Abstract:
A method transmits a multiplicity of digital data packets from a transmitter to a receiver arranged in a mobile device. A plurality of data packets in each case is combined to form a block. The multiplicity of data packets are sent out by the transmitter in such a manner that the time intervals between the individual data packets of the respective block vary over the blocks for a plurality of successive blocks, and/or the time duration of the blocks varies for a plurality of successive blocks, and/or the time intervals between the individual data packets in the block vary for a number of blocks. The blocks of data packets are received and decoded by the receiver.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority, under 35 U.S.C. §119, of German application DE 10 2015 208 948.7, filed May 13, 2015; the prior application is herewith incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    The invention relates to a method for transmitting a multiplicity of digital data packets from a transmitter to a receiver arranged in a mobile device, a plurality of data packets in each case being combined to form a block and blocks of data packets being received and decoded by the receiver. 
         [0003]    For hearing aids, digital wireless connections have hitherto been used primarily for being able to adjust operating parameters of the hearing aid, such as, for example, the volume, from a handset. In recent times, digital wireless transmission protocols are also used for streaming audio data from a source configured for this purpose, for example a television set or a telephone, to the hearing aid. In this connection, the source has a wire-based signal link to a transmitter which sends out a digital radio signal which can be received by a hearing aid which is equipped with a corresponding receiver. 
         [0004]    In this connection, hearing aids often have two operating modes: in the regular mode, a microphone or microphone system of a hearing aid in each case picks up acoustic signals from the environment which are amplified in the hearing aid and are correspondingly reproduced to the ear of the user by means of a loudspeaker. In the streaming mode, a digital radio signal in which audio data are coded is received by the receiver and the audio data are reproduced by the loudspeaker. Optionally, a handset can also be provided here for controlling the volume or for changing between the operating modes etc. 
         [0005]    Due to the demands on the size and the life of a battery in a hearing aid, considerable restrictions result in a hearing aid. A transmission protocol transmits the audio data usually in short-time data packets with a comparatively high data rate, the digital data being modulated mostly onto an analog carrier signal of a particular frequency. In most cases, a transmission protocol provides for a number of carrier frequencies which in each case form a transmission channel by the corresponding modulation of the digital data. In an interval between two data packets, the carrier signal is modulated in none of the transmission channels by the transmitter. Within this period, the power supply can be reduced in the receiver of the hearing aid to a minimum for stand-by operation in order to save energy. 
         [0006]    Since, for a stable reproduction of the transmitted audio data, this rest period must be compensated for by a correspondingly higher data rate in the transmission of the data packets and, on the other hand, the received audio data of the data packets are temporarily stored in a memory and read out of the latter for the reproduction. The duration of a rest period between two data packets is usually only a few milliseconds in a transmission protocol in order to be able to keep time delays, among other things, as short as possible when reading out the memory. The operating voltage of batteries which are used in conventional hearing aids is mostly of an order of magnitude of 1.5 Volts. For those applications in a hearing aid which require a higher voltage, the operating voltage of the battery is raised, for example via a voltage upconverter (step-up converter). The control system for the stability of the voltage is limited for reasons of efficiency, among other things, by the capacity of the capacitors used for smoothing. 
         [0007]    These restrictions in the voltage or power supply can lead to the following problem in the operation of the signal receiving unit: during the reception of the data packet, the receiver draws a comparatively high current which can be up to a few milliamperes. During the rest periods in which no data packets are transmitted, the consumption of the receiver is distinctly lower. The control system for the stability of the voltage is usually not designed for keeping the voltage provided by the battery completely constant with such fluctuations in the current consumption. As a result, the periodic power operation of the receiver and other signal processing units which are connected to it leads to periodic changes in the operating voltage. 
         [0008]    Since the analog circuits for signal processing in the hearing aid such as, for example, the amplification or preamplification are operated via this operating voltage and the periodic fluctuations in the operating voltage are caused by the reception of data packets in the receiver, 100 to some 1000 data packets being received per second depending on the transmission protocol, these fluctuations in the operating voltage can create audible artifacts in the reproduced sound signal of the hearing aid. 
       SUMMARY OF THE INVENTION 
       [0009]    The invention is, therefore, based on the object of specifying a method for transmitting digital data packets from a transmitter to a receiver arranged in a mobile device which, with low energy consumption, has the least possible effects on the stability of the operating voltage of the mobile device. 
