System and method for re-aligning antennas

A system for re-aligning an antenna communicating signals point-to-point. The system may include a first antenna, a second antenna configured to communicate a communications signal with the first antenna using point-to-point communications, and a position controller coupled to the first antenna and configured to re-align the first antenna with respect to the second antenna in response to determining a misalignment of the antenna.

BACKGROUND OF THE INVENTION

Antennas are used for a wide-variety of communications applications. One of the more recent applications for antennas has been for communications of point-to-point links for wireless fidelity “WiFi” communications. Various types of antennas may be used for point-to-point links for WiFi communications, but longer range communications, such as 20 miles, typically use dish-style antennas that have a radiation pattern that focuses an antenna beam more intensely along a communication path with another antenna. For example, while a flat panel antenna may have an antenna beam with a 60 degree angle, a dish antenna may have an antenna beam with a 6 degree angle, a much narrower beam than the flat panel antenna beam.

While the use of dish antennas for WiFi and other network communications is useful for providing long-distance communications between antennas, dish antennas that have such a small angle can result in problems if a misalignment occurs, especially at long distances. Misalignment of a dish antenna as small as one-half an inch can cause a dramatic loss of power at a range of 20 miles, for example, due to the antenna pattern not being focused on an antenna to which the dish antenna is in communication.

These antennas are often mounted on towers that situate the antennas between 50 feet and 400 feet above the ground. Dish antennas that may be used for such long distance communications are generally in the 18-inch to 6 foot diameter range and may weigh 100 to 150 pounds. The use of such large antennas may provide for communications qualities suitable for network communications, but may be problematic for maintaining alignment.

FIG. 1is an illustration of a conventional point-to-point antenna communications system100illustrating the aforementioned misalignment of the antennas.FIG. 1depicts two towers102aand102bwith antennas106aand106bbeing coupled to the towers using mounts104aand104b. The mounts104aand104btypically include brackets and other hardware to lock the associated antenna in a fixed position on the respective towers. As a result of a slight misalignment, the signal108from antenna106ais angled slightly downward, away from the receiving antenna106band, therefore, the antenna pattern110of the signal108is outside of the optimal receiving range of the receiving antenna108.

Alignment problems may result from a number of reasons, including, and most often, weather conditions. Even though the brackets104aand104bare configured to lock the antennas106aand106bin a fixed position, weather conditions that produce a lot of wind, such as rainstorms and hurricanes, may cause the dish antennas being used for point-to-point network communications to become misaligned such that point-to-point communications degrade. While storms can be a problem, because an antenna may be located high above the ground, a ground wind speed of 20-30 miles per hour may be a wind speed of 80-100 miles per hour at the antenna. While these problems are generally associated with dish antennas being mounted on towers, the same or similar problems may exist from non-dish antennas or antennas positioned on other structures, such as buildings, poles, or the ground.

One problem that occurs due to the degradation of communications is that reliability of a network degrades to the point of an outage occurring. If an outage occurs for more than 6 minutes, a report to a governmental body, such as the Federal Communications Commission, must be made and, in some cases, fines may be imposed on a communications carrier that operates the network or maintains the communications link between the point-to-point antennas. Furthermore, the antenna manufacturer may have to lower reliability reporting of the antenna (e.g., from 0.999 to 0.99), which may cause communications carriers to lower their desire to purchase the antenna.

Another problem that results from misalignment of an antenna is that the cost for re-alignment pole or tower climbers (i.e., technicians who climb communications poles or towers) is expensive. For example, for a pole climber to climb a communications tower and re-align an antenna may cost $1,000 or more for a single climb. Furthermore, pole climbers are limited in supply and the time to have one perform the re-alignment may take hours or days. If a misalignment occurs during a storm with precipitation, pole climbers cannot climb the pole, so the misalignment may not be corrected until the storm passes, which may sometimes take several days. The costs due to misalignment may further be measured in customer attrition, which, if a misalignment occurs each time the wind blows strongly, can be significant.

SUMMARY OF THE INVENTION

To overcome the problems associated with antennas used for point-to-point communications, the principles of the present invention provide for auto re-alignment or remote re-alignment of antennas. By either the antenna being able to self re-align or an operator being able to remotely re-align the antenna, the cost and delay of an antenna becoming misaligned may be reduced for a network operator. Furthermore, reliability of a network link that uses an antenna that is configured using the principles of the present invention may be improved or otherwise remains high.

