Apparatus for position-dependent control

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.

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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1shows a DECT telephone10. In another exemplary embodiment a mobile radio telephone is used instead of the telephone10, 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 telephone10is provided with a housing11. Located in the housing11is for example an earpiece aperture12behind which is arranged an earpiece. Located at the back34of the housing10is, for example, a loudspeaker aperture behind which is arranged a loudspeaker72; seeFIG. 2. In the lower section of the front32, the housing11also includes a microphone aperture14behind which is arranged a microphone78; seeFIG. 2.

The housing11also includes an aperture for a display16, in particular for a color display. A control function with reference to the display16is explained in more detail below with reference toFIG. 9. Also arranged on the front32of the telephone10are a plurality of keys; see key18, for example.

Whereas the left side ofFIG. 1shows a plan view onto the front32of the telephone10, the right side ofFIG. 1shows a side view of the telephone10. Internally the telephone10contains a printed circuit board30on which is disposed a position sensor20, in the exemplary embodiment a triple-axis position sensor20, 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 board30. The z-direction lies e.g. in the normal direction of the topside of the printed circuit board30.

Also shown on the right-hand side ofFIG. 1are a back34and a base36of the telephone10.

The position sensor20is for example a dual-axis position sensor ADXL320from 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. 2shows a voice module50of the telephone10. The voice module50is 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 module50contains a deviation control unit52whose functions are performed by the processor in the exemplary embodiment. Alternatively, however, the voice module50can also be implemented without a processor, i.e. only by an electronic circuit in which no program instructions are stored and executed.

A receive signal54arrives at an input E1of the deviation control unit. The receive signal54is represented for example by a sequence of sampled values, by 16-bit sampled values for example. The receive signal54originates, for example, from a radio-frequency section (not shown) of the telephone10. 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 telephones10are operated, with data being transmitted to the telephones10e.g. in accordance with the DECT standard.

The receive signal54is also applied to an input of a level detector unit LD1. The level detector unit LD1outputs an output signal for an input E2of the deviation control unit52. The deviation control unit52implements 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 unit52switches between two operating modes TX and RX, depending e.g. on the strength of the receive signal54and the strength of the transmit signal104of the voice module50. In the exemplary embodiment the transmit signal104is stronger than the receive signal54in the operating mode TX. In the operating mode RX, on the other hand, the receive signal54is stronger than the transmit signal104. This evaluation is performed by a decision unit inside the deviation control unit52which is controlled by the level detectors LD1to LD4.

The deviation control unit52outputs an intermediate signal56generated from the input signal54, in particular a digital signal, at an output A1. The intermediate signal56is routed to the input of a level detector unit LD2. The output of the level detector unit LD2is connected to an input E3of the deviation control unit52.

The intermediate signal56is routed as an input signal57to an echo canceller unit EK, the function of which will be explained in more detail below. In addition the intermediate signal56is routed to a filter switchover unit58which has, for example, three operating modes which are assumed as a function of a switchover signal60. For example, a filter operating mode with a filter unit F1, a filter operating mode with a filter unit F2and an operating mode in which the input signal is output unchanged as the output signal. The filter units F1and F2are embodied for example as digital filter units with different coefficients.

A filter output signal62is output at the output of the switchover unit58. At a digital/analog interface64the filter output signal62is converted into an analog signal which is routed on a line66to an output amplifier68. The digital/analog interface includes in particular a digital/analog converter.

The output amplifier68performs an output amplification and at its output outputs an amplified signal on a loudspeaker line70. The loudspeaker line70leads to the loudspeaker72.

At the loudspeaker72the voice signal received by the voice module50is output very audibly in handsfree mode. Operating the voice module50in a handsfree mode results in a feedback74of the voice signal output at the loudspeaker72to the microphone78.

In the exemplary embodiment the subscriber using the telephone10or the voice module50is 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 telephone10is used by a B-party, i.e. by a called subscriber.

In the exemplary embodiment voice76of the A-party also reaches the microphone78. From the microphone78, a microphone line80leads to the input of an input amplifier82. At its output the input amplifier82generates an analog amplified signal on a line84. The line84leads to an analog/digital converter or to what is referred to as an encoder. These units form an analog/digital interface86behind which, viewed in the signal flow direction, digital data is processed, said digital data representing a microphone signal88.

