Method for decoding distorted radio signals in multichannel audio signals

Technical field

p0001The invention relates to a method for decoding multi-channel audio broadcasts, especially from two-channel stereo audio broadcasts, with a respective useful signal per channel, where a spatial for each transmitted from the useful frequency spectrum of a signal source by different time of onset and different levels in the different channels impression or location information for the corresponding signal source is generated, according to the preamble of claim 1.

State of the art

p0002Radio receiver for multi-channel audio signals, such as stereo broadcasts, should reflect the low (audio) signal originating realistically as possible at different signal levels, with level variations of the high-frequency carrier signal and radio frequency interference. Among them also understand the spatial arrangement of the different sound sources reproduced. This spatial arrangement is also referred to as location information. In a multi-channel audio transmission, in particular two-channel stereo audio program, is to provided a respective useful signal per channel, for each transmitted from the useful frequency spectrum of a signal source by different time of onset and different levels in the different channels a spatial impression or location information is generated for the corresponding signal source. In some reception conditions, the audio quality of a multi-channel signal, for example, deteriorates at low Nutzsignalpegeln and fading or multipath reception. To these situations an acceptable sound quality continue to be able to provide, the channel separation is to remedy the situation in conventional receivers is reduced, to the single-channel (mono) operation. This gives the listener the impression that all previously distributed in space sources are closer together at one point. Such an alteration of the original signal is so far accepted as the least disruptive action under difficult reception conditions.

p0003The strategy described above is particularly promising when the channel signal obtained has a lower susceptibility to the aforementioned interference due to the modulation method used. This is particularly the widespread frequency-modulated FM broadcasting (Multplexsignal on the pilot tone) of the case. Here, the mono information is transmitted in the low frequency, due to the system less affected parts of the useful.

p0004Further methods are known to process a mono signal so that the impression of a spatial distribution of signal sources arises. For this purpose, the mono signal is broken down into several frequency ranges. These areas are different degrees and / or with different delays to different audio signal paths distributed (+ Hall or other known means for generating an artificial surround sound effect). The more elaborate this processing is done, the more closer and frequency segments can be distinguished. Always further splitting ultimately lead while continuous functions for damping-over-frequency and delay-over-frequency, each a separate function for each signal path. For discrete frequency ranges whose width can be selected different sizes, adapted to the stereo sensitivity of the human ear at different frequencies (eg no channel separation or bass narrow segments at about 1kHz, large segments at high frequencies).

p0005<patcit id="pcit0001" dnum="EP0714222A"><text>EP 0714222</text></patcit> describes a mobile broadcast receiver, which comprises a pseudo-stereo circuit using this prepared in the presence of a mono signal into a pseudo-stereo signal. This is especially of particular advantage when a stereo signal reception to increase the reception quality is enhanced as Monosiganal yet an upscale sound experience is to be achieved. In this type the umschalteen is at an early stage lowering of the reception quality made to mono operation with subsequent processing for pseudo-stereo signal

p0006Conventional stereo decoder are relatively simple and thus constructed inexpensive. The method previously used in stereo receivers with such a stereo decoders with Mono Stereo Blend is based, as already explained above, only on the control of the channel separation. If problems occur is remapped very early single-channel, whereby a possibly still existing location information is no longer reproduced. The known simple stereo decoder have with noisy stereo signals thus no choice but to reject the location information entirely or partially.

