DE19508223C1 - Telecommunications system with variable subscriber line matching - Google Patents

Abstract

Analogue subscriber connection units (TAE1,TAE2) are linked in a network (GSTN) contg. e.g. three exchanges (GSW,GSW1,GSW2) serving different numbers of communication terminals (KEA,KEB,KEn). A controller (SI) sends measurement signals from a generator (MTG) to one connection unit (e.g. TAE1) and receives them (MTE) back from the other when the units are interconnected. A microcontroller ascertains transmission parameters of the physical link between the units on the basis of the transmitted and received measurement signals. It produces commands for varying the input impedance of the two-wire/four-wire sides by a switching device (SW1) in e.g. an analogue switch matrix (SW).

Description

The invention relates generally to telecommunications direction with at least two telecommunications connections to Connecting two via a communication network with at least a switching device connectable analog subscribers connection units.

Telecommunications equipment with telecommunications network connection shortcuts for connecting analog subscriber line units are, also with at least two telecommunications connections in the form of small communication private branch exchanges for example from the "ascom CASATEL 3" manual from Ascom Busi ness Systems AG, CH-4503 Solothurn and the company brochure "HICOM 100, the new standard to simply tele more conveniently fonieren ", (1989) Siemens AG, D-8000 Munich, known.  

The invention also relates to an optional device Forward one over one of the subscriber line units incoming call on the other subscriber line unit a specific remote subscriber line.

Such facilities are from the installation and operation Instructions for the call divider TC202 from WIPE ELECTRONIC GMBH & CO KG / ALBRECHT ELECTRONIC GMBH. Such facilities switch after initiating a connection from ih rem a second network connection to a second remote terminal come from a first remote terminal at the first network connection the call to your second network connection. Here, at Connections with high attenuation between speech quality two far end devices may be very bad or an understanding damage be completely excluded. Especially at Verbin between facsimile devices or data terminals is one such poor reception quality due to a resul high transmission error rate very unfavorable.

A problem with all the telecommunications equipment mentioned is the eavesdropping on the remote side, the Mi Nimation in analog communication systems very complex is. If the listening amplification is too high, the speech quality will increase acted on the received signals adversely affected.  

Another problem with the mentioned telecommunications directions is the determination of the signal level in the connected communication network emitted useful signal Telecommunication devices can only use useful signals limited signal level in the connected communication network to prevent crosstalk between each other to avoid other independent connections. In addition, may no attenuation within a communication network be of any size in order to be conditioned by positive feedback To avoid swinging. The tendency to crosstalk and the There is a tendency for a telecommunications system to oscillate depend on local conditions of the communication network gig, so that the maximum useful signal level of the transmission signal or its maximum gain for the worst case the network conditions must be designed. Too low Signal level leads to a less favorable one Signal / noise ratio. A too high signal level leads to Crosstalk and possibly vibrations. In any case the signal detectability, such as B. the speech quality to egg nem distant end device adversely affected.

DE 39 11 915 A1 describes a telecommunications device with two telecommunication network connections for connection two over a communication network with at least one Switching device connectable analog subscribers known connection units, the telecommunications power connections one each according to the switched on Have adjustable input impedance. This is on a 2-wire / 4- Wire transfer device provided, which may be as electro African hybrid with automatic line impedance adaptation and / or a line length dependent amplifier can be implemented. This telecommunications tion device has at least one terminal connection Connecting a communication terminal and one Switching device for connecting one or both  Telecommunication network connections with the terminal Enough. A switching device can optionally each the four-wire signal output of a fork scarf device with the four-wire signal input of the others Connect hybrid circuit. There is a reinforcement for this direction intended for the increased delivery of each signals received at a telecommunications network connection the other telecommunications network connection. In addition, a line-length-dependent gain regulation can be used.

DE 33 39 695 A1 describes a telecommunications unit direction with a telecommunications network connection to Connection to an analog subscriber line unit, at which is a self-tuning to optimize the hybrid is provided. Here, a Signals in the telecommunications network connection through Varia tion of RC elements an impedance matching with respect to Eavesdropping made to signal degradation, by switching operations in an electromechanical Communication network dependent impedance fluctuations occur would have to compensate for each connection establishment.

The object of the invention is to provide a telecom Communication device for connection to at least two analog telecommunication network connection units with which the signal recognizability can be further improved.  

