This invention relates to an antenna system.
Antenna positioning systems typically point an antenna towards a satellite in geosynchronous orbit above the earth to acquire the signals emitted from the transponder of the satellite. Antenna positioning systems typically include, inter alia, a dish or reflector and a feed or feed horn. The reflector receives the signals broadcast from the satellite transponder and focuses them on a focal point where the feed is located.
Some antenna reflectors focus the signals on a focal point located at the center axis of the reflector. Other antenna reflectors focus the signals on a focal point which is offset from the center axis of the reflector. The purpose of the offset design is to move the antenna feed out of the path of the incoming signal from the satellite to reduce the shadowing found in satellite systems with center axis feeds.
Some satellites may transmit signals in a circular band or in a linear polarization plane. In order to acquire signals transmitted in the linear polarization plane, the skew angle, or skew offset, of the reflector must be adjusted.
Some conventional antenna positioning systems with a centrally located focal point and feed rely on manually rotating the antenna to adjust the skew angle. Conventional antenna positioning systems with an offset focal point and offset feed similarly rotate the reflector and feed about the offset axis to adjust the skew angle. Such offset positioning systems may include features to automatically adjust the skew angle. However, the offset antenna positioning systems may require various components associated with transmitting and receiving signals to be located in or on the offset feed. The offset feed also requires a longer RF path which will induce losses. The offset design also results in a larger moment arm and therefore requires a larger and more powerful drive motor to rotate the antenna reflector.
Commercial and military satellites have both beacon and transponder broadcasts. Each satellite typically has multiple transponders that are used for data transfer. These transponders often have overlapping areas of reception on the surface of the earth. Users of satellite antenna systems need to orient the receiving antenna dish to the correct azimuth and elevation to receive an optimal signal from the desired satellite. For satellite signals broadcast in a linear polarization plane, the correct skew angle must also be set. Users need to differentiate between the desired signal from all other signals that can be received at a single location.
Conventional satellite antenna systems, for acquiring broadcast transponder signals from a satellite, may use the GPS location of the satellite antenna, the coordinates of the satellite, and a compass to orient the receiver dish to the correct azimuth. An inclinometer may be used to orient the reflector or dish to the correct elevation, and a skew adjustment is done manually or automatically by inputting the values from a preset table of values for a particular satellite and transponder. Such steps may have inherent errors due to the mechanical placement of the various components.
After the antenna dish is pointed to the desired satellite, conventional systems rely on a terminal and software to identify the received signals. Using the manually input information, the user identifies multiple signals, each of varying strength, which the terminal is receiving. Software may then be used to identify which of the broadcasted transponder signals the antenna positioning system is receiving and the result may be displayed on a terminal. If the signal strength is inadequate, the user must manually adjust the antenna orientation to maximize the signal. This alignment can be performed either by mechanical adjustments or motorized adjustments via a terminal application. The antenna is moved again until the data appears to be consistently streamed via the software application. However, such a technique requires significant user analysis and intervention. The manual acquisition of the satellite signal is also cumbersome, time consuming and inefficient. The existing process also relies on a single, fixed satellite configuration, however satellite configurations may change.
Conventional antenna positioning systems also typically include a modem to form a signal lock after the operator has positioned the antenna to maximize the energy per bit of signal. However, using a modem may require additional components, complexity, and expense to the antenna positioning system. Also, a modem provisioned for one satellite broadcast signal may not operate correctly for other satellite broadcast signals. Other conventional antenna positioning systems may rely on a reference satellite to calculate the position of the desired satellite. However, the configuration of the reference satellite may change resulting in the need to recalibrate the system.
Thus, there is a need for an antenna positioning system with centrally located feed and a need to automatically adjust the skew angle of the reflector to acquire satellite signals broadcast in a linear polarization plane. Featured is a transportable KU band antenna system with fully automated satellite signal acquisition.
