Patent Application
20050248498
1. Field of the Invention
Embodiments of the invention described herein pertain to the field of antenna positioning systems. More particularly, but not by way of limitation, these embodiments enable the positioning of antennas by way of a compact, lightweight, portable, self-aligning antenna positioner that is easily moved by a single user and allows for rapid setup and alignment.
2. Description of the Related Art
An antenna positioner is an apparatus that allows for an antenna to be pointed in a desired direction, such as towards a satellite. Many satellites are placed in geosynchronous orbit at approximately 22,300 miles above the surface of the earth. Other satellites may be placed in low earth orbit and traverse the sky relatively quickly. Generally, pointing may be performed by adjusting the azimuth and elevation or alternatively by rotating the positioner about the X and Y axes. Once oriented in the proper direction, the antenna is then best able to receive a given satellite signal.
Existing antenna positioners are heavy structures that are bulky and require many workers to manually setup and initially orient. These systems fail to satisfactorily achieve the full spectrum of compact storage, ease of transport and rapid setup. For example, currently fielded antenna systems capable of receiving Global Broadcast System transmissions comprise an antenna, support, positioner, battery, cables, receiver and PC. These antenna systems require over a half dozen storage containers that each require 3 to 4 workers to lift. Other antenna systems are mounted on trucks and are generally heavy and not easily shipped. Many antenna systems comprise static mounts that are initially set and are never altered, for example antenna dishes configured to receive television transmissions. Static antenna mounts generally require manual setup.
Embodiments of the invention provide a lightweight, collapsible and rugged antenna positioner for use in receiving low earth orbit and geosynchronous satellite transmissions. By collapsing the antenna positioner, it may be readily carried by hand or shipped in a compact container. For example, embodiments of the invention may be stored in a common carry-on bag for an airplane. The antenna positioner may be used in remote locations with simple or automated setup and orientation. Embodiments of the invention may be produced at low cost for disposable applications. The apparatus can be scaled to any size by altering the size of the various components. The gain requirements for receiving any associated satellite transmission may be altered by utilizing more sophisticated and efficient antennas as the overall size of the system is reduced.
The movement of an antenna coupled with embodiments of the portable antenna positioner allows for low earth orbit, geostationary or geosynchronous location and tracking of a desired satellite. Since the slew rate requirements are small for geosynchronous satellites, the motors used in geosynchronous applications may be small.
One embodiment of the invention may be used, for example, after extending stabilizer legs and an adjustable leg to provide a stable base upon which to operate. With a battery already in the apparatus, pinch paddles are squeezed in order to extend the antenna mounting plate to the full range of one positioning arm arrangement. Next, the second positioning arm is locked via a release knob. A motor release knob is engaged and after a PC is connected to the apparatus, the apparatus is ready to acquire a satellite. The entire setup process can occur in rapid fashion. Another embodiment of the invention may utilize alternate mechanical positioning devices such as an arm that extends upward and allows for azimuth and elevation motors to adjust the antenna positioning. Another embodiment of the invention utilizes a smaller azimuth motor and limited range in order to lower the overall weight of the apparatus.
One or more embodiments utilize an adjustable leg or legs that may be motorized with for example a stepper motor. These embodiments are able to alter the effective azimuth angle of a satellite relative to the apparatus so that the satellite is far enough away from the zenith to prevent “keyholing”.
In one embodiment of the invention, positioning of an associated antenna is performed by rotating positioner support frame in relation to a positioner base in order to set the azimuth. Setting the elevation is performed by altering the angle of a first positioning arm attached to an antenna mounting plate wherein the antenna mounting plate is further attached to a second positioning arm. Both positioning arms are attached to the positioner support frame. One or both of the positioning arms may be duplicated on opposite sides of the antenna mounting plate. Since the elements are rotationally coupled to each other, rotation of the first positioning arm alters the angle of the antenna mounting plate in relation to the positioner support frame. The motion of the antenna mounting plate alters the angle of the second positioning arm with relation to the positioner support frame. Hence, altering the positioning arm angles with respect to the positioner support frame alters the angle of the antenna mounting plate with respect to the positioner support frame. The resulting motion positions a vector orthogonal to the antenna mounting plate plane in a desired elevation and with the positioner support frame rotated to a desired azimuth, the desired pointing direction is achieved. Another embodiment of the invention makes use of an arm that comprises azimuth and elevation motors that are asserted in order to point an antenna to a desired pointing direction.