According to the invention, a telecommunications device with min at least two telecommunications network connections for connection two over a communication network with at least one ver averaging device connectable analog subscriber line units provided. Here, the telecommunications network Connections each have an adjustable input impedance. A Control device is provided to measure signals at one of the Telecommunications network connections to output this Meßsi signals over the other of the telecommunications network connections when connecting the two telecommunications network connections to receive over the communication network to transmit para meters of the physical connection via the participants closing units and the communication network based to determine the transmitted and received measurement signals and order the input impedance of at least one of the telecommunications to vary network connections.

The telecommunications network connections for connecting analog Subscriber line units of known telecommunications directions are flat rate for their input impedance the network operator's specifications or not at all the associated subscriber line unit present network adapted pedanz.  

In contrast, a telecommunications according to the invention enables tion device in the event that at least two Telekommuni cation network connections for connecting two via one communication cation network with at least one switching device ver bindable analog subscriber line units are provided, a simple exact adjustment of the input impedance of the individual NEN telecommunications network connections to the actual Network conditions. Here it is particularly possible to depend depending on the individual application - for example data transfer transmission, voice transmission to a to the facility closed terminal, voice transmission from a telecommunications university cation network connection to the other telecommunications network conclusion, switching one from a remote terminal via the first subscriber network connection incoming call to a wide ren remote terminal via the second subscriber network connection etc. - a desired ef due to a certain mismatch perfect, for example a subjectively optimal speech quality or a line loss between the two participants network connections and the nearest switchboard Setup of the communication network compensating muffler to achieve.

For example, if the transmission parameter is the frequency down dependent attenuation provided, the input impedance of a or both telecommunications network connections can be varied, until a desired frequency response of the damping is reached. The goal of adaptation is an objectively optimal language quality action, an input impedance can be set that is within a linear damping ver of a certain frequency range run supplies. The goal of customization is one of application case dependent subjective optimization of speech quality, so can the input impedance in the desired manner within be certain limits to achieve a mismatch  to achieve a desired filtering effect, i.e. H. a desired to achieve the non-linear damping curve.

Another setting criterion for the cheapest input vaccine danz to improve the voice quality is a maximum Eavesdropping. When adjusting the input impedances of both Subscriber network connections with the criterion of maximum eavesdropping damping is u. a. a maximum transmit signal level can be set, without vibrations.

If switching through one of a remote terminal via the first subscriber network connection incoming call to a wide ren remote terminal via the second subscriber network connection is intentional, with a telecommunications according to the invention tion device the transmission loss of a participant Network connection to the other subscriber network connection determined be used as a criterion for an optimal Input impedance of each subscriber network connection the maximum Monitoring is selected. The determination of the passage damping and the optimal input impedance values for both parts Subscriber network connections are made when installing Telekom communication device made once. The corresponding Input impedance values are then in a named application always adjustable and a gain factor with which the each received useful signal is transmitted depends on adjustable from the damping factor once determined.

Determines the control device in a Te according to the invention Communication device a transmission parameter that as a setting criterion for the most favorable input impedance is seen, several times, each time the input vaccine is varied danz one or both subscriber line units, so see a simple control flow before that the control device an input impedance value for one or both telecommunications nications network connections that selects the cheapest than  Setting criterion provides selected transmission parameters. This For example, the input impedance value or Input impedance values that are the most linear frequency response deliver. Another criterion for ending already mentioned above choosing input impedance values is the largest listening attenuation fung.

In a favorable embodiment of the invention, depending on that of the telecommunications network connections a 2-wire / 4-wire Transfer device provided. This allows u. a. a targeted reinforcing the benefits to be sent into the communication network signals. Another benefit of using this 2-wire / 4-wire conversion device is that the listening damper fung (transhybrid loss) is easy to determine.

A variable input impedance is u. a. through use of 2-wire / 4-wire transfer devices with adjustable on Gang impedance achievable. In this case the tax is canceled direction of the input impedance via a variable manipulated variable on.

Another way to vary the input impedance, he occurs when using signal coding or decoding fil tern, as for example from the "User’s Manual 03.92, ICs for Communications, Signal Processing Codec Filter SICOFI PEB 2060 ", pages 42 and 43 of Siemens Aktiengesellschaft and out the "Telecom’s IC Handbook" by GEC Plessey, February 1994, Pages 262 to 263 are known, each a 4-wire Ana Log signal input with bidirectional analog-digital separation point have and that on the digital signal side of the input signal derived using an impedance matching filter Add components to the output signal to the input amp to vary.  