In one aspect a method of receiving a satellite signal using a satellite dish connected to a receiver is featured. The method includes a peak identification stage including automatically sweeping the satellite dish to identify peaks of satellite signals received by the receiver having a center frequency matching the center frequency of the satellite signal, a peak evaluation stage including automatically evaluating one or more said peaks by determining the bandwidth thereof and choosing the peak having a bandwidth matching the bandwidth of the satellite signal. A signal strength maximizing stage including automatically sweeping the satellite dish until the signal strength of a satellite signal having said bandwidth is maximized.
In one example, the peak evaluation stage may include off-tuning the receiver until a satellite signal strength is reduced by a predetermined amount to calculate the satellite signal bandwidth. The peak evaluation stage may include determining the center frequency of a chosen peak and determining if it matches the center frequency of the satellite signal. The peak identification stage may include elevating the satellite dish to an elevation matching the location of the satellite and then automatically sweeping the antenna dish in azimuth at said elevation. The peak identification stage may include adjusting the skew of the satellite dish to maximize signal reception. Elevating the satellite dish may include elevating the satellite dish based on the position of the satellite, the location of the satellite dish, and the orientation of the satellite dish. The peak identification stage may include automatic azimuth sweeps of the satellite dish at different elevations. The signal strength maximizing stage may include both azimuth and elevation sweeps of the antenna dish. The signal strength maximizing stage may include course azimuth and elevation sweeps followed by fine azimuth and elevation sweeps. The peak evaluation stage may be performed for each sweep increment in the azimuth and elevation sweeps. The method may include a first physical positioning of the satellite dish as a function of the position of the satellite, the position of the satellite dish, and the azimuth of the satellite dish. The first physical positioning stage may include providing an indicator informing the user how to physically position the satellite dish.
In another aspect, a satellite antenna system is featured. The system includes a satellite dish maneuverable via an elevation drive and a azimuth drive, a receiver for receiving satellite signals, and a controller subsystem responsive to the receiver and configured to identify peaks of satellite signal by controlling the azimuth drive to sweep the antenna dish, evaluate one or more of the peaks by off-tuning said receiver to determine the bandwidth of one or more received peak satellite signals, and maximize signal strength by controlling said azimuth and/or elevation drive to sweep said antenna dish until satellite signal strength is maximized.
In one example, off-tuning said receiver may include off-tuning the receiver until the satellite signal strength is reduced by a predetermined amount to calculate the received satellite signal bandwidth. The controller subsystem may be configured to elevate the satellite dish to an elevation matching the location of the satellite prior to identifying peaks of satellite signals. The system may include a skew drive and the controller subsystem is configured to control the skew drive to maximize signal reception. The system may include a GPS subsystem for determining the location of the satellite dish and one or more sensors for determining the orientation of the satellite dish. The controller subsystem may be configured to identify peaks of the satellite signals by controlling the azimuth drive to sweep the antenna dish at different elevations. The controller subsystem may be configured to off-tune said receiver to determine the bandwidth of one or more received satellite signals while controlling the azimuth and/or elevation drives to sweep the antenna dish until satellite signal strength is maximized.
In another aspect, a method of receiving a satellite signal is featured. The method includes using a dish connected to a receiver to identify satellite signal peaks as the dish is automatically moved to different elevations and/or azimuth orientations, evaluating one or more said peaks to determine the bandwidth and center frequency thereof by automatically moving the dish to receive said identified satellite signal peaks, and automatically sweeping said satellite dish in elevation and/or azimuth until signal strength is maximized while evaluating the bandwidth of a received satellite signal.
The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives.
Other objects, features, and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:
Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer.
As discussed in the Background section above, conventional antenna positioning systems with a feed located at the center axis of the reflector usually rely on manually rotating the reflector to adjust the skew angle. Other conventional antenna positioning systems rely on rotating the reflector and feed horn about a focal point which is offset or off-axis from the center axis reflector to adjust the skew angle to acquire satellite signals broadcast in a linear polarization plane. For example, U.S. Pat. No. 7,839,348, incorporated by reference herein, includes parabolic reflector 10,
U.S. Pat. No. 8,284,112, incorporated by reference herein, similarly discloses an antenna with offset feed and an offset focal point which is rotated about an offset axis point to adjust the skew of antenna system.
