Wireless multichannel audio system with increased reliability

Abstract

The invention proposes a wireless multichannel audio system (101), comprising a production base station (400) that is connected to an antenna (200), and comprising multiple mobile devices. The production base station and the mobile devices are configured to exchange audio data with one another in a multiplex procedure. The production base station provides an RF channel on which the production base station (400) and the mobile devices transmit and receive audio data. The production base station and the mobile devices, connected to one another in the audio system, exchange unique device identifiers with one another in such a way that a data exchange is possible only between devices whose device identifier is known to both parties. The production base station stores settings and data of the audio system as production data. A substitute base station (401) is communicatively connected to the production base station during the transmission of the production data. The substitute base station (401) stores the production data of the production base station, wherein the substitute base station (401) does not transmit or receive any audio data for as long as the production base station (400) is functioning.

Description

[0001] Wireless multi-channel audio system with increased reliability

[0002] Area

[0003] The present invention relates to a wireless multi-channel audio system with increased reliability.

[0004] Wireless multichannel audio systems are known from the ETSI EN 300422 standard as Wireless Multichannel Audio Systems (WMAS). This type of audio system uses multiple channels for audio transmission. Multiple wireless transmitters (e.g., wireless microphones) and multiple wireless receivers (e.g., in-ear monitoring units) can communicate simultaneously with a base station. If the base station fails, the entire audio system becomes inoperable.

[0005] Based on this, it is the object of the present invention to provide an audio system with increased reliability, in which the failure of a single component, in particular the base station, does not result in the entire audio system no longer being functional.

[0006] In the priority-substantiating German patent application, the German Patent and Trademark Office searched the following document: CN 101426247 A.

[0007] To achieve this object, the invention proposes, according to a first aspect, a wireless multi-channel audio system comprising a production base station connected to an antenna and a plurality of mobile devices. The production base station and the mobile devices are configured to exchange audio data with one another using a multiplexing method. The production base station provides an RF channel on which the production base station and the mobile devices send and receive audio data. Unique device identifiers of the mobile devices connected to the production base station in the audio system are stored in the production base station. A unique device identifier of the production base station is stored in the mobile devices connected to the production base station in the audio system, so that data exchange is only possible between devices whose device identifiers are mutually known.Data exchange between known devices is encrypted. All audio system settings and data, including the keys used, are stored in the production base station as production data. All production data from the production base station is stored in the backup base station. As long as the production base station is functioning normally, the backup base station does not send or receive any audio data. In particular, the backup base station does not send or receive any audio data to or from the mobile devices.

[0008] The proposed multi-channel audio system ensures that even if the production base station fails, a production in progress is not completely aborted, but rather temporarily interrupted and can be continued using the backup base station. For large and important events, this is a significant advantage and much less costly than maintaining two complete and redundant audio systems, which in many cases would be impractical for practical and / or economic reasons anyway.

[0009] A backup base station is communicatively connected to the production base station at least during the transmission of production data. Once the production data is stored in the backup base station, communication between the production and backup base stations is no longer necessary.

[0010] In an advantageous embodiment, the production base station and the mobile devices are configured to exchange data with each other using a TDMA method. The TDMA method is a reliable and proven method for transmitting multiple audio channels over a single RF channel.

[0011] In a preferred embodiment, an audio link is provided between the production base station and each connected mobile device, after which audio transmission occurs based on repeating frames divided into a number of time slots, with each connected mobile device sending or receiving audio data in at least one specified time slot of the frame. The specified time slot(s) are stored as production data in the production base station. The production data contains all the necessary settings to configure the backup base station so that the backup base station can take over the function of a failed production base station at the push of a button. Time-consuming settings are therefore not necessary in the event of a failure.

[0012] Advantageously, the carrier frequency, the modulation method, synchronization data, and / or the bandwidth of the RF channel are stored as production data in the production base station. This data is also conveniently stored in the backup base station.

[0013] If the production base station fails or the audio system receives a command to switch, the backup base station takes over the function of the production base station. The increased reliability of the audio system is of great importance to users, especially for expensive or otherwise critical productions.

[0014] In a preferred embodiment, the backup base station adopts the unique identifier of the production base station. This ensures that data exchange between the mobile devices and the backup base station takes place without interruption, because the respective unique device identifiers are then mutually known.

