NETWORK DEVICE FOR AN INTERCOM NETWORK

Description

[0001] The invention relates to a network device for an intercom network according to claim 1.

[0002] Such network devices enable duplex listening and speaking operation for audio communication with other participants in an intercom network.

[0003] Such a network device within the meaning of claim 1 is also commonly referred to as a call station. A distinction is made between stationary call stations and mobile call stations, e.g., belt-worn call stations (belt packs).

[0004] An intercom network can have one or more stationary participants and one or more mobile participants. Intercom networks that have only stationary or only mobile participants are also known.

[0005] The participants are connected to each other via so-called switching centers.

[0006] Network devices according to claim 1 have been developed and marketed by the applicant for some time and are used in corresponding intercom networks. For an assessment of the prior art, reference is made, for example, to the applicant's German patent applications DE 10 2014 011 963 A1, DE 10 2016 123 966 A1, and DE 10 2016 123 968 A1.

[0007] The known network device of the type described above by the applicant comprises a housing in which a communications module is located. The communications module is a standard, commercially available electronic module that can be used to establish a radio connection to other participants in the intercom network. A radio connection is established with other participants via the communications module, which serves to transmit audio signals. The radio connection thus enables bidirectional transmission of audio signals.

[0008] Duplex audio communication, i.e. the bidirectional transmission of audio data between the individual participants, takes place, if wireless, via this radio connection.

[0009] The invention relates only to network devices designed to enable a radio connection using the DECT protocol or another protocol. The DECT protocol is commonly referred to as an international standard for telecommunications using radio technology, developed for cordless telephones. The DECT radio standard is designed for telephony within buildings, with a maximum range of approximately 50 meters. Data transmission is based on time-division duplex, time-division multiple access, and frequency-division multiple access methods. A frequency range between 1,880 and 1,900 MHz is primarily used. Extension frequency bands in the frequency ranges between 1,900 and 2,480 MHz also exist.

[0010] Other protocols within the meaning of this patent application are those protocols that enable corresponding radio signal transmission in the VHF, UHF, 2.4 GHz or 5.8 GHz frequency ranges.

[0011] To avoid repetition, the term DECT protocol is understood in a broader sense in this patent application and includes, in addition to the actual DECT frequency ranges, also VHF, UHF, 2.4 GHz and 5.8 GHz frequency bands or frequency ranges.

[0012] Generic network devices for intercom networks are used in intercom networks, especially those that are deployed temporarily, in or on buildings, especially in large halls. Multiple mobile network devices of this type can also be used simultaneously.

[0013] In some applications, the operation of the known network devices may lead to disruptions in communication between the participants of the intercom network.

[0014] Based on this, the object of the invention is to develop a network device in such a way that such interference is avoided.

[0015] The invention solves this problem with the features of claim 1.

[0016] The principle of the invention is to assign a device to the network device that prevents or reduces possible multipath interference.

[0017] This device includes a signal correction device to prevent or reduce the multipath phenomenon.

[0018] The invention recognizes that in certain application situations, a radio connection between two wirelessly connected participants of the intercom network leads to the generation of several radio paths.

[0019] For example, a first radio path between a first network device and a second network device can be aligned along the shortest path (line of sight) between these two network devices.

[0020] However, since radio signals are not emitted along a straight line like a laser beam, for example, but rather along a potentially very large solid angle range, a portion of the radiated signal power can be transmitted from the transmitting network device to the receiving network device, forming a second radio path or a second radio path, and being reflected, for example, by a building surface. Such reflected radio signals are thus also transmitted along a second radio path between these two network devices.

[0021] This phenomenon, known as multipath propagation, can occur particularly in large halls, and particularly when there are large distances between network devices connected to one another via the radio link, and particularly when operating an intercom network with many network devices. In the current state of the art, the network device receiving the radio signal experiences superposition or interference between the essentially identical radio signals received along different paths or routes. As a result of this interference, for example due to different propagation times or phase shifts, constructive or destructive superposition of the radio signals can occur. This can significantly degrade the signal quality of the received radio signals. Under certain circumstances, the radio connection may even be partially or temporarily interrupted.