The pointing process is normally accomplished via powered means using the mechanisms described above. Various components are utilized by the apparatus to accomplish automated alignment with a desired satellite. A GPS receiver is used in order to obtain the time and the latitude and longitude of the apparatus. In addition, a tilt meter (inclinometer) or three axis accelerometer and magnetometer are be used to determine magnetic north and obtain the pointing angle of the antenna. By placing a group of sensors in both the electronics housing and antenna housing, differential measurements of tilt or magnetic orientation may be used for calibration purposes and this configuration also provides a measure of redundancy. For example, if the magnetometer in the positioner base fails, the magnetometer coupled with the antenna or in the antenna housing may be utilized. Such failure may be the result of an electronics failure or a magnetic anomaly near the positioner base. A low noise block down converter (LNB) along with a wave guide allows high frequency transmissions to be shifted down in frequency for transmission on a cable. One or more embodiments of the invention comprise a builtin receiver that enables the apparatus to download ephemeris data and program guides for channels. Motors and motor controllers to point the antenna mounting plate in a desired direction are coupled with at least one positioning arm in order to provide this functionality. Military Standard batteries such as BB-2590/M for example may be used to drive the motors. Any other battery of the correct voltage may also be utilized depending on the application. A keypad may be used in order to receive user commands such as Acquire, Stop, Stow and Self-Test. A microcontroller may be programmed to accept the keypad commands and send signals to the azimuth, elevation and optional adjustable leg motor in order to achieve the desired pointing direction based on a satellite orbit calculation based on the time, latitude, longitude, north/south orientation and tilt of the apparatus at a given time and the various orbital constants of a desired satellite. Optionally, a PC may host the satellite orbit program and user interface and may optionally transfer commands and receive data from the apparatus via wired or wireless communications.
By way of example an embodiment may weigh less than 20 pounds, comprise an associated antenna with 39 dBic gain, LHCP polarization, frequency range of 20.2 to 21.2 GHz and fit in an airplane roll-on bag of 14×22×9 inches. Embodiments of the invention may be set up in 10 minutes or less and are autonomous after initial setup. Although this example embodiment has a limited frequency range, any type of antenna may be coupled to the apparatus to receive any of a number of transmissions from at least the following satellite systems.
Any other geosynchronous or low earth orbiting satellite may be received by coupling an appropriate antenna to the apparatus. For example, a dish or patch array antenna may be coupled to the antenna mounting plate. An example calculation of the size of dish or patch array to achieve desired gains follows. An ideal one-meter dish, at 20 GHz, has a gain of 46.4 dBi. With 68% efficiency, it would have a gain of 44.7 dBi. A one-half meter diameter dish, therefore, would be 6 dB less, for a gain of 38.7 dBi. Certain patch arrays have efficiencies on the order of 30%, or about 3.6 dB below a dish of similar area. A patch array with a gain of 39 dBi would have an area of 0.474 square meters. A dish with a gain of 39 dBi would have an area of 0.209 square meters, or a diameter of 0.516 meters. For a patch array consisting of four panels, this implies each panel should have an area of 0.119 square meters, or 184 square inches. This is a square with sides of 13.6 inches. A panel that measures 20 in. by 12 in. has an area of 240 square inches (0.155 square meters). For the 4-panel system, the area is 960 square inches or 0.619 square meters; with a calculated gain of 40.2 dBi. Embodiments of the invention are readily combined with these example antennas and any other type of antennas. Optionally a box horn antenna may be coupled with the apparatus that is smaller and more efficient than a patch array antenna, but that is generally heavier and thicker.
Position Sensors used in embodiments of the invention allow for mobile applications. One or more accelerometer and/or gyroscope may be used to measure perturbations to the pointing direction and automatically adjust for associated vehicle movements in order to keep the antenna pointed in a given direction.
Some example components that may be used in embodiments of the invention include the Garmin GPS 15H-W, 010-00240-01, the Microstrain 3DM-G, the Norsat LNB 9000C the EADmotors L1SZA-H11XA080 and AMS motor driver controllers DCB-241. These components are exemplary and non-limiting in that substitute components with acceptable parameters may be substituted in embodiments of the invention.
In addition, one or more embodiments of the invention may comprise mass storage devices including hard drives or flash drives in order to record programs or channels at particular times. The apparatus may also comprise the ability to transmit data, and transmit at preset times. Use of solar chargers or multiple input cables allows for multiple batteries or the switching of batteries to take place. The apparatus may search for satellites in any band and create a map of satellites found in order to determine or improve the calculated pointing direction to a desired satellite. The apparatus may also comprise stackable modules that allow for cryptographic, routing, power supplies or additional batteries to be added to the system. Such modules may comprise a common interface on the top or bottom of them so that one or more module may be stacked one on top of another to provide additional functionality. For lightweight deployments all external stackable modules including the legs may be removed depending on the mission requirements.
Embodiments of the invention provide a self contained lightweight, collapsible and rugged antenna positioner for use in receiving and transmitting to low earth orbit, geosynchronous and geostationary satellites. In the following exemplary description numerous specific details are set forth in order to provide a more thorough understanding of embodiments of the invention. It will be apparent, however, to an artisan of ordinary skill that the present invention may be practiced without incorporating all aspects of the specific details described herein. Any mathematical references made herein are approximations that can in some instances be varied to any degree that enables the invention to accomplish the function for which it is designed. In other instances, specific features, quantities, or measurements well-known to those of ordinary skill in the art have not been described in detail so as not to obscure the invention. Readers should note that although examples of the invention are set forth herein, the claims, and the full scope of any equivalents, are what define the metes and bounds of the invention.