[0015] It is advantageous for the production base station not to send and / or receive any audio data while the backup base station functions as the production base station and sends and receives audio data to or from the mobile devices. This ensures that only one base station is active in the audio system at any one time.

[0016] Since the audio transmission is encrypted, the key exchanged during connection establishment is crucial for communication. A replacement base station can therefore only be activated if it also has the key. A simple copy of the configuration is therefore not sufficient. On the other hand, the key must be secured with the necessary care to prevent unauthorized eavesdropping.

[0017] In a further development of the invention, the production data in the replacement base station cannot be changed. This prevents a user from creating multiple replacement base stations and using them in different productions. This approach would undermine efforts to ensure data security during audio transmission between the mobile devices and the respective base station, because all replacement base stations would use the same key to encrypt the data transmission. This exemplary embodiment expediently provides for the replacement base station to be reset to its factory default state by a command, after which all configuration and command parameters can be reset.After the replacement base station has been restored to its factory state, it can be used as a production base station with full functionality like any other base station, because at the hardware level there are no differences between a production and a replacement base station.

[0018] In an advantageous embodiment, the production and backup base stations are connected to a network router or switch that establishes wired connections either to the production base station or to the backup base station. This embodiment has the advantage that an operator does not need to perform any manual intervention to switch from a failed production base station to a backup base station during production.

[0019] In a further development of the invention, the wired connections are network connections.

[0020] In a preferred embodiment of the invention, the production base station is connected to a control console that receives input commands from an operator to modify production data. The control console provides an ergonomic user interface for operating the audio system. The control console is, for example, a control computer connected to the production base station.

[0021] In a method not belonging to the invention for operating an audio system according to the first aspect of the invention, the backup base station receives data from mobile devices and production data from the production base station during normal operation, when the production base station is functioning normally, but does not transmit any data. In the event of a malfunction, when the production base station no longer functions properly, the backup base station is activated by a switch command and takes over all functions of the production base station. The method realizes the advantages already described in connection with the audio system according to the first aspect of the invention.

[0022] According to a second aspect, the invention proposes a method for operating an audio system according to the first aspect of the invention. During normal operation, when the production base station is functioning normally, the backup base station is switched off. In the event of a fault, when the production base station is no longer functioning properly, the production base station is switched off and the backup base station is switched on, taking over all the functions of the production base station. If multiple base stations are used in a production, the settings of all base stations can be loaded into the backup base station. If an error occurs at one of the active base stations, its configuration can be selected at the backup base station.

[0023] In a further development of the process, in the event of a malfunction, a user interface of the control console is completely or partially locked to prevent changes to the production data. This ensures that multiple productions cannot be made in parallel using identical production data, especially not using identical keys for encoding the audio data.

[0024] Alternatively, it can also be specified that in the event of a malfunction, the backup base station does not allow changes to the already stored production data. This also ensures that multiple identical backup base stations are not used for different productions.

[0025] The invention will be explained in more detail below using an exemplary embodiment with reference to the accompanying figures. All figures are purely schematic and not to scale. They show:

[0026] Fig. 1 is a schematic diagram of a wireless multi-channel audio system;

[0027] Fig. 2 is a schematic representation of time slots of various wireless transmitters;

[0028] Fig. 3 is a schematic representation of a frame during the transmission of audio data;

[0029] Fig. 4 shows a first embodiment of an audio system according to the invention without mobile devices;

[0030] Fig. 5 shows a second embodiment of an audio system according to the invention without mobile devices; and

[0031] Fig. 6 shows a third embodiment with two base stations of an audio system according to the invention without mobile devices.

[0032] Identical or similar elements are provided with identical or similar reference numerals in the figures.

[0033] Wireless multi-channel audio systems (WMAS) are known from the ETSI EN 300422 standard. These systems allow multiple mobile devices, such as multiple microphones or in-ear monitoring units, to be used simultaneously with a base station.

[0034] If multiple audio transmitters (e.g., a handheld microphone or other microphones) simultaneously transmit audio signals to a base station, and the base station transmits a second audio signal composed of these audio signals to an in-ear monitoring unit or a beltpack, the microphones do not transmit simultaneously. Instead, subscriber access is achieved using a Time Division Multiple Access (TDMA) method with a repeating frame containing a number of time slots per RF channel. For example, 128 time slots per frame can be allocated for the transmission of audio streams. Additional time slots can be allocated for control data. This allows up to 128 mobile devices to communicate with the base station.