         [0010]    According to the invention, the object is achieved by a method for transmitting a multiplicity of digital data packets from a transmitter to a receiver arranged in a mobile device, a plurality of data packets in each case being combined to form a block, the multiplicity of data packets being sent out by the transmitter in such a manner that deterministically. The time intervals between the individual data packets of the respective block vary over the blocks for a plurality of successive blocks, and/or the time duration of the blocks varies for a plurality of successive blocks, and/or the time intervals between the individual data packets in the block vary for a number of blocks, and the blocks of data packets being received and decoded by the receiver. Advantageous and inventive embodiments partially considered individually are the subject matter of the subclaims and of the subsequent description. 
         [0011]    In particular, the fact that the time intervals between the individual data packets of the respective block vary over the blocks for a plurality of successive blocks is meant to mean that in each individual one of the successive blocks considered the individual time intervals between the data packets of the block have a constant value which varies over the successive blocks considered. In this context, the time interval from the end time of a data packet to the start time of the subsequent data packet, in particular, can be utilized for the definition of the time interval between two successive data packets. The two times mentioned as well as a data packet as such can be defined via a transmitting activity of the transmitter, for example via a transmitting power present in a transmission channel. The time duration of a block, in particular, can be defined by the distance of the starting time of the first data packet of the block from the starting time of the first data packet of the next block. 
         [0012]    In this context, a reception and a decoding of the blocks of data packets by the receiver also contains the possibility that, due to transmission losses, not all data packets of a block are received completely. The decoding in this case contains the reading out of the data provided for further processing in a data packet, the removal of protocol-specific information in a preamble of a data packet from the data provided for further processing, the consideration of redundant data, taking place only once, in a number of data packets of a block for further processing, and generally the provision of the useful information coded by the data packets of a block. A variation of the time intervals between data packets or the durations of the blocks, respectively, contains, in particular, that, in a plurality of time intervals or durations of the blocks considered, at least one value deviates from the other ones by more than one tolerance amount. 
         [0013]    The starting point of the invention is the transmission of the digital data in data packets delimited in time, having a high data rate in each case. The advantages resulting for the energy consumption of the mobile device during the times free of transmission, and thus also of reception, are thus retained as well as the extensive possibilities for correction of transmission errors of individual bit values by redundancies correspondingly provided for this purpose in the data packets or distinct redundancy data packets. The reception of an individual data packet can lead to a fluctuation of the operating voltage in the mobile device which, additionally, can be all the greater the higher the data rate of the data packet is, that is to say the more different signal characters are to be resolved per unit time on reception. A time-continuous transmission of the data, initially conceivable in this respect, or a lowering of the data rate of the data packets with an extension in time of the individual data packets, which would lead to a reduction in the time free of transmission, is discarded based on the above-mentioned considerations. 
         [0014]    The invention then recognizes that disturbances in the analog signal processing of the mobile device, which are caused by the fluctuations in the operating voltage, only become significant at all due to the high regularity of the receiver activity caused by the disturbances. If, for example, further processing of the received data packets to form an audio signal is provided in the mobile device, disturbances in the analog signal processing of the mobile device which are caused by the fluctuations of the operating voltage lead to interfering noises in the audio signal to be output only due to the high regularity of the received data packets, with well defined frequencies in the audio signal which can be perceived audibly. 
         [0015]    The invention counters this by breaking through the strict periodicity on sending and receiving the individual data packets. This leads to the voltage fluctuations not being repeated at a preset frequency on reception of the data packets and leading to an interference signal of the corresponding frequency in the analog signal processing but rather possible interference signals being spread over a wider frequency range by frequency modulation of the reception of the data packets. While in this case the number of data packets to be sent out over a plurality of successive blocks, usually by a corresponding protocol for the further processing of the received data packets, is predefined and, as a result, a basic frequency for the reception of the data packets is defined, a corresponding signal can be modulated onto this basic frequency by a variation of the time intervals between individual data packets for such smoothing. For this purpose, the time intervals can be varied in a pseudo-random, quasi-chaotic manner, or simulate a deliberately selected modulation signal. 
         [0016]    In this context, a variation of the time intervals between the individual data packets can be achieved, on the one hand, in that, within each block, the time intervals between the individual data packets have in each case a constant value up to the last data packet of the block in each case, this value varying, however, for various blocks following one another. In particular, the transmission-free rest period from the last data packet of a block up to the first data packet of a following block should not be used for calculating the time intervals. On the other hand, the time duration of the blocks can be varied for a plurality of successive blocks, as a result of which the periodicity of the data packets is broken through even in the case of identical time intervals in each case between the individual data packets for the blocks involved over these blocks. Furthermore, the time intervals between the data packets can also be varied directly in a block. 
