Abstract:
An apparatus for position-dependent control has a control unit, where the control unit takes the position of the apparatus as a basis for: a) controlling damping and/or echo cancellation for the apparatus, and/or b) switching a summit of the apparatus on or off or to a power saving mode, and/or c) prompting call acceptance.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and hereby claims priority to PCT/EP2006/008751 filed on Sep. 7, 2006, the contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The invention relates in particular to a mobile telephone having attenuation control, as used in connection with handsfree systems. Telephone terminal devices should maintain a certain decoupling between received and transmitted signal in order to operate properly or to comply with regulatory requirements. In the case of handsfree terminal devices the high levels of amplification required would make it necessary to introduce a very great attenuation/decoupling in order to avoid, for example, feedback, echoes or what is termed reverberation. 
     This attenuation/decoupling should be implemented for example either by a deviation control unit and/or by way of an acoustic echo canceller and/or by a combination of different decoupling methods. A deviation control unit inserts the necessary attenuation for example alternately in the transmitting or in the receiving direction. 
     Particularly in the case of mobile handsfree devices, such as e.g. cordless telephones or mobile telephones, the decoupling possible by an acoustic echo compensator is not usually sufficient on its own, however, to get by without an additional deviation control unit and/or further decoupling measures. A problem in this case is that said deviation control unit must be adjusted to the most unfavorable position, e.g. lying on the microphone, in order that the mobile handsfree device will still also operate sufficiently well under these “bad” conditions. 
     SUMMARY 
     One potential object is to provide a simply constructed apparatus which enables in particular efficient attenuation control. In particular the attenuation control is intended to allow high voice quality, preferably also a mode of operation which is scarcely different from a full-duplex mode of operation. 
     The inventors propose an apparatus for controlling attenuation, comprising:
         at least one transmission branch for transmitting signals,   either a): an attenuation control unit which controls the attenuation of the signals, and/or b): an echo canceller unit which is coupled to the transmission branch by an input or output.       

     The control unit controls the attenuation in variant a) and/or the echo cancellation in variant b) as a function of the position of the apparatus. 
     The first aspect is based inter alia on the following considerations. If the device is operated in a favorable position, e.g. upright, a decoupling is inserted which would possibly not even be necessary for this positioning. As a result of the additional decoupling the duplex communication becomes worse than actually necessary for this position. Similarly to this situation, the transmit and receive frequency responses for example are then also different in the respective positions, e.g. upright or horizontal, and may negatively affect handsfree operation. 
     For this reason the position of the apparatus is taken into account by the attenuation controller. For example, the position can be transmitted manually to the attenuation control unit, by actuating an input key for example. Preferably, however, the position is detected with the aid of a sensor. 
     Thus, in a development the apparatus includes a detection unit which is coupled on the output side to an input of the control unit. The detection unit detects the position of the apparatus. 
     In a next development the detection unit is: 
     an acceleration sensor, in particular a capacitively operating acceleration sensor and/or a sensor fabricated on a silicon basis in integrated technology. The sensor is consequently very sensitive and very small. 
     at least one switching contact, disposed for example on the base of the apparatus, such that the position upright is detected. 
     at least one photoelectric relay with the aid of which the presence or absence of a contact surface is detected. 
     a sensor unit having a movably mounted liquid or at least one movably mounted solid body. Examples of sensors of said kind are mercury sensors or sensors which contain one or more metal bodies or pellets. 
     A single-axis sensor, a dual-axis sensor or a triple-axis position sensor can be preferably be used as the position sensor. With multi-axis position sensors the positions that are possibly not required may be used for example for other application purposes. Thus, for example, a position sensor supplies at two outputs or at three outputs in each case a voltage level or a mark/space-modulated or pulse-width-modulated output signal matching the acceleration value into the relevant axis, which output signal is output via a port or an analog/digital converter. In order to save on ports or analog/digital converters, in one embodiment the two or three signals are also multiplexed unit onto just one output signal with the aid of a multiplexer. The read-out values of the position sensor are preferably averaged such that minor movements of the device do not lead to the switching over of the parameter sets for different positions. 