Positioner base 100 and positioner support frame 101 may be any geometrical shape although they are roughly shown as rectangular in
Collapsible antenna positioner 103 is further described below and in
Stiffness in collapsible antenna positioner 103 as shown in
Operation of embodiments of the invention comprise initial physical setup and powered acquisition of a desired satellite. Initial physical setup may comprise extending one or both of stabilizer legs 117 and 200 and in addition, optionally unfolding adjustable leg 115. As adjustable leg 115 may optionally comprise a powered stepper motor for altering the elevation of the apparatus when a satellite is near the zenith to eliminate keyholing. Alternatively, adjustable leg 115 may be manually adjusted. After any desired legs are deployed, pinch paddles 107 and 108 may be asserted in order to extend the associated axle up into the locked position on positioner arms 110 and 111. The opposing side of antenna 102 may then be lifted in order to lock the axle associated with release knob 112 in the extended position in positioner arm 109. When the axle associated with release knob 112 travels the full length of collapse groove 203, release knob 112 is in the locked position and must be asserted in order to release the associated axle and collapse the apparatus. With opposing sides of antenna 102 locked into position, motor release knob 113 is asserted in order to engage worm drive 441 and hence elevation motor 401. For connection based configurations not employing wireless communications, connecting desired communications links to a PC or other communications processor is performed. For configurations dependent upon an external computer, microcontroller 300 is optional so long as motor controller 303 comprises a communications port. As long as the external PC comprises the requisite drivers and satellite orbit calculation programs it may be substituted for microcontroller 300.
After physically deploying the apparatus, keypad port 116 may be accessed in order to operate keypad 320. Operations accessible from keypad 320 comprise acquire, stop, stow and test.
Asserting the acquire button and selecting a satellite initiates an orbital calculation that determines the location of a satellite for the time acquired via the GPS receiver. With the latitude and longitude acquired via GPS receiver 324 and the direction North and tilt of the apparatus measured via tilt sensor and magnetometer 106 all of the parameters required to point antenna 102 towards a desired satellite may be achieved. Positioner support frame 101 is rotated to the desired azimuth via drive hub 331, azimuth motor 330 and motor controller 303. Antenna 102 is elevated to the desired elevation via antenna mounting plate 222, plate mounts 402, 403 and 404, positioner arms 110, 111 and 109, worm drive 441 and elevation motor 401. Communications and control lines, not shown for ease of illustration, extend through a center hole in drive hub 331 to and from positioner base 100 and positioner support frame 101. These communications and control lines allow for the control of elevation motor 401 and receipt of down converted satellite signal via LNB 105 and measurement data from tilt sensor and magnetometer 106. For satellite locations near the zenith in the reference frame of the apparatus, an optional stepper motor at the end of adjustable leg 115 may be activated in order to shift the observed zenith of the apparatus away from the desired satellite near the observed zenith in order to prevent keyholing.
Asserting the stop button on keypad 320 stop whatever task the apparatus is currently performing. This button can be activated prior to activating the stow button. The stow button realigns positioner support frame 101 with positioner base 100 and performs a system shutdown. The test button performs internal system tests and may be activated with or without collapsible antenna positioner 103 deployed. These operations may be modified in certain embodiments or performed remotely by an attached PC or over a wireless network in other embodiments.
After physically deploying the apparatus, keypad 804 as shown in
Asserting the acquire button and selecting a satellite initiates an orbital calculation that determines the location of a satellite for the time acquired via the GPS receiver. With the latitude and longitude acquired via GPS receiver and the direction North and tilt of the apparatus measured via tilt sensor and magnetometer all of the parameters required to point the antenna towards a desired satellite are achieved. Antenna housing 601 is rotated to the desired azimuth via azimuth motor 800. The antenna in antenna housing 601 is elevated to the desired elevation via elevation motor 802. The internal RSSI receiver may also be used in order to optimize the direction that the antenna is pointing to maximize the signal strength.
Asserting the stop button on keypad 804 stops whatever task the apparatus is currently performing. This button can be activated prior to activating the stow button. The stow button realigns positioner arm 801 with positioner base 600 and performs a system shutdown. The test button performs internal system tests and may be activated with or without antenna housing 601 deployed. These operations may be modified in certain embodiments or performed remotely by an attached PC or over a wireless network in other embodiments.
Thus embodiments of the invention directed to a Collapsible Antenna Positioner Apparatus and Method have been exemplified to one of ordinary skill in the art. The claims, however, and the full scope of any equivalents are what define the metes and bounds of the invention.
This application takes priority from United States Provisional Patent Application to Webb et al., entitled “Portable Antenna Positioner Apparatus and Method”, Ser. No. 60/521,436 filed Apr. 26, 2004, which is hereby incorporated herein by reference.
This invention was made with Government support under F19628-03-C-0039 awarded by US Air Force, Department of Defense. The Government has certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 60521436 | Apr 2004 | US |
