GB2603137A

GB2603137A - Communication system

Info

Publication number: GB2603137A
Application number: GB2101080.6A
Authority: GB
Inventors: Quintana-Sanchez Cristanto; Erry Gavin; Thueux Yoann
Original assignee: Airbus SAS
Current assignee: Airbus SAS
Priority date: 2021-01-27
Filing date: 2021-01-27
Publication date: 2022-08-03
Also published as: GB202101080D0

Abstract

An aircraft 10 has an optical communications system with four optical transceivers 12,14,16,18, each with a field of regard 30 of at least 90 degrees in a common plane, and the four transceivers are located around the aircraft such that, when combined, they provide a 360 degree field of regard in the common plane. The aircraft may be a node in an optical communications network. Preferably, the transceivers are located around a fuselage 20 of the aircraft, with a front and rear pair, and the common plane is the horizontal plane, the transceivers having a field of regard in the pan and tilt planes. A fifth and sixth transceiver (fig.2,22,24) may be located in a bottom and top section of the fuselage, respectively. A control system 42 may allow handover between linked transceivers. Also claimed is an optical transceiver, suitable for an aircraft, having a moveable laser and receiver arrangement (fig.3,304) with a field of regard of at least 90 degrees, and an optical aperture (fig.3,306), such as an optical flat, through which optical signals can be emitted and received which is shaped to conform to an external surface (fig.3,308) of an aircraft; preferably providing a smooth, uninterrupted, aerodynamic surface.

Description

Communications System

BACKGROUND OF THE INVENTION

[0001] The present disclosure relates to an optical communications system for use on an aircraft. More particularly, but not exclusively, the disclosure relates to an aircraft including an optical communications system.

[0002] Various free-space optical communications systems exist, in which optical signals are sent between a transmitter and receiver to wirelessly transfer information. Such signals may be more robust than radiofrequency (RF) communications, and less vulnerable to jamming or interception. Additionally, optical signals may have a higher data rate than RF communications.

[0003] For example, laser communications systems may utilise a laser transmitter and receiver to transmit data at a high data rate. Such systems may be useful on aircraft, for example to send and/or receive weather data, or control signals if the aircraft is an unmanned aerial vehicle (UAV). Typically, an aircraft is provided with a laser transceiver mounted on a gimbal, encased in a turret extending from the fuselage of the aircraft. The gimbal allows rotational movement of the transceiver in order to track a paired receiver, for example on the ground. The turret and gimbal add weight and complexity to an aircraft, and they may also significantly increase drag during flight.

[0004] Optical communications do require relatively clear visibility and line of sight between the transmitter and receiver. Therefore, weather and/or ground conditions can cause difficulties, particularly when trying to communicate with a moving object such as an aircraft.

[0005] The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved aircraft and aircraft wing

SUMMARY OF THE INVENTION

[0006] The present invention provides an aircraft comprising an optical communications system comprising four optical transceivers, each optical transceiver with a field of regard of at least 90 degrees in a common plane, the four optical transceivers disposed around the aircraft such that, when combined, the four optical transceivers provide a 360 degree field of regard in the common plane.

[0007] The aircraft may comprise a fuselage, and the four optical transceivers may be disposed around the fuselage. In an alternative arrangement, the aircraft may comprise a wing, and at least one optical transceiver may be wing mounted.

[0008] The four optical transceivers may provide a 360 degree field of regard in a horizontal plane. The horizontal plane may also be considered the pan plane. The terms horizontal and vertical are used with reference to the aircraft orientation. The vertical plane may also be considered the tilt plane. When the aircraft is on the ground, the horizontal plane corresponds to the horizontal plane defined by the ground, and the vertical plane corresponds to the vertical plane defined by the ground. In flight it is understood that the movement of the aircraft may change the horizontal and vertical plane defined with reference to the aircraft and the horizontal and vertical plane defined with reference to the ground.

[0009] Each optical transceiver may comprise an optical aperture through which optical signals may pass. The optical aperture may be integrated into the fuselage or wing such that a smooth aerodynamic surface is provided. The optical aperture may be integrated into the fuselage or wing such that an uninterrupted aerodynamic surface is provided. Provision of a smooth and/or uninterrupted aerodynamic surface may eliminate or reduce any negative effect the optical transceiver has on the aerodynamic performance of the aircraft. This contrasts with prior art optical transceiver arrangements, which are often mounted on gimbals in turrets which extend from the fuselage of an aircraft into the airflow, thereby increasing drag.

[0010] The four optical transceivers may be arranged in pairs, one pair at the front of aircraft and one pair at the rear of the aircraft. The aircraft may have a central axis, running from the front of the aircraft to the rear of the aircraft, such that a left side and right side of the aircraft are situated to the respective sides of the central axis.