     In another development the apparatus includes an acoustic-electric converter unit which is situated at the start of the receive transmission branch. An electret microphone, for example, is used as the microphone. In addition the apparatus preferably also includes an electro-acoustic converter unit which is disposed at the end of a second transmission branch of the apparatus. The electro-acoustic converter unit is a loudspeaker for example. 
     In a next development the control unit controls the attenuation as a function of the position and independently of the frequency of the signals. In this context reference is also made to a conventional deviation control unit. 
     In an alternative development, by contrast, the control unit controls the attenuation as a function of the position and as a function of the frequency of the signals. It is sensed, for example, which frequencies are present in the current receive signal that is output by the loudspeaker. The frequencies present in the receive signal are suppressed or very strongly attenuated in the case of a transmit signal. A feedback can be avoided by this measure. Furthermore the speaking subscriber at the distant station hardly notices while speaking that certain frequencies are missing in the backward-transmitted voice signal. What is referred to as a comb filter unit is preferably used for this attenuation. 
     The control unit specifies for example filter coefficients for filter units in the transmission branch in order to achieve a frequency-selective attenuation. Alternatively, different filter units with filter coefficients that are different from one another are switched between. 
     In another development, the apparatus contains a memory unit in which a data record or at least two data records each containing at least one item of data is or are stored. The data record or one of the data records is selected by the control unit as a function of the preferably detected position for the purpose of processing the voice data. For example, a data record contains predefined attenuation values or attenuation factors, filter coefficients, or other data which specify the above-explained influencing possibilities. Alternatively, subcircuits corresponding to the data records can also be selected. 
     In a next development, the apparatus contains a determination unit which determines and stores at least one data record as a function of the preferably detected position. By this measure influences of the further environment or of the underlying surface can be taken into account even more effectively. Thus, it can be provided that different parameter sets are determined only at the user of the apparatus by an adjustment by measured signals, e.g. with the aid of the sampling of a frequency range from 200 to 3400 hertz, in the different positions. For example the necessary residual deviation is determined or frequency response corrections are determined. Alternatively the coupling is reduced for critical frequencies. 
     In a variant without determination unit, however, predefined parameters are used and transferred according to the detected position. This is advantageous in particular in order not to place an excessive load on a processor of the apparatus. 
     According to a second aspect, the inventors propose an apparatus which contains a control unit and a detection unit for detecting the position of the apparatus. The control unit switches the apparatus or a subunit of the apparatus off or into a power-saving mode, dependent on a signal coming from the detection unit. This apparatus is therefore closely related to the apparatus of the first aspect, in particular if a position sensor is also used for this. In particular both functions can also be implemented in a single apparatus. 
     The second aspect is based inter alia on the consideration that the lighting of an apparatus should be activated as soon as the apparatus is moved or, for example, as soon as the device is placed in an upright position. In the rest position a color display, for instance, is switched off for power-saving reasons. Displayed content can consequently no longer be read until a key is pressed. For example, a time of day could be displayed on the display. However, the lighting of the display or the display itself cannot be switched off completely; instead it is merely switched into a power-saving mode in which a certain readability is still present. Of course, this power-saving mode also costs power, in particular also at times when the device is lying on the display and the lighting or more specifically the display cannot even be required in this case. 
     If the lighting of the display or the display itself is switched off or switched to a darker level for power-saving reasons, a movement of the device should cause the lighting or the display itself to be activated. Ideally, however, the lighting or the display itself should even be switched off completely if the device is lying on the keypad or the display. For this purpose the output signals of the position or acceleration sensor, for example, are read out and checked for a change. If a change that exceeds a predefined value is detected, the evaluating processor, for example, switches the lighting or the display to active. If this function is to be used on its own, a single-axis position sensor or a dual-axis position sensor is also sufficient. Compared to the first aspect, therefore, a comparatively brief averaging of the output signals of the position sensor is performed. 
