摘要:
A system and method for selectively enabling and disabling wireless connectivity between cellular or PDA users on-board commercial aircraft having a shielded fuselage, and remotely located wireless access points, while the aircraft is at an airport or airfield. The system and method does not require access to an on-board LAN system of the aircraft. The system includes one or more antennae disposed in the cabin area of the aircraft that are coupled via an RF switch with an exterior antenna mounted on an exterior of the fuselage. The RF switch is controlled by a switch control subsystem, and enables or disables communication between the interior antennae and the exterior antenna. The exterior antenna is connected to the switch via a conductor that extends through the shielding of the aircraft. When the RF switch is in the closed position, cellular or PDA users can connect through the interior antennae and the exterior antenna directly to remotely located wireless access points.
摘要:
A method and apparatus for identifying which one of a plurality of mobile terminals in communication with a ground-based base station, via a transponded satellite, is causing interference with a non-target satellite orbiting in a vicinity of the transponded satellite. The method involves using the base station to sequentially check each of the mobile terminals to identify which one is causing the interference. The check is made by the base station commanding each mobile terminal to modulate the power level of its transmitted signals and then checking with an operator of the interfered with non-target satellite to see if the interference condition has changed. Once the mobile terminal causing the interference condition is identified, the base station can command the mobile terminal to reduce its transmit power accordingly.
摘要:
An apparatus and method for correcting antenna beam misalignment between a transmit antenna and a receive antenna on a mobile platform such as an aircraft. The beam alignment method makes use of sequential lobing to determine the pointing angles in azimuth and elevation of a receive beam received by the receive antenna. For the transmit antenna, sequential lobing is used for the transmit antenna beam transmitted to a transponded satellite and then to a ground station. The ground station performs received signal strength indicator (RSSI) measurements and transmits these measurements back to the aircraft 16 via the target satellite. From these measurements, the beam misalignment between the receive and transmit antenna beams, both in azimuth and elevation, can be determined and a correction applied to the transmit antenna. The beam alignment procedure of the present invention can be implemented without interfering with normal use of the transmit and receive antennas and further ensures that interference with satellites adjacent to the target satellite will not occur during return link transmissions from the aircraft to the ground station.
摘要:
The corporate feed network employs light emitting opto-electronic components, such as laser diodes (12), connected together in a string (14) for distributing RF, microwave, MMW, digital signals, and pulse modulated light. Each diode provides two ports or facets which are coupled to optical fibers (16, 18) to connect to an active phased array antenna, for example. The diodes are selected in number and impedance to provide a good wideband impedance match to the RF/microwave/MMW/digital driving source. Multiple series strings of diodes may be employed, connected in parallel for larger corporate feed structures.
摘要:
A method of providing a communication link for a mobile platform. The method may involve generating a single beam and controlling the single beam to simultaneously generate first and second communication lobes from the single beam, with the first communication lobe being steered to communicate with a first base transceiver station (BTS). The method may further involve simultaneously using the second communication lobe to communicate with the second BTS and fading out the first lobe so that communication with the mobile platform is transferred to the second BTS.
摘要:
A blower system to remove precipitation from an antenna may include a blower air plenum extending substantially completely along one side of the antenna. A vent is in communication with the blower air plenum and extends substantially completely along the one side of the antenna to direct an airstream across a surface of the antenna to remove precipitation from the antenna. The vent may include a contour to conform to a contour of the one side of the antenna. The blower system may also include an air compressor to force air into the blower air plenum and out the vent to form the airstream flowing across the surface of the antenna.
摘要:
A system and method for communicating information from a base station to one or more user terminals via a forward link to a relay and distribution device is provided. The method includes determining a separate information rate for information to be transmitted from the base station to each of the user terminals. Each information rate is determined to allow successful communication with the respective user terminal and to provide a predetermined amount of link margin above a threshold energy-to-noise ratio (Eb/No) in the forward link. The method additionally includes formatting data received at the base station into a continuous time division multiplexed (TDM) data stream that includes a plurality of data frames to be transmitted to the user terminals. Each data frame is formatted to have the determined information rate of the respective user terminal destine to receive the data frame. The TDM data stream is transmitted using a single carrier of the forward link. Furthermore, the method includes continuously and dynamically adjusting the information rate of subsequent data frames for each user terminal to maintain successful communication and maintain the predetermined amount of margin as operating conditions of each user terminal change.
摘要:
A system and method for managing access to a satellite-based transponder by a plurality of aircraft each having a mobile radio frequency (RF) system. The system employs a ground-based, central control system for managing access to the satellite-based transponder so that the aggregate power spectral density (PSD) of the RF signals of all the mobile systems does not exceed, at any time, limits established by regulatory agencies to prevent interference between satellite systems. This is accomplished by a dual control loop arrangement for monitoring the signal-to-noise ratio (Eb/No) of the RF signal transmitted by the satellite-based transponder. A ground-based control loop is used whereby a ground-based central controller monitors the Eb/No and transmits commands to the aircraft (via the satellite transponder) to maintain the Eb/No of the transmitted signal within a predetermined range. A fast scan angle compensation is used by the mobile system of the aircraft to implement another control loop to further adjust the transmit power. This control loop maintains the Eb/No of the signal transmitted to the satellite-based transponder at the commanded level inbetween updates from the ground-based central controller.
摘要:
A system and method for managing access to a satellite-based transponder by a plurality of aircraft each having a mobile radio frequency (RF) system. The system employs a ground-based, central control system for managing access to the satellite-based transponder so that the aggregate power spectral density (PSD) of the RF signals of all the mobile systems does not exceed, at any time, limits established by regulatory agencies to prevent interference between satellite systems. This is accomplished by a dual control loop arrangement for monitoring the signal-to-noise ratio (Eb/No) of the RF signal transmitted by the satellite-based transponder. A ground-based control loop is used whereby a ground-based central controller monitors the Eb/No and transmits commands to the aircraft (via the satellite transponder) to maintain the Eb/No of the transmitted signal within a predetermined range. A fast scan angle compensation is used by the mobile system of the aircraft to implement another control loop to further adjust the transmit power. This control loop maintains the Eb/No of the signal transmitted to the satellite-based transponder at the commanded level inbetween updates from the ground-based central controller.
摘要:
An optical sensing system with a rotation sensor head for sensing the rotation of a rotatable object while simultaneously sensing the position of a displaceable object with a position sensor head. An electro-optical unit outputs a modulated optical signal and a chirped rf signal. The envelope of the modulated optical signal has a phase that has a known relation to the phase of the chirped rf signal. The electro-optical unit is coupled to a light guide element and receives and transmits the modulated optical signal along an optical path for reflection off a disk secured to the rotatable object in order to provide a rotation sensing optical signal. A transducing unit receives the rf signal at one input and has another input optically coupled to receive the rotation sensing optical signal while simultaneously receiving position sensing optical signals from the position sensor heads. The transducing unit produces a multi-frequency electrical signal which includes first and second frequencies, the first frequency corresponding to the rotation sensor location and the difference between the first and second frequencies corresponding to the rotation rate of the rotatable object. A rotation detecting unit coupled to the output of the transducing unit processes the multi-frequency signal in order to determine the difference frequency corresponding to the rotation rate of the rotatable object.