If a reinforcement to be given to the communication network the signal for at least one of the telecommunications network conclusions is provided, the required reinforcement device when using such signal coding or decoding Filters through this signal coding or decoding filter reali be settled.

Is intended in a telecommunications according to the invention tion device the two telecommunications network connections to connect using a switching device, so this switching device when using signal coding or decoding filters for each telecommunications network connection on the digital signal side this signal coding or decoding Filters, each on the pulse code transmission provided modulated signals provided PCM interface.

In a further embodiment of the invention is Telekom communication device with one or more terminals exclude for connecting communication terminals equips, these terminal connections by a Schaltvor direction with at least one of the telecommunications network connections are connectable. A particularly affordable option Form of such a telecommunications device can also at least one of these terminal connections simultaneously connect to both telecommunications network connections. There is a conference call with two remote devices and at least one on the telecommunications according to the invention tion device connected terminal allows.

Said switching device for connecting at least one the telecommunications network connections with at least one end device connection is preferably realized by a switching matrix siert.  

Such a switching matrix, for example a commercial one available analog switch matrix of type SC11390 from SIERRA, can also be used to switch the two telecommunications Network connections are used. However, they will Signal coding or decoding filter mentioned above as part of egg ner used control device according to the invention, so that is Switching through the two telecommunications network connections in recommended above, where the analog signal at conclusions of the two signal coding and decoding filters on the named switching matrix to the respectively assigned telecommunication unit cation network connections are switchable.

If the two telecommunications networks are switched on conclude by connecting the 4-wire side Ana log signal output of a 2-wire / 4-wire converter with the 4-wire side analog signal input of the others 2-wire / 4-wire transfer device, a provided reinforcing device for reinforcing each signals to be delivered to the connected communication network, seen in the signal flow direction, preferably after each Switching device and in front of the 2-wire / 4-wire transfer device to arrange. Appropriate arrangement eliminates the danger a tendency to oscillate due to this damping reduction graces.

Is in a telecommunications device according to the invention a reinforcement device is provided which at a connec that of the two telecommunications network connections with each other each emp on one of the telecommunications network connections captured useful information is amplified by an amplification factor surrenders to the other telecommunications network connection, so this gain factor is preferably dependent on the egg attenuation between the tele determined at an earlier point in time communication network connections via the connected commu network established. For this purpose, the damper is preferably used  value from the 4-wire side of the 2-wire / 4-wire converter the first telecommunication network connection via the commun cation network and the nearest switching center of the Communication network up to the 4-wire side of the 2-wire / 4-wire Converter of the other telecommunications network connection telt. Is a damping, that is, the aforementioned gain In this case, the factor of determination is of the order of magnitude specified damping value, then a connection between two two remote devices via the two telecommunications tion network connections the conditions of the operator of the ent speaking communication network.

The gain factor should be one in the aforementioned cases maximum value dependent on the connected communication network do not exceed. This maximum value should preferably be used not be greater than that prescribed by the network operator maximum attenuation between two end devices 2 subscriber calls.

A telecommunication device according to the invention with through switching device thus enables two subscriber lines units of a global communication network a global number assigned to a user. If egg ne call forwarding to one of a subscriber usable terminal is made, this participant is un depending on his whereabouts and the one for each Time used communication system under one, the ge called telecommunications device assigned number reachable. This is regardless of whether the call is forwarded in an ISDN communication network, a GSM communication network or any other, from the telecommunications facility he accessible communication network is made.  

A telecommunication device according to the invention enables thus the realization of a global personal number with the help of a peripheral device.

The invention is explained in more detail below with reference to the figures tert. Show it:

Figure 1 shows a first embodiment of a telecommunication device according to the invention, wherein the control device according to the invention is realized by a microcontroller and;

Fig. 2 shows a second embodiment of a telecommunication device according to the invention, wherein the control device according to the invention is implemented by a microcomputer and two signal coding or decoding filters.

Both Fig. 1 and Fig. 2 each show a telecommunication device with two telecommunication network connections a / b1, a / b2, each of which is connected to a subscriber line unit TAE1, TAE2 of a communication network GSTN. In the exemplary embodiment shown, the communication network GSTN contains three switching devices GSW, GSW1, GSW2, which can be connected to one another. The two subscriber line units TAE1, TAE2 can be connected to one another via a switching device GSW. In the exemplary embodiment shown, a first remote communication terminal KEA is assigned to the switching device GSW1 and can be connected to other terminal devices via this, and a second communication terminal KEB and another communication terminal KEn are assigned to another switching device GSW2 and can be connected to other terminal devices within the communication network GSTN.