     A development of another aspect relates to an apparatus which likewise contains a control unit and a detection unit for detecting the position of the apparatus. On the output side the detection unit is coupled to the input of the control unit. In addition the apparatus includes a signaling unit which signals an incoming call arriving at the apparatus. The control unit initiates acceptance of the call as a function of an output signal of the detection unit. This third aspect also is closely related to the other two aspects and can be implemented in particular together with the latter in one apparatus. 
     The third aspect proceeds from the consideration that when an incoming call occurs a line or a radio channel is to be seized by the device being picked up. This function should be independent of the initial position of the device. 
     In the call mode of the device, therefore, a movement of the device should lead to the acceptance of the call such that a key does not have to be actuated first. For this purpose, however, the output signals of the position sensor should only be averaged correspondingly briefly so that the change in acceleration or the change in position can be quickly evaluated. Accordingly a method could be used similarly to the detecting of a movement for the purpose of switching on a display unit, for example. Needless to say, the response “seize” may only be initiated when a call is also actually present, i.e. when the apparatus is called. The evaluation therefore takes place only within a specific time window from the time the call is received, in order to avoid incorrect seizures. For example the end of the time window occurs e.g. a maximum of 2 seconds after the last ringing signal. If this function is used on its own, a dual-axis position sensor or even only a single-axis position sensor is sufficient. 
     The sensor units cited for the first aspect can also be used for the apparatuses according to the second and third aspects. 
     To sum up, for the first aspect it holds that high-end terminal devices in particular benefit from an increase in handsfree quality, since only that decoupling is inserted that is absolutely necessary. Thus, the duplex communication is less strongly attenuated in favorable positions than previously. In conjunction with an acoustic echo canceller or echo compensator a true full-duplex handsfree connection could be implemented in which both parties to a call can speak as peer entities on a totally equal basis without having to sacrifice good volume. 
     With regard to the second aspect, a considerable gain in convenience results from the fact that the display is instantly readable. In the case of an already “powersave”-illuminated display, power can be saved in particular when the device is lying on the display side and consequently the lighting is not required. The power consumption of the position sensor in this case is far below the power consumption of the lighting for a display. 
     A considerable gain in convenience is likewise achieved with regard to the third aspect. 
     The gain in convenience is particularly great when all three aspects are used in a terminal device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and advantages of the present invention will become more apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  shows a DECT telephone (digital Enhanced (formerly: European) Cordless Telephone), 
         FIG. 2  shows a voice module of the telephone, 
         FIGS. 3 to 5  show frequency curves as examples of a deviation requiring to be saved, as a function of the position of the telephone, 
         FIGS. 6 to 8  show frequency curves as examples of a frequency response correction, as a function of the position of the telephone, 
         FIG. 9  shows a further exemplary embodiment having a position-dependent display controller, and 
         FIG. 10  shows a third exemplary embodiment having position-dependent call acceptance. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
       FIG. 1  shows a DECT telephone  10 . In another exemplary embodiment a mobile radio telephone is used instead of the telephone  10 , in particular a telephone of a GSM network (formerly: Groupe Spéciale Mobile; Global System for Mobile Communication) or of a UMTS network (Universal Mobile Telecommunication System), or of a further-developed UMTS network. 
     The mobile telephone  10  is provided with a housing  11 . Located in the housing  11  is for example an earpiece aperture  12  behind which is arranged an earpiece. Located at the back  34  of the housing  10  is, for example, a loudspeaker aperture behind which is arranged a loudspeaker  72 ; see  FIG. 2 . In the lower section of the front  32 , the housing  11  also includes a microphone aperture  14  behind which is arranged a microphone  78 ; see  FIG. 2 . 
     The housing  11  also includes an aperture for a display  16 , in particular for a color display. A control function with reference to the display  16  is explained in more detail below with reference to  FIG. 9 . Also arranged on the front  32  of the telephone  10  are a plurality of keys; see key  18 , for example. 