[0022] This phenomenon of multipath propagation is generally known in applications other than those described in the present invention, particularly in mobile phones and GPS systems. Electronic solutions for preventing or reducing interference are also known from these application areas.

[0023] However, in the case of network devices for intercom networks of this type that establish radio connections according to the DECT protocol, no devices are known to reduce or mitigate multipath interference.

[0024] Since DECT is a radio standard designed for cordless telephones with only short ranges, the problems described above, which were observed with network devices in an intercom network, did not occur at all with cordless telephones and other devices that use DECT radio technology.

[0025] The invention recognizes that to reduce multipath interference, appropriate electronics can be arranged in the network device.

[0026] This makes it possible to solve the problems encountered in the state of the art.

[0027] The network device according to the invention is a mobile device that can be carried by a person. The network device according to the invention establishes a radio connection to another participant in the intercom network. Provision can be made for two network devices, e.g., two mobile network devices, to directly establish a radio connection with one another using the DECT protocol. However, the invention also encompasses the network device according to the invention establishing a radio connection using the DECT protocol to another participant in the intercom network, e.g., to an exchange or to a so-called base station or to an antenna. A base station or antenna is a participant in the intercom network via which radio signals can be received from or sent to mobile network devices.

[0028] The invention relates to a network device for an intercom network in which users can move around with portable network devices and can establish DECT radio connections with different other participants in the network at different times.

[0029] The network device according to the invention enables duplex audio communication with other participants in the intercom network, in particular simultaneous listening and speaking. In particular, the network device according to the invention is also referred to as a call station.

[0030] According to the invention, the network device comprises a device for preventing or reducing multipath interference. This can utilize known methods and electronic components that are already used in the prior art for other applications, such as mobile phones. However, this requires adaptation to the specific frequencies used in a DECT protocol and the specific signal processing method used in a DECT protocol.

[0031] The device provided according to the invention for preventing or reducing multipath interference can, for example, utilize adaptive filters based on the least-squares method. The relevant information can be found, for example, in the article "An adaptive multipath estimation / elimination technique for GPS signals reception," Masateru Minami et al., Electron CommJpan Pt1, 86(1): 74-82, 2003.

[0032] Other suitable devices and methods that can be used with the device according to the invention are available, for example, from Novatel. Information can be found, for example, in "Mattos, Philip G., "Multipath Elimination for the Low-Cost Consumer GPS," Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996), Kansas City, MO, September 1996, pp. 665-671."

[0033] The network device according to the invention can also describe devices and methods for forming a device for preventing or reducing multipath interference, as described in the article "Eliminating multipath fading improves wireless signal reception, SPIE August 7, 2006" by George W. Webb et al.

[0034] Furthermore, commercial components or modules that can be used to provide a device for use in the network device according to the invention - provided that they are adapted to the DECT method - have been available, for example, from Novatel under the name MET (Multipath Elimination Technology) since at least 1994.

[0035] Finally, for a better understanding of the technology that can be used to set up a network device according to the invention, reference is also made to Section 22.4.2 "Single-Antenna Multipath Mitigation Techniques" in the Signal Processing for Mobile Communications Handbook. This section adequately describes both the "Narrow Correlator" and "Multipath Elimination Delay Lock Loop" techniques as possible methods, both of which can be used in the setup.

[0036] Further devices and methods which can be used for a network device according to the invention and for forming the device are described - for other application purposes - for example in the documents EP 2 244 098 B1, EP 2 215 794 B1, EP 2 211 516 A1, EP 1 982 523 B1, EP 1 679 818 A1, EP 1 616 368 B1, EP 1 361 687 B1 and EP 1 221 793 B1.

[0037] EP 1 735 935 B1 discloses a method for transmitting a data stream to a destination. This can, in particular, involve audio data streams. The data stream comprises a sequence of a plurality of data packets. If an individual data packet does not arrive properly at the destination, it is retransmitted by the source. While the initial transmission of the data packet is uncompressed, the retransmission of the data packet is compressed. The described method for repeating the data transmission of individual packets can be supplemented by other known techniques. Mentioned in this regard are DFE (determination feedback equalization) and FSE (fractionally spaced equalizer). This is intended to equalize multipath-weakened signals and cancel additional narrowband interference.The document does not disclose a network device having a device for preventing or reducing multipath interference in radio connections subject to the DECT protocol. Reference is also made to the documents US 2003 / 176194 A1, US 2004 / 116071 A1, EP 1 361 687 A1, EP 1 071 228 A1, US 5 870 430 A, US 2002 / 123318 A1, and US 2006 / 068715 A1.