One embodiment includes a system for communicating signals point-to-point. The system may include a first antenna, a second antenna configured to communicate a communications signal with the first antenna using point-to-point communications, and a position controller coupled to the first antenna and configured to re-align the first antenna with respect to the second antenna in response to determining a misalignment of the antenna.

Another embodiment may include a method for communicating signals point-to-point. A first antenna may receive a communications signal communicated to the first antenna in a point-to-point manner from a second antenna. A determination that the first antenna is misaligned may be made. At least one offset angle for re-aligning the first antenna may be determined. The first antenna may be re-aligned based on the offset angle(s) independent of a person having to perform the re-alignment at the first antenna.

DETAILED DESCRIPTION OF THE INVENTION

The principles of the present invention provide a system and method for re-aligning antennas. The description that follows is directed to one or more embodiments, and should not be construed as limiting in nature. In one embodiment, an auto-sensing algorithm is incorporated into a position controller that is attached to an antenna to automatically adjust the elevation and azimuth positions of the antenna. The principles of the present invention may also include a semi-automatic and manual mode for allowing a remote operator to manually adjust the antenna using signal strength or position information returned from a position controller.

FIG. 2Ais an illustration of an exemplary antenna system200including a position controller202for re-aligning an antenna. The position controller202may be configured to rotate the antenna106in both the elevation and azimuth directions as depicted by rotation arrows205a-205d. In one embodiment, the position controller202and antenna204are integrated as a single unit. Alternatively, the position controller202and antenna204are separate components that may be coupled together during installation.

The position controller202may be mounted to tower206. Although shown as a tower206, the position controller202may be mounted to a variety of structures, including buildings, poles, or otherwise. The position controller202remains stationary relative to the tower206, while the position controller202may adjust position of the antenna204in a range of directions. Being able to adjust the position of the antenna204in azimuth and elevation angles allows an antenna element208used for transmitting and receiving communications signals210to be re-aligned for improving communication performance, especially when used in point-to-point communications.

FIG. 2Bis an illustration of a frontal view of the antenna204ofFIG. 2Adepicting four antenna elements208a-208d(collectively208) used for receiving communications signals. These antenna elements208may also be used for transmitting the communications signals. Alternatively, another antenna element (not shown) positioned in front of a center point of the antenna204may be used to transmit the communications signals. As understood in the art, the antenna elements208may be positioned to receive the communications signals reflected from quadrants A, B, C, and D of the antenna204, respectively. Collecting communications signals reflected from each quadrant of the antenna enables power being received at each quadrant to be separately determined and used for re-aligning the antenna. The antenna elements208being separate elements is exemplary. Other configurations are possible, including an antenna array positioned at a focal plane of the dish antenna204.

FIG. 2Cis an illustration of a frontal view of the dish antenna204ofFIG. 2Adepicting an antenna array212used for sensing communications signals from the dish antenna204. The antenna array212is positioned in a focal plane of the dish antenna204. The focal plane is the distance at which radio frequency communications signals are focused from the dish antenna204to maximize signal power. If the dish antenna204is aligned such that it is pointing directly toward another antenna with which communications signals are being communicated, the communications signals will be focused at the center point of the antenna array212(i.e., the antenna array is at boresight). If, however, the dish antenna204is misaligned, the communications signals being reflected from the dish antenna204will be focused off of the center of the antenna array212, such as at focal point location214. The antenna array212may be configured such that the position controller202can determine the position of the focal point location214and re-align the dish antenna204to cause the focal point location214to be re-centered on the antenna array212.

Continuing withFIG. 2B, communication signals210communicated between antennas may be composed of any type of communications signal, including WiFi signals. In alternate embodiments, there may be more than four antenna elements, such as an antenna array, representing a larger number of subdivisions of the antenna204for more precise communications signal sensing. In other words, signal strength in any given location on the antenna can be more finely detected based on a higher number of inputs. The use of four or more antenna elements208provides for sensing signal strength being received by the antenna204to enable determination of antenna orientation or alignment, thereby enabling a determination of re-alignment in the event of the antenna204becoming misaligned due to weather conditions, for example.