SUMMARY OF THE INVENTION, OBJECT, SOLUTION, benefits

p0007It is an object of the present invention to provide an improved method and an improved receiver of the type mentioned above is available, which significantly reduces the disadvantages mentioned above.

p0008This object is achieved by a method of the aforementioned type having the features characterized in claim 1 and by a receiver of the aforementioned type having the features characterized in claim 12 features.

p0009For this it is inventively provided that during the reception of multi-channel audio broadcast in time slots in which the reception is disrupted such that a direct multi-channel playback is not possible, the location information is extracted from the useful signals and with this current location information from a the useful signals all mono signal channels containing an artificial space sound on the channel number of the multi-channel audio broadcast corresponding channels each having a different time delay and / or different damping of the levels generated in the different channels by distributing different frequency bands.

p0010This has the advantage that, although a multi-channel decoder according to the prior art can not perform multi-channel decoding with acceptable quality more, the still existing location information is extracted in the disturbed useful signals and carried out a reproduction with a corresponding "artificial" surround sound, said "artificially" generated surround substantially corresponds to the original surround sound.

p0011Preferable further developments of the method are described in claims 2 to eleventh

p0012In a preferred embodiment, spectral distributions of the useful signals of the various channels and / or propagation time differences or time differences of two or more different spectral components in the respective useful signal of various channels are compared with each other. Parameters for signal attenuation and / or a signal delay be determined in such a way from the comparison for each channel for at least two or more different spectral components and delays the corresponding spectral components from a containing the useful signals of all the channels one-channel signal according to the determined parameters and / or attenuated to the channel number of multichannel audio broadcast corresponding channels distributed such that for a listener for the corresponding spectral components a spatial sound impression is generated that is substantially equivalent to a spatial sound impression of the directly reproduced audio signals of the channels. This has the advantage that should not be switched to single channel mode during a reception interference and therefore no risk of implying that sources would coincide in the center of the room. The distortion by the signal-dependent shaped artificial surround the listener appears less disruptive than a falsification by mono operation. Short disturbances are no longer perceived by the listener. You can return to the multi-channel operation with shorter time constants and delays as a pulsation (seems the signal source to quickly jump between different places in the periodic disturbances) or not occur to a much lesser degree.

p0013An undesirable impression of a quick change in location of a reproduced in the audio signal source, if the frequencies of these signal source exceed an area boundary between adjacent spectral is avoided in that the parameters for attenuation and / or delay determined as a continuous function of the level / maturity difference in function of the frequency will.

p0014For digital signal processing, it is particularly suitable when the spectral range is divided into a plurality of predetermined spectral components, wherein frequencies of a spectral component in the determination of the parameters are taken into account weighted differently. Here the disturbing impression of a spatially-catching signal source is reliably avoided in that the predetermined spectral components in the frequency partially overlap and the frequencies of a spectral component in the overlapping region to an adjacent spectral component may be weighted less. Appropriately, the division of the spectral function of the analysis of the useful signals is dynamically changed.

p0015To prevent short-term events in the useful influence a surround sound unduly strong, once certain parameters over time are supplemented by a weighting function. This occurs, for example as a weighting function, a communication on predetermined periods or a summary of a predetermined period, with greater emphasis on recent specific parameters.

p0016To keep noise components in the payload of the design of an artificial room sound far, only those spectral components are considered in the determination of the parameters that exceed a predetermined level threshold or a frequency-dependent threshold function. The existing within a spectral component or the frequency range signal components no longer affect thereby a location determination by the comparison of the useful signals of different channels of the dominant signal.

p0017A good prediction of a future spatial location of a signal source is achieved by use of such spectral components, in which a determination of the parameters is not possible, these interpolated from adjacent spectral components, predetermined parameters weighted possibly further, predetermined parameters or parameter functions used and / or random parameters are used.

p0018Further, a receiver of the aforementioned type is inventively characterized by an analysis module which spectral distributions of the useful signals of the various channels and / or time differences or time differences of two or more different spectral components in the respective useful signal of the different channels together compares, from the comparison for each channel for at least two or more different spectral parameters for signal attenuation and / or signal delay in such a manner determined and a surround sound assembly which delays the corresponding spectral components from a containing the useful signals of all the channels one-channel signal according to the determined parameters and / or attenuated to the channel number of the multichannel audio broadcast corresponding channels distributed so that a listener gets a spatial sound impression for the corresponding spectral components, which essentially corresponds to a spatial sound impression of the directly reproduced audio signals of the channels.