[0038] According to an advantageous embodiment of the invention, the network device comprises a loudspeaker and a microphone. This makes it possible to use the network device as a call station and to utilize known, conventional designs and constructions of network devices.

[0039] According to the invention, the network device has at least one programmable or configurable key. In particular, the network device can have a plurality of such keys.

[0040] The button's programmability allows for the provision of a direct audio connection between the network device and another selected participant in the intercom network.

[0041] According to the invention, the network device is designed as a mobile device that can be worn by a person. The network device is designed as a belt pack. According to this patent application, a belt pack is a mobile network device that allows the connection of a headset, i.e., a microphone and headphone combination.

[0042] According to the invention, the device comprises one or more equalizers. The device may additionally comprise an RF filter. These electronic components can be used to prevent or reduce multipath interference. These electronic components can be used to perform signal correction to prevent or avoid the multipath phenomenon.

[0043] Equalizers are electronic components that are used in other applications, such as GSM transmission, to correct signals in order to reduce multipath phenomena.

[0044] According to a further advantageous embodiment of the invention, the device uses an OFDM (Orthogonal Frequency Division Modulation) method or a corresponding demodulation method. Electronic components that rely on such methods are also well known in the art for eliminating or reducing multipath interference.

[0045] According to a further advantageous embodiment of the invention, the device according to the invention comprises a rake receiver. Rake receivers of this type are also known in the prior art—for other applications—to prevent multipath interference.

[0046] According to a further advantageous embodiment of the invention, the device is arranged within the housing. This enables a compact design of the network device according to the invention.

[0047] The invention is based on the object of developing an intercom network of the known type in such a way that the audio signal transmission between the participants is improved.

[0048] Further advantages of the invention emerge from the uncited subclaims, as well as from the following description of the embodiments shown in the figures.

[0049] The figures show: Fig. 1 shows a schematic block diagram view of an embodiment of an intercom network according to the invention, wherein two mobile network devices according to the invention are shown, Fig. 2 shows a partially sectioned schematic and partially perspective view of an embodiment of a network device according to the invention, which is designed as a belt pack, and a headset connected to it, illustrating two different radio paths between the belt pack and a transmitter device of the intercom network, and Fig. 3 shows a schematic view of an operator wearing a network device according to the invention designed as a belt pack and a headset connected to it.

[0050] Embodiments of the invention are described by way of example in the following description of the figures, also with reference to the drawings. For the sake of clarity, identical or comparable parts, elements, or regions are designated by identical reference numerals, sometimes with the addition of lowercase letters, even where different embodiments are concerned.

[0051] Even though numerous features are designated as optional in the following embodiments, it is nevertheless acknowledged that all features defined in claim 1 are not to be understood as optional.

[0052] A network device according to the invention is illustrated in the figures using the exemplary embodiment and is designated in its entirety by 10.

[0053] Fig. 2 shows such a network device 10 according to the invention, which is designed as a belt pack 11. According to Fig. 2 A headset 22 is connected via a connecting line 25. The headset 22 has a microphone 23 and loudspeaker 24.

[0054] The Belt-Pack 11 can, as Fig. 3 schematically indicates, are attached to a belt 32 of an operator 30 with a fastening device not shown, and are worn by the operator 30.

[0055] The Belt-Pack 11 is part of an Intercom network 13, as shown in its structure and architecture in the block diagram of the Fig. 1 is shown.

[0056] The intercom network 13 comprises in the embodiment of the Fig. 1 A total of six stationary participants, designated by reference numerals 14a, 14b, 14c, 14d, 14e, and 14f. These stationary participants 14 are so-called call stations.

[0057] Each of the intercom stations 14a, 14b, 14c, 14d, 14e, 14f is connected to one of the two exchanges 15a, 15b via a separate connecting line 16a, 16b, 16c, 16d, 16e, 16f. The exchanges 15a, 15b can be interconnected via a connecting line 16g.

