Antenna apparatus including movement means, system and method of use thereof

Abstract

An apparatus 2 for signal communication with a group of satellites comprises an antenna array (4, Figure 1) with a signal receiving surface (7, Figure 3a) initially positionable to a desired angular o

Description

Antenna Apparatus including Movement Means. System and Method of Use Thereof The invention to which this application relates is an antenna apparatus including an array of antennas for signal communication with a remote satellite and, in particular, a plurality or group of satellites in a spaced apart orbit sequence about the Earth. The communication is most typically the receipt of signals transmitted from the satellites by the antenna array and the signals may include any of telecommunication signals, data communications and / or broadcasting signals. Typically the satellite is in communication with a head end or source of the signals from which the signals are transmitted to the satellites and, in turn, communicated to a plurality of antenna arrays each provided at a geographical location at or near to a particular end user location for each of the respective antenna arrays. Signal communication with remote orbiting satellites is known in the art. Satellite communication allows wireless transfers of signals across vast distances to multiple end user recipients via an antenna array provided for each recipient or group of recipients at the same location. Some orbiting satellites are fixed with respect to a geographical point on the Earth’s surface, known as being in geosynchronous orbit, to maintain a steady communication with a predefined or selectively variable area on the Earth’s surface, however these satellites require precise control to maintain their location and are therefore often expensive to manufacture and complex to control. Geosynchronous satellites are often limited to military use or the like. A more frequently implemented form of satellite is a low Earth orbit (LEO) satellite that orbits at a relatively lower altitude and has an orbit that may be tilted about the Earth’s equator, greatly increasing the available routes of travel. This increased availability and reduced orbit altitude make LEO satellites more commercially viable and, as such, more commonly used. In order to communicate with a satellite, an antenna on or near the Earth’s surface must be orientated appropriately to allow the same to be exposed to the receipt of the signals. In the case of a geosynchronous satellite, it is known to provide an antenna on a mechanically movable frame such that, on installation of the antenna, the antenna may be configured to align with the satellite initially and be fixed in position to maintain communication with the same. This is conventionally unsuitable for non-geosynchronous satellites, such as LEO satellites, as the satellites travel across and through the receiving range of the antenna from an edge of the antenna at which the transmitted signals start to be received and increase in strength as the satellite moves, to an opposing edge at which the signal transmission drops off and then stops. Antennas with mechanical movement means on the frame of the type described above are found to be unsuitable for tracking the travelling LEO satellites, as they are prone to failure due to constant actuation with varied movement patterns and are often have to be mounted on relatively complex mechanical rigs to enable efficient tracking. An alternative is to implement a fixed position antenna and increase the number of satellites in a group of satellites to a sufficient number such that at any stage there is at least one satellite in the group which is positioned so that the signals transmitted therefrom are within the range of the antenna so as to communicate with the antenna. Typically the antenna is formed as an antenna array and is initially moved to a position which is predetermined as providing the best possible signal reception given the known or estimated geographical location of the antenna array. However, this solution incurs significant cost due to the need to launch a relatively large number of satellites into respective orbits so as to ensure that at least one satellite is in the range of the antenna so as to provide for the reception of signals which are of sufficient strength and quality in order to allow the service or services to be provided from the received data signals. Furthermore, with antenna arrays which have a flat external signal receiving surface it is known that the quality of the signal received will decrease as the angle of the position of the satellite from which the signals are being received reduces from the angle when the satellite emitted signals are in a perpendicular direction to the surface at 90 degrees to an angle approaching 0 degrees to the surface. Thus the system operator has the problem that as one satellite initially moves into range of the antenna and subsequently moves towards the opposing edge of being out of range of the antenna the signal reception strength drops off and becomes too poor to provide an effective service generated from the data signals and to the user of the antenna, or the service is lost completely, until the next satellite in the group of satellites moves into range. This problem then repeatedly occurs as the satellites in the group of satellites sequentially move into and out of range with respect to the antenna. While the increase in the number of satellites in the group of satellites means that there is less of a “gap” between adjacent satellites in the group of satellites and can effectively create a sufficient overlap of signals from at least two of the satellites in the group at any instant of time so that any loss in signal is reduced to such an extent that the service is not adversely affected, the additional cost involved in launching more satellites is prohibitive to many service providers and, as a result, is not a practical solution to the problem. An aim of the present invention is therefore to provide an antenna apparatus that overcomes the above-mentioned problems. A further aim of the invention is to provide an antenna apparatus with an increased quality of reception with a satellite as the satellite moves with respect to the antenna array. A yet further aim of the invention is to provide an antenna apparatus that is deployable by a user and, after deployment, is able to track and communicate with a remote satellite without user intervention. In a first aspect of the invention there is provided apparatus for signal communication with a group of satellites, the apparatus including an antenna array with a signal receiving surface which is initially positionable to a desired angular orientation with respect to the known geographical location of use of the antenna array, for receipt of signals from at least one satellite in said known group of satellites and wherein the apparatus further includes movement means to mechanically adjust the orientation of the said antenna array receiving surface with respect to said at least one satellite to retain the quality and / or increase the duration of receipt of signals from the said at least one satellite as the satellite moves through at least one part of the reception range of said signals by the said antenna array. In one embodiment the antenna array is initially electronically steerable at the time of installation to the said desired angular orientation which is deemed to be best suited with respect to said geographical location of use and selected group of satellites from which signals are to be received. Typically once in that said position no further electronic adjustment is