Each of the telecommunication network connections a / b1, a / b2 of the telecommunication device is via a fork switch HOOK1, HOOK2 provided for seizing the corresponding line and for pulse dialing and a transmitter TR1, TR2 to the 2-wire connection of the corresponding subscriber mernetzanschluß a / b1, a / b2 assigned 2-wire / 4-wire converter device GABEL1, GABEL2 switched. In the exemplary embodiment of FIG. 1, this 2-wire / 4-wire conversion device GABEL1, GABEL2 is designed such that the 2-wire input impedance can be set via a manipulated variable.

The further structure of the telecommunication device shown in FIG. 1 is explained in more detail below.

The control device SI shown in Fig. 1 contains a measuring signal generator MTG for outputting analog measuring signals to the tele communication network connections a / b1, a / b2, a measuring signal detection device MTE for receiving these measuring signals via the other of the telecommunication network connections a / b2 , a / b1 when connecting the two telecommunications network connections via the telecommunications network GSTN and a microcontroller µCONT to control the measuring signal generator MTG and the measuring signal detection device MT1, to determine transmission parameters of the physical connection via the subscriber line units TAE1, TAE2 and the communication network GSTN the basis of the transmitted and received measurement signals and for outputting manipulated variables for respectively controlling the input impedance of the 2-wire / 4-wire conversion devices GABEL1 and GABEL2. Here, for converting digital signals into analog signals, digital-to-analog converter DAC and for converting analog signals into digital signals, ADC are provided.

The 4-wire connections of the two 2-wire / 4-wire conversion devices GABEL1 and GABEL2 can each be connected to one another via a switching device SW1. In the exemplary embodiment according to FIG. 1, the switching device SW1 is part of a switching device SW, which can be implemented, for example, by an analog switching matrix. This switching device SW can inter alia connect the two telecommunications network connections a / b1 and a / b2 to terminal devices in each case via corresponding terminal device interfaces SL11, SL12 and SL13. In the exemplary embodiment shown, three terminal connections SL11, SL12 and SL13 are shown, to each of which a fax machine FAX, an answering machine ANB and a telephone set TEL are connected.

To attenuate when switching through the two telecommunications network connections a / b1 and a / b2 each to the 2-wire / 4-wire converter on the 4-wire output device output signal OUT1 of the telecommunications device TE, is in each case in the transmission direction before the 2-wire / 4-wire Umsetzvorrich device GABEL1 and GABEL2 an amplifier device AMP1 and AMP2 provided. These amplifier devices AMP1 and AMP2 can be set by the control device SI in the exemplary embodiment shown. In one embodiment of the exemplary embodiment shown in FIG. 1, the amplifier devices AMP1 and AMP2 may or may not be activated depending on the switching state of the switching device SW1. In a further embodiment of the embodiment shown, the gain of the amplifier device AMP1 or AMP2 can be adjustable by the control device SI depending on the respective application.

The structure of the telecommunications device TE of the second embodiment is explained in more detail below with reference to FIG. 2.

In the embodiment shown in FIG. 2, the 4-wire connections of the two 2-wire / 4-wire conversion devices GABEL1 and GABEL2 are each connected to a switching device SW, preferably a switching device in the form of a switching matrix. The control device SI is also connected to this switching device via two 4-wire connections Vin1, Vout1 and Vin2, Vout2. Each of these 4-wire connections Vin1, Vout1 and Vin2, Vout2 is connected in the control device SI to the analog signal connection of a signal coding or decoding filter SICOFI1 and SICOFI2. Such signal coding or decoding filters SICOFI1 and SICOFI2 can, for example, as shown for the signal coding or decoding filter SICOFI1, consist of a pre-filter VF and a downstream analog-digital converter ADC for the analog input signal Vin1 and a post-filter NF and this upstream digital-to-analog converter DAC for the analog output signal Vout1 exist. The above-mentioned analog-to-digital converter and the above-mentioned digital-to-analog converter are each connected to a digital signal processor DSP on the digital signal side. The digital signal processor DSP is used to output measurement signals, to receive these measurement signals and to vary the input impedance of the telecommunications network connections a / b1 and a / b2. The signal coding or decoding filter SICOFI1, SICOFI2 also contains a coefficient memory CM in which coefficient sets for setting the transmission behavior of the respective signal coding or decoding filter can be stored. Depending on these components, for example an amplification factor of an amplification device for the analog signal to be emitted can be adjustable and the input impedance effective towards the analog signal side. The signal coding or decoding filter SICOFI1 and SICOFI2 can each communicate on the digital signal side with at least one digital signal interface IF with a microcomputer µCOMP and are also connected via this digital signal interface IF to the switching device SW1 shown.

