Method and system for providing a data connection by means of satellites

Abstract

The invention relates to a method (100) for providing a data connection via satellites (21, 23) on board vehicles, in particular aircraft (1), and to a correspondingly designed system (10). In the method (100) for providing a data connection via satellites (21, 23) on board vehicles, in particular aircraft (1), having an antenna (11) and at least one modem (12, 13) connected to the antenna for alternative connection to a separate satellite (21) or satellite network (22), characteristic variables are determined for the quality of each data connection, on the basis of which variables a preferred data connection is determined, which is finally established. The system (10) for providing a data connection via satellites (21, 23) on board vehicles, in particular aircraft (1), comprises an antenna (11) and at least one modem (12, 13) connected to the antenna for alternative connection to a separate satellite (21) or satellite network (22) and a control unit (14) which is data-connected to the at least one modem (12, 13) and which is designed to carry out a method (100) according to the invention.

Description

Method and system for providing a data connection via satellite

[0001] The invention relates to a method for providing a data connection via satellite on board vehicles, in particular aircraft, as well as a correspondingly designed system.

[0002] It is known, particularly for vehicles such as ships or aircraft that are not regularly within the reception range of terrestrial wireless data transmission networks (e.g., mobile radio networks), to provide a data connection via satellite. If this data connection is not only used for operational purposes of the vehicle by the crew, for example to retrieve navigation and / or weather data and / or to transmit data on the vehicle's operating status to a higher-level authority, but is also to be made available to passengers on board the vehicle for use, for example, for the Internet, a reliable data connection with a permanently high bandwidth is desirable.

[0003] Various systems are known from the state of the art in which a modem designed to connect to a specific, predefined satellite or satellite network is installed on board the vehicle. The modem connects to the predefined satellite (network) via a generally directional antenna in order to provide a data connection. The modem usually has either a positioning module for determining its geographical position or a suitable input via which it is supplied with corresponding position information from the vehicle. The modem can then In the case of antennas with electronic beam steering (“Electronical Steerable Antenna" , ESA) - the effective direction of the Align the antenna appropriately to the specified satellite or a satellite in the specified satellite network.

[0004] A disadvantage of this state of the art is that the modem is tied to a specific satellite or satellite network. Because modems are often tied to a specific satellite or satellite network or to the respective operator by software, known modems generally only allow a data connection via a specific satellite or satellite network. If a data connection cannot be established via the specified satellite or satellite network, for example because the vehicle is outside the geographical coverage of the satellite (network), technical problems with the satellite (network) prevent a connection, or there is congestion on the satellite (network), then there is no data connection inside the vehicle, for example.No internet access will be available to passengers until all obstacles to a functioning data connection have been removed.

[0005] The object of the present invention is to create a method and a system in which the disadvantages of the prior art no longer occur or only occur to a reduced extent.

[0006] This object is achieved by a method according to claim 1 and a system according to claim 12. Advantageous further developments are the subject of the dependent claims.

[0007] Accordingly, the invention relates to a method for providing a data connection via satellite on board vehicles, in particular aircraft, with an antenna and at least one, preferably at least two, connected thereto Modems for alternative connections to a separate satellite or satellite network, comprising the steps of: a) If a data connection to a separate satellite or a satellite of a satellite network exists via a modem, disconnecting this existing data connection; b) setting up a data connection to a separate satellite or a satellite of a satellite network; c) determining at least one variable characteristic of the quality of the data connection; d) evaluating the characteristic variables determined for data connections according to predetermined criteria to identify a preferred data connection; e) If the preferred data connection is not the existing data connection, disconnecting the existing data connection and setting up a data connection to a separate satellite or a satellite of a satellite network.

[0008] Furthermore, the invention relates to a system for providing a data connection via satellite on board vehicles, in particular aircraft, with an antenna and at least two modems connected thereto for alternative connection to a separate satellite or satellite network and a control unit data-connected to the modems, wherein the control unit is designed to carry out the method according to the invention.

[0009] First, individual terms used in connection with the invention will be explained.

[0010] In the context of the present invention, a "satellite" is used to mean a spacecraft orbiting the Earth on a predetermined orbit, which is designed on the one hand for radio communication with modems on board vehicles, and on the other hand for radio communication with one or more ground stations in order to be able to provide a data connection via these radio connections. If a single satellite is provided for this purpose, it is usually a satellite in a geostationary orbit (orbit inclination 0°, radius 42,164 km, direction of rotation eastwards) which always covers the same area of ​​the Earth and can, for example, supply it with the Internet. The illumination zone of such a satellite is limited to approximately ±70° in north-south and east-west directions, starting from the base of the satellite on the equator; outside of this area, no contact with the satellite and therefore no data connection is possible.