As discussed in the Background section above, conventional antenna positioning systems such as the '348 patent and the '112 patent require various components associated with transmitting and receiving signals to be located on the offset feed, e.g., LNB 33,
Featured here is an antenna positioning system with automated skew positioning. One embodiment of this invention includes antenna subsystem 52,
In this particular example, the portable antenna system includes base unit 64,
In one preferred design, an elevation motor (e.g., a harmonic drive) is configured to rotate bracket 72 relative to post 68 to vary and adjust the elevation or inclination of reflector 54. Also, an azimuth motor is configured to rotate post 68 to vary and adjust the azimuth of reflector 54. The computer subsystem associated with base unit 64 controls the elevation motor and azimuth motor to adjust the elevation and azimuth of reflector 54 automatically. Known elevation and azimuth control algorithms can be used but preferably the algorithms described herein are used.
Preferably skew drive 60,
As shown in
As shown in
For the azimuth drive, various designs can be used.
Computer subsystem 200,
In one example, the adjustment algorithms primarily rely on the RF strength of the signals broadcast from the transponder of a satellite to acquire the antenna. Once the user selects a desired satellite and inputs the required information, computer subsystem 200 calculates and programs transceiver 80 to the appropriate frequency. The adjustment algorithms then use the latitudinal and longitudinal position via GPS (not shown) to determine where the reflector should be aimed initially using azimuth motor 190 and elevation motor 120 in order to acquire the transponder signals broadcast by the satellite. Algorithm 214 automatically adjusts the skew angle of reflector to acquire the satellite transponder signals broadcast in a linear polarization plane.
Note that skew drive 60,
In one specific preferred design, which can also be used to acquire satellite signals using other antenna system, the satellite signal processing/controller subsystem operates as follows.
There is shown in
The result is an automated, modem-less method for tracking satellite transponder signals without the need for significant user intervention.
Ground reception of satellite broadcasts typically requires a number of data points to locate and lock onto an orbiting satellite. The following information is preferably provided to the automatic acquisition terminal controller subsystem 600,
The GPS location of the satellite dish is provided via on-board GPS unit 602. The compass orientation of satellite dish is provided via compass unit 604. The physical orientation of dish placement (i.e., a level surface, an inclined surface) is provided using a three axis accelerometer 606. The Clarke Belt Position (Orbital Position) of the satellite is input using I/O section 608 or it can be retrieved from memory. The Transponder Center Frequency for the desired satellite can be entered, or is retrieved from memory. The Occupied Channel Bandwidth or Channel Symbol Rate of the satellite signal can be entered or retrieved from memory 604. The Antenna Beam Width is typically stored in memory based on the size of the dish.
In the first stage, the antenna is physically positioned on the ground or other surface. The automated, modem-less method for tracking satellite transponder signals of one or more embodiments of this invention is preferably part of an antenna positioning system which uses the stored Clarke Belt position of a satellite in conjunction with the compass and GPS data the terminal receives from its onboard software to determine the proper azimuth, elevation, and skew for the satellite in question.