p0019With this receiver, the already above-mentioned advantages of the method according to the invention can be achieved.

p0020Preferable further developments of the receiver are described in claims 12 to 17th

p0021In a preferred embodiment, the analysis module for each channel on a filter assembly which breaks down the respective useful signal or portions of the useful signal into a plurality, in particular four, spectral components. The analysis assembly has to be evaluated for each spectral component on a level detector and a corresponding number of the spectral components of this number of Pegelvergleichern, each level comparator, the level of an assigned spectral component in several, optionally compares all channels. Each level comparator is a Signalumformerstufe downstream which determines from the result of the comparison in the level comparator for each channel of the artificial sound space the parameter for signal attenuation and / or the parameter for signal delay. The spatial sound module has a filter module in which decomposes a the useful signals of all the channels containing a mono signal into a plurality of, particularly five, spectral components, wherein one of the number of processing Kanläle is provided corresponding number of Abschwächerbaugruppen and / or delay stages for at least one spectral component, wherein Abschwächerbaugruppen and / or delay stages produce a according to the provided for this channel and this spectral component of the analysis module parameters verzögerts and / or attenuated output signal. For each channel of the artificial surround sound ever combined an adder the so obtained spectral component signals.

p0022A time offset between the straight analyze segment of the multi-channel audio signal, and manipulated using this information segment of the mono signal has the advantage that a significantly prominent only in the course of the signal segment space information already can act on the creation of surround sound at the beginning of this signal segment.

Brief Description of Drawings

p0023The invention will be explained in more detail with reference to the accompanying drawings. These show in<dl id="dl0001"><dt>Fig. 1</dt><dd>a graphical representation of the channel separation, depending on the reception quality of a received signal for different decoding,</dd><dt>FIG. 2</dt><dd>a graphical representation of time resolution depending on the reception quality of a received signal for different decoding, </dd><dt>Fig. 3</dt><dd>a graphical representation of the frequency resolution depending on the reception quality of a received signal for different decoding,</dd><dt>Fig. 4</dt><dd>a graph of the reproduction of the current location information or of the stereophonic sound as a function of the reception quality of a received signal for different decoding,</dd><dt>Fig. 5</dt><dd>a schematic block diagram of a preferred embodiment of a receiver according to the invention,</dd><dt>Fig. 6</dt><dd>a schematic block diagram of a preferred embodiment of an analysis module of the inventive receiver of <figref idrefs="f0001">Fig. 1</figref>.</dd><dt>Fig. 7</dt><dd>a schematic block diagram of a preferred embodiment of a surround sound module of erfindungsgemäβen recipient of <figref idrefs="f0001">Fig. 1</figref> and</dd><dt>Fig. 8</dt><dd>different spectral weighting funct Onen.</dd></dl>

BEST MODE FOR CARRYING OUT THE INVENTION

p0024According to the invention are analyzed during the reception of multi-channel broadcasts information signals of different channels of multi-channel audio signal in their spectral distribution. By comparing the analysis of different channels is determined in space have which spectral components at which point their origin. This invention ascertained data for description of the original signal are referred to as "location information". While faulty reception hours is switched or remapped, which is designed based on the determined date from the disturbed Merkanal signal location information, so as distributes the spectral components of the mono signal on the various channels on an artificial surround sound, so that the impression is created that the spectral components would continue originated on this determined location. After the end of the disturbance is switched back on or -geblendet multi-channel operation. The parameters, such as cut-off frequencies of sub-frequency bands, and control signals for the design of the artificial room sound are referred to as "surround parameters". Depending on the technical realization surround parameters can be identical to the location information. The location information and / or surround parameters take data on single frequencies or signal components together in frequency ranges. The acquisition of the location information is carried out at certain times or for certain time intervals.