The microphone signal88is input into a filter switchover unit90which, dependent on a switchover signal92, has, for example, three operating modes:

a filter operating mode with a filter unit F3,

a filter operating mode with a filter unit F4which has a different frequency response from the filter unit F3, and

a “transit” operating mode in which the microphone signal88is output unchanged at an output of the filter switchover unit90. A filter output signal94is output at the output of the filter switchover unit90.

The filter output signal94is added to an output signal98generated by the echo canceller unit EK at a summing unit96. An aggregate signal100is produced at the output of the summing unit96. The aggregate signal100also serves as a further input signal102of 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 signal94as a result of the feedback74.

The echo canceller unit EK has a further input at which a control signal103is present. Said control signal103is dependent on the position of the telephone10; for example, what is referred to as an echo loss level, i.e. a measure for the acoustic coupling of the acoustic path74, is input here dependent on the position that is detected by the position sensor20.

The aggregate signal100reaches an input E4of the deviation control unit52. The aggregate signal100is also routed to an input of a level detector unit LD3. The output of the level detector unit LD3leads to an input E5of the deviation control unit52.

The deviation control unit52attenuates the aggregate signal100as a function of the current operating mode TX or RX and as a function of the position20detected by the position sensor. The attenuated signal is output at an output A2of the deviation control unit52as a transmit signal104, 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 signal104is also routed to a fourth level detector unit LD4whose output signal is routed to an input E6of the deviation control unit52.

In the example the deviation control unit52, 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 LD1, LD4or alternatively with the acoustic-side level detectors LD2, LD3.

In addition a line106leads from the position sensor20to an input E7of the deviation control unit52. This enables the deviation control unit52to detect in which position the telephone10is 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 signal104of the module50is stronger than the receive signal54, the receive signal54is more strongly attenuated in the horizontal position L than in the upright position S. In the exemplary embodiment the following applies:

The reason why a greater attenuation is necessary in the horizontal position of the telephone10in the exemplary embodiment is explained in more detail below with reference toFIGS. 3 to 5.

In the operating mode TX the aggregate signal100is not attenuated by the deviation control unit52, 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 signal54is much stronger than the transmit signal104, the receive signal54is not attenuated regardless of the current position of the telephone10, i.e. with 0 dB. However, the aggregate signal100is very strongly attenuated in the operating mode RX, and what's more as a function of the position detected with the aid of the position sensor20, 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 unit52with 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 signals60,92. The influencing of the frequency responses by the filter units F1to F4is explained in more detail below with reference toFIGS. 6 to 8for the upright position of the telephone10.

In other exemplary embodiments with influencing of the frequency responses the filter units F1to F4can also be disposed at a different point in the voice module50, for example as circuit elements upstream or downstream of the output amplifier68or the input amplifier82.

FIG. 3shows in a coordinate system KS1three frequency curves114,116and118for three positions of the telephone10. In this case the frequency curves114,116and118were recorded by way of sound signals output by the loudspeaker72, when passing through a spectrum from 200 hertz to 4 kilohertz, for example by a swept sinusoidal signal.

The coordinate system KS1has an x-axis110on 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-axis112, in particular in a range from 0 dB (Pascal/Volt) to −40 dB.

The curve114relates to an upright telephone10. The curve116relates to a telephone10lying on its back34. The curve118relates to a telephone10lying on its front.

It can be seen from the curves114to118that in the case of the telephone10the 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 telephone10. 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 curves114to118that they rise approximately linearly from approx. 200 hertz. In the range von 500 hertz to approx. 1.2 kilohertz the curves114to118remain roughly at a constant acoustic level of approx. −15 dB. From a frequency of 1.2 kilohertz the curves114to118deviate more sharply from one another, the curve116and the curve118rising somewhat and exhibiting comparatively little fluctuation. By contrast the curve114drops in the frequency range from approx. 2 kilohertz to 3 kilohertz significantly below the value of the curves116and118in this range.

FIG. 4shows in a coordinate system KS2three curves124,126and128for 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 microphone78in the three aforementioned different positions of the telephone. The curve shapes124,126and128shown inFIG. 4were measured for example upstream of the input amplifier82or downstream of the input amplifier82.

The coordinate system KS2has an x-axis120on which the frequency in hertz is represented logarithmically in the range from 200 hertz to 4 kilohertz. The levels recorded by the microphone78, in particular in the range from 0 dB to −40 dB, are represented on a y-axis122.