[0011] A "satellite network" comprises several satellites to which a suitable modem can selectively connect in order to establish a data connection. For a data connection, it is sufficient if a modem can establish a radio connection to one of the satellites in the satellite network and if a connection handover from one satellite to another in the network is possible. The satellites in such a satellite network do not have to be geostationary, but can be in lower orbits, in particular in low or medium Earth orbit. Networks equipped with a sufficient number of satellites can also supply areas of the Earth's surface that cannot be covered by geostationary satellites with internet access, for example.

[0012] The "reception field strength" refers to the field strength that can be detected on a modem from the satellite with which a radio connection currently exists. The reception field strength is an indicator of whether the existing connection is usable for actual communication. If the modem is connected to a satellite network, a low reception field strength can trigger a change in the connection from one satellite to another satellite in the satellite network.

[0013] "Latency" refers to the time it takes for a signal to travel from the modem to a given instance, e.g., a central server on the ground. Latency can also be measured in terms of the round-trip time (RTT) of a data packet from the modem to a given instance and back.

[0014] "Data throughput" indicates the net amount of data per unit of time that can be transmitted via a modem and the data connection established with it.

[0015] Various methods are known from the state of the art for determining, at least approximately, the received field strength, latency, and data throughput. While the received field strength can usually be determined directly by the respective modem, latency and data throughput can also be determined by components connected to the modem, such as a control unit.

[0016] The invention has recognized that by selectively Connection to various satellites (network) on board vehicles can achieve a more reliable data connection, for example to provide passengers with On board the vehicle a stable and as broadband as possible To be able to provide a data connection. Depending on the satellites or satellite networks accessible by the modem(s) provided on board the vehicle, the geographical area in which a data connection is generally possible can also be expanded.

[0017] The invention takes into account that even in the case of two or more modems the number of antennas cannot or should not usually be adjusted accordingly, but rather several modems have to use a single antenna together. For example, the installation of antennas in aircraft is usually only possible outside the shielding fuselage structure within radomes arranged on the outside of the fuselage, which must be structurally designed and connected in a suitable manner in order to be able to withstand the effects of the weather and the flow load during flight. The aim is therefore to keep the number and size of radomes as small as possible. As a result, the number of possible antennas is also limited. This applies in particular to existing aircraft, where the provision of additional radomes and / or antennas is only possible with considerable effort, if at all.

[0018] The invention has recognized that an antenna technically suitable for data connection with a first separate satellite or a satellite of a first satellite network is in principle also suitable for establishing a data connection to a second separate satellite or a satellite of a second satellite network; the different signal processing regularly required for the connection to different satellites or satellites of different satellite networks can be carried out by a modem designed for this purpose or by modems each tuned to individual satellites or satellite networks can be ensured without the need to adjust the antenna.

[0019] Against this background, the invention provides that even if a data connection with a separate satellite and a satellite of a satellite network exists via a modem and the antenna connected to it, this connection is interrupted in order to use the antenna together with the same or a different modem to connect to another separate satellite or a satellite of a different satellite network, in order to determine at least one characteristic value for the connection then established to the other satellite, which provides information, for example, about its stability and / or bandwidth. This at least one characteristic value can then be checked according to predetermined criteria and used to identify the connection to a separate satellite or a satellite network which promises the "better" or preferred data connection.

[0020] If the preferred data connection corresponds to the data connection currently existing, it can remain in place. If it turns out that another, previously existing data connection is preferred, the currently existing data connection is terminated and a data connection is established via the modem associated with the preferred data connection. This can, in particular, also be the modem via which a data connection existed at the beginning of the procedure.

[0021] Even if a possibly existing data connection is fundamentally interrupted when carrying out the method according to the invention in order to determine characteristic properties of other data connections, the disadvantage of the The generally very brief interruption of an existing data connection until a preferred data connection is identified and finally established is more than offset by the fact that at the end of the process a data connection identified as the preferred data connection based on predefined criteria exists. Depending on the predefined criteria, the data connection ultimately deemed preferred can, for example, have greater stability, a higher reception field strength, lower latency, and / or a higher data throughput.

