Patent Publication Number: US-7898476-B2

Title: Method and system for controlling the direction of an antenna beam

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 60/886,024, entitled “BEAM CONTROL SYSTEM FOR AN ANTENNA,” which was filed on Jan. 22, 2007. 
    
    
     TECHNICAL FIELD OF THE DISCLOSURE 
     This disclosure relates generally to antenna systems, and more particularly to a method and system for controlling the direction of an antenna beam. 
     BACKGROUND OF THE DISCLOSURE 
     Wireless communication involves transmission of signals between transceivers. A transceiver points its antenna beam in the proper direction in order to effectively communicate with another transceiver. In some cases, transceivers may move with respect to each other. 
     SUMMARY OF THE DISCLOSURE 
     In one embodiment, a system for controlling the direction of an antenna beam includes a location identifier, an orientation sensor, and an antenna beam controller. The location identifier determines a transmit antenna location indicating the location of a transmit antenna, where the transmit antenna produces an antenna beam. The orientation sensor determines a transmit antenna orientation indicating the orientation of the transmit antenna. The antenna beam: accesses target data describing a receive antenna of a target, the target data comprising a location of the receive antenna relative to the transmit antenna; calculates a deviation value from the transmit antenna location, the transmit antenna orientation, and the target data; and adjusts the direction of the antenna beam to reduce the deviation value. 
     Particular embodiments of the present disclosure may exhibit some, none, or all of the following technical advantages. For example, an advantage of one embodiment may be that a beam control system may include a location identifier and an orientation sensor that provide the location and orientation of an antenna that may be moving with respect to a target. The antenna location and orientation may be compared with target data to track the target. 
     Other technical advantages will be readily apparent to one skilled in the art from the following figures, description, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of embodiments of the disclosure will be apparent from the detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a block diagram showing one embodiment of a beam control system according to the teachings of the present disclosure; 
         FIG. 2  is a block diagram showing one embodiment of the antenna beam controller and the antenna of  FIG. 1 ; 
         FIG. 3  is a block diagram showing another embodiment of the antenna beam controller and the antenna of  FIG. 1 ; and 
         FIG. 4  is a flowchart showing one embodiment of a method that may be taken by the antenna beam controller of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
       FIG. 1  is a block diagram showing one embodiment of a beam control system  10  for an antenna  12 . Beam control system  10  may include a location identifier and an orientation sensor that provide the location and orientation of an antenna that may be moving with respect to a target. The antenna location and orientation may be compared with target data to track the target. 
     In one embodiment, a path between transmit antenna  12  and a receive antenna allows energy from antenna  12  to reach the receive antenna. In the embodiment, system  10  determines the attitude and location of antenna  12 , and uses the antenna attitude and location to define the perpendicular to the radiating surface of antenna  12 . System  10  uses the perpendicular and the location of the receive antenna to direct the antenna beam of antenna  12  in the direction of the receive antenna. 
     In the illustrated example, beam control system  10  includes a housing  11  that houses an antenna beam controller  14  coupled to a location identifier  16 , an orientation sensor  18 , and antenna  12  as shown. Antenna  12  is mounted to a structure  20 , which may be moving or stationary. In this description, movement, location, and orientation of an object may be with any suitable frame of reference, such as the reference frame of the Earth. For example, an object may be considered stationary or moving with respect to any suitable reference frame. In this description, orientation may be given by azimuth and elevational angles. 
     Antenna  12  generates a beam  22  for communication with a target. A target may represent any suitable entity that can communicate signals to and/or from antenna  12 . Examples of a target include an orbiting satellite or a ground-based communication station. Antenna  12  may move or may be stationary with respect to the target. For example, antenna  12  and a target may stationary with respect to each other, antenna  12  may move with respect to a stationary target, a target may move with respect to a stationary antenna  12 , or both antenna  12  and a target may move. 
     Housing  11  represents a substantially rigid or flexible housing that houses antenna beam controller  14 , location identifier  16 , and/or orientation sensor  18 . In one embodiment, location identifier  16  and orientation sensor  18  are integrated into housing  11 . Location identifier  16  provides an antenna location indicating the location of antenna  12 . In one embodiment, location identifier  16  comprises a Global Positioning System (GPS) receiver that communicates with a GPS satellite to determine location. In another embodiment, location identifier  16  comprises an Inertial Measurement Unit (IMU) that senses its own rate and direction of motion to track its position. 
     Orientation sensor  18  determines the orientation of antenna  12 . Orientation sensor  18  may include a north finding module and an attitude sensor. The north finding module locates the due North direction. The attitude sensor detects orientation. For example, the attitude sensor may include gyroscopes that detect changes in orientation. The north finding module and the attitude sensor may be used to determine the orientation of antenna  12  with reference to due North. 
     In one example, antenna  12  moves with structure  20 . Accordingly, the location and/or orientation of structure  20  indicates the location and/or orientation of antenna  12 . In the example, location identifier  16  may determine the location of structure  20  to provide the antenna location. Orientation sensor  18  may determine the orientation of structure  20  to determine the antenna orientation of antenna  12 . 
     Antenna beam controller  14  adjusts the direction of beam  22  generated by antenna  12 . In one embodiment, antenna beam controller  14  compares the antenna location and orientation with target data to derive a deviation value, and adjusts the direction of beam  22  to reduce the deviation value. 
     In the embodiment, antenna beam controller  14  receives the antenna location from location identifier  16  and the antenna orientation from orientation sensor  18 . The target data may describe a location of the receive antenna relative to the transmit antenna. The target data includes mappings. A mapping maps a location to a target position that an antenna at the location can use to communicate with the target. For example, the antenna may direct a beam in the direction given by the target position. 