FIG. 2Dis an illustration of a side view of the dish antenna204ofFIG. 2Cdepicting the antenna array212positioned at a focal plane of the dish antenna204. As shown, a communications signal216is incident on the dish antenna204and is reflected onto the antenna array212at a focal point214. The focal point214of the reflected communications signal218is shown to be at an offset distance D from boresight, which can also be represented as azimuth and elevation angles (AZ, EL). The position controller202may use information of the offset distance and re-align the antenna to boresight, thereby minimizing loss of communications signals or information contained in the communications signals.

FIG. 3is an illustration of an exemplary communications system300enabling remote re-alignment of an antenna204. In one embodiment, the principles of the present invention include a network operations center (NOC)302operating a remote controller304in communication, via a network306, with the position controller200(FIG. 2). The NOC302is located remotely from the tower206and uses the remote controller304for manually, semi-automatically, or automatically controlling the direction of the antenna204. The remote controller304receives signal data provided by the position controller202over the network306. The operator can view a display (FIG. 5) showing signal strengths received from each antenna element208and manually adjust the direction of the antenna from the remote NOC302. In an automatic adjustment embodiment, the remote controller304may receive signals from the position controller202, but the user would not manually control the antenna as the antenna204would be controlled using embedded algorithms at the remote controller similar or the same as those in the position controller202. In any embodiment (i.e. automatic, semi-automatic, or manual), the system can be configured to notify an operator of the antenna106when the power level of the communications signal drops below a set threshold (e.g., −3 dB below an initial setting). In one embodiment, a calibrated communications signal having a predetermined power level that causes a certain measured power level at the position controller202or remote controller304to be measured may be communicated periodically, aperiodically, in response to an event, or by an operator to cause re-alignment of the antenna. The calibrated communications signal may include re-calibration triggering information, such as a specific sequence of bits that the position controller202or remote controller304can identify and execute a re-calibration operation based on the received calibration signal.

FIG. 4is a depiction of an exemplary position controller202for use in re-aligning an antenna204. The position controller202includes a processing unit402that executes software404. The processing unit402may be in communication with an input/output (I/O) unit406, motion controller408, and radio receiver circuit410. The motion controller408may be in communication with a rotating assembly412, which is coupled to antenna204for re-aligning the antenna204. The software404may be configured to perform automatic feedback processing for re-aligning the antenna204. In one embodiment, the position controller202may be a stand-alone device, such that the position controller202does not communicate or receive position information from a remote device, such as the remote controller304, of the antenna204, but may communicate information received from communication signals210as received by antenna element208. The software404may be configured to perform automatic position control for controlling re-alignment operations of the antenna204based on the communication signals210received by the antenna element208. In one embodiment, the processing unit402executing the software404may perform conventional automatic position control functionality, such as using a proportional-integral-derivative (PID) control algorithm, in both azimuth elevation planes. In performing the position control functionality, the radio receiver circuit410receives the communications signals210from an antenna element, where the antenna element may be an antenna element208(FIG. 2B) or antenna array212(FIG. 2C). The radio receiver circuit410may perform an analog-to-digital (A/D) conversion to convert the communication signals210into digital signals414.

In the case of the communication signals210being received by four or more antenna elements208, the radio receiver circuit410may convert the communication signals210received from each of the individual antenna elements208and the software404may distinguish between each of the signals being received by the different antenna elements208. The software404may perform difference and summation algorithms to determine signal strengths being received by each antenna element208so that a re-alignment determination for the antenna204may be made. In other words, the antenna elements208that are positioned in different quadrants of the antenna may be used to perform re-alignment of the antenna204depending upon which quadrant is receiving communications signals210with the highest power. Performing such determination using software is well understood in the art of object tracking using remote sensors. In the case of using an antenna array, such as antenna array212ofFIG. 2C, then a determination of peak power location may be made by the processing unit402to determine position of the communications signals focused on the antenna array212by the dish antenna204. The processing unit402may use the position of the communications signals focused on the antenna array212as feedback to re-align the dish antenna204.