[0035] The TDMA method ensures multiple access to a wireless audio transmission through a temporal sequence of multiple participants. The minimum latency is determined by the largest separation between two consecutive time slots.

[0036] Fig. 1 shows a schematic representation of a wireless multi-channel audio system. The wireless multi-channel audio system WMAS 100 is based on the ETSI EN 300422 standard and comprises a base station 400, at least one antenna 200, and a plurality of mobile devices 300, e.g., at least one handheld microphone (mobile transmitter) 310, optionally at least one multi-channel microphone (mobile transmitter) 320, optionally a first beltpack (mobile receiver) 330, 340 with an output for in-ear monitoring, optionally a combined second beltpack (mobile receiver) 350 with an input for microphone signals and an output for in-ear monitoring. Thus, the number of mobile transmitters 310, 320 or mobile receivers 330, 340, 350 in the wireless multi-channel audio system 100 can vary.

[0037] In the wireless multi-channel audio system 100, the base station 400 is connected to an antenna 200 via a cable 202 and provides an RF channel. Optionally, further antennas can be connected to the base station 400, which can provide additional RF channels. The antenna 200 can have an RF transmitter ("radiohead"), so that digital signals are transmitted via the cable 202, which are converted into analog RF signals in the radiohead. A control console 500 connected to the base station 400 can provide a user interface via which an operator can enter configuration and control commands for the base station 400. The control console 500 is, for example, a computer running a software program for controlling the base station 400.The configuration and control commands, as well as the associated parameters, are stored in the base station 400 in a non-volatile memory as production data. Optionally, the base station 400 can be coupled to a mixer 600. Using the mixer 600, the audio signals from the respective wireless audio transmitters (e.g., microphones) can be mixed into an overall audio signal. In one embodiment of the invention, configuration and control commands are transmitted directly from the mixer 600 to the base station 400.

[0038] The wireless multi-channel audio system 100 can, for example, have a number of microphones, namely a handheld microphone 310, a multi-channel or stereo microphone 320, and mobile receiving devices 330, 340, 350. The mobile receiving devices 330-350 can have an output for so-called in-ear monitoring, which allows a wearer to receive an audio channel. The mobile receiving device 350 is additionally equipped with a microphone input for a clip-on microphone or lavalier microphone. The user of the mobile receiving device 350 is thus able to simultaneously receive one audio channel and transmit another audio channel. The microphones 310, 320 and mobile receiving devices 330-350 are collectively referred to below as mobile devices. In other applications, more or fewer mobile devices than those shown in Fig. 1 can be integrated into the wireless multi-channel audio system 100.

[0039] The microphone 310 sends first audio data 311 in the form of an audio stream to the base station 400. The second microphone 320 sends second audio data 321 in the form of an audio stream to the base station 400. Finally, the mobile device 350 (beltpack) sends third audio data 351 in the form of an audio stream via the antenna 200 to the base station 400. The mobile devices 330 and 340 receive audio data 331, 341, 351 in the form of an audio stream from the base station 400.

[0040] The base unit 400 transmits control data 201 via the antenna 200 to the respective mobile devices, e.g., transmitter / receivers 310, 320, 330, 340, 350. The control data 201 is used by the mobile devices 310-350 to set wireless transmission parameters. Using the control data 201, the base station 400 can specify transmission parameters for the mobile devices 300, such as a transmission frequency, a time slot in the transmission frame, a transmission power, etc. These transmission parameters belong to the previously mentioned production data. The base station 400 can use the production parameters to control the transmission from the mobile devices to the base station 400 and from the base station 400 to the mobile devices 300.

[0041] The control data 201 includes control and / or status information that is exchanged between the mobile devices and the base station. In addition to the control information or control data, further data can be exchanged as part of the control data 201.

[0042] For example, in a case with 128 TDMA time slots per frame, one time slot can be reserved after every 16 time slots. This time slot can be used for control data such as synchronization information and control and status signals.

[0043] Optionally, a frame can have 128 TDMA time slots for audio transmission and 8 time slots for control signals, so that a frame has, for example, 136 time slots.