[0058] Each call station has a microphone-speaker combination. Fig. 1 It is shown that each call station 14a, 14b, 14c, 14d, 14e, 14f has its own, permanently installed microphone 17a, 17b, 17c, 17d, 17e, 17f. Not shown in Fig. 1 that each call station 14a, 14b, 14c, 14d, 14e, 14f also has its own loudspeaker.

[0059] Further not shown is in Fig. 1 that each of the call stations 14a, 14b, 14c, 14d, 14e, 14f has a plurality of configurable keys or programmable keys with which, by actuating one key, an operator of a call station 14 can establish an immediate direct point-to-point connection to another subscriber at another call station 14a, 14b, 14c, 14d, 14e, 14f.

[0060] The administration of these connection paths is handled by the switching centers 15a, 15b. For this purpose, each switching center 15a, 15b has at least one controller 18a, 18b, which carries out the corresponding interconnections.

[0061] The stationary participants 14a, 14b, 14c, 14d, 14e, 14f are, as the name suggests, fixed and not designed to be moved. The intercom network 13 according to Fig. 1 but also has any number of mobile participants, i.e. mobile network devices.

[0062] This includes the already described and in Fig. 1 indicated Belt-Pack 11, but also one in Fig. 1 illustrated mobile microphone 12.

[0063] Mobile network devices 11, 12 are portable and movable by operators 30. While the switching centers 15a, 15b, in particular, are fixed, ie, stationary, the operators can be moved freely within the range of the intercom network 13 during an event.

[0064] A mobile network device 11, 12 can also establish a radio connection with different exchanges 15a, 15b or other participants of the intercom network 13 at different times.

[0065] In order to be able to provide such a radio connection between a mobile network device 11, 12 and another subscriber, e.g. 15a, 15b, of the intercom network 13, the Fig. 1 A communication module 19a, 19b is arranged in each of them. A corresponding communication module 20a, 20b is also arranged in each mobile network device 11, 12.

[0066] The mobile network device 10 in the form of the belt pack 11 can, for example, establish a radio connection to the exchange 15b. For this purpose, the communication module 20a of the belt pack 11 establishes a radio connection with the communication module 19b of the exchange 15b. The radio connection is subject to the DECT protocol. Audio signals can be transmitted bidirectionally over the radio link.

[0067] If the belt pack 11 is moved by the operator 30, the belt pack 11 can later establish a corresponding radio connection with the communication module 19a of the second exchange 15a, for example via the communication module 20a.

[0068] Evidenced Fig. 2 It should be illustrated that the radio connection between a belt pack 11 and an antenna 31 is subject to a multipath problem.

[0069] The antenna 31 of the Fig. 2 can be made, for example, by one of the two exchanges 15a, 15b of the intercom network 13 of the Fig. 1 Alternatively, the antenna 31 can also be another, additional element in the intercom network 13 of the Fig. 1 which is connected to one of the exchanges 15a, 15b and participates in the bidirectional audio data exchange. Finally, the antenna 31 of the Fig. 2 may also be provided by another mobile network device 10 if an immediate direct transmission of radio signals between mobile network devices is required.

[0070] Fig. 2 illustrates that a radio connection is achieved by the antenna 31 by providing a first radio path P a. The first radio path is the direct, shortest connection (line of sight) between the antenna 31 and the Fig. 2 not shown communication module of the antenna 31, and the communication module 20a of the belt pack 11.

[0071] Fig. 2 but also clarifies that a second radio path is generated, which has a radio path P b and a further section, which is generated after reflection from a building surface 29, is designated P c.

[0072] The first radio path is also designated overall by reference number 27, the second radio path by reference number 28.

[0073] Both radio paths 27, 28 connect the antenna 31 to the communication module 20a.

[0074] It is clear to those skilled in the art that, due to the two different radio paths 27, 28, interference between the electromagnetic waves can occur in the area of ​​the communication module 20a of the belt pack 11. In particular, constructive or destructive interference can occur. This superposition can weaken or even cancel out signals.