If, rather than using the communications signals as feedback electromechanical or optical components of the rotating assembly412are used to monitor alignment of the dish antenna204, then the processing unit402may be configured to receive feedback signals from the rotating assembly412and use those signals to re-align the dish antenna204. The position controller202, in this instance, may be established with an initial boresight alignment and use angular offsets from that initial boresight to re-align the antenna204. The automatic control algorithms for maintaining alignment of the antenna204is understood in the art. Such re-alignment may be performed continuously, periodically, or otherwise.

The processing unit402may generate command signals416based on determining the position of the aggregated or focused communications signals and communicate the command signals416to the motion controller408. The motion controller408, in response to receiving the command signals416, may perform a digital-to-analog (D/A) conversion and generate analog command signals418for communication to the rotating assembly412. The rotating assembly may be configured to receive the analog command signals418and perform an electromechanical operation to drive or otherwise reposition the antenna204for re-alignment. The rotating assembly412may include motors, gears, and other mechanical drive components in both elevation and azimuth planes for moving the antenna204. Such drive mechanisms are understood in the art. The motion controller408may include preamplifiers, amplifiers, and other electronic hardware for generating analog command signals418that are used to drive motors or other electromechanical devices in the rotating assembly412.

The I/O unit406may be in communication with network308. Data packets420may be communicated between the I/O unit406and network308. The data packets420may include information received within the communication signals210in the form of digital data. Additionally, the data packets420may include position signals indicative of the position of the antenna204. In one embodiment, the position signals may include actual or relative position signals to allow an operator located in the NOC302to monitor position in operation of the position controller202and antenna204.

As previously described, there are several operational modes that the position controller202can operate. The operational modes may include an automatic, semi-automatic, and manual mode. The position controller202, however, can have several different configurations depending upon the mode that the position controller202is designed to operate. For example, in the automatic mode, the position controller202may include software404that operates independent of receiving any external inputs from the NOC302by receiving the communication signals210received by the antenna element208and processing those signals to determine a precise direction that the antenna204is pointing. It should be understood that because of the precision used to communicate and receive the signals to maintain a signal-to-noise ratio without losing information being communicated in the communication signals210. In a semi-automatic mode, an operator at the NOC302may communicate signals to the position controller202via the I/O Unit406to cause the processing unit402to automatically re-align the antenna204. An operator at the NOC302may issue the re-alignment command to the position controller202when the communication signals210are determined by an operator to be below a threshold value, for example. Alternatively, the operator may issue a re-calibration command to the position controller202as a routine procedure to ensure quality communications. Still yet, an operator may issue a re-calibration command signal to the position controller during or after a weather phenomenon, such as a thunderstorm to ensure that the antenna204is properly aligned. The position controller202may operate in a manual mode by having software404operate as a slave to position commands communicated from the NOC302via the I/O unit406. The position commands may be generated by an operator entering information via a graphical user interface (FIG. 5) or pointing device, such as a computer mouse or joystick. In one embodiment, the software404is configured to receive position commands and communicate the commands to the motion controller408, which, in response, drives the rotating assembly412to move the antenna204to the desired position. An operator may receive feedback of the position of the antenna204in a number of ways, including signal strength of the communication signals210being received by the antenna element208, position sensors contained within the rotating assembly412, or otherwise as understood in the art. In the case of position sensors being utilized, the rotating assembly412may include mechanical, electrical, or optical sensors that monitor absolute or relative positions of the antenna204.

FIG. 5is a depiction of an exemplary remote controller500operating within a network operations center. The remote controller500may include a server502or other computing device that is used to receive information via network308from a position controller (not shown). The server502may be in communication with an electronic display504that may be utilized to display a graphical user interface (GUI)506that an operator may use to interface and control position of an antenna via a position controller, for example. The server502may include a processor508that executes software510. The processor508may be in communication with a memory512, I/O unit514, and storage unit516that may store a database518thereon.

The software510may be configured to collect information being communicated via data packets520representative of position information of an antenna and information communicated in communications signals being received at the antenna. In one embodiment, the position information is representative of power received by antenna elements at different quadrants, thereby enabling the software510to determine a direction to adjust or re-align an antenna. In another embodiment, the position information may be representative of angular position relative to an initial position of the antenna in both azimuth and elevation directions. The information received by the processor508may be stored in the memory512during operation or in the database518.