p0025The determination of the location information of the multi-channel signal and / or the surround parameters for the design of surround sound for example be implemented as a continuous function of the level as a function of frequency. A continuous function of the level in function of the frequency prevents the impression of a rapid change in location of a signal source, when the frequency of the source exceeding a range limit.

p0026The frequencies of common processed region flow optional with different weighting in the calculations (frequency-dependent evaluation function). The weighting can be chosen differently in the location information, as for the surround parameters. There are examined or edited parts of the spectrum that are clearly delimited or partially overlap. In this more suitable for digital signal processing division in frequency bands adjacent frequencies with lower weightings would be applied, so that even here the disturbing impression of a jumping signal source is reliably prevented.

p0027In addition to or in place of the analysis of signal levels, the time difference of the spectral (time differences) in the various channels is to the dam above taken in the destination rubbed method. In various useful signals (eg rhythm accented pop music), the time difference between the channels provides a more reliable indication of the location of the signal generation and is therefore more suitable as initial information for the simulation of artificial surround sound.

p0028Once detected location information is alternatively not replaced by the next measurement, but adds a weighting function, for example, averaged over longer periods of time or combined with a stronger emphasis on recent measurements. Thus, the acquisition of the location information may also take place continuously. With a weighting function can prevent short-term events in the useful signal affect the surround sound unduly strong

p0029When determining the location information only those spectral components are considered optional, that exceed a certain level threshold and a frequency-dependent threshold function. Noise components in the useful signal are thus kept away from the design of the artificial surround sound. The existing within a frequency range of small signal components further not affect the location determination of the dominant signal.

p0030For frequency ranges, their analysis does not provide sufficient information on the location of the signal origin, the required location information or surround parameters are interpolated from adjacent frequency bands, previously established values ​​used further (possibly weighted), predefined values ​​or functions used (eg those gaps as mono treated, so all channels equally distributed) and / or (possibly partially) replaced by random parameters. The re-use of the parameters determined from the last useful signal components and the interpolation of adjacent frequency ranges allow often good prognosis on the future location of the signal source.

p0031The division into frequency ranges (eg range limits), the evaluation functions and / or threshold functions for example, are made variable, in particular, they can be changed dynamically based on the analysis of the useful signal. This method makes it possible to edit individual spectral priorities of the useful signal as a whole, it prevents the splitting and spatial separation of such areas. Moreover, the Nutzsignalanalyse detect smaller signal amplitudes in quiet passages. The timing may be better adapted to the characteristics of the current interference situation, eg frequency of the fading dips. When disturbances in the single-channel information signal, such as noise, can be individually responsive, eg reducing the signal level and / or the channel separation in the high frequencies, so that the noise components not in the offices just for the treble channel are particularly strongly audible.

p0032Even with good reception signals of artificial surround sound is maintained optional temporarily or permanently. During these periods is temporally performed overlapping and / or alternatively, the determination of the location information and surround parameters and the creation of surround sound. There this eliminates exchange of multi-channel operation to surround and back, and their number is reduced. The result is a harmonious space and sound impression.

p0033All variants have in common that the distortion components of a disturbed signal no longer influence the signal amplitude and thus reduce the signal to noise ratio, but it suffers only the location information in poor werdendem signal. A complete multi-channel audio signal including at any time or the smallest time interval and for each frequency information on the location of the signal generation and a spatial arrangement of different sources related. Recording a microphone and thus with respect to the listener. The human ear is not able to fully evaluate this wealth of information. Fast switching from one channel to another usually come not before and would not be covered in the rest in the full speed from the ear. Now, when the multi-channel audio signal, for example, by noise components in signal becomes weaker, losing information, so still remains for a long time left enough remaining information to provide an acceptable impression of space for the ear. The invention uses this residual information to synthesize a surround sound again.