[0044] Alternatively, the control data can also be transmitted in those time slots that are not reserved and therefore free. In this case, no separate time slots are reserved for the transmission of the control data; instead, the control data is transmitted depending on the availability of time slots not used for audio transmission.

[0045] For example, communication from the base station 400 to the mobile devices 330, 340, 350 takes place in a multicast and communication from the mobile devices 310, 320 to the base station 10 takes place in a unicast.

[0046] The control console 500 is connected to the base station 400 and has a user interface (UI) that enables the user to enter configuration and / or control commands for the base station 400.

[0047] The handheld microphone 310 transmits audio data as first audio data 311 in the form of an audio stream, wirelessly transmitted as a unidirectional radio transmission to the base station 400. This transmission 311 occurs, for example, in a unicast. The audio transmission can occur in the form of mono microphone data. The microphone 320 transmits audio signals 321 as an audio stream in the form of a unidirectional radio transmission. Stereo or multi-channel microphone data can be transmitted in a unicast. The first and / or second beltpacks 330, 340 (mobile receiving units) receive audio data 331, 341, all in a unidirectional radio transmission, from the base station 400. This radio transmission can, for example, comprise in-ear monitoring data. In a practical application, the audio data 331, 341 are composed of the audio data 321, 311 from the two microphones 310, 320 and optionally further audio data.This data can be transmitted as a unicast or multicast from the base station 400. The beltpack 350 (receiving unit) can communicate with the base unit 400 via a bidirectional radio transmission 351. For example, the microphone data that the beltpack has received via the microphone input is transmitted to the base station 400 as a unicast. In-ear monitoring data is transmitted from the base station 400 as a unicast or multicast.

[0048] In one embodiment, the audio data from the respective audio data transmitters (microphones 310, 320) is transmitted using a TDMA method. The TDMA method ensures multiple access to a wireless audio transmission through a temporal sequence of multiple participants. For low-latency transmission, for example, a deterministic and equidistant grid of time slots per audio channel can be used. The minimum latency is determined by the largest distance between two consecutive time slots.

[0049] If a multi-channel audio system is to be implemented, where more than two audio channels are to be transmitted from the base station to the mobile receivers, the transmittable audio samples in a frame must be distributed among the available audio channels. If three audio channels are to be transmitted, for example, the possible number of samples that can be transmitted in a frame can be distributed among the three audio channels, meaning that audio samples from the available audio channels are transmitted in each frame.

[0050] Thus, each audio channel contributes only a portion of the audio samples in a frame or time slot. While this reduces the number of audio samples transmitted per channel per frame, this is offset by the reduced frame latency between consecutively transmitted frames. The wireless multi-channel audio system 100 can have a channel bandwidth of 6 MHz, 8 MHz, or 10 MHz. Transmission occurs, for example, in the frequency ranges 470-698 MHz (UHF) and 1350-1525 MHz (1 G4).

[0051] Subscribers access the transmission channels using the Time Division Multiple Access (TDMA) method. Optionally, the number of subscribers can be up to 128 independent audio channels per broadband channel, for example. The modulation method can be Orthogonal Frequency Division Multiplexing (OFDM) in combination with various subcarrier modulation or coding methods. Audio coding can be done using various methods and sampling rates, as well as in mixed mode. For example, the sampling rates can be 48 kHz or 96 kHz. Audio coding can be done using the OPUS method, the ADPCM method, the PCM method, or another suitable coding method. Synchronization of the TDMA raster and the carrier offset estimation (CFO estimation) can be ensured using synchronization patterns. A basic TDMA raster is < 10 ms and can be divided into 1 / 2, 1 / 4, 1 / 8, or 1 / 16 sub-raster.

[0052] The audio transmission is preferably encrypted. Base station 400 provides a synchronization signal, manages connected or "paired" (explanations below) devices, and allocates the corresponding communication resources. Base station 400 can generate audio signals from the received audio signals from the wireless transmitters, which can represent a mix of the audio signals from the wireless transmitters. These audio signals can then represent an in-ear monitoring audio signal.

[0053] The mobile devices 300, 310-350 can register with the base station 400 to enable communication with the base station 400. The mobile devices 310-350 can optionally initiate a transmission of audio data if they have previously detected a base station 400 with which they should communicate.