The position information, whether communicated from a position controller at an antenna (not shown) via the network308or generated by the server502, may be displayed on the GUI506. The GUI506may include a display portion522that includes information associated with one or more antennas. The information associated with the antenna(s) may include antenna number, antenna location, antenna azimuth angle, antenna elevation angle, and mode (e.g., automatic) for re-aligning the antenna. In addition, the GUI506may include a graphics portion524that may display power or signal strength associated with communication signals being received by the antenna. Alternatively or additionally, the graphics portion524may display a graphical representation of absolute or relative angle of the antenna as currently positioned. For example, a graph showing azimuth and elevation angles relative to boresight as originally positioned and calibrated may be displayed using Cartesian or other graphical format. An operator may manually adjust position of the antenna by entering new azimuth and elevation values in text entry fields526aand526b, respectively. Rather than using text entry fields, it should be understood that other graphical user interface elements, such as up and down arrows, may be utilized for adjusting position of the antenna. Furthermore, the operator may select the mode of operation of the position controller by selecting automatic, semi-automatic, or manual in entry field528. If selected to be in automatic mode, the position controller202may operate to re-align the antenna independent of commands by the remote controller500. The operator may use a keyboard530or pointing device532, such as a computer mouse, joystick or otherwise. The software510may be configured to re-align antennas in manual, semi-automatic, and automatic modes. In one embodiment, the software510may be configured the same or similar to the software in the position controller202ofFIG. 4, whereby the software determines the position of the antenna by determining power levels being received by the antenna elements at each quadrant. In making such a determination, a calibration signal may be communicated from a different antenna to the antenna being re-aligned. Command signals for re-aligning the antenna may be communicated via the data packets520by the processor508via the I/O unit514over the network308to the position controller associated with the antenna being re-aligned.

FIG. 6is a graph600depicting overall power or signal strength of an exemplary communications signal received at an antenna. The graph600has three axes, including signal strength on the left vertical axis602, frequency on the bottom horizontal axis604, and antenna alignment angle on the right vertical axis606. Three signal power curves608,610, and612are shown on the graph600. Each of these curves608,610, and612represents an antenna being at different angles with respect to another antenna to which the antenna is communicating. Signal curve608is at 0 degrees (boresight) and has a signal strength of −10 dBm Signal curve610is at a 1 degree offset angle from boresight and has −13 dBm signal strength. As understood in the art, a difference of −3 dBm is a loss of half of the power from the antenna being at boresight, which means that errors in a communications signal may occur due to the misalignment of 1 degree of the antenna. The signal curve612is reflective of the antenna being at a 2 degree offset angle from boresight and has a −16 dBm power level. The −16 dBm power level is 6 dBm below the power level of the antenna from boresight, which is a significant drop below the maximum power level and interruptions of communication may undoubtedly result. Such significant drops for such small angular deviations are a result of the antennas being configured to have point-to-point communications and using a narrow beam for communications.

FIG. 7is a depiction of an exemplary polar chart showing location of aggregated power of a communication signal being received by an antenna. The polar chart700is configured to have four quadrants, A, B, C, and D. Each of these quadrants are representative of the quadrants of an antenna (see, for example,FIG. 2B). A communications signal received by antenna elements, such as antenna elements208ofFIG. 2B, may be aggregated to determine position of the antenna so as to determine how to re-align the antenna to cause the antenna to be returned to boresight. As shown, a processor receiving the communications signal from each of the antenna elements determine that the aggregated communications signal is positioned at a point702that is 2 degrees offset from boresight. In automatic mode, the position controller or remote controller, depending on which one is controlling re-alignment of the antenna, may determine that the antenna needs to be re-aligned by driving the antenna in both the azimuth in elevation directions in quadrant D so as to move the aggregated communications to boresight.

FIG. 8is a graph depicting signal strength from various quadrants of an antenna. Five signal curves are shown, including a total signal curve T and signal curves from each of four antenna elements located in respective quadrants A, B, C, and D. As shown, signal curve B has the highest power level, signal curve A has the second highest power level, signal curve D has the third highest signal level, and signal curve C has the lowest signal power. Aggregating the signal levels of each of the antenna elements results in the signal curve T, which is at −13 dBm. Because the signal levels are spread, the position controller or remote controller can determine that the antenna is not at boresight. In addition, an operator may view the graph800and also determine that the antenna is not at boresight. Once the antenna is re-aligned, the individual signal curves A, B, C and D, should substantially overlap with one another and the total signal power curve should increase from −13 dBm to −10 dBm.