performed on the antenna array during subsequent use of the antenna at said geographical location and with said group of satellites. In one embodiment the surface of the antenna array facing towards said satellite signals is substantially flat. In one embodiment the mechanical movement means includes one or more members connected between a movement means and the antenna array. Typically the apparatus includes a base with respect to which the said antenna array is mechanically moved. In one embodiment the base includes movement means in the form of one or more motors provided to impart a movement force on the said one or more members so as to cause angular adjustment of the said flat surface of the antenna array so as to vary the rotation and / or angle of the apparatus with respect to a satellite from which signals are received over a period of time in which the satellite is in range of the said antenna array. In one embodiment the mechanical movement means is controllable by a control unit provided as part of the apparatus and said control and movement occurs automatically. Typically the movement occurs when the signal quality between the satellite and the apparatus falls below a predetermined level and most typically at one or both extremes of said range so as to have the effect of extending the duration for which the received signals from said satellite allow an acceptable service to be generated and therefore prevent or reduce problems caused by the received signals dropping off after the passage of a first satellite and / or as a second satellite comes into range or both In one embodiment the control unit includes a processor. In one embodiment the processor is configured to process the signals transmitted to and / or received from the remote satellite. Typically the processor allows for the signals to be identified by the control unit. In one embodiment the apparatus includes or is connectable to a power source. Typically the same or a similar sequence of mechanical movement of the antenna array occurs with respect to each of the satellites in the said group of satellites when the specific satellite is in range of the antenna array. Typically the mechanical movement is such as to cause the duration of the receipt of effective and usable signals from the satellite by the antenna array to be extended and preferably to be extended to a sufficient extent so that a substantially continuous receipt of effective signals are received from the sequential passage of satellites in the group of satellites and so, in turn, allow a substantially continuous service to the end user to be provided. In one embodiment the apparatus may also include the ability to transmit signals to the said satellite which is in range at that time. In one embodiment the apparatus is for use for the receipt of signals from satellites in low earth orbits. In a further aspect of the invention there is provided a system for transmitting to and / or receiving signals from a group of satellites in sequence, the system including: an apparatus for the receipt of said signals communication, said apparatus including an antenna array having a surface and mechanical movement means which are operable during the receipt of the signals from one of said satellites so as to adjust the position of said surface so as to extend the duration of receipt of effective signals received from said satellite. In one embodiment mechanical movement of the said surface is repeated during the receipt of signals from each of said satellites in the group of satellites, when the particular satellite is range of the antenna apparatus. In one embodiment the type of mechanical movement may be the same for each satellite or may vary from satellite to satellite. Typically the movement of the said surface and antenna array is controlled by the control unit and most typically occurs when the signal quality between the satellite and the antenna array falls below a predetermined level. Typically this occurs when the satellite enters into or approaches to enter the boundary of the receiving range of the antenna array and / or leaves or approaches to leave the boundary of said receiving range. This means that the extent of mechanical movement is relatively limited and that the movement occurs for limited periods of time rather than continuously and therefore means that the movement means is less prone to malfunction and wear and tear. Thus, there is provided a means to effectively extend the receiving range of the antenna array. In one embodiment the apparatus includes orientating means such that the orientation of the antenna array at the time of installation at a geographical position is determined by the control means via the orientating means. Typically the orientating means includes a means to orientate the array with respect to true north. Preferably the orientating means includes global position system (GPS) technology. Alternatively or in addition, the orientating means includes a compass. In one embodiment the position of at least one remote satellite with respect to the antenna array is calculated by a processor of the control means. Typically the processor includes a database with the expected locations of the remote satellite or a series of remote satellites at a given time. The processor is configured to calculate the position of the remote satellite with respect to the array at a given time by comparing the calculated position of the apparatus via the orientating means with the expected locations of the remote satellite at a given time via the database. In one embodiment the database can be connected with processing means to be in communication with the same such that the expected position of the at least one remote satellite may be updated with records of the processing means. Typically the calculated position of the satellite by the apparatus is supplied to the processing means to update the same. In one embodiment the apparatus is portable and / or deployable such that the apparatus may be selectively located by a user. Typically the orientation of the array at a given time and / or the geographical position of the apparatus is redetermined by the control means via the orientating means when the apparatus is redeployed. In a further aspect of the invention there is provided a method of orientating at least one antenna of an antenna array with at least one satellite, the method comprising the steps of: locating an apparatus including an antenna array at a geographical position; electronically steering the array of antennas to a required position with respect to the orbit of the satellite and the geographical location of the apparatus; and reorientating the array by a mechanical movement means as the satellite approaches and / or passes through the signal receiving range of the array. In one embodiment the mechanical movement occurs as the signal quality between the satellite and the antenna falls below a predetermined level. Typically this occurs as the satellite enters and / or leaves the boundary or approaches the boundary of said signal receiving range. Specific embodiments of the invention will now be described with reference to the following drawings wherein: Figure 1 illustrates an antenna apparatus including an array of antennas; Figure 2 illustrates the range of the individual antennas of the array as the apparatus is in communication with a satellite; Figure 3a illustrates an embodiment of the antenna apparatus including a mechanical movement means in accordance with the invention in a first position; Figure 3b illustrates the range of the antenna apparatus in the position of Figure 3a with respect to a remote satellite; Figure 4a illustrates the embodiment