p0034According to the invention also still won during a disturbance information from the disturbed signal to make the "artificial" surround sound effect according to the currently transmitted location information. For critical reception situations reaches only the mono signal to the speakers, which is subjected to an artificial surround sound. There is a recording of the still existing in the distorted signal location information even in the times when the signal is so severely disturbed that it is no longer suitable for multi-channel playback, but again is not yet as strongly distorted than that the location information in largely had been distorted. Thus, the information for the design of artificial surround sound effect from the still available, recovered albeit low-quality multi-channel audio signal.

p0035In periods particularly poor reception for detectable by this method remains of spatial information are not sufficient to make an artificial surround sound. In these times the detection of spatial information is temporarily interrupted and continued with the last determined values ​​or performed Umblendung to mono mode.

p0036Expediently carried out with sufficient reception quality averaging the measurements over longer periods or frequency ranges in order to eliminate the noise components in the disturbed signal. This relationship graphically show the<figref idrefs="f0001">FIGS. 1-4</figref>,

p0037In the <figref idrefs="f0001">FIGS. 1-4</figref> is respectively plotted on the horizontal axis 10, a reception quality of a multi-channel audio transmission is normalized to one. When "1" is the optimal reception quality, whereas decreases in the direction of the origin of the coordinate system to the reception quality continued to increase until at "0" no reception is recorded. On the respective vertical axis 12 channel separation is (<figref idrefs="f0001">Fig. 1</figref>), A time resolution (<figref idrefs="f0001">FIG. 2</figref>), A frequency resolution (<figref idrefs="f0001">Fig. 3</figref>) And a quality of the reproduction of the current location information or the room sound each on one plotted normalized. The dashed line 14 shows the respective characteristics of a conventional decoder with transition from stereo to mono when signal interference occurs (mono-stereo blend). The crossed, solid line 16 shows the respective characteristics when using the location information before the occurrence of a fault and no further evaluation of the location information in the useful signal during the disturbance. The solid line 18 shows the characteristic at respective extracting the location information also from the disturbed signal, according to the invention.

p0038The location information or the location information may be distorted in three parameters, namely in the channel separation, the time resolution and the frequency resolution. The channel separation (<figref idrefs="f0001">Fig. 1</figref>) Corresponds to the spatial separation of the signal sources. The time resolution (<figref idrefs="f0001">FIG. 2</figref>) Shows, for example, in the maximum rate at which a source changes its place. The frequency resolution (<figref idrefs="f0001">Fig. 3</figref>) Indicates the extent to which frequency-related signal sources can be located at different locations. The quality of the reproduction of location information (<figref idrefs="f0001">Fig. 4</figref>) Is simply expressed the product of the three parameters. In this illustration initially remains unconsidered that the human ear evaluates the parameters vary, and this in turn varies the level and other parameters of the signal with the frequency.

p0039The <figref idrefs="f0001">Figures 1 to 4</figref> show for different decoding basic relationships for the three parameters (<figref idrefs="f0001">FIGS. 1-3</figref>) And the overall quality of the reproduction (<figref idrefs="f0001">Fig. 4</figref>) Depending on the quality of the received signal, which is plotted on the horizontal axis 10 in the manner previously described. This quality can be applied as a signal to noise ratio, in other sturgeon species, such as fading or multipath reception could another scale make sense. Conventional stereo decoder are relatively simple and thus constructed inexpensive. The method previously used in stereo receivers Mono Stereo Blend is based solely on the control of the channel separation (line 14). If problems occur is remapped quite early on single-channel operation, the remaining location information is no longer reproduced.

p0040Continuing to use previous location information before the fault (line 16) already at slightly disturbed signals, the time resolution is reduced to zero (<figref idrefs="f0001">FIG. 2</figref>), So that although a spatial impression is maintained, but this may differ considerably from the original information when prolonged disturbances. The reception interference is apparent with information bridged with the assumption that this bogus information the actual signal is initially very close. In contrast, (18 line) appears when the method according to the invention even during difficult a good spatial sound impression (<figref idrefs="f0001">Fig. 4</figref>), Which as far as possible reflects the original signal itself.