In the coordinate system KS2also, it can be seen that the levels recorded by the microphone78are considerably different from one another at frequencies from 1 kilohertz to 4 kilohertz, dependent on the position of the telephone10. 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 curves124to128rise 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 curve124for an upright telephone10remains at a roughly constant value of −18 dB and shows an abrupt drop only at a frequency of 3.5 kilohertz.

The curve126applies to the telephone10when it is lying on its back34. The curve126drops roughly linearly in the range from 600 hertz to 3.5 kilohertz in the chosen representation.

The curve128applies to a telephone10that is lying on its front32. The curve128remains 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. 5shows in a coordinate system KS3the overall coupling losses resulting in the case of an addition of the curves shown inFIG. 3or4for the respective position of the telephone10:

a curve134for an upright telephone10,

a curve136for the telephone10that is lying on its back34, and

a curve138which applies to the telephone10when it is lying on its front32.

The coordinate system KS3has an x-axis130in which frequencies of 100 hertz to approx. 4 kilohertz are plotted in logarithmic representation. The decoupling in dB is represented on a y-axis132in the range from 0 dB to −50 dB against the y-axis.

In this case the aggregate curve138reaches 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 curve138lies at approx. −20 dB.

For the situation in which the telephone10is standing upright, i.e. for the curve134, 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 curves134,138results in a deviation140to be saved of approx. 10 dB, which has been taken into account above with reference toFIG. 2in the different operating modes TX and RX of the deviation control unit52.

The curve136lies even below the curve134, so that in this regard what was said about the curve134applies similarly here.

FIG. 6shows a coordinate system KS5having an x-axis150on 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-axis152, once again in logarithmic representation for example.

A curve154applies for the reception in the voice module50, i.e. during the output of sound signals by the loudspeaker72. The curve154corresponds to the curve shape114which has already been explained with reference toFIG. 3. This means in particular that the curve shape154applies to a telephone10that is upright. As can be seen fromFIG. 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 loudspeaker72compared to the speech spoken by the B-party.

In order to correct this, the filter unit F1for example (seeFIG. 2) is used with the frequency response curve164shown inFIG. 7when the telephone10is upright.

FIG. 7shows in a coordinate system KS6a filter frequency response164which 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 KS6has an x-axis160on which the frequency f is once again represented in logarithmic scale. The attenuation value in dB is represented on a y-axis162, with the value 0 dB being highlighted.

FIG. 8shows in a coordinate system KS7a frequency response174which results from the overlaying or addition of the curve154and the curve164. The coordinate system KS7has an x-axis170on which the frequency f is represented in logarithmic scale. The acoustic level L is likewise represented in logarithmic scale on a y-axis172. As can be seen fromFIG. 8, the curve174rises continuously to a value M, at approx. 600 hertz for example. Then the curve174remains 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 F2for a telephone10that is lying horizontal.

Frequency response corrections can also be performed in respect of the transmit branch for an upright telephone10with the aid of the filter unit F3as well as for a horizontal telephone, in which case the filter unit F4is then used.

FIG. 9shows in a further example a position-dependent display controller. As depicted inFIG. 9, a control unit200, e.g. with processor or without processor, evaluates an output signal202of the position sensor20. If the control unit200establishes that the display16is facing downward, the display16is switched off or alternatively is switched into a power-saving mode. If the control unit200detects with the aid of the position sensor20that the telephone10is upright again or has been turned over so that the display16is visible, the display16is activated; see arrow204, i.e. the display16is switched back on again or switched into the power-saving mode (standby). Instead of the display16a backlight can also be controlled accordingly.

In the standby mode the display16still consumes, for example, 3 to 10 milliamperes. When the display16or the display lighting is fully activated, on the other hand, 6 to 20 milliamperes are required.

FIG. 10shows a third exemplary embodiment having a position-dependent call acceptance controller. A control unit210, for example with processor or else without processor, receives an input signal212from the position sensor20. The control unit210also receives signaling notifying an incoming call; see arrow214. The control unit210thereupon initiates the output of a ringing signal by way of the loudspeaker72or in some other way. The position sensor20is monitored at the same time. As soon as the position of the telephone10is changed beyond a threshold value, the control unit210automatically accepts the call. This action is symbolized by an arrow216.

In another exemplary embodiment all three applications, i.e.FIGS. 1 to 8, as well asFIGS. 9and/or10, are implemented in one telephone10.