[0022] It is preferred if at least two modems are connected to the antenna, wherein a data connection to a separate satellite or a satellite of a satellite network can be established only via one of the at least two modems. In other words, one of the generally available data connections should only be able to be established via one of the modems, and another generally available data connection should only be able to be established via a different modem. Even when multiple modems are used, only one shared antenna should be provided for them.

[0023] In order to be able to directly take into account a data connection that may already exist at the start of the method when identifying the preferred data connection, it is preferred if, prior to step a) of the method, at least one variable that is characteristic of the quality of the data connection is determined for any existing data connection. The determination of the characteristic variable(s) is generally carried out while the data connection is maintained, so that no connection interruption occurs for the determination of this variable(s). If at least one variable that is characteristic of the quality of the data connection exists for the data connection that exists at the start of the method, this At least one variable is compared with the characteristic variable(s) subsequently determined for one or more alternative data connections based on the specified criteria in order to identify the preferred data connection. In particular, with such a procedure, the initially existing data connection can also be easily identified as the preferred data connection, which can then be restored accordingly.

[0024] In particular, if more than two data connections are possible, but also in the case of two available data connections, unless, as described above, at least one variable characteristic of the quality of the data connection is determined for the data connection existing at the start of the method before step (a), it is preferably provided that steps (a) to (c) of the method according to the invention are repeated until at least one variable characteristic of the quality of the data connection has been determined for each of the data connections that are generally available. This ensures that, when determining the preferred data connection, all data connections can be taken into account on the basis of the characteristic variables in question and can be compared with one another.

[0025] It is preferred if, before establishing a data connection via another modem, the geographical position of the vehicle is detected - for example using a satellite navigation system such as GPS, GALILEO and / or GLONASS - and based on the determined position of the vehicle, the basic availability of the separate satellite assigned to the data connection or of a satellite of a satellite network is determined, wherein the establishment of a data connection for the subsequent determination of at least one variable characteristic of the quality of the data connection is only possible if Availability of at least one satellite. This ensures that a connection to a satellite or satellite network is only attempted if a data connection appears possible. In particular, no connection is attempted if the vehicle is outside the coverage area of ​​the satellite or satellite network due to its geographical position. This avoids interrupting an existing data connection in order to determine parameters characteristic of the quality of a data connection that is already known to be unavailable. If a specific data connection is unavailable, the characteristic parameters for its connection quality can be set to the worst possible value. Alternatively, the affected modem can be marked as "not connected" and ignored when determining the preferred data connection.

[0026] The characteristic value for the quality of a data connection can be the reception field strength, the latency or the data throughput of a data connection. If more than one characteristic value is to be determined, any selection of the aforementioned or further values ​​can be determined. The method according to the invention does not require any specially designed modems, but rather relies solely on functionalities generally available in modems for satellite communication, such as the determination of the reception field strength. The latency and the data throughput can be determined independently of the modem via which the data connection is established, for example, by a control unit connected to it. For this purpose, the control unit only needs to be able to send and / or receive suitable data packets via the respective modems. Consequently, the method according to the invention can be used with any satellite modems which do not require any special adaptation.

[0027] To enable better comparability of the at least one characteristic variable determined for different data connections for identifying the preferred data connection, it is preferred if the at least one characteristic variable, in particular the reception field strength, the latency and / or the data throughput, is standardized with reference values ​​specified for the respective modem. The respective reference values ​​for the individual modems can be location-dependent—i.e., dependent on the geographical position of the vehicle—and / or time-dependent.

[0028] In order to keep the interruption of an existing data connection during the method according to the invention as short as possible, it can be provided that if more than one variable characteristic of the quality of the data connection is determined, the determination of a second variable only takes place if a first previously determined and possibly standardized variable is above or below a predetermined threshold. For example, the latency can only be determined if the received field strength is above a predetermined threshold and / or the data throughput can only be determined if the latency is below a predetermined threshold, since if the respective thresholds are exceeded or undershot, it can be immediately assumed that the variables which would otherwise be determined subsequently do not assume a value which would make the checked data connection the preferred data connection. The time required for step (c) of the method can thus be shortened.