of the antenna apparatus of Figure 3a in a second position; and Figure 4b illustrates the range of the antenna apparatus in the position of Figure 4a with respect to a remote satellite. Referring firstly to Figure 1, there is illustrated an antenna apparatus 2 including an antenna array 4, shown in broken lines, which for reference purposes comprises three antennas 4a,4b,4c located within a housing 5 which has a relatively flat satellite facing surface 7. The antennas of the array 4 have varying orientations, such that the angle at which signals are received by the antennas vary between the antennas 4a, 4b, 4c, as indicated by 6a, 6b, 6c respectively. It will be appreciated that the antennas of the array 4 in other embodiments are also used for the transmission of signals. As illustrated in Figure 2 a remote satellite 8 orbiting around the Earth at a fixed distance is transmitting signals 10 to the surface of the Earth. The ranges 6a,6b,6c of the antennas 4a,4b,4c intersect the orbit 12 of the satellite as it travels in direction 14. The ranges 6a,6b,6c of the antennas 4a,4b,4c overlap at least at the distance at which the satellite 8 orbits, and as such the signals 10 transmitted from the satellite 8 are in communication with at least one of the antennas when the satellite is within the combined range 6. In this way, the antenna array 4 has a potential signal reception range 6. When the antenna array is initially placed in position at a location of use the antenna array is electronically steered by a control unit (not shown) to the best orientation to receive the signal transmission from the successive satellites 8 in the known group of satellites on a known orbit. Conventionally the reduction in effective reception of the signals by the surface 7 occurs at the edges of the range 6 and the signal drop off can mean that the effective signal receiving range is less than the combined range 6 and so an effective service cannot always be generated from the received signals and so cannot be provided to the end user of apparatus connected to the antenna array. Figure 3a illustrates an antenna apparatus 2 including a movement means 20 in accordance with the invention. The antenna apparatus 2 is as described in Figures 12, having a combined range 6 for communicating with a satellite 8 as illustrated in Figure 3b. In this embodiment, the movement means 20 includes a tilting table 22 on which the housing 5 in which the antenna array 4 is located is mounted and acted upon by a first and second ram 24,26. The rams are controlled by the control unit of the apparatus 2 and are powered by a power supply 28 mounted with a frame 30 of the apparatus. The power supply 28 further supplies the power for the antenna array 4, processor, control unit and the like. In the embodiment illustrated in Figures 3a-b, the apparatus is in a first position. That is, the rams 24,26 maintain the tilting table 22 in the predetermined orientation position, such as, for example, the centreline 32 of the range 6 of the array is perpendicular to the support surface on which the apparatus 2 is located, h a surface 7 of the housing 5. As the remote satellite 8 travels across the range 6 of the antenna array 4 the antenna array is fixed in position. However as the satellite 8 approaches the edge portions 6’ of the range 6, as for example indicated by satellite 8’, the signal communication strength between the satellite and the apparatus decreases whilst the satellite is still within communication range with the antenna array, however the signal quality will drop below a predetermined level which is the minimum quality for signal communication determined by the user of the apparatus. When this occurs the control unit commands the rams 24,26 to move the apparatus 2 to the second position illustrated in Figure 4a. Ram 24 increases in length as indicated by 34, and ram 26 decreases in length as indicated by 36. This partially rotates or tilts the tilting table 22 on which the array 4 is mounted as indicated by 38, such that the centreline 32 of the range 6 and the surface 7 is varied by angle 40 as illustrated in Figure 4b so as to improve the strength of the signals received in the portion 6’. In this way, the effective receiving range for the antenna apparatus now includes the portion 6’ at the end of the range and the portion 6’ at the start of the range. The mechanical movement of the array 4 by the movement means 20 is only carried out when the satellite 8 approaches the portions 6’ at the boundaries of the range 6. In other embodiments, the mechanical movement of the apparatus includes the rotation of the array 4, linear translation of the array with respect to the support surface on which the apparatus is located, or any combination of the like. The controller of the apparatus includes a database of the expected locations of the satellites that are to be communicated with by the apparatus at a given time as they orbit the Earth. This database is updated by communicating the database with a computer mainframe with information relating to new satellites to be communicated with and / or updating the locations of satellites at given times. Alternatively, the database is in constant communication with a computer mainframe. The location of a satellite in communication with the apparatus at a given time with respect to the apparatus is calculated by a processor of the apparatus, as varying signal strengths across the antennas of the antenna array in communication with the satellite are computed to identify the location of the transmitting satellite with respect to the apparatus. This process is carried out to automatically adjust the database of the location of the satellites with the newly calculated position. The apparatus includes an orientating means, such as a compass or GPS technology to identify the geographical position of the apparatus when it is deployed. In this way, the processor of a deployed apparatus calculates the geographical position of the apparatus using the orientating means. The pre-installed database of satellite locations with respect to a given geographical location is then accessed by the processor to calculate where and when satellites to be communicated with will cross the range of the array. The control unit of the array electronically steers the array to receive signals from the satellite at the expected position. If the apparatus establishes a signal communication with the satellite, the location of the satellite is verified in the database of the apparatus. If no communication is established with a satellite at an expected location at an expected time, the control unit of the apparatus configures the apparatus to a searching mode. In the searching mode, all the antennas of the array are activated to maximise the effective range of the array. When a signal is received by the apparatus in the search mode, the processor processes the signal to identify the satellite. The position and direction of travel of the satellite is calculated by the processor. This information is used to update the expected position of the satellite at a given time within the database of the apparatus. Alternatively, this information is used to correct any errors in the calculated geographical location of the apparatus by the orientating means. In an alternative embodiment, the database of the apparatus is in communication with a central database of a system of multiple antenna apparatus. This central database is updated by the antenna apparatus to provide continuously updated data on the position and direction of travel of satellites at a given time. The central database then periodically updates the database of the individual antenna apparatus.