[0075] To counteract this phenomenon, the belt pack 11 according to the invention has a device 21 which is assigned to the communication module 20a. The assignment can be made, for example, by the device - as in Fig. 2 As indicated, the device 21 is directly connected to the communication module 20a via a connecting line 35. The device 21 can also be a component of the communication module 20a. Alternatively, the device 21 can also be connected upstream of the communication module 20a in the reception path of the radio signals.

[0076] The device 21 can, for example, prevent destructive interference as a result of electronic processing of the audio radio signals arriving via the different paths 27, 28, and / or correct a corresponding received signal and thereby prevent or reduce the multipath phenomenon.

[0077] For example, the device 21 of the belt pack 11 according to the invention may be capable of detecting different radio paths, separating them, and, for example, selecting the radio path 27 with the best signal quality, while suppressing the other radio signals arriving via other paths 28.

[0078] The network device 10 according to the invention in the form of the belt pack 11 in Fig. 2 comprises, like the mobile microphone 12, at least one programmable or configurable button 26a, 26b, 26c, 26d, 26e. The network device 10 according to the invention, in the form of the belt pack 11, can also be a Fig. 2 have a display not shown.

[0079] The expert, when considering the Fig. 2 It is clear that, in addition to the two radio paths 27, 28 shown, a multitude of additional, parallel radio paths can naturally arise, possibly leading to disruptive interference. Likewise, it is clear to those skilled in the art that the problem of multipath propagation increases as a number of mobile network devices 10 are present in the intercom network 13.

[0080] According to the embodiment of the Fig. 2 The device 21 is arranged within the housing 33 of the belt pack 11. The invention also encompasses the device 21 being arranged on the housing 33 of the network device 10, 11.

[0081] Fig. 2 illustrates a DECT radio link from the antenna 31 to the belt pack 11. However, it is clear to the person skilled in the art that the radio signal transmission is bidirectional. Accordingly, the antenna 31, or the alternatively Fig. 2 schematically indicated exchange 15a, as well as further advantageously every other subscriber of the intercom network 13, which enables a DECT radio connection for the transmission of audio signals, has a corresponding device 21 for reducing or avoiding multipath interference.

[0082] The network device 10 according to the invention in the form of the belt pack 11 of the Fig. 2 has a connector 34 for connection to the headset 22. The invention also encompasses network devices which have a loudspeaker and a microphone directly in or on the housing or associated with the housing.

[0083] According to the presentation of the Fig. 1 A communication module 20b is provided on the mobile microphone 12, which corresponds, or substantially corresponds, to the communication module 20a of the belt pack 11. Furthermore, the mobile microphone 12 can also have programmable or configurable buttons 26e, 26f with which certain presets or configurations can be implemented.

[0084] The microphone 12 is primarily used to transmit audio information from the microphone to another subscriber, e.g., to the exchange 15b. However, microphones 12 are also to be considered network devices within the meaning of the present patent application, which additionally have a Fig. 1speaker not shown, or a connection for a speaker not shown.

[0085] The invention thus encompasses network devices for intercom networks that enable bi-directional communication with other participants in the intercom network.

Claims

1. Network device (10, 11, 12) for an intercom network (13), to enable duplex-audio communication with other participants (14a, 14b, 14c, 14d, 14e, 14f) of the intercom network, comprising a housing (33) and a communication module (20a, 20b) arranged therein or thereon, with which a radio connection can be created for transmitting audio signals to another participant, wherein the radio connection is subject to the DECT protocol or another protocol, wherein the network device (10, 11, 12) has an apparatus (21) to prevent or avoid multipath interferences, wherein the apparatus comprises one or more equalizers, wherein the network device (11) has at least one programmable or configurable key (26a, 26b, 26c, 26d, 26e, 26f) for providing a direct audio connection between the network device and another participant of the intercom network to be selected, wherein the network device (10) is designed as a mobile device (11, 12) that can be carried by a person, and wherein the network device (10) is designed as a belt pack (11).

2. Network device according to claim 1, characterised in that the network device (11) has a loudspeaker and a microphone and / or a connector for a loudspeaker and a microphone.

3. Network device according to one of the preceding claims, characterised in that the apparatus (21) comprises an RF filter.

4. Network device according to one of the preceding claims, characterised in that the apparatus (21) is arranged inside the housing (33).