         [0017]    In this context, the transmitter and the receiver are to be equipped in each case with corresponding information about the time sequence of the data packets and thus about the individual time intervals to be expected. In addition, such a procedure has the advantage, in particular, that, in the case of a faulty or incomplete transmission of a data packet due to disturbances in a transmission channel used, negative effects for the reception of subsequent data packets can be avoided due to the predefined time intervals. 
         [0018]    Preferably, a time-continuous reproduced signal is generated in the mobile device from data packets received by the receiver. In particular, it can be provided in this context that a number of data packets in a block carries an item of redundancy information so that a time-continuous reproduced signal can be generated in the mobile device even if not all data packets of a block are received completely and faultlessly. For the generation of a time-continuous reproduced signal, particularly of an audio signal, as stable as possible an operating voltage in the mobile device is particularly desirable in order to minimize effects of possible fluctuations of the operating voltage on signal processing of the reproduced signal. In this context, the proposed method contributes to a particular extent to fluctuations in the operating voltage only having unnoticeably perceptible effects. 
         [0019]    The transmitter suitably sends out individual data packets in which in each case the digital information of a data packet is coded into an analog carrier signal of a preset frequency. In particular, this can be done by phase modulation or frequency modulation of the carrier signal. Such a coding is used particularly frequently in practice, temporarily producing a high energy consumption in the receiver of the mobile device especially in the case of comparatively high data rates due to the demodulation to be performed there of the information modulated onto the analog carrier signal. This high energy consumption can impair the stability of the operating voltage in the mobile device, a transmission of the data packets by the method proposed being able to prevent the formation of a periodic interference signal by the fluctuations of the operating voltage on the reception of the data packets in the mobile device. 
         [0020]    It is also found to be advantageous if the frequencies of the respective analog carrier signals are varied by the transmitter for the multiplicity of data packets, and during this process the receiver utilizes stored information on the sequence of the frequencies of the analog carrier signals for the time intervals of successive data packets. In this process, the frequencies of the analog carrier signals are varied by the transmitter in accordance with a predetermined pattern so that a frequency band channel is formed by each of the frequencies used and possibly a bandwidth surrounding the frequency for a modulation. 
         [0021]    The variation of the frequencies of the analog carrier signals for the transmission of different data packets thus means that individual data packets are transmitted on different frequency band channels. This so-called frequency hopping is a method frequently used in practice in the transmission of data packets in order to be able to minimize, in particular, data losses, which may occur due to possible disturbances in a frequency band channel, by distributing the transmission of the data packets to a number of frequency band channels in conjunction with sending out redundancy data packets. For this purpose, a list, determined by the respective transmission protocol, with the sequence of the frequency channels to be used for each data packet to be sent out is deposited in advance both at the transmitter and at the receiver. 
         [0022]    This information available anyway in frequency hopping can now be supplemented by information about the respective time intervals to the subsequent data packet in each case with relatively little memory expenditure. Such a procedure also has the advantage, in particular, that in the case of a faulty or incomplete transmission of a data packet due to disturbances in the relevant frequency band channel, due to the predefined time intervals for the receiver, no effects need to be feared a priori for the reception of subsequent data packets. 
         [0023]    Advantageously, the transmitter in each case inserts an information item about the starting time of the respective subsequent data packet into the data packets at the beginning thereof. Such information can additionally increase the stability of the transmission protocol in order to be able to compensate, for example, for errors in the reading out of stored information about the sequence and time intervals of the data packets at the receiver. 
         [0024]    The time duration of the data packets preferably remains essentially identical during the sending out. This is understood to mean in particular that the time interval for which the transmitter outputs transmitting power for transmitting a data packet in a transmission channel remains identical for the data packets except for technically necessitated fluctuations. This makes it easier to determine the time intervals between the individual data packets. 
         [0025]    The invention also mentions a transmitter which is configured to transmit a multiplicity of digital data packets to a mobile device by the method described above, and a mobile device containing a receiver which is configured to receive and to decode a multiplicity of digital data packets which are transmitted in accordance with the above-described method. The advantages listed for the method and its developments can be transferred correspondingly in this case to the transmitter and to the mobile device. 