[0029] It is preferred if the described method for providing the data connection via satellite on board vehicles is repeated regularly in order to ensure that the best available connection is always used. For this purpose, the procedure can be repeated at regular, predefined intervals. Alternatively or additionally, it is possible to perform the procedure after a change in the vehicle's geographical position. For this purpose, position information that is recorded on board the vehicle for other reasons, e.g., for navigation purposes, can be used. If a change in position by a predefined amount is detected, the connections via the individual modems can be re-evaluated.

[0030] It is preferred if the data connection provided allows access to the Internet.

[0031] It is further preferred if the antenna is directional and / or multi-frequency capable. This directional capability, which can be achieved in particular by electronic beam steering ("Electronically Steerable Antenna", ESA), enables rapid switching of data connections to different satellites or satellite networks. If the antenna is multi-frequency capable, the method can also be carried out with satellites and satellite networks that communicate on different frequencies.

[0032] The vehicle for which the method according to the invention is carried out is preferably an aircraft, in particular a passenger aircraft.

[0033] To explain the system according to the invention, reference is first made to the above explanations.

[0034] At least one of the modems and / or the control unit may comprise a positioning module, wherein it is advantageous if those components without a positioning module, if necessary, Can receive position information from the component with the positioning module and are suitably data-connected for this purpose. Alternatively, it is possible for at least some of the modems and / or the control unit to receive position information via suitable inputs from a separate positioning module that is not part of the system. For example, the system can thus utilize position information from a vehicle's navigation system.

[0035] The invention will now be described by way of example using an advantageous embodiment with reference to the accompanying drawings. They show: Figure 1 : a schematic representation of a system according to the invention on board an aircraft; and Figure 2 : a schematic representation of a method according to the invention as carried out by the system according to Figure 1 .

[0036] Figure 1 schematically illustrates a system 10 according to the invention in a state installed on board an aircraft 1. Figure 1 also outlines the integration of the system 10 with regard to its basic mode of operation.

[0037] The system 10 comprises an orientable antenna 11 to which two modems 12, 13 are connected. One modem 12 is designed, with appropriate alignment of the antenna 11, for radio communication with a geostationary satellite 21, while the other modem 13 - also with appropriate alignment of the antenna 11 - is designed for radio communication with a satellite 23' of a satellite network 22, whose satellites 23 are in low earth orbits. Above the satellite 21 or the satellite network 22 and associated A data connection can be established between ground stations 31, 32, which enables access to the Internet 40 and, via this, access to a predetermined server 41.

[0038] The modems 12, 13 are designed according to the state of the art. In particular, the modems 12, 13 can be modems 12, 13 provided by the respective operator of the satellite 21 or the satellite network 22, which generally have sufficient functionality for the system 10 according to the invention—in addition to the actual data transmission, for example, also the determination of the reception field strength—so that no adaptation to the modems 12, 13 is necessary.

[0039] The modems 12, 13 are data-connected to a control unit 14. In addition to exchanging the actual data to be transmitted, the control unit 14 also receives information regarding the respective reception field strength from the modems 12, 13 via the connection. The control unit 14 is also connected to the antenna 11 in order to align it or to specify a modem 12, 13 for it, via which the alignment of the antenna 11 is to be carried out using suitable control signals.

[0040] In the illustrated embodiment, the modems 12, 13 each also comprise a position determination module for determining the geographical position via satellite navigation systems such as GPS, GALILEO and / or GLONASS, among other things, in order to enable a suitable alignment of the antenna 11 based thereon. This information on the geographical position is also transmitted to the control unit 14. Alternatively, the control unit 14, and possibly also the modems 12, 13, can be connected to the control system of the aircraft 1, which usually also has a satellite navigation system. geographical position data. In this case, the positioning module of the modems 12, 13 can be omitted.

[0041] Also connected to the control unit 14 is a local wireless access point 15 ("Wireless Access Point"), for example a Wireless Access Point according to the IEEE 802.11 standard. Passengers' mobile devices can connect to this wireless access point 15 and then access an existing data connection to the Internet 40 via the access point 15 and the control unit 14.

[0042] The control unit 14 is designed to carry out a method 100 according to the invention, as explained below with reference to Figure 2.

[0043] In the following, it is assumed that at the beginning of the method shown in Figure 2, a data connection exists via the modem 12 and the satellite 21, via which terminal devices connected to the access point 15 can communicate via the Internet, for example, with the server 41. However, it is of course also possible for a data connection to exist via the other modem 13.