     Whereas the left side of  FIG. 1  shows a plan view onto the front  32  of the telephone  10 , the right side of  FIG. 1  shows a side view of the telephone  10 . Internally the telephone  10  contains a printed circuit board  30  on which is disposed a position sensor  20 , in the exemplary embodiment a triple-axis position sensor  20 , for an x-direction, a y-direction and a z-direction. The x-direction and the y-direction lie e.g. parallel to a topside of the printed circuit board  30 . The z-direction lies e.g. in the normal direction of the topside of the printed circuit board  30 . 
     Also shown on the right-hand side of  FIG. 1  are a back  34  and a base  36  of the telephone  10 . 
     The position sensor  20  is for example a dual-axis position sensor ADXL  320  from the company Analog Devices. In addition to the sensor element, this sensor or another position sensor includes in particular an a.c. voltage amplifier, a demodulator and for example two output amplifiers. The two-axis position sensor detects, for example, in the x-direction and z-direction or alternatively in the y-direction and z-direction. 
     In another exemplary embodiment a position sensor of the HAAM-301A or 302B type from the company HOKURIKU, for example, or a similarly designed position sensor is used. These sensors include for example a multiplexer, an amplifier and a demultiplexer. The type 301A in particular contains a pulse width controller. 
     In other exemplary embodiments a three-axis position sensor comprising three analog/digital converters is used. In an alternative exemplary embodiment a three-axis position sensor comprising a multiplexer and only one analog/digital converter is used. In a third variant a three-axis position sensor having three outputs at which pulse-width-modulated or mark/space-modulated signals are output which are routed directly to inputs of a processor. In this case the processor, by scanning the ports, evaluates the length of the high/low phases in order to obtain a value that is proportional to the mark/space ratio. 
       FIG. 2  shows a voice module  50  of the telephone  10 . The voice module  50  is implemented with the aid of components that operate in analog fashion and with the aid of a component that operates digitally, e.g. a digital signal processor (DSP) or a different processor. The voice module  50  contains a deviation control unit  52  whose functions are performed by the processor in the exemplary embodiment. Alternatively, however, the voice module  50  can also be implemented without a processor, i.e. only by an electronic circuit in which no program instructions are stored and executed. 
     A receive signal  54  arrives at an input E 1  of the deviation control unit. The receive signal  54  is represented for example by a sequence of sampled values, by 16-bit sampled values for example. The receive signal  54  originates, for example, from a radio-frequency section (not shown) of the telephone  10 . The signal was sent to the radio-frequency section by, for example, what is referred to as a base station from which e.g. a plurality of telephones  10  are operated, with data being transmitted to the telephones  10  e.g. in accordance with the DECT standard. 
     The receive signal  54  is also applied to an input of a level detector unit LD 1 . The level detector unit LD 1  outputs an output signal for an input E 2  of the deviation control unit  52 . The deviation control unit  52  implements for example the functions of what is referred to as a duplex controller, the functions of which are known per se. In particular the deviation control unit  52  switches between two operating modes TX and RX, depending e.g. on the strength of the receive signal  54  and the strength of the transmit signal  104  of the voice module  50 . In the exemplary embodiment the transmit signal  104  is stronger than the receive signal  54  in the operating mode TX. In the operating mode RX, on the other hand, the receive signal  54  is stronger than the transmit signal  104 . This evaluation is performed by a decision unit inside the deviation control unit  52  which is controlled by the level detectors LD 1  to LD 4 . 
     The deviation control unit  52  outputs an intermediate signal  56  generated from the input signal  54 , in particular a digital signal, at an output A 1 . The intermediate signal  56  is routed to the input of a level detector unit LD 2 . The output of the level detector unit LD 2  is connected to an input E 3  of the deviation control unit  52 . 
     The intermediate signal  56  is routed as an input signal  57  to an echo canceller unit EK, the function of which will be explained in more detail below. In addition the intermediate signal  56  is routed to a filter switchover unit  58  which has, for example, three operating modes which are assumed as a function of a switchover signal  60 . For example, a filter operating mode with a filter unit F 1 , a filter operating mode with a filter unit F 2  and an operating mode in which the input signal is output unchanged as the output signal. The filter units F 1  and F 2  are embodied for example as digital filter units with different coefficients. 