Claims

1. Apparatus for signal communication with a group of satellites, the apparatus including an antenna array with a signal receiving surface which is initially positionable to a desired angular orientation with respect to the known geographical location of use of the antenna array, for receipt of signals from at least one satellite in said known group of satellites and wherein the apparatus further includes movement means to mechanically adjust the orientation of the said antenna array receiving surface with respect to said at least one satellite to retain the quality and / or increase the duration of receipt of signals from the said at least one satellite as the satellite moves through at least one part of the reception range of said signals by the said antenna array.

2. Apparatus according to claim 1 wherein the antenna array is initially electronically steerable at the time of installation to said desired angular orientation which is best suited with respect to said geographical location of use and group of satellites from which signals are to be received.

3. Apparatus according to claim 2 wherein once the said position is set, no further electronic adjustment is performed on the antenna array during subsequent use of the antenna at said geographical location with respect to said group of satellites.

4. Apparatus according to any of the preceding claims wherein the receiving surface of the antenna array facing towards said satellite signals is substantially flat.

5. Apparatus according to any of the preceding claims wherein the mechanical movement means includes one or more members connected between a drive means and the antenna array receiving surface.

6. Apparatus according to any of the preceding claims wherein the apparatus includes a base with respect to which the said antenna array receiving surface is mechanically moved.