[0044] In step 110, parameters characteristic of the quality of the existing data connection are determined, namely - also in this order - the reception field strength, the latency and the data throughput. Latency is only determined if the determined reception field strength exceeds a predetermined threshold, while the data throughput is only determined if the determined latency falls below a predetermined threshold. If one of the parameters cannot be determined, the maximum worst-case value is assumed, i.e. Reception field strength or a data throughput of zero or a very high latency. However, since in the example shown, a connection to the Internet 40 is actually supposed to exist via the existing data connection, it can be assumed that all of the above-mentioned parameters can actually be determined.

[0045] To determine the reception field strength, the control unit 13 can access corresponding values ​​from the modem 12, which regularly determines the reception field strength.

[0046] To determine the latency, the control unit 14 sends a request via the modem 12 to the server 41 via the data connection and the Internet 40, which is answered immediately by the server. The times it takes to send the request and receive the response at the control unit 14 result in a packet round trip time, which represents a measure of the latency. In order to mitigate various effects that may impair the packet round trip time - such as different packet transport paths between the control unit 14 and the server 41 - the packet round trip time can be determined multiple times and then an average value calculated. In doing so, it must be ensured that the packets for measuring the packet round trip time are as small as possible to avoid congestion of the satellite 21. The maximum size of a packet for determining the packet round trip time is preferably 64 bytes.

[0047] To determine the data throughput via the modem 12, the control unit 14 sends suitable data packets to the server 41 and receives them from the server 41 in order to check the data rate for both the transmission and reception of data packets.

[0048] In the next step 120, the geographical position of the aircraft 1 is recorded. This can be done either by one of the Modem 12, 13 or another aircraft system (not shown), for example, position data determined on the basis of satellite navigation systems can be used. Based on the position of the aircraft 1, it is then determined whether a data connection via the other modem 13 is even conceivable, in particular whether the satellite network 22 accessible via this modem 13 is available at the geographical position of the aircraft 1 (step 130). If this is not the case, the method is aborted; otherwise, the process continues with step 140.

[0049] In the next step 140, the existing data connection is disconnected. While this inevitably interrupts the connection to the Internet 40, the time until a data connection is restored (see steps 170 or 240) is generally so short that this brief interruption is hardly significant and is more than offset by the advantages achievable with the aid of the invention.

[0050] Immediately after the existing data connection has been disconnected (step 140), a data connection to one of the satellites 23 of the satellite network 22, namely the satellite 23', is established in step 150 via the other modem 13.

[0051] If, despite the basic availability of the satellite network 22 determined in step 130, no connection can be established (which is checked in step 160), the data connection previously existing via the modem 12 via the satellite 21 is restored in step 170 and the method 100 is terminated.

[0052] In step 180, the reception field strength is determined via the Model 13 - as previously described - and in step 190 compared with a predetermined threshold value. If the reception field strength is below the threshold value, the data connection previously established via the modem 12 is restored via the satellite 21 in step 170, and the method 100 is terminated.

[0053] If the reception field strength is above the predetermined threshold, the latency of the data connection via the modem 13 is subsequently determined according to the procedure explained above (step 200). If the latency thus determined is above a predetermined threshold (step 210), the data connection previously established via the modem 12 is restored via the satellite 21 in step 170, and the method 100 is terminated.

[0054] Otherwise, the data throughput via modem 13 is subsequently determined in step 220 (step 220). The procedure for this has also already been described above.

[0055] The logic shown in steps 180 to 220 can also be applied in step 140 to determine the said characteristic variables of an existing data connection. Furthermore, steps 140 to 220 can also be carried out for a third or further modems (not shown), whereby instead of restoring the previously existing data connection (step 170), steps from 140 onwards are repeated until an attempt has been made to determine the characteristic variables for each modem. If, at the end of this loop, characteristic variables are only available for the data connection that existed at the start of the method 100, this connection is restored (step 170). Otherwise, the process continues with step 230.

[0056] At the conclusion of step 220, three variables characteristic of the quality of the respective data connection are available for both or all modems 12, 13 or the data connections that can be established via them: the received field strength, the latency, and the data throughput. These variables can be standardized at any time during the process, using specific reference values ​​for each modem 12, 13, which can also vary depending on location and / or time. With early standardization, the same threshold values ​​can be applied to all modems 12, 13 in steps 190 and 210. Otherwise, individual threshold values ​​may need to be specified for the individual modems 12, 13.