     A filter output signal  62  is output at the output of the switchover unit  58 . At a digital/analog interface  64  the filter output signal  62  is converted into an analog signal which is routed on a line  66  to an output amplifier  68 . The digital/analog interface includes in particular a digital/analog converter. 
     The output amplifier  68  performs an output amplification and at its output outputs an amplified signal on a loudspeaker line  70 . The loudspeaker line  70  leads to the loudspeaker  72 . 
     At the loudspeaker  72  the voice signal received by the voice module  50  is output very audibly in handsfree mode. Operating the voice module  50  in a handsfree mode results in a feedback  74  of the voice signal output at the loudspeaker  72  to the microphone  78 . 
     In the exemplary embodiment the subscriber using the telephone  10  or the voice module  50  is a subscriber who has set up the call, i.e. what is referred to as a calling subscriber or A-party. The subscriber at the distant station is a B-party. However, all the explained methods also work when the telephone  10  is used by a B-party, i.e. by a called subscriber. 
     In the exemplary embodiment voice  76  of the A-party also reaches the microphone  78 . From the microphone  78 , a microphone line  80  leads to the input of an input amplifier  82 . At its output the input amplifier  82  generates an analog amplified signal on a line  84 . The line  84  leads to an analog/digital converter or to what is referred to as an encoder. These units form an analog/digital interface  86  behind which, viewed in the signal flow direction, digital data is processed, said digital data representing a microphone signal  88 . 
     The microphone signal  88  is input into a filter switchover unit  90  which, dependent on a switchover signal  92 , has, for example, three operating modes: 
     a filter operating mode with a filter unit F 3 , 
     a filter operating mode with a filter unit F 4  which has a different frequency response from the filter unit F 3 , and 
     a “transit” operating mode in which the microphone signal  88  is output unchanged at an output of the filter switchover unit  90 . A filter output signal  94  is output at the output of the filter switchover unit  90 . 
     The filter output signal  94  is added to an output signal  98  generated by the echo canceller unit EK at a summing unit  96 . An aggregate signal  100  is produced at the output of the summing unit  96 . The aggregate signal  100  also serves as a further input signal  102  of the echo canceller unit. The echo canceller unit EK initially operates in a known manner and serves to remove signal components which are still included in the filter output signal  94  as a result of the feedback  74 . 
     The echo canceller unit EK has a further input at which a control signal  103  is present. Said control signal  103  is dependent on the position of the telephone  10 ; for example, what is referred to as an echo loss level, i.e. a measure for the acoustic coupling of the acoustic path  74 , is input here dependent on the position that is detected by the position sensor  20 . 
     The aggregate signal  100  reaches an input E 4  of the deviation control unit  52 . The aggregate signal  100  is also routed to an input of a level detector unit LD 3 . The output of the level detector unit LD 3  leads to an input E 5  of the deviation control unit  52 . 
     The deviation control unit  52  attenuates the aggregate signal  100  as a function of the current operating mode TX or RX and as a function of the position  20  detected by the position sensor. The attenuated signal is output at an output A 2  of the deviation control unit  52  as a transmit signal  104 , which then reaches the HF unit and is sent via a radio communications link to the base station. 
     The base station transmits the voice data to a network conforming, for example, to ISDN, to an analog method, to a VoIP (Voice over Internet Protocol) method or to a WLAN (Wireless Local Area Network) method. 
     The transmit signal  104  is also routed to a fourth level detector unit LD 4  whose output signal is routed to an input E 6  of the deviation control unit  52 . 
     In the example the deviation control unit  52 , in order to detect the operating mode TX or RX, operates with what is referred to as a four-point query. In other exemplary embodiments only a two-point query is used, for example with the aid of the level detector units LD 1 , LD 4  or alternatively with the acoustic-side level detectors LD 2 , LD 3 . 