7. Apparatus according to claim 6 wherein the said base includes drive means in the form of one or more motors to impart a movement force on the said one or more members so as to cause angular adjustment of the said receiving surface of the antenna array to vary the rotation and / or angle of the receiving surface with respect to said satellite from which signals are received over the period of time in which the satellite is in the range of the said antenna array.

8. Apparatus according to any of the preceding claims wherein the mechanical movement means is controlled by a control unit provided as part of the apparatus.

9. Apparatus according to claim 8 wherein the mechanical movement is controlled automatically.

10. Apparatus according to any of the preceding claims wherein the movement occurs when the signal quality of the signals received from the said satellite falls below a predetermined quality level.

11. Apparatus according to claim 10 wherein the movement occurs at one or opposing extremes of said receiving range of signals from said satellite in order to extend the duration for which the received signals from said satellite enable an acceptable service to be generated therefrom.

12. Apparatus according to any of the preceding claims wherein the control unit includes a processor configured to process signals transmitted to and / or received from said satellite.

13. Apparatus according to any of the preceding claims wherein the satellites in said group of satellites come into range of the receiving surface of the antenna array in sequence and mechanical movement of the receiving surface of the antenna array is sequentially performed with respect to each of the satellites in the said group of satellites.

14. Apparatus according to any of the preceding claims wherein the mechanical movement causes the duration of receipt of effective and usable signals from the said satellite by the receiving surface of the antenna array to be extended to a sufficient extent so that a substantially continuous receipt of effective signals are received from the sequential passage of satellites in the said group of satellites and so allow a substantially continuous service to be provided to the end user of the apparatus.

15. Apparatus according to any of the preceding claims wherein the apparatus includes transmission means to transmit signals to said satellite or group of satellites which is in range at that time.

16. A system for transmitting to and / or receiving signals from satellites in a group of satellites in sequence, the system including apparatus for the receipt of said signals communication, said apparatus including an antenna array having a receiving surface, mechanical movement means which are movable during the receipt of the signals from one of said satellites so as to adjust the position of said surface so as to extend the duration of receipt of effective signals from said satellite.

17. Apparatus according to claim 16 wherein mechanical movement of the said receiving surface is repeated during the receipt of signals from each of said satellites in the group of satellites and for each particular satellite when in range of the antenna apparatus.

18. A system according to claim 17 wherein the movement of the said receiving surface of the antenna array is controlled by a control unit which operates when the detected received signal quality from the satellite falls below a predetermined level and the movement of the said receiving surface is performed to improve said signal quality.

19. A system according to claim 18 wherein the signal quality falling below the predetermined level occurs when the satellite enters into or approaches entry into a boundary of the receiving range of the receiving surface of the antenna array and / or leaves or approaches leaving the boundary of said receiving range of the receiving surface of the antenna array.

20. Apparatus according to claims 16-19 wherein the movement occurs for a period of time and only when the signal quality between the satellite and the receiving surface of the antenna array are detected to fall below a predetermined level.

21. Apparatus according to any of claims 16-20 wherein the apparatus includes orientating means such that the orientation of the receiving surface of the antenna array at the time of installation at a geographical location is determined by control means via the orientating means.

22. A system according to claim 21 wherein the orientating means includes a means to orientate the receiving surface of the antenna array with respect to true north.

23. A system according to any of claims 16-22 wherein the position of at least one satellite with respect to the antenna array is calculated by a control means which includes a database with the expected locations of the satellite of a group of satellites at a given time and so calculate the position of the saidsatellite with respect to the antenna array at a given time by comparing the calculated position of the apparatus via the orientating means with the expected location of the said satellite as indicated by said database.

24. A system according to claim 23 wherein the database is connected with the processing means to be in communication with the same such that the expected position of the at least one said satellite is updated with records of the processing means.

25. Apparatus according to any of the preceding claims wherein the apparatus is portable and / or deployable at selected geographical locations.

26. A method of orientating at least one antenna of an antenna array with respect to at least one satellite, the method comprising the steps of locating an apparatus including an antenna array at a geographical location, electronically steering the array of antennas to a required position with respect to the orbit of the said satellite and the location of the apparatus and reorientating the array by a mechanical movement means as the satellite approaches and / or passes through a signal receiving range of the array.

27. A method according to claim 26 wherein the mechanical movement occurs as the signal quality received by the receiving surface of the antenna array from the said satellite falls below a predetermined level.

28. A method according to claim 27 wherein the signal quality between the satellite and the antenna array falls below the predetermined level as the satellite enters and / or leaves the boundary or approaches the boundary of said signal receiving range.

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