[0054] For this to happen, the mobile devices must be paired with the base station. Pairing can take place in several steps. First, the operator decides which frequency the base station will use to provide the RF channel. Optionally, the base station can be configured to identify other transmitters in the permitted frequency band, allowing the operator to select the frequency for the RF channel so that interference from other transmitters is avoided as far as possible. The base station transmits a control slot within a frame on the RF channel. The control slot contains a unique ID for the base station. After the pairing process has been initiated on the mobile devices, for example by pressing a button, the mobile device searches for an RF signal, finds the RF channel of the base station, and reads the control slot.In another control slot, the mobile device then sends its unique ID to the base station and is displayed there as a device ready for pairing. The base station operator confirms the mobile device has been found, and the base station saves the mobile device's unique ID. The mobile device receives confirmation from the base station in the next control slot and, in turn, saves the base station's unique ID.

[0055] Optionally, the base station operator can complete the pairing process by verifying the mobile device's PIN code. Only after pairing are the mobile devices ready to transmit a signal. Typically, the sound engineer pairs the mobile devices with the base station before a production in such a way that all mobile devices are physically present, making it impossible for third parties to "sneak" a mobile device into the audio system and, for example, to eavesdrop without authorization. Furthermore, the base station cannot process signals from unpaired devices.

[0056] For each TDMA resource (i.e., for each stream) in the audio transmission system, the RF modulation used for wireless transmission can be specified. Examples of RF modulation are Q-PSK or QAM 64. While Q-PSK modulation allows for greater robustness against interference and greater directivity, QAM 64 modulation enables higher data rates. The total available data rate for a stream is then determined by the RF modulation used and the number of time slots provided in a frame.

[0057] The audio data transmitted in a stream can be transmitted uncompressed or compressed. The required data rate for uncompressed transmission of an audio channel is the product of the sample rate (e.g., 48 kHz, 96 kHz) and the resolution (e.g., 16 bits). Audio codecs can be used to reduce the data rate. An audio codec can be configured using parameters to increase the audio quality at the expense of the data rate, or conversely, to decrease the data rate at the expense of the audio quality. The parameters for audio coding and decoding are also stored as production parameters in the base station 400. To meet data protection requirements, communication between the mobile devices and the base station can be encrypted with a symmetric key. The key exchange between the base station and the mobile devices takes place using a public / private key method.

[0058] Fig. 2 shows a representation of time slots from various wireless transmitters received by the wireless receiver. In the TDMA method, each audio transmitter is assigned a time slot within a frame. In Fig. 2, eight time slots SL1–SL8 are provided per frame SF. However, this is only an example for illustration purposes. Thus, eight time slots SL1–SL8 can be transmitted per frame. The time slots SL1–SL8 are repeated in each frame SF.

[0059] In this example, there are three streams S1, S2, and S3. Each stream is assigned a wireless audio transmitter. Furthermore, the frame SF may contain unused time slots SO. In the example shown in Fig. 2, the first stream S1 requires 2 / 8 of the resources, stream S2 requires 4 / 8, and stream S3 requires 1 / 8.

[0060] The first stream S1 occupies time slots SL4 and SL8. The first, third, fifth, and seventh time slots SL1, SL3, SL5, and SL7 are occupied by the second stream S2. The third stream S3 occupies time slot SL2. The sixth time slot SL6 is unused.

[0061] When transmitting audio data from the respective wireless audio transmitters, it is important that the latency of the respective audio transmission is as low as possible.

[0062] Fig. 3 shows a schematic representation of a frame during the transmission of audio data. In particular, Fig. 3 shows a frame SF with eight time slots SL1 - SL8. Two time slots SL7, SL8 are not required for transmitting the audio data. These time slots are therefore free time slots SO. In this example, a first stream S1 uses 2 / 8 of the resources, and four further streams S2 - S5 each use 1 / 8 of the resources. Since two time slots SO are not used, another stream requiring 2 / 8 of the resources could be included in the frame SF. However, if this stream is inserted at the point where the two unused time slots SL7, SL8 are intended, this can lead to a deterioration in the latency of the new stream.

[0063] From the perspective of Audio System 100 users, high reliability is essential for critical productions. A total production failure, as a worst-case scenario, is something that must be avoided at all costs. To avoid a single point of failure, an obvious and always possible solution is to set up the system twice—with different frequencies, power supplies, building components, etc. However, this is not cost-effective in practical applications.