     In addition a line  106  leads from the position sensor  20  to an input E 7  of the deviation control unit  52 . This enables the deviation control unit  52  to detect in which position the telephone  10  is currently to be found, in a vertical position, for example, or in a horizontal position. The vertical position is referred to hereinafter as “upright” and is indicated by the letter “S”. The horizontal position is referred to hereinafter as the “horizontal” position, and is indicated by the letter “L”. 
     In the operating mode TX, i.e. the transmit signal  104  of the module  50  is stronger than the receive signal  54 , the receive signal  54  is more strongly attenuated in the horizontal position L than in the upright position S. In the exemplary embodiment the following applies: 
     TXS=−30 dB (decibels), and 
     TXL=−40 dB. 
     The reason why a greater attenuation is necessary in the horizontal position of the telephone  10  in the exemplary embodiment is explained in more detail below with reference to  FIGS. 3 to 5 . 
     In the operating mode TX the aggregate signal  100  is not attenuated by the deviation control unit  52 , i.e. either in the upright position TXS=0 dB or in the horizontal position TXL=0 dB. 
     In the operating mode RX, in which the receive signal  54  is much stronger than the transmit signal  104 , the receive signal  54  is not attenuated regardless of the current position of the telephone  10 , i.e. with 0 dB. However, the aggregate signal  100  is very strongly attenuated in the operating mode RX, and what&#39;s more as a function of the position detected with the aid of the position sensor  20 , as follows: 
     in the upright position RXS an attenuation of −30 dB is used. 
     In the horizontal position RXL an even stronger attenuation of −40 dB is used. 
     The attenuation values just cited are merely examples and apply in particular to the situation in which no echo canceller unit EK is used. If the echo canceller unit EK is used, an attenuation of at least 20 dB can be achieved by said unit alone. In this case the above-cited attenuation values should be increased by at least 20 dB. This means, for example, that the attenuation TXS must now only amount to −10 dB. 
     In addition or alternatively to the above-explained deviation control unit  52  with position-dependent control and/or in addition to the echo canceller unit EK with position-dependent control, the frequency responses can also be controlled on a position-dependent basis; see control signals  60 ,  92 . The influencing of the frequency responses by the filter units F 1  to F 4  is explained in more detail below with reference to  FIGS. 6 to 8  for the upright position of the telephone  10 . 
     In other exemplary embodiments with influencing of the frequency responses the filter units F 1  to F 4  can also be disposed at a different point in the voice module  50 , for example as circuit elements upstream or downstream of the output amplifier  68  or the input amplifier  82 . 
       FIG. 3  shows in a coordinate system KS 1  three frequency curves  114 ,  116  and  118  for three positions of the telephone  10 . In this case the frequency curves  114 ,  116  and  118  were recorded by way of sound signals output by the loudspeaker  72 , when passing through a spectrum from 200 hertz to 4 kilohertz, for example by a swept sinusoidal signal. 
     The coordinate system KS 1  has an x-axis  110  on which the frequencies are represented logarithmically in the frequency range from 200 hertz to approx. 4 kilohertz. The acoustic level is represented on a y-axis  112 , in particular in a range from 0 dB (Pascal/Volt) to −40 dB. 
     The curve  114  relates to an upright telephone  10 . The curve  116  relates to a telephone  10  lying on its back  34 . The curve  118  relates to a telephone  10  lying on its front. 
     It can be seen from the curves  114  to  118  that in the case of the telephone  10  the loudspeaker levels are considerably different from one another at frequencies of approx. 1.4 kilohertz to 3.5 kilohertz dependent on the position of the telephone  10 . Apart from the sound at the A-party end, the acoustic coupling also changes as a result hereof at these frequencies. 
     It is common to all three curves  114  to  118  that they rise approximately linearly from approx. 200 hertz. In the range von 500 hertz to approx. 1.2 kilohertz the curves  114  to  118  remain roughly at a constant acoustic level of approx. −15 dB. From a frequency of 1.2 kilohertz the curves  114  to  118  deviate more sharply from one another, the curve  116  and the curve  118  rising somewhat and exhibiting comparatively little fluctuation. By contrast the curve  114  drops in the frequency range from approx. 2 kilohertz to 3 kilohertz significantly below the value of the curves  116  and  118  in this range. 