The microcomputer µCOMP is used to control the measuring process Determination of transmission parameters of the physical connection  tion over the subscriber line units TAE1 and TAE2 and Writing coefficients in the coefficient memory CM intended.

For the function of the telecommunication device TE to make a connection between the two subscriber network connections a / b1 and a / b2 via the switching device SW1, the switching device SW in the embodiment shown in FIG. 2 is not necessary. In this case, the switching device SW connects the 4-wire side of a 2-wire / 4-wire conversion device GABEL1 or GABEL2 to the analog signal connection of a signal coding or decoding filter SICOFI1 or SICOFI2.

The switching device SW is, however, in the embodiment of FIG. 2, just like in the embodiment of FIG. 1, via terminal connection interfaces SLI1, SLI2 and SLI3 with communication terminals, such as. B. a fax machine FAX, an answering machine ANB or a telephone set TEL.

Thus, the switching device SW enables both in the exemplary embodiment according to FIG. 1 and in the exemplary embodiment according to FIG. 2 to connect one or more of the terminal connections SLI1, SLI2 and SLI3 to one or both of the telecommunications network connections a / b1 and a / b2, so that both a conventional private branch exchange functionality and the functi on of a conference call can be realized. In a particularly favorable embodiment of the invention, it is possible to have both one and several communication terminals FAX, ANB, TEL directly connected to the telecommunications device TE simultaneously via the two subscriber connection units TAE1 and TAE2 of the communication network GSTN with two remote communication terminals KEA and to connect KEB.

It is also possible, starting from a connection between directly to the telecommunications facility connected communication terminal TEL, ANB or FAX to ei another connection establishment in the first remote terminal KEA to cause a second remote terminal KEB and then to connect the two remote terminals KEA and KEB with each other the.

Reference list

GSTN Global Communication Network
TE telecommunication facility
KEA first remote terminal
KEB second remote terminal
GESW1, GSW2, GSW switching facility of the global network
TAE1, TAE2 subscriber line unit
a / b1, a / b2 telecommunications network connection
HOOK1, HOOK2 fork switch
TR1, TR2 transformer
GABEL1, GABEL2 2-wire / 4-wire transfer device
SW switching device, switching matrix
SW1 switching device
OUT1, OUT2 4-wire output signal from the telecommunications device
IN1, IN2 4-wire input signal of the telecommunication device
Vin1, Vin2 analog input signal of a signal codec filter
SICOFI1, SICOFI2 signal coding or decoding filter
Vout1, Vout2 analog output signal of a signal coding or decoding filter
VF pre-filter
NF post filter
DSP digital signal processor
AMP1, AMP2 amplification device
CM coefficient memory
IF digital signal interface
µCOMP microcomputer
SLI1, SLI2, SLI3 terminal device connection (interface)
FAX fax machine
ANB answering machine
TEL telephone set
SI control device
MTG signal generator
MTE measuring signal detection device
µCONT microcontroller.

Claims (24)

1. Telecommunication device with at least two telecommunications network connections (a / b1, a / b2) for connecting two via a communication network (GSTN) with at least one switching device (GSW) connectable analog subscriber line units (TAE1, TAE2), the tele communication network connections (a / b1, a / b2) each have an input impedance that can be set according to the connected line, characterized by a control device (SI)

• - for outputting measurement signals at one of the telecommunications network connections (a / b1, a / b2),
• to receive these measurement signals via the other of the telecommunications network connections (a / b2, a / b1) when connecting the two telecommunications network connections (a / b1, a / b2) via the communication network (GSTN),
• - To determine transmission parameters of the physical connection's rule over the subscriber line units (TAE1, TAE2) and the communication network (GSTN) on the basis of the transmitted and received measurement signals and
• - to vary the input impedance of at least one of the telecommunications network connections (a / b1, a / b2).