[0064] Possible malfunctions include radio interference, power outages, broken cables, defective control consoles or control computers, defective microphones, and defective base stations. A base station used for an audio production is referred to below as a production base station. The present invention specifically addresses the problem of the production base station unexpectedly failing during an ongoing production. In this case, a backup base station is available, in which all production data from the production base station is already stored.

[0065] Figure 4 schematically illustrates an audio system 101 according to the invention, omitting the mobile devices. In contrast to the audio system 100 illustrated in Figure 1, in the audio system 101, a backup base station 401 is connected to the production base station 400 via a communications link 402. In the interest of the greatest possible data security, the communications link 402 is preferably a wired connection. In principle, in other exemplary embodiments, it is also possible to provide a correspondingly secured wireless connection 402 between the production base station 400 and the backup base station 401. The production data and any changes thereto are transmitted from the production base station to the backup base station 401 via the connection 402, so that all production data that was set at the production base station before a production is also stored in the backup base station.The backup base station 401 is synchronized with the production base station 400 and with the mobile devices 310-350. The backup base station 401 adopts the unique ID of the production base station 400, but remains "silent" during normal operation as long as the production base station 400 is functioning properly, i.e., does not fail completely or partially. Specifically, the backup base station 401 does not send any signals to the mobile devices and does not output any signals to its wired outputs. Only when a problem occurs at the production base station 400 and the operator decides to switch to the backup base station, then in one embodiment, a single command from the operator is sufficient for the backup base station 401 to assume the role of the production base station 400.In this case, the production base station 400 is switched off, in particular the production base station 400 no longer sends or receives audio signals from the mobile devices, and the backup base station 401 takes over all tasks that were previously performed by the production base station 400.

[0066] According to another embodiment, the backup base station is turned off during normal operation of the audio system 101. If the production base station 400 fails, the operator turns off the production base station 400 and ideally disconnects it from the power supply. All connecting cables are then plugged into the backup base station 401 in the same way as they were plugged into the failed production base station 400. The operator then starts the backup base station 401 to continue production with the backup base station 401.

[0067] By completely transferring the production data from the production base station 400, the base station 401 is already configured the moment it is switched over or switched on so that it can take over all connections from the production base station 400. This means that the operator must have copied the entire configuration of the production base station 400 to a replacement base station 401 before the event or production. The production data can, for example, be saved as a production file and copied as a file that is ideally encrypted with a public / private key pair. In an alternative embodiment, the transmission of the production data is carried out in the background by the control software of the control console 500. The replacement base station 401 receives the encryption keys and all pairing information along with the production data.To fully restore the functionality of the audio system 101, the operator then only needs to switch wired connections from the production base station 400 to the replacement base station 401.

[0068] Figure 5 shows another embodiment of an audio system 102 according to the invention. In the audio system 102, the production base station 400, the backup base station 401, the control console 500, the mixer 600, and the antenna 200 are connected to a switch RX. During normal operation, when the production base station 400 is functioning properly, the switch 700 establishes the data connections between the production base station 400, the control console 500, the mixer 600, and the antenna 200.In the event of a malfunction, if the production base station 400 fails completely or partially and the operator decides to switch to the backup base station 401 to continue production, then a corresponding command from the operator not only activates the backup base station 401, but also switches the switch 700 so that the backup base station 401 is connected to the control console 500, the mixer 600, and the antenna 200 instead of the production base station 400. In the audio system 102, no manual intervention by the operator is necessary to switch from the production base station 400 to the backup base station 401, for example, to change wired connections.

[0069] Figure 6 illustrates an extension of the audio system 101 from Figure 4. Another audio system 101' is connected to the backup base station 401 via a connection 402', comprising a production base station 400', a control console 500', a mixing console 600', and an antenna 200'. The audio systems 101 and 101' are used, for example, for different productions on two different stages in a theater or other venue. The backup base station 401 stores the production data from both the production base station 400 and the production base station 400'. This enables the backup base station 401 to replace the production base station 400 or the production base station 400' if necessary, by the operator making an appropriate selection.The operator's concrete further procedure for replacing one of the two production base stations is identical to the procedure described in connection with Figure 4. The concept described with reference to Figure 6 is transferable to use cases in which more than two production base stations are connected to a replacement base station.