p0041The inventive method uses as far as possible, of all remaining information (line 18). An appropriate mix of time and frequency averaging is based on the resolution of the human auditory system and the computing power of the signal processing modules. In general, the temporal resolution is first, cause hardly audible loss of quality due to the inertia of the hearing. The summary in frequency bands due but for simple systems discernible distortions of the spatial information (arrow 20, fine resolution requires great computing power). A fading information content necessary to reduce one or both resolutions on. The channel separation is only withdrawn when the available signal in the rest of information is no longer sufficient for an acceptable audio quality. The process is particularly suitable for decoding of weak and broadly stable signals, ie below the conventional "Mono" level decoder. This sector of the gains in location information showing arrow 22nd

p0042<figref idrefs="f0002">figure 5</figref> shows a portion of a block diagram of an FM stereo radio receiver as a preferred embodiment of a receiver according to the invention. An antenna 1010 receives radio frequency signals from radio stations and transmits them to a selection and Demodulationsbaugruppe 1020 on. In this assembly in 1020, the signal of a radio station is detected and extracted the modulation content. An output 1021 of assembly 1020, the sum signal of both stereo channels L + R (left plus right). Another output signal 1022 includes the differential signal of the two channels LR. A third output 1023 indicates the extent to which the signal reception is subject to interference, whether by too low or rapidly fluctuating signal strength, multipath reception or other events. The sum signal 1021 reaches an assembly in 1100 to make an artificial surround sound. Both the sum signal 1021, and the difference signal 1022 to a stereo decoder 1030 is supplied, the generates two outputs 1031 to the right channel R and 1032 the left channel L. These two signals are applied to an analysis module 1300 for determining the parameter space. The module 1300 is also connected to the signal 1023rd The determined space parameters for signal attenuation and signal delay are passed over several lines in 1301 and 1302 to the surround assembly 1100th They serve as surround parameters for the realistic reproduction of surround sound.

p0043About two signals 1101 and 1102 get two signals artificially generated from the single-channel signal 1021 Rs (right synthetically) and Ls (left synthetically) to a superimposing unit 1040. The signals 1031 and 1032 are used to fade out unit 1040. The signal 1023 to provide information on interference is also forwarded to the superimposing unit 1040th Depending on this signal 1023 remapped in poor werdendem reception of the signals 1031 and 1032 to the synthetic signals 1101 and 1102nd Two signals 1041 and 1042 lead the outputs of superimposing unit 1040 through two amplifiers 1051 and 1052 to two speakers in 1061 and 1062. The modules 1030, 1100, 1300, 1040 and 1050 are exemplary in a digital signal processor (DSP) are summarized in 1500, the functions described are in particular constructed as software.

p0044<figref idrefs="f0002">figure 6</figref> shows an exemplary embodiment of the surround assembly 1100. The mono signal (L + R) 1021 is separated in a filter assembly 1110 in five spectral sub-signals 1111 to 1115, with the highest frequency components are output via signal 1111, the lowest frequency via signal 1115. The signal 1111 is applied to a first Abschwächerbaugruppe 1121, then passes through a first delay stage 1131 and passes to a first summing junction or adder 1141. a second path leads the signal 1111 via a second Abschwächerbaugruppe 1122 and a second delay stage 1132 to a second summing junction or adder 1142 . the signals 1112, 1113 and 1114 from 1133 to 1138 respectively guided via two paths through the attenuator 1123 to 1128 and delay stages to the summing points or adder 1141 and 1142nd Output lines 1143 and 1144 of two summing points 1141, 1142 form the outputs of the block 1100 and thus lead to the signals 1101 and 1102. The signal attenuation in the attenuators 1121-1128 and the throughput time of the delay stages 1131 to 1138 are controlled via signal buses 1129 and 1139, each consisting of eight lines, each line to be controlled per module. Since man is unable to recognize the origin of deep or low-pitched sound in this frequency range does not require a signal division. The signal 1115 is therefore routed directly to the two summation points or adder 1141 and 1142nd