When powered ON, step 502,
Having the antenna oriented to the approximately correct location of the satellite allows the terminal to perform the necessary steps to maximize the broadcast signal reception. The receiving antenna needs to orient in such a manner so the reception of a given signal is optimized for maximum data reception. The acquisition and maximization of the signal is performed in multiple stages. First, the proper skew angle of the antenna dish is set to correspond to the main lobe of the broadcast signal from the satellite, step 516. Using the stored satellite and transponder data, the controller controls the skew drive 60,
In the second stage, power peaks are identified. Using the stored Clarke Belt position of the satellite, GPS, and orientation of the satellite antenna, the controller calculates the signal to be located and then rotates the antenna dish to the correct elevation, step 518 by controlling elevation motor 120,
The controller initially looks for RF power (from transceiver 80,
When a power peak (438,
In the third stage, the power peaks are evaluated. The power peak evaluation is preferably conducted in three steps. This evaluation process algorithm for automated, modem-less method for tracking satellite transponder signals may be embedded in firmware. The first step in the power peak evaluation is to determine the Channel Bandwidth of a received peak signal at the particular center frequency. The Channel Bandwidth is determined by taking an RSSI (Received Signal Strength Indicator) reading at the center frequency of the signal, and then off-tuning receiver 80,
For enablement purposes only, the following code portions are provided which can be executed on one or more microcontrollers, drivers, microprocessors, one or more processor, a computing device, or computer to carry out the primary steps and/or functions of systems and the methods thereof discussed above with reference to one or more
The second step in the power peak evaluation is to compare this calculated Channel Bandwidth of the carrier in question to the Channel Symbol Rate or Occupied Channel Bandwidth inputted to the terminal, step 526,
The signal strength maximizing stage is preferably conducted in four steps using the antenna beam width and the found channel bandwidth to maximize RSSI signal strength. The first step is a rough azimuth peak, step 530,
The second step is a rough elevation peak, step 532 utilizing the found channel bandwidth as a qualifier for each peaking step measurement. If the channel bandwidth edges are not within a specified percentage of each other, the peaking step is discarded. This allows the terminal to peak on only the carrier in question and prevents the antenna from peaking onto adjacent satellite signals. The controller will move the antenna dish in an elevation sweep by increasingly smaller increments based on a percentage of the antenna beam width. The rough elevation peak will maximize the signal to about 0.25 degrees of accuracy in elevation.
The third step is a fine azimuth peak utilizing the found channel bandwidth as a qualifier for each peaking step measurement. If the channel bandwidth edges are not within a specified percentage of each other, the peaking step is discarded. This allows the antenna to peak on only the carrier in question and prevents the antenna from peaking onto adjacent satellite signals. The controller will move the antenna dish in an azimuth sweep by increasingly smaller increments, step 534 based on a percentage of the antenna beam width. The fine azimuth peak will maximize the signal to about 0.025 degrees of accuracy in azimuth.
The fourth step is a fine elevation peak sweep, step 536 utilizing the found channel bandwidth as a qualifier for each peaking step measurement. If the channel bandwidth edges are not within a specified percentage of each other, the peaking step is discarded. This allows the antenna to peak on only the carrier in question and prevents the antenna from peaking onto adjacent satellite signals. The controller will move the antenna in an elevation sweep by increasingly smaller increments based on a percentage of the antenna beam width. The fine elevation peak will maximize the signal to about 0.025 degrees of accuracy in elevation.
Once the azimuth and elevation are peaked at about the 0.025-degree of accuracy the antenna system has located and locked onto the specified transponder and signal from the specified satellite, step 540. This terminal then stores and uses this data to maintain automatic signal lock during the communication time between the satellite antenna system and the satellite. In the event that the signal is lost due to environmental or other conditions, the controller will use the prior, stored data and peaking steps to re-acquire the signal from the satellite transponder. In a maintenance mode, every time period X (e.g., ½ hour), power peaking and/or other stages described above can be performed to lock into a signal in case the satellite gets bumped or otherwise moves. For satellite antenna systems without an automated skew adjustment, the skew angle adjustment steps described above are not employed.
Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments.
In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant cannot be expected to describe certain insubstantial substitutes for any claim element amended.
Other embodiments will occur to those skilled in the art and are within the following claims.
This application claims benefit of and priority to U.S. Provisional Application Ser. Nos. 61/861,522 and 61/861,550 both filed Aug. 2, 2013 under 35 U.S.C. §§119, 120, 363, 365, and 37 C.F.R. §1.55 and §1.78 and is incorporated herein by this reference.
Number | Date | Country | |
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61861522 | Aug 2013 | US | |
61861550 | Aug 2013 | US |