       FIG. 4  shows in a coordinate system KS 2  three curves  124 ,  126  and  128  for a frequency range from 200 hertz to approx. 4 kilohertz, the transmit frequency spectrum having been investigated this time. Using, for example, a sine-wave generator, the frequency band from 200 hertz to 4 kilohertz was swept through, sound signals having been directed to the microphone  78  in the three aforementioned different positions of the telephone. The curve shapes  124 ,  126  and  128  shown in  FIG. 4  were measured for example upstream of the input amplifier  82  or downstream of the input amplifier  82 . 
     The coordinate system KS 2  has an x-axis  120  on which the frequency in hertz is represented logarithmically in the range from 200 hertz to 4 kilohertz. The levels recorded by the microphone  78 , in particular in the range from 0 dB to −40 dB, are represented on a y-axis  122 . 
     In the coordinate system KS 2  also, it can be seen that the levels recorded by the microphone  78  are considerably different from one another at frequencies from 1 kilohertz to 4 kilohertz, dependent on the position of the telephone  10 . Thus, apart from the sound at the B-party end, this also causes a change in the acoustic couplings at these frequencies. 
     Specifically it holds that the curves  124  to  128  rise in the frequency range from 200 hertz to approx. 600 hertz from levels of −40 dB to levels of approx. −18 dB. 
     The following applies for the frequency range from 600 hertz to 3.5 kilohertz: 
     the curve  124  for an upright telephone  10  remains at a roughly constant value of −18 dB and shows an abrupt drop only at a frequency of 3.5 kilohertz. 
     The curve  126  applies to the telephone  10  when it is lying on its back  34 . The curve  126  drops roughly linearly in the range from 600 hertz to 3.5 kilohertz in the chosen representation. 
     The curve  128  applies to a telephone  10  that is lying on its front  32 . The curve  128  remains roughly in the range of −20 dB in the frequency range from 600 hertz to 3.5 kilohertz and then drops abruptly to values of −40 dB at 3.5 kilohertz. 
       FIG. 5  shows in a coordinate system KS 3  the overall coupling losses resulting in the case of an addition of the curves shown in  FIG. 3  or  4  for the respective position of the telephone  10 : 
     a curve  134  for an upright telephone  10 , 
     a curve  136  for the telephone  10  that is lying on its back  34 , and 
     a curve  138  which applies to the telephone  10  when it is lying on its front  32 . 
     The coordinate system KS 3  has an x-axis  130  in which frequencies of 100 hertz to approx. 4 kilohertz are plotted in logarithmic representation. The decoupling in dB is represented on a y-axis  132  in the range from 0 dB to −50 dB against the y-axis. 
     In this case the aggregate curve  138  reaches the highest values or the smallest attenuation values. This means that the highest coupling arises here and consequently must be decoupled by a correspondingly high additional attenuation. In the exemplary embodiment the maximum of the curve  138  lies at approx. −20 dB. 
     For the situation in which the telephone  10  is standing upright, i.e. for the curve  134 , its maximum value lies at approx. −30 dB only. This means that in this case considerably less additional attenuation is required. 
     The deviation of the curves  134 ,  138  results in a deviation  140  to be saved of approx. 10 dB, which has been taken into account above with reference to  FIG. 2  in the different operating modes TX and RX of the deviation control unit  52 . 
     The curve  136  lies even below the curve  134 , so that in this regard what was said about the curve  134  applies similarly here. 
       FIG. 6  shows a coordinate system KS 5  having an x-axis  150  on which the frequency f for the relevant frequency range of e.g. 200 hertz to 4 kilohertz is plotted, in logarithmic representation for example. The acoustic level in dB is plotted on a y-axis  152 , once again in logarithmic representation for example. 