2. Device according to claim 1, characterized in that the transmission parameter to be determined the frequency pending damping is.   3. Device according to claim 1, characterized in that the transmission parameter to be determined fung is. 4. Device according to one of the preceding claims, ge characterized by a repeated determination of the transfer parameters, depending on the variation of the input vaccine danz. 5. Device according to claim 4, characterized by a Selector for selecting the input impedance tes that the when determining transmission parameters most linear frequency response. 6. Device according to one of claims 1 to 4, characterized net by a selector for selecting the on gangsimpedanzwert, which when determining transmission parameters has caused the greatest attenuation. 7. Device according to one of the preceding claims, ge is characterized by a 2-wire / 4-wire conversion direction (GABEL1, GABEL2) on each of the telecommunications network connections (a / b1, a / b2). 8. Device according to claim 7, characterized in that at least one of the 2-wire / 4-wire transfer devices (GABEL1, GABEL2) one over at least one by the tax establishment (SI) variable manipulated variable adjustable Has input impedance. 9. Device according to claim 7, characterized in that the input impedance on the 2-wire side at least one ner of the 2-wire / 4-wire transfer devices (GABEL1, FORK2) by adding the input signal to the  4-wire side derived components to the output signal on the 4-wire side. 10. Device according to one of the preceding claims, ge characterized by at least one terminal device connection (SLI1, SLI2, SLI3) for connecting at least one commu nikationsendgerätes and by a switching device (SW) for connecting at least one of the telecommunications network Connections (a / b1, a / b2) with the terminal device connection (SLI1, SLI2, SLI3). 11. The device according to claim 10, characterized in that the switching device is a switching matrix (SW). 12. Device according to one of claims 10 or 11, characterized characterized in that the terminal connection (SLI1, SLI2, SLI3) via the switching device with both telecommunications tion network connections (a / b1, a / b2) can be connected at the same time is. 13. Device according to one of the preceding claims, ge characterized by a switching device (SW1) to Connect the two telecommunications network connections (a / b1, a / b2). 14. Device according to claim 13, characterized in that the switching device (SW1) part of the switching matrix (SW) is. 15. The device according to claim 13 or 14, characterized net that through the switching device (SW1) each the 4-wire signal output of the 2-wire / 4-wire Um setting devices (GABEL1, GABEL2) and the 4-wire side Signal input of the other of the 2-wire / 4-wire Um setting devices (GABEL2, GABEL1) can be connected.   16. Device according to one of claims 13 to 15, characterized characterized that the 4-wire signal output depending the 2-wire / 4-wire transfer device (GABEL1, GABEL2) each because an analog / digital converter (ADC) is assigned and the 4-wire signal input of each 2-wire / 4-wire Transfer device (GABEL1, GABEL2) a Digi tal / analog converter (DAC) is assigned and that of the Switching device (SW) a connection between the two 2-wire / 4-wire transfer devices on the Digi valley signal side can be effected. 17. Device according to claim 7 in connection with one of the Claims 13 to 16, characterized in that the to determining transmission parameters the attenuation between the 4-wire sides of the 2-wire / 4-wire converter (GABEL1, GABEL2) over the communication network (GSTN). 18. Device according to one of claims 13 to 17, characterized characterized by a reinforcement device (AMP1, AMP2) for the increased delivery of each at a tele-university cation network connection (a / b1, a / b2) received useful information tion to each other's telecommunications network conclusion (a / b2, a / b1). 19. The device according to claim 18, characterized in that the amplification factor of the amplification device (AMP1, AMP2) depending on the determined damping is. 20. Device according to one of claims 18 or 19, characterized characterized in that the gain factor of the gain device (AMP1, AMP2) does not have a maximum value exceeds.   21. The device according to claim 20, characterized in that the maximum value corresponds to an attenuation of 29 dB. 22. Device according to one of the preceding claims, there characterized in that the control device (SI) min at least two signal coding or decoding filters (SICOFI1, SICOFI2) with an impedance matching filter for variation of their input impedance. 23. Device according to claim 18 in connection with claim 22, characterized in that the reinforcement device device (AMP1, AMP2) through the signal coding or decoding Filter (SICOFI1, SICOFI2) is realized. 24. Device according to one of claims 22 to 23, characterized characterized in that the switching device (SW1) the Digital inputs / outputs of the two signal encoders or deco dier filter (SICOFI1, SICOFI2) connects together.