         [0026]    In an advantageous embodiment, the mobile device is configured as a hearing instrument, particularly a hearing aid, with a loudspeaker, which is configured to generate a reproduced audio signal from the received and decoded multiplicity of data packets and to reproduce this via the loudspeaker. Due to the restrictions in the dimensions and the battery power of a hearing instrument, the transmission of digital data packets according to the method described above is particularly advantageous for such a hearing instrument with regard to the stability of the operating voltage and thus the quality of the reproduced audio signal reproduced via the loudspeaker. 
         [0027]    Other features which are considered as characteristic for the invention are set forth in the appended claims. 
         [0028]    Although the invention is illustrated and described herein as embodied in a method for transmitting digital data packets from a transmitter to a receiver arranged in a mobile device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
         [0029]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0030]      FIG. 1  is an illustration of a transmitter which transmits a digital signal for the reproduction of audio data to a hearing aid; 
           [0031]      FIG. 2  is an illustration showing variation with time of the signal according to  FIG. 1  in a transmission according to the prior art; 
           [0032]      FIG. 3  is an illustration showing the variation with time of the signal with a variation of the time intervals of the data packets for the respective block over a number of blocks; 
           [0033]      FIG. 4  is an illustration showing the variation with time of the signal with a variation of the duration of the individual blocks; 
           [0034]      FIG. 5  is an illustration showing the variation with time of the signal with a variation of the time intervals of the data packets in the individual blocks; 
           [0035]      FIG. 6  is an illustration showing the variation with time of the signal with a combination of the variations according to  FIG. 3 ,  FIG. 4  and  FIG. 5 ; and 
           [0036]      FIG. 7  is an illustration showing the variation with time of the signal with variable time intervals of the data packets with a distribution of the transmission to a number of frequency band channels. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    Mutually corresponding parts and sizes are in each case provided with identical reference designations in all figures. 
         [0038]    Referring now to the figures of the drawings in detail and first, particularly to  FIG. 1  thereof, there is shown a mobile device  2  configured as a hearing aid  1  is shown diagrammatically. The hearing aid  1  is configured to record sound from the environment by a microphone, not shown in greater detail, to amplify it for correcting hearing impairment of a user of the hearing aid  1  and to reproduce it via a loudspeaker  4  to an ear of the user. 
         [0039]    In order to provide the user, when using entertainment electronics as can be given, for example, by a television set  6 , with a better quality of sound than would be possible by the acoustic recording and reproduction of the sound generated by the loudspeakers of the television set  6 , described above, the hearing aid  1  is equipped with a receiver  8  which is configured to receive a digital signal  10  which is sent out by a transmitter  12  connected to the television set  6 . In this arrangement, the receiver  8  can have, for example, an antenna and a decoder which decodes, and correspondingly processes, signals received by the antenna for further audio-specific signal processing in the hearing aid  1 . 
         [0040]    In the digital signal  10 , the respective current sound track of the television set  6  is coded in the process. The hearing aid  1  can thus receive the sound track digitally via the receiver  8  so that losses of sound on the acoustic transmission path from the loudspeakers of the television set  6  via the environment to the microphone of the hearing aid  1  can be avoided. 
         [0041]      FIG. 2  shows the variation with time of the digital signal  10  according to  FIG. 1  which is sent out by the transmitter  12  according to the prior art. In this figure, the instantaneous volume of data I in all transmission channels is plotted with respect to a time axis t. In the digital signal  10 , the information is transmitted in data packets  20 . An individual data packet  20  here represents a unit terminated in time. From the starting time  22  up to the end time  24  of an individual data packet  20 , the signal is modulated continuously in accordance with the bit values to be transmitted in a particular transmission channel which can be determined, for example, by a carrier frequency. Between various data packets  20  there is no transmission of information, i.e. if the transmitter is emitting transmitting power at all, this goes into an unmodulated carrier frequency. 