[0057] In step 230, the data connections via modems 12, 13 are evaluated based on the previously determined characteristic variables according to predefined criteria. This evaluation can then be used to identify the preferred data connection or the modem 12, 13 with which this preferred data connection was established.

[0058] In step 240, the preferred data connection is then established. This may also be the data connection already existing at the beginning of method 100. If the preferred data connection is the one for which the characteristic variables were last determined, it generally still exists at this point in time and can simply be maintained. Otherwise, the currently existing, but non-preferred, data connection is disconnected, and the preferred data connection is established.

[0059] Procedure 100 is thus terminated.

[0060] Method 100 is preferably performed whenever the position of aircraft 1 has changed by a predetermined amount compared to the position at which method 100 was last performed, or a predetermined time has passed since the method was last executed. If this is the case, method 100 begins again with step 110.

[0061] By regularly checking the data connections via the modems 12, 13 according to the method 100, it can be ensured that the best available data connection is always used for access from the aircraft 1 to the Internet 40.

[0062] It is also possible that only one modem 12 is provided instead of two separate modems 12, 13. In this case, the modem 12 must be suitably designed to communicate with different satellites 21 or satellite networks 22 to connect.

Claims

Patent claims 1. Method (100) for providing a data connection via satellite (21, 23) on board vehicles, in particular aircraft (1), with an antenna (11) and at least one modem (12, 13) connected thereto for alternatively connecting to a separate satellite (21) or satellite network (22), comprising the steps of: a) If a data connection to a separate satellite (21) or a satellite of a satellite network (22) exists via a modem (12), severing this existing data connection; b) establishing a data connection with a separate satellite (21) or a satellite (23') of a satellite network (22); c) determining at least one variable characteristic of the quality of the data connection; d) evaluating the characteristic variables determined for data connections according to predetermined criteria in order to identify a preferred data connection;e) If the preferred data connection is not the existing data connection, disconnecting the existing data connection and establishing a data connection with a separate satellite (21) or a satellite (23') of a satellite network (22); 2. Method according to claim 1, characterized in that at least two modems (12, 13) are connected to the antenna (11), wherein in each case a data connection to a separate satellite (21) or a satellite of a satellite network (22) can be produced only via one of the at least two modems (12, 13).

3. Method according to claim 1 or 2, characterized in that before step a) at least one variable characteristic of the quality of an existing data connection is determined.

4. Method according to one of the preceding claims, characterized in that steps a) to c) are repeated until at least one parameter characteristic of the quality of the data connection has been determined for all data connections that are generally available.

5. Method according to one of the preceding claims, characterized in that: - the geographical position of the vehicle (1) is recorded before a data connection is established, - based on the determined position of the vehicle (1), the basic availability of the separate satellite (21) assigned to the data connection or of a satellite (23) of a satellite network (22) is determined, wherein the establishment of a data connection for the subsequent determination of at least one variable characteristic of the quality of the data connection only takes place when the availability of at least one satellite (21, 23') has been determined.

6. Method according to one of the preceding claims, characterized in that at least one quantity characteristic of the quality of the data connection comprises the reception field strength, the latency and / or the data throughput.

7. Method according to claim 6, characterized in that the reception field strength, the latency and / or the data throughput are standardized with reference values ​​predetermined for each modem, wherein the reference values ​​can be location- and / or time-dependent.

8. Method according to claim 6 or 7, characterized in that when determining several characteristic variables for a data connection, the latency is determined only when the reception field strength is above a predetermined threshold and / or the data throughput is determined only when the latency is below a predetermined threshold.

9. Method according to one of the preceding claims, characterized in that the method (100) is repeated at regular intervals and / or upon detection of a change in the geographical position of the vehicle (1).

10. Method according to one of the preceding claims, characterized in that the provided data connection enables access to the Internet (40).

11. Method according to one of the preceding claims, characterized in that the antenna (11) is alignable and / or multi-frequency capable.

12. System (10) for providing a data connection via satellites (21, 23) on board vehicles, in particular aircraft (1), with an antenna and at least one modem (11, 12) connected thereto for alternative connection to a separate satellite (21) or satellite network (22) and a control unit (13) data-connected to the at least one modem (11, 12), characterized in that the control unit (13) is designed to carry out a method (100) according to one of the preceding claims.

13. System according to claim 12, characterized in that the control unit (13) and / or at least one of the modems (11, 12) has a position determination module and / or an input for position information of a separate position determination module.

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