     In the embodiment, the deviation value may be calculated from the antenna orientation and the target position. If the antenna orientation and the target position are with respect to the same reference frame, the deviation value may be the difference between the orientation. Otherwise, one or both orientations may be converted to the same reference frame, and a difference may then be taken. 
     Acceptable deviation values may be determined according to the factors of the antenna system, such as the signal and geometry of the antenna. In one example, the target is a geosynchronous satellite operating in the L-band (approximately 1 to 2 Giga-Hertz). Given this frequency range, the direction of beam  22  may be satisfactorily controlled by maintaining a deviation value consistent with the link margin of the system. For L-band systems, an acceptable deviation value may be as large as approximately 10 degrees. 
     Antenna beam controller  14  adjusts the direction of beam  22  in any suitable manner. For example, antenna beam controller  14  may physically and/or electronically steer beam  22 . 
     In one embodiment, antenna beam controller  14  may be coupled to location identifier  16  and orientation sensor  18  using any suitable link, such as a digital communication link, for example, a RS-422 serial data link. According to another embodiment, location identifier  16  and/or orientation sensor  18  may be integrated within antenna beam controller  14  and coupled to antenna beam controller  14  through an internal system bus. 
     Structure  20  may represent a moving and/or stationary object. Examples of structure  20  include an automobile, an aircraft, or a watercraft. 
     A component of system  10  may include an interface, logic, memory, and/or other suitable element. An interface receives input, sends output, processes the input and/or output, and/or performs other suitable operation. An interface may comprise hardware and/or software. 
     Logic performs the operations of the component, for example, executes instructions to generate output from input. Logic may include hardware, software, and/or other logic. Logic may be encoded in one or more tangible media and may perform operations when executed by a computer. Certain logic, such as a processor, may manage the operation of a component. Examples of a processor include one or more computers, one or more microprocessors, one or more applications, and/or other logic. 
     A memory stores information. A memory may comprise one or more tangible, computer-readable, and/or computer-executable storage medium. Examples of memory include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), database and/or network storage (for example, a server), and/or other computer-readable medium. 
       FIG. 2  is a block diagram showing one embodiment of system  10  of  FIG. 1  in which antenna beam controller  14  is coupled to an active electronically scanned array (AESA) antenna  12 . AESA antenna  12  includes a number of radiating elements  28 , a number of transmit/receive modules  32 , a signal distribution circuit  34 , and a control circuit  36  coupled as shown. A radiating element  28  may be a horizontal, vertical, or general (horizontal and vertical) radiating element. 
     Signal distribution circuit  34  distributes signals to radiating elements  28  via transmit/receive modules  32 . Control circuit  36  controls the amplitude and phase of signals transmitted and/or received by radiating element  28  to electronically steer the direction of beam  22 . 
     Antenna beam controller  14  comprises a computer processor  38 , an input/output port  40 , and a memory  42  coupled through a system bus  44  as shown. Computer processor  38  executes instructions stored in memory  42 . Input/output port  40  may be coupled to control circuit  36  using any suitable protocol, such as an RS-422 serial communication protocol. 
     Memory  26  stores target data  46 . Target data  46  includes mappings. A mapping maps a location to a target position that an antenna at the location can use to communicate with the target. 
       FIG. 3  is a block diagram showing another embodiment of system  10  of  FIG. 1 . In the embodiment, control port  36  is coupled directly to system bus  44 . Control port  36  receives control signals from computer processor  38  and distributes the control signals to each transmit/receive module  32  for electronically adjusting the direction of beam  22  relative to structure  20  or to antenna  12 . 
     Modifications, additions, or omissions may be made to beam control system  10  without departing from the scope of the disclosure. Moreover, beam control system  10  may comprise more, fewer, or other elements. For example, orientation sensor  18  may include other components, such as magnetometers. As used in this document, “each” refers to each member of a set or each member of a subset of a set. 
       FIG. 4  is a flowchart showing one embodiment of a method that may be performed by beam control system  10  to control the direction of beam  22  relative to structure  20 . The method starts at step  200 . At step  202 , beam control system  10  receives the antenna location from location identifier  16 . At step  204 , beam control system  10  receives the antenna orientation from orientation sensor  18 . 
     At step  206 , beam control system  10  calculates a deviation value from the antenna information and the target data. In one embodiment, the target position is determined from a mapping of the antenna location to the target position. The deviation value is then calculated from the difference between the target and antenna orientations. 
     Beam control system  10  adjusts the direction of beam  22  according to the deviation value at step  208 . Beam control system  10  may physically or electronically steer beam  22 . Steps  202  through  208  may be repeated during operation of beam control system  10  in order to point beam  22  towards the target. The methods ends at step  210 . 
     Modifications, additions, or omissions may be made to the method without departing from the scope of the disclosure. The method may include more, fewer, or other steps. For example, the method described directs beam  22  towards an orbiting satellite. In other embodiments, beam control system  10  may direct beam  22  towards a stationary antenna mounted on Earth. 
     Particular embodiments of the present disclosure may exhibit some, none, or all of the following technical advantages. For example, an advantage of one embodiment may be that a beam control system may include a location identifier and an orientation sensor that provide the location and orientation of an antenna that may be moving with respect to a target. The antenna location and orientation may be compared with target data to track the target. 
     Although the present disclosure has been described in several embodiments, a myriad of changes, variations, alterations, transformations, and modifications may be suggested to one skilled in the art, and it is intended that the present disclosure encompass such changes, variations, alterations, transformations, and modifications as falling within the spirit and scope of the appended claims.