         [0042]    The data packets  20  are in each case combined to form coherent blocks  26  (“frames”). In each block  26 , all data packets  20  of the respective block  26  are in this case sent out in a transmitting time  28 . After conclusion of the last data packet  20 , a rest period  30  begins up to the beginning of the next block  26  in which no further data packets are sent out. The rest period  30  lasts longer than the time interval  32  between two successive data packets  20  in this case. The information coded in the data packets  20  of a block  26  is partially redundant here in order to provide for a reproduction, nevertheless, in the case of a transmission error of a data packet  20 . This can be done, for example, by individual redundancy packets  33  provided for this purpose. An individual block  26  in this case represents the smallest unit provided in the transmission protocol, which can be reproduced after decoding. The mean data rate  34  of the transmitter relates to the quantity of data actually sent out, averaged over a number of blocks  26 . Due to the redundancies, the mean volume of data  36  as the quantity of transmitted information, averaged over a number of blocks  26 , is less than the mean data rate  34 . Minus information which relates to instructions for the protocol and is usually stored in a preamble of each data packet  20 , the mean volume of data  36  corresponds to the sample rate in the reproduction in the ideal case. 
         [0043]    Due to the fact that the time intervals  32  between the respective data packets  20  are in each case identical within the individual blocks  26  and due to the fact that the transmitting periods  28  and rest periods  30  are in each case identical over the blocks, the temporal pattern which is formed by the sequence of transmitting the data packets  20  over the blocks  32  remains identical. However, in the receiver  8  of the hearing aid  1 , the reception of the data packets  20  leads to fluctuations in the operating voltage which largely simulate this temporal pattern. These voltage fluctuations also affect the analog signal processing in the hearing aid. 
         [0044]    Due to the regularities in the time intervals  32  between the data packets  20  and in the transmitting times  28  and rest periods  30 , said voltage fluctuations modulate the frequency corresponding to the inverse time intervals  32  as interfering noise onto a useful signal in the analog signal processing. Since the transmission protocols usually provide time intervals of the order of magnitude of milliseconds, particularly between 0.1 ms and 10 ms, such interfering noises are audible to a user of the hearing aid  1  due to the corresponding frequencies (within the range of 100 Hz to 10 kHz). In order to suppress such interfering noises in the analog signal processing, the sequence in time of the data packets  20  can now be varied when they are sent out, as shown in the text which follows. 
         [0045]      FIGS. 3-6  in each case show the variation of the digital signal  10  by plotting the instantaneous volume of data I in all transmission channels with respect to a second axis t. In  FIG. 3 , the duration  38  for the individual blocks  26   a ,  26   b ,  26   c  is in each case identical, the time intervals  32   a ,  32   b ,  32   c  between the individual data packets  20  of the respective blocks  26   a ,  26   b ,  26   c  in each case being constant block by block but having different values in each case for different blocks  26   a ,  26   b ,  26   c . The distance  32   a  between two data packets  20   a  is to be defined in each case as the time between an end time  24   a  of a data packet  20   a  up to a starting time  22   a  of the subsequent data packet  20   a . In this context, only the time intervals up to the respective last data packet  33   a ,  33   b ,  33   c  of the respective block  26   a ,  26   b ,  26   c  are used for defining the time intervals  32   a ,  32   b ,  32   c . The time interval from an end time  24   b  of the last data packet  33   b  of a block  26   b  up to the starting time  22   c  of a first data packet  20   c  of the following block  26   c  which, at the same time, marks the starting time of block  26   c  is not considered as time interval  32   b  within block  26   b , according to definition, but as rest period  30   b  in which the transmission of all data packets  20   b ,  33   b  of block  26   b  is already concluded. 
         [0046]    The variation with time, shown in  FIG. 4 , of the digital signal  10  shows individual blocks  26   a ,  26   b ,  26   c  of data packets  20   a ,  20   b ,  20   c , blocks  26   a ,  26   b ,  26   c  in each case having a different duration  38   a ,  38   b ,  38   c . The duration  38   a  of a block  26   a  is here defined as the time between the starting time  22   a  of the first data packet  20   a  of block  26   a  up to the starting time  22   b  of the first data packet  20   b  of the following block  26   b . The time intervals  32  between two data packets  20   a  or  20   b  or  20   c , respectively, are identical for all blocks  26   a ,  26   b ,  26   c . The variation of the durations  38   a ,  38   b ,  38   c  of blocks  26   a ,  26   b ,  26   c  is achieved by in each case different rest periods  30   a ,  30   b ,  30   c , that is to say in each case a time free of transmission of different length after the respective last data packet  33   a ,  33   b ,  33   c  in block  26   a  or  26   b  or  26   c , respectively, up to the beginning of the next block. 