FIG. 9is a timing diagram representing an exemplary signal flow between various components of a position controller202. The components of the position controller202include a processing unit402, radio receiver circuit410, motion controller408, and rotating assembly412. It should be understood that these components may be combined or further separated but operate in the same or similar manner as described herein in accordance with the principles of the present invention. The radio receiver circuit410receives communication signals and generates power levels at step902. The power levels generated may be associated with four or more antenna elements that are configured in association with quadrants with an antenna. At step904the power levels are communicated from the radio receiver circuit410to the process unit402. In step906, the processing unit402determines one or more angles to re-align the antenna. The angles may be both azimuth and elevation angles. It should be understood that if another coordinate system other than a Cartesian coordinate system is used, then other parameters may be generated. For example, the processing unit402may determine distance and angle (r, ø) if a polar coordinate system is being used. At step908, the processing unit402may communicate the offset angles to re-align the antenna to the motion controller408. At step910, the motion controller may generate control signals that are used to drive the rotating assembly412. At step912, the control signals may be communicated to the rotating assembly412and the rotating assembly, in response, performs a re-align positioning of the antenna in both azimuth and elevation planes. In response to the motion controller408completing re-alignment of the antenna via the rotating assembly412, the motion controller408may communicate and indicated to the processing unit402that the re-alignment is complete at step916. At step918, the processing unit may repeat the process of re-aligning the position of the antenna. The re-alignment process may be performed continuously, periodically, in response to an event, in response to a manual notification by an operator, or at any other interval. For example, the processing unit402may be configured to wait for the power levels904to drop below a threshold level, optionally established by an operator using a GUI, in the aggregate or at each antenna element before performing a re-alignment operation. Alternatively, in the case of monitoring position of the antenna relative to boresight, the antenna may be re-aligned in response to becoming out of alignment by a predetermined angle (e.g., 1 degree).

By having the ability to re-align the antenna automatically or remotely, an operator of the antenna may have costs substantially reduced due to not having a technician having to climb a tower to perform the antenna re-alignment. Furthermore, quality of the antenna and communications system may be improved by not having communications problems caused degradation of communication signals for point-to-point communications. Although described as dish antennas, other types of antennas having narrow beam widths for point-to-point communications that can utilize the principles of the present invention may be utilized.

FIG. 10is a flow chart of an exemplary process1000for re-aligning an antenna. The process1000starts at step1002. At step1004, a communications signal communicated in a point-to-point manner (i.e., a dedicated communications link from one antenna to another antenna) is received at an antenna. At step1006, a determination is made that the antenna is misaligned. The determination may be made using one of a number of different techniques, including determining that power of the communications signal has dropped below a threshold value, determining that an aggregated power location of the communications signal (i.e., the effective center of power) has moved from a boresight location to an off-boresight location on the antenna, determining that the antenna has physically moved based on electromechanical (e.g., motor, gear, potentiometer, etc.) or optical components (optical encoder) sensing an offset from an initial or calibrated boresight position. At step1008, offset angle(s) in azimuth and elevation planes are determined for re-aligning the antenna to be at boresight. The determination may be made automatically, semi-automatically, or manually. In addition, the determination may be made at the antenna (e.g., by a position controller at the antenna location), remotely (e.g., by a remote controller over a network or manually by an operator at the remote controller). The antenna may be re-aligned based on the offset angle(s) independent of a person having to perform the re-alignment at the antenna at step1010. In other words, the antenna may be re-aligned using electromechanical components without a technician or other person having to climb a tower or otherwise physically access the antenna to move the antenna into a re-aligned position. The re-aligning may use automatic control feedback algorithms (e.g., PID controller), non-feedback control methods (e.g., slave commands to a stepper motor), or manually (e.g., graph or other image on a GUI at a remote controller). The process ends at step1012.

The previous description is of at least one embodiment for implementing the invention, and the scope of the invention should not necessarily be limited by this description. The scope of the present invention is instead defined by the following claims.