[0011] The front pair of optical transceivers may be located such that one transceiver is on the left side of the central axis and the other transceiver is on the right side of the central axis. The front pair of optical transceivers may be arranged such that one optical transceiver is located to have a field of regard of 90 degrees in the pan plane, starting from the central axis in a forwards direction and extending to cover 90 degrees to the left side of the aircraft, with the other optical transceiver having a field of regard starting from the central axis in a forwards direction and extending to cover 90 degrees to the right side of the aircraft. Each of the front pair of optical transceivers may also have a field of regard of 90 degrees in the tilt plane, the field of regard in the tilt plane extending 45 degrees to either side of the pan plane.

[0012] The rear pair of optical transceivers may be located such that one transceiver is on the left side of the central axis and the other transceiver is on the right side of the central axis. The rear pair of optical transceivers may be arranged such that one optical transceiver is located to have a field of regard of 90 degrees when viewing the aircraft in the pan plane, starting from the central axis in a backwards direction and extending to cover 90 degrees to the left side of the aircraft, with the other optical transceiver having a field of regard starting from the central axis in a rearwards direction and extending to cover 90 degrees to the right side of the aircraft. Each of the rear pair of optical transceivers may also have a field of regard of 90 degrees in the tilt plane, the field of regard in the tilt plane extending 45 degrees to either side of the pan plane.

[0013] Each of the four optical transceivers may have a field of regard of greater than 90 degrees, for example, 92 degrees, in order that there is some overlap between the various quadrants covered by the optical transceivers. Alternatively, there may be a very slight, and in practice negligible gap, between the quadrants due to the spacing of the optical transceivers to the front and the rear of the aircraft fuselage. Error correction and/or interleaving techniques may be utilised by the optical communication system to compensate for any brief loss of contact as a signal moves between quadrants. A predictive tracking system may be utilised in order to manage the handover from one quadrant to another quadrant.

[0014] The aircraft may comprise a fifth optical transceiver with a field of regard of at least 90 degrees. The fifth optical transceiver may be disposed in a bottom section of the fuselage such that the field of regard extends downwardly in a vertical plane. The field of regard may extend 45 degrees to either side of the vertical axis of the aircraft.

[0015] The aircraft may comprise a sixth optical transceiver with a field of regard of at least 90 degrees. The sixth optical transceiver may be disposed in a top portion of the fuselage such that the field of regard extends upwardly in a vertical plane. The field of regard may extend 45 degrees to either side of the vertical axis of the aircraft. -4 -

[0016] Provision of a fifth and/or sixth optical transceiver may improve the ground and sky coverage of the optical communications system, for example allowing communication with a paired transceiver directly above or below the aircraft.

[0017] Some or all of the optical transceivers may be monostatic, such that a single set of optics transmits and receives data. Some or all of the optical transceivers may comprise a laser, a fine pointing system, and/or adaptive optics. The laser may have a wavelength of 1550nm, or any other suitable wavelength as would be understood by the skilled person. Some or all of the optical transceivers may comprise a detector, for example a high-sensitivity detector. Some or all of the optical transceivers may comprise one or more of an electrically steered mirror, galvanometer, or rotating prism, arranged to direct the laser beam generated by the laser. The optical aperture may be an optical flat. The arrangement of the mechanical components of the optical transceiver may be arranged to generate and receive an optical signal, with a field of regard of 90 degrees in the pan and tilt directions, through movement of the mechanical components. All of the moveable mechanical components of the optical transceivers are housed within the aircraft fuselage, such that a smooth, uninterrupted external surface is presented to airflow across the aircraft fuselage [0018] The aircraft may also comprise a control system. The control system may generate and receive the data transmitted and received by each of the optical transceivers. Each of the optical transceivers may be linked to each of the other optical transceivers, for example via physical means such as optical fibres or copper transmission lines, or a wireless communications protocol. The control system may be arranged to allow handover of optical communications between two or more of the optical transceivers. For example, a data exchange may be initiated between a ground source and the left side front optical transceiver. The left side front optical transceiver may maintain the data exchange whilst the ground source remains in the corresponding field of regard. However, a change of direction of the aircraft may result in the ground source leaving the field of regard of the left side front optical transceiver and moving into the right side front optical transceiver. The control system may be arranged to track the movement of the left side front optical transceiver and, when the transition to the right side front optical transceiver is -5 -imminent, control the right side front optical transceiver to be pointing in the right direction to seamlessly pick up the data transmission.