         [0047]      FIG. 5  shows the variation with time of the digital signal  10  in which the individual blocks  26   a ,  26   b ,  26   c  have in each case the same duration  38 , but the time intervals  32  between individual data packets  20  of a respective block  26   a  or  26   b  or  26   c , respectively, vary. In the version shown here, the time intervals  32  between the data packets  20   a  of a first block  26   a  increase continuously, whereas the time intervals  32  between the individual data packets  20   b  of the subsequent block  26   b  decrease continuously. Over the time intervals  32  in the first block  26   a , the rest period  30   a  in the first block  26   a  and the time intervals  32  in the second block  26   b , the modulation of a discretized sinusoidal half wave train can here be simulated by the temporal pattern of the data packets  20   a ,  20   b  of blocks  26   a ,  26   b . Block  26   c  shows a further possibility of varying the time intervals  32  between the individual data packets  20   c  within block  26   c . The first and the second time intervals  32  or the third and the fourth time intervals  32 , respectively, between the individual data packets  20   c  are in each case identical to one another. 
         [0048]      FIG. 6  shows the variation with time of a digital signal  10  which combines the variations, shown in  FIGS. 3-5 , of the time intervals between data packets and the different durations  38   a ,  38   b ,  38   c  of the individual blocks  26   a ,  26   b ,  26   c . In the present case, the time intervals  32   a  between the data packets  20   a  of the first block  26   a  decrease continuously. The same temporal pattern is found in the case of the time intervals  32   b  between the data packets  20   b  of the second block  26   b . Due to a rest period  30   b , which is longer compared with the rest period  30   a  of the first block  26   a , of the second block  26   b , the latter has a longer duration  38   b  compared with the first block  26   a . By comparison, the time intervals  32   c  increase continuously between the data packets  20   c  in the third block  26   c , block  26   c  also having a longer duration  38   c  than the two preceding blocks  26   a ,  26   b . Other possible combinations of the variations of time intervals between data packets and durations of the blocks, shown here, are conceivable. 
         [0049]      FIG. 7  shows the variation with time of the digital signal  10  when the transmission of the data packets  20  is distributed to a number of frequency band channels. In the case shown here, a new frequency band channel C is used in each case for each data packet  20  of a block  26   a ,  26   b ,  26   c . Such a frequency band channel C is here in each case defined by the frequency f 1 -f 6  of a carrier signal and a certain bandwidth provided for the modulation of the bits of the digital signal  10  onto the carrier signal. The time intervals  32   a ,  32   b ,  32   c  between data packets  20  are in each case constant within a block  26   a  or  26   b  or  26   c , respectively, but vary over the individual blocks  26   a ,  26   b ,  26   c.    
         [0050]    The sequence of the individual frequency band channels C for the transmission of the data packets  20  is predefined in the transmitter and in the receiver by means of a corresponding table. This information, which is already present, can now be supplemented by additional time differences and also used in the transmitter and in the receiver for the time interval  32   a ,  32   b ,  32   c  to the data packet  20  following in each case. By this utilizing of information, used in the protocol in any case, for determining the time intervals  32   a ,  32   b ,  32   c , the expenditure of memory and software for the variation of the time intervals  32   a ,  32   b ,  32   c  can be reduced, particularly on the side of the receiver, which simplifies the method for the transmission. Depending on the transmission protocol, a preamble of a data packet  20  can also contain an information item with respect to the frequency band channel C in which the data packet  20  following in each case is transmitted. In this case, too, the preamble of the data packet can be supplemented by an information item with respect to the time interval to the next data packet  20 . Such an information item can also be conducted independently of information relating to the frequency band channel C. 
         [0051]    Although the invention has been illustrated and described in greater detail by the preferred exemplary embodiment, the invention is not restricted by this exemplary embodiment. Other variations can be derived therefrom by the expert without departing from the scope of the invention. 
         [0052]    The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:
     1  Hearing aid     2  Mobile device     4  Loudspeaker     6  Television set     8  Receiver     10  Digital signal     12  Transmitter     20 ,  20   a - c  Data packet     22 ,  22   a - c  Starting time     24 ,  24   a - c  End time     26 ,  26   a - c  Block     28 ,  28   a - c  Transmitting time     30 ,  30   a - c  Rest period     32 ,  32   a - c  Distance between two data packets     33 ,  33   a - c  Redundancy packet     34  Mean data rate     36  Mean volume of data     38 ,  38   a - c  Duration of a block   C Frequency band channel   f 1 -f 6  Frequency of the carrier signal   I Volume of data   t Time axis