[0070] In another embodiment, after switching to the replacement base station, its configuration can no longer be changed, making continued use after a disaster unattractive. This is intended to prevent a situation where a large number of cloned base stations are created "in reserve" for use in different productions, as all base stations would then have the same encryption key. This would compromise data security. Once a base station has been cloned, it can be reused in a production run with full functionality after a reset, and configuration parameters are retransmitted from a control computer. In this case, a newly generated individual key for the respective base station would be used to encrypt the data.

Claims

Claims 1. A wireless multi-channel audio system (100-102) comprising a production base station (400) connected to an antenna (200) and comprising a plurality of mobile devices (310-350), wherein the production base station (400) and the mobile devices are configured to exchange audio data with one another in a multiplexing process, wherein the production base station provides an RF channel on which the production base station and the mobile devices (310-350) transmit and receive audio data, wherein unique device identifiers of the mobile devices (310-350) connected to the production base station in the audio system are stored in the production base station (400), wherein a unique device identifier of the production base station is stored in the mobile devices (310-350) connected to the production base station in the audio system, so that data exchange is only possible between devices whose device identifiers are mutually known,wherein settings and data of the audio system (100-102) are stored as production data in the production base station (400), wherein the production data of the production base station (400) are also stored in the replacement base station (401), and wherein the replacement base station (401) does not send or receive any audio data as long as the production base station (400) is functioning [p. 13, lines 22-27], 2. Audio system according to claim 1, characterized in that the unique identification of the production base station is also stored as production data in the production base station (400).

3. Audio system according to claim 1 or 2, characterized in that a replacement base station (401) is communicatively connected to the production base station at least during the transmission of the production data.

4. Audio system according to one of the preceding claims, characterized in that the production base station (400) and the mobile devices (310-350) are configured to exchange data with each other using a TDMA method.

5. Audio system according to one of the preceding claims, characterized in that between the production base station (400) and each connected mobile device (310- 350) an audio link is provided, according to which audio transmission takes place on the basis of repeating frames (SF) which are divided into a number of time slots (SL) and each connected mobile device (310-350) sends or receives audio data in at least one specified time slot of the frame (SF), and that the specified time slot(s) are stored as production data in the production base station.

6. Audio system according to one of the preceding claims, characterized in that the carrier frequency, the modulation method, synchronization data and / or the bandwidth of the RF channel is / are stored as production data in the production base station (400).

7. Audio system according to one of the preceding claims, characterized in that in the event of a failure of the production base station (400) or when the audio system receives a change command, the replacement base station (401) takes over the function of the production base station.

8. Audio system according to claim 7, characterized in that the replacement base station (401) takes over the unique identification of the production base station (400).

9. Audio system according to claim 7 or 8, characterized in that the production base station (400) does not send and / or receive any audio data as long as the replacement base station (401) has the function of the production base station and sends audio data to the mobile devices or receives audio data from the mobile devices.

10. Audio system according to one of the preceding claims, characterized in that the production data in the replacement base station (401) cannot be changed.

11. Audio system according to claim 9, characterized in that the replacement base station (401) can be reset to a factory state by a command and then all configuration and command parameters can be set again.

12. Audio system according to one of the preceding claims, characterized in that the production and replacement base stations are connected to a switch (700) which establishes wired connections selectively either with the production base station (400) or with the replacement base station (401).

13. Audio system according to claim 11, characterized in that the wired connections are network connections.

14. Audio system according to one of the preceding claims, characterized in that the production base station is connected to a control console (500) which receives input commands from an operator to change production data.

15. Audio system according to one of the preceding claims, characterized in that the data exchange between the production base station and the mobile devices or between the replacement base station and the mobile devices is encrypted.

16. A method for operating an audio system according to any one of claims 1 to 15, wherein in normal operation, when the production base station (400) is functioning normally, the replacement base station (401) is switched off, the method being characterized in that in the event of a fault, when the production base station (400) is no longer functioning properly, the production base station (400) is switched off and the replacement base station (401) is switched on and takes over all functions of the production base station (400).

17. The method according to claim 16, characterized in that in the event of a fault, a user interface of the control console (500) is completely or partially blocked in order to prevent changes to the production data.

18. Method according to claim 16 or 17, characterized in that in the event of a fault, the replacement base station (401) does not permit any changes to the production data already stored.

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