[0019] Some or each optical transceiver may be arranged to scan a search area in order to acquire a new data transmission, or reconnect with a data transmission which was previously being sent through one of the other optical transceivers. Such scanning techniques, for example sp person [0020] ral scanning, are well understood by the skilled The provision of a plurality of optical transceivers may allow communication with a plurality of distinct data sources. For example, the aircraft may optically communicate with a plurality of other aircraft, or a combination of other aircraft and ground and/or space stations. Such an arrangement may allow the aircraft to act as a node in a networked communication system. This may allow communications between various parts of the networked communication system that would otherwise not be able to communicate with each other, for example because of physical distance or intervening objects preventing direct optical communication.

[0021] According to a second aspect, the invention provides an optical transceiver for an aircraft, the optical transceiver comprising a moveable laser and receiver arrangement with a field of regard of at least 90 degrees, and an optical aperture through which the moveable laser and receiver arrangement is arranged to emit and receive optical signals, the optical aperture shaped to conform to tan external surface of an aircraft.

[0022] When installed within the fuselage of an aircraft, the optical transceiver conforms to the fuselage, such that there is no, or no significant, increase in drag during flight. A plurality of optical transceivers may be installed within the fuselage of an aircraft, positioned to provide greater coverage than a single optical transceiver.

[0023] According to a third aspect, the invention provides an optical communications network comprising a plurality of communication nodes, wherein at least one communication node comprises an aircraft according to the first aspect of the invention.

[0024] It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the first aspect of the invention may incorporate any of the -6 -features described with reference to the second or third aspect of the invention and vice versa.

DESCRIPTION OF THE DRAWINGS

[0025] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: [0026] Figure 1 shows a schematic plan view of an optical communications system including an aircraft according to an embodiment the invention; [0027] Figure 2 shows a schematic front view of an aircraft according to an embodiment of the invention; and [0028] Figure 3 shows a schematic representation of a pair of optical transceivers according to an embodiment of the invention.

DETAILED DESCRIPTION

[0029] Figure 1 shows an aircraft 10 with a first optical transceiver 12, second optical transceiver 14, third optical transceiver 16, and fourth optical transceiver 18. The aircraft 10 further comprises a fuselage 20. The first optical transceiver 12 is located on a front left portion of the fuselage 20. The second optical transceiver 14 is located on a front right portion of the fuselage 20. The third optical transceiver 16 is located on a rear left portion of the fuselage 20. The fourth optical transceiver 18 is located on a rear right portion of the fuselage 20.

[0030] Figure 2 shows the aircraft 10, with a fifth optical transceiver 22, and sixth optical transceiver 24. The fifth optical transceiver 22 is located on a bottom portion of the fuselage 20. The sixth optical transceiver 24 is located on a top portion of the fuselage 20.

[0031] Each of the optical transceivers 12, 14, 16, 18, 22, 24, has a field of regard of 90 degrees in a pan plane and tilt plane. The first optical transceiver 12 defines a first quadrant 30 corresponding to the field of regard of the transceiver, the first quadrant extending 90 degrees from a forwards direction parallel with the longitudinal axis of the aircraft 10 to a direction perpendicular to the longitudinal axis of the aircraft 10. The quadrant also extends ± 45 degrees to the horizontal, as best shown in figure 2. -7 -

[0032] The second optical transceiver 14 defines a second quadrant 32 corresponding to the field of regard of the transceiver, the second quadrant extending 90 degrees from a forwards direction parallel with the longitudinal axis of the aircraft 10 to a direction perpendicular to the longitudinal axis of the aircraft 10. The quadrant also extends 45 degrees to the horizontal, as best shown in figure 2.

[0033] The third optical transceiver 16 defines a third quadrant 34 corresponding to the field of regard of the transceiver, the third quadrant 34 extending from a rearwards direction parallel with the longitudinal axis of the aircraft 10 to a direction perpendicular to the longitudinal axis of the aircraft 10. The quadrant also extends ± 45 degrees to the horizontal in a similar way to the first quadrant 30 and second quadrant 32 as shown in figure 2.

[0034] The fourth optical transceiver 18 defines a fourth quadrant 36 corresponding to the field of regard of the transceiver, the third quadrant 36 extending from a rearwards direction parallel with the longitudinal axis of the aircraft 10 to a direction perpendicular to the longitudinal axis of the aircraft 10. The quadrant also extends ± 45 degrees to the horizontal in a similar way to the first quadrant 30 and second quadrant 32 as shown in figure 2.

[0035] The fifth optical transceiver 22 defines a fifth quadrant 38 corresponding to the field of regard of the transceiver, the fifth quadrant extending downwardly and ± 45 degrees to the vertical, both in a side to side and front to back direction.

