and transmitting module for transmitting the data modulated by the modulating module to the data receiver as a carrier of illumination light, the data receiver includes illumination light detecting module for detecting the illumination light received by the transmitting module in accordance with an output variation of power converting module, demodulating module for demodulating the illumination light detected by the illumination light detecting module, and displaying module for displaying the data demodulated by the demodulating module.

Provided is an apparatus for determining the present position of a vehicle (1), by utilizing a visible-light communication system. The apparatus uses a visible-light communication beacon and video data representing an image photographed by one camera. The beacon emits a visible optical signal (310), thus transmitting position data. The visible-light communication beacon comprises a road-illuminating lamp (30) and a visible-light communication apparatus (31), both secured to a lamp post (3). The vehicle (1) has the camera and a vehicle position determination apparatus (10). The vehicle position determination apparatus (10) demodulates the visible optical signal (310), there restoring the position data, and calculates the present position of the vehicle (1) from the position data.

A node for satellite system communications between a ground station and a satellite includes a fiber optic bus on the satellite. An optical drop is coupled to the bus. The optical drop resolves an optical signal destined to the given satellite from the optical bus. An uplink and downlink receive and transmit communications from a ground terminal. A router is coupled to the optical drop and the uplink and downlink. An address reader and a table are used by the router to determine the destination of the received RF signals. The received RF signals are converted to optical signals by an optical source. The optical source has a wavelength that corresponds with the destination satellite. The optical signals are transmitted to an adjacent satellite by an optical transmitter such as a transmitting telescope.

An apparatus for determining the present position of a vehicle, by utilizing a visible-light communication system. The apparatus uses a visible-light communication beacon and video data representing an image photographed by one camera. The beacon emits a visible optical signal, thus transmitting position data. The visible-light communication beacon comprises a road-illuminating lamp and a visible-light communication apparatus, both secured to a lamp post. The vehicle has the camera and a vehicle position determination apparatus. The vehicle position determination apparatus demodulates the visible optical signal, there restoring the position data, and calculates the present position of the vehicle from the position data.

A satellite or spacecraft in low Earth orbit, when in eclipse and not illuminated by sunlight, represents a low-bandwidth datastream through modulation of a source of uncollimated light, such as a set of light emitting diodes. Transmission modes include generating patterns in the color, intensity or polarization of a light source, or precise timing control of a strobe signal. A ground station tracks the satellite in a telescope, stewing the telescope to follow the satellite as it moves across the sky, recording light generated by the satellite with a light sensor such as a video camera. The datastream is regenerated through analysis of recorded video. Satellite downlink is initiated by detection of eclipse, by command via radio uplink, or in response to a periodic automatic timer. In an alternative embodiment, the satellite represents the datastream through modulation of its effective albedo or reflective flux during periods of solar illumination.

An illumination apparatus is used in the light communication system. The apparatus receives electricity from a commercial alternating-current power source and a light-emitting element in the apparatus emits light. The zero passage time of commercial alternating-current power source is detected and signals are transmitted from illumination apparatus, or intercommunications between terminals of communication equipment take place, during a specific reserved time that is in synchronization with this zero passage time.

A PLC modem performs communication via transmission lines made of a pair of cables as an example of a wired transmission line. Data displaying an operation state of the PLC modem is transmitted to a light emitting part via a modulator, and is converted into a high-speed flash signal for output.

A positioning system includes an illumination device, a terminal, and a positioning server. The illumination device transmits identification information. The terminal transmits the identification information received from the illumination device, to the positioning server. The positioning server uses the identification information received from the terminal, thereby searching an illumination installation position database registered in advance so as to identify the terminal position. This eliminates power supply for positioning infrastructure and facilitates attachment to a ceiling, thereby realizing the positioning infrastructure at a low cost.

An illuminating light communication device is provided to construct a communication system in which, when data are transmitted by using an electric power line and illuminating light, light intensity fluctuations of the illuminating light are suppressed and communication by means of the electric power line and the illuminating light can be well carried out. When data to be transmitted are sent through an electric power line, signal components are extracted in a filter (12), they are demodulated in an electric power line modulating unit (13), so that data are obtained. The obtained data are tentatively stored in a protocol converting unit (14). The data are then converted to an optical communication protocol, a semiconductor light emitting element (16) is turned on or off, or its light quantity is controlled to modulate illuminating light in accordance with data to be transmitted by a light source controller (15). Thus, the data are transmitted by making use of the illuminating light. As a modulation system for the light communication, multiple-value PPM may be used, wherein an existing pulse is set to OFF while a non-existing pulse is set to ON.

An apparatus for determining the present position of a vehicle, by utilizing a visible-light communication system. The apparatus uses a visible-light communication beacon and video data representing an image photographed by one camera. The beacon emits a visible optical signal, thus transmitting position data. The visible-light communication beacon comprises a road-illuminating lamp and a visible-light communication apparatus, both secured to a lamp post. The vehicle has the camera and a vehicle position determination apparatus. The vehicle position determination apparatus demodulates the visible optical signal, there restoring the position data, and calculates the present position of the vehicle from the position data.

An optical head is provided for a free space optical communications system. The optical head is utilized for transmitting and receiving modulated infrared laser beams. The optical head includes an optical amplifier, a circulator, an ultrafine-steering element, a fine-steering element, a course-steering element, and a fine track sensor. Additionally, a method is provided for facilitating airborne free space optical communications between an airborne host platform and a link platform. Each platform has an optical head which transmits and receives data via modulated infrared laser beams, wherein the host includes at least an optical head having a fine, coarse, and ultrafine steering element configured in a cascaded three-tier steering element architecture.

The invention discloses an optical network self-adapting route system for a low / middle orbit double-layer satellite. The system is connected with a satellite-ground access segment by a space segment route, a middle orbit satellite managing layer consists of at least four manager satellites and a manager satellite, the manager satellites and the manager satellite manage a low orbit satellite route layer directly, and the low orbit satellite route layer consists of one main proxy satellite, four secondary proxy satellites and at least 8 ordinary satellites which are connected. The calculating method comprises topological parameters; determination of the life span report of the access to the middle orbit satellite by the low orbit satellite; main proxy node and link; link time delay among satellites; time delay report of the low orbit satellite; time delay report of the middle orbit satellite; wavelength usage rate business load; and the calculation of route cost function. The optical network of the double-layer satellite is divided into an access network with highly dynamic change and a space segment core network of periodic change, the access network takes charge of network convergence between the space segment and the ground network, and the space segment uses a laser link among satellites to relay until reaching a service target satellite.

A semiconductor device is disclosed that comprises a board, a ground terminal disposed on the board, a connection terminal disposed on the board, a semiconductor chip mounted on the board, and a shield member electrically connected to the ground terminal. The semiconductor chip, the ground terminal, and the connection terminal are disposed on one side of the board, and the shield member is disposed directly on and covers the other side of the board.

A position dependent information retrieval system is disclosed including a light source having a driver and an encoder. The driver and the encoder are coupled to the light source so that the light source produces a modulated light signal in accordance with a predetermined signature. The system also includes a receiver having a photosensitive detector capable of detecting the modulated light signal and a decoder capable of decoding the predetermined signature. A controller is communicatively coupled to the receiver, a memory and output device. The controller is arranged to receive the decoded predetermined signature, based upon the decoded predetermined signature, obtain at least one localized message in the memory, and output the localized message using the output device.