     A curve  154  applies for the reception in the voice module  50 , i.e. during the output of sound signals by the loudspeaker  72 . The curve  154  corresponds to the curve shape  114  which has already been explained with reference to  FIG. 3 . This means in particular that the curve shape  154  applies to a telephone  10  that is upright. As can be seen from  FIG. 6 , frequencies in the upper frequency range, from approx. 2 kilohertz to 3.5 kilohertz, are more strongly attenuated than frequencies in the frequency range from 300 hertz to 2 kilohertz. This means that speech is output at a more muted level by the loudspeaker  72  compared to the speech spoken by the B-party. 
     In order to correct this, the filter unit F 1  for example (see  FIG. 2 ) is used with the frequency response curve  164  shown in  FIG. 7  when the telephone  10  is upright. 
       FIG. 7  shows in a coordinate system KS 6  a filter frequency response  164  which corresponds to that of a high-pass filter, with frequencies in the frequency range from 200 hertz to 2000 hertz being more strongly attenuated than frequencies in the range from 2 kilohertz to 4 kilohertz. The coordinate system KS 6  has an x-axis  160  on which the frequency f is once again represented in logarithmic scale. The attenuation value in dB is represented on a y-axis  162 , with the value 0 dB being highlighted. 
       FIG. 8  shows in a coordinate system KS 7  a frequency response  174  which results from the overlaying or addition of the curve  154  and the curve  164 . The coordinate system KS 7  has an x-axis  170  on which the frequency f is represented in logarithmic scale. The acoustic level L is likewise represented in logarithmic scale on a y-axis  172 . As can be seen from  FIG. 8 , the curve  174  rises continuously to a value M, at approx. 600 hertz for example. Then the curve  174  remains roughly constant on the value M up to 4 kilohertz. 
     Thus, what is achieved is that the B-party no longer sounds muted, but sounds as he/she usually speaks. 
     Similar corrections in respect of the receive branch can be performed by the filter unit F 2  for a telephone  10  that is lying horizontal. 
     Frequency response corrections can also be performed in respect of the transmit branch for an upright telephone  10  with the aid of the filter unit F 3  as well as for a horizontal telephone, in which case the filter unit F 4  is then used. 
       FIG. 9  shows in a further example a position-dependent display controller. As depicted in  FIG. 9 , a control unit  200 , e.g. with processor or without processor, evaluates an output signal  202  of the position sensor  20 . If the control unit  200  establishes that the display  16  is facing downward, the display  16  is switched off or alternatively is switched into a power-saving mode. If the control unit  200  detects with the aid of the position sensor  20  that the telephone  10  is upright again or has been turned over so that the display  16  is visible, the display  16  is activated; see arrow  204 , i.e. the display  16  is switched back on again or switched into the power-saving mode (standby). Instead of the display  16  a backlight can also be controlled accordingly. 
     In the standby mode the display  16  still consumes, for example, 3 to 10 milliamperes. When the display  16  or the display lighting is fully activated, on the other hand, 6 to 20 milliamperes are required. 
       FIG. 10  shows a third exemplary embodiment having a position-dependent call acceptance controller. A control unit  210 , for example with processor or else without processor, receives an input signal  212  from the position sensor  20 . The control unit  210  also receives signaling notifying an incoming call; see arrow  214 . The control unit  210  thereupon initiates the output of a ringing signal by way of the loudspeaker  72  or in some other way. The position sensor  20  is monitored at the same time. As soon as the position of the telephone  10  is changed beyond a threshold value, the control unit  210  automatically accepts the call. This action is symbolized by an arrow  216 . 
     In another exemplary embodiment all three applications, i.e.  FIGS. 1 to 8 , as well as  FIGS. 9  and/or  10 , are implemented in one telephone  10 . 
     The invention has been described in detail with particular reference to preferred embodiments thereof and examples, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention covered by the claims which may include the phrase “at least one of A, B and C” as an alternative expression that means one or more of A, B and C may be used, contrary to the holding in  Superguide v. DIRECTV,  69 USPQ2d 1865 (Fed. Cir. 2004).