[0036] The sixth optical transceiver 24 defines a sixth quadrant 40 corresponding to the field of regard of the transceiver, the sixth quadrant extending upwardly and ± 45 degrees to the vertical, both in a side to side and front to back direction.

[0037] As can be seen in figure 1, the first, second, third, and fourth quadrants together provide a 360 degree field of regard around the aircraft in a horizontal plane. The fifth and sixth quadrants provide further coverage around the aircraft in a vertical plane. Therefore, the various optical transceivers may be used to communicate with paired optical transceivers wherever the location of those paired optical transceivers (assuming a clear line of sight etc.) as will be explained further below.

[0038] The aircraft 10 includes a control system 42, which is arranged to control the various optical transceivers, including receiving data from and sending data via the optical transceivers -8 - [0039] Figure 1 shows the aircraft 10, a ground communication station 100 and a second aircraft 200, similar in configuration to the aircraft 10. The ground communication station 100 may be fixed, such as a communications tower, or mobile, for example being vehicle mounted. In alternative embodiments, a satellite communication station may replace or be provided alongside a ground communication station and second aircraft.

[0040] The ground communication station IOU is located in the third quadrant 34.

The ground communication station comprises an optical transceiver which is paired with the third optical transceiver 16, such that optical signals may be sent back and forth between the ground communication station 100 and the third optical transceiver 16.

[0041] The second aircraft 200 is located in the second quadrant 32. The second aircraft 200 comprises an optical transceiver which is paired with the second optical transceiver 14, such that optical signals may be sent back and forth between the second aircraft 200 and the second optical transceiver 14.

[0042] As can be seen, the provision of a plurality of optical transceivers allows the aircraft 10 to communicate with a number of distinct parties. Additionally, the aircraft 10 may form part of a network comprising the ground communication station 100 and second aircraft 200. Use of the aircraft 10 as a node in this network allows the ground communication station 100 to communicate with the second aircraft 200, which may not be possible without the aircraft 10, for example because there is no clear line of sight between the ground communication station 100 and the second aircraft 200.

[0043] Relative movement between the aircraft 10, ground communication system 100, and second aircraft 200, may result in the ground communication system 100 or second aircraft 200 moving into a different quadrant. For example, the second aircraft 200 may fly in front of and across the flight path of the aircraft 10, such that the second aircraft 200 moves into the first quadrant 30. The control system 42 is arranged such that as the second optical transceiver tracks the second aircraft 200 to the limit of the second quadrant 32, towards the first quadrant 30, the first transceiver 12 is positioned to pair with the second aircraft 200 as the second aircraft 200 moves into the first quadrant 30. This allows communication to be maintained despite the change in relative positions of the aircraft 10 and second aircraft 200. The control -9 -system 42 is also arranged such that similar quadrant shifts may be effected when the ground communication system and aircraft 10 change relative positions.

[0044] Each of the first to sixth optical transceivers is disposed within the fuselage 20, with an optical aperture through which optical signals may be transmitted. The optical aperture is conformant with the surrounding fuselage, in a similar way to the side windows of a passenger aircraft, such that a smooth and uninterrupted external surface is presented when the aircraft is flying. By providing skin conformant optical transceivers, the aerodynamic performance of the aircraft remains unchanged.

[0045] Figure 3 shows a pair of optical transceivers 300 and 302, each optical transceiver located on a different aircraft. The aircraft correspond to the aircraft 10 described with reference to figures 1 and 2, and the optical transceivers could be any of the optical transceivers described with reference to figures 1 and 2. The optical transceiver 300 comprises a laser generator and receiver 304, which is arranged to generate and send, and also receive, optical signals through an optical aperture 306. The optical aperture 306 is located within the fuselage 308 of the aircraft, and is conformant with the fuselage 308 such that airflow is not interrupted. The optical transceiver 302 similarly comprises a laser generator and receiver 310, which is arranged to generate and send, and also receive, optical signals through an optical aperture 312. The optical aperture 312 is located within the fuselage 314 of the aircraft, and is conformant with the fuselage 314 so that airflow is not interrupted. Each of the optical transceivers 300, 302, has a field of regard of 90 degrees in a pan and tilt direction, as a result of the laser generator and receiver 304, 310, comprising various moveable elements, such as mirrors or prisms to direct the light generated and received as required. The skilled person will appreciate that various different arrangements may be suitable to provide this effect, and no further description is required.

[0046] Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein.

[0047] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are -10 -herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments, may not be desirable, and may therefore be absent, in other embodiments.

[0048] The features of any dependent claim may be combined with the features of any of the independent claims or other dependent claims. Features described in relation to one example or embodiment may be used in other described examples or embodiments, e.g. by applying relevant portions of that disclosure.

[0049] Although the invention has been described above mainly in the context of a fixed-wing aircraft application, it may also be advantageously applied to various other applications, including but not limited to applications on vehicles such as helicopters, drones, trains, automobiles and spacecraft

Claims

Claims 1 An aircraft comprising an optical communications system comprising four optical transceivers, each optical transceiver with a field of regard of at least 90 degrees in a common plane, the four optical transceivers disposed around the aircraft such that, when combined, the four optical transceivers provide a 360 degree field of regard in the common plane.
2. An aircraft as claimed in claim 1, comprising a fuselage, and wherein the four optical transceivers are disposed around the fuselage.
3. An aircraft as claimed in claim 1 or claim 2, wherein the common plane is the horizontal plane.
4. An aircraft as claimed in any preceding claim, wherein each optical transceiver comprises an optical aperture through which optical signals may pass.
5. An aircraft as claimed in claim 4, wherein the optical aperture is integrated into the aircraft such that a smooth aerodynamic surface is provided.
6. An aircraft as claimed in claim 4 or claim 5, wherein the optical aperture is integrated into the aircraft such that an uninterrupted aerodynamic surface is provided.
7. An aircraft as claimed in any preceding claim, wherein the four optical transceivers are arranged in pairs, one pair at the front of aircraft and one pair at the rear of the aircraft.
8 An aircraft as claimed in claim 7, wherein the front pair of optical transceivers are located such that one transceiver is on the left side of the aircraft and the other transceiver is on the right side of the aircraft, and the rear pair of optical transceivers are located such that one transceiver is on the left side of the central axis and the other transceiver is on the right side of the central axis -12 - 9 An aircraft as claimed in claim 8, wherein the front pair of optical transceivers are arranged such that one optical transceiver is located to have a field of regard of 90 degrees in the pan plane, starting from a central axis of the aircraft in a forwards direction and extending to cover 90 degrees to the left side of the aircraft, with the other optical transceiver having a field of regard starting from the central axis of the aircraft in a forwards direction and extending to cover 90 degrees to the right side of the aircraft, and the rear pair of optical transceivers are arranged such that one optical transceiver is located to have a field of regard of 90 degrees when viewing the aircraft in the pan plane, starting from the central axis of the aircraft in a backwards direction and extending to cover 90 degrees to the left side of the aircraft, with the other optical transceiver having a field of regard starting from the central axis of the aircraft in a rearwards direction and extending to cover 90 degrees to the right side of the aircraft An aircraft as claimed in claim 9, wherein each of the front pair of optical transceivers has a field of regard of 90 degrees in the tilt plane, the field of regard in the tilt plane extending 45 degrees to either side of the pan plane, and each of the rear pair of optical transceivers has a field of regard of 90 degrees in the tilt plane, the field of regard in the tilt plane extending 45 degrees to either side of the pan plane.11. An aircraft as claimed in any preceding claim, comprising a fifth optical transceiver with a field of view of at least 90 degrees.12. An aircraft as claimed in claim 11, wherein the fifth optical transceiver is disposed in a bottom section of the fuselage such that the field of regard extends downwardly in a vertical plane, and the field of regard extends 45 degrees to either side of the vertical axis of the aircraft.13 An aircraft as claimed in any preceding claim, comprising a sixth optical transceiver with a field of regard of at least 90 degrees.14 An aircraft as claimed in claim 13, wherein the sixth optical transceiver is disposed in a top portion of the fuselage such that the field of regard extends upwardly in a vertical plane, and the field of view extends 45 degrees to either side of the vertical axis of the aircraft.15. An aircraft as claimed in any preceding claim, wherein at least one of the optical transceivers is monostatic.16. An aircraft as claimed in claim 4, or any claim dependent on claim 4, wherein the optical aperture is an optical flat.17. An aircraft as claimed in any preceding claim, comprising a control system arranged to generate and receive the data transmitted and received by each of the optical transceivers.18. An aircraft as claimed in any preceding claim, wherein each of the optical transceivers is linked to each of the other optical transceivers.19. An aircraft as claimed in claim 18, wherein the control system is arranged to allow handover of optical communications between two or more of the optical transceivers.20. An optical transceiver for an aircraft, the optical transceiver comprising a moveable laser and receiver arrangement with a field of regard of at least 90 degrees, and an optical aperture through which the moveable laser and receiver arrangement is arranged to emit and receive optical signals, the optical aperture shaped to conform to an external surface of an aircraft.21. An optical communications network comprising a plurality of communication nodes, wherein at least one communication node comprises an aircraft according to claim 1.