p0045<figref idrefs="f0003">figure 7</figref> shows a Ausführgungsbeispiel for analysis module 1300. The coming out of the stereo decoder 1030 signals 1031 and 1032 for the right and left audio channels are separated into two filter assemblies 1310 and 1320 in four spectral partial signals 1311-1314 and 1321-1324, the lowest, from the human ear is not locatable frequencies will not be considered. The amplitude of the signal line 1311 with the highest frequency components of the right channel is determined by a level detector 1331st A resultant signal 1351 reaches a level comparator 1371. Here it is compared with the corresponding level of the left channel, which is connected via signal 1321 and a detector 1341 and 1361 line also reaches the stage 1371st A signal conversion step 1381 is generated from the result of the comparison, four control signals 1401-1404 for controlling the attenuator 1123 to 1128 and delay stages 1133 to 1138 in the surround assembly 1100. Corresponding signals and processing steps are available for the signals of the other three spectral components.

p0046To analyze the data transmitted in different channels signals no filter 1310/1320 for individual frequency ranges are used as an alternative, but one determined for each channel is a function of the level of frequency, from a list of a parameter set with characteristic frequencies and corresponding level values. The frequencies in between can be obtained, for example, by interpolation. For each channel to be created artificially, in place of the module 1100, for example, an analog multi-stage filter, such as operational amplifiers, controlled such that it transforms the accessing mono signal in accordance with these functions / parameters.

p0047In the filtering and determination of the parameters for signal attenuation and signal delay, for example, the frequency spectrum is divided into different parts which are in accordance with the <figref idrefs="f0004">Fig. 8</figref> illustrated different weighting functions are weighted. As a direct<figref idrefs="f0004">Fig. 8</figref> result, some areas overlap. further in some areas frequencies in the peripheral areas are weighted less than frequencies in the middle of such areas.

p0048Alternatively, the levels are measured in the frequency sub-segments over a longer period and these gradients for example, stored in a circular buffer and fed to a correlation stage. This level is determined by different time shifts and subsequent comparison of the channels for which time shift a distinct agreement is detectable. This time difference is used as information on the origin of the signal. The above-described simple level comparison may continue to be, a subsequent stage decides which in this case, better information (credible, pronounced, constant, or other criterion) gives the two localization strategies and is processed further.

p0049In a preferred development for averaging and weighting of Won ennen location information lowpass is provided in the to module 1371 and corresponding modules s.

p0050The frequency ranges generated in steps 1310 and 1320 (eg, signal 1311) alternatively be split into much finer frequency parts of the spectrum. All partial spectra with low signal levels are discarded, the remaining portions are added back to signals that correspond to those according to the first frequency division (eg 1311).

p0051If a gap in the local signal occurs, so for this spectral portion in all channels temporarily present a sufficient level, the DSP in digital computed lowpass function is stopped for this measurement. In an implementation in digital hardware, for example, the various measurements are written into a shift register. Each new measurement generates a clock signal and shifts in the transmission, the oldest from the register. A weighted addition of all registry components is the surround sound parameters. For the duration of a gap in the spatial signal of the clock is stopped to the shift register. Alternatively, first all frequency ranges are calculated with sufficient information and then interpolates the gaps in other frequency ranges linearly from neighboring areas.

p0052The levels in the frequency sub-segments are measured in an alternative embodiment for a longer period, and these curves stored in a ring buffer. At the beginning of a fault signal rise or drop is calculated from this recording of the level curve, which is further incorporated for the duration of the disturbance in the surround parameters.

p0053In a continuation of the invention, the highest peaks are determined in the frequency spectrum. This 1110 used as the center frequencies of the filters for spectral division.

p0054The signal at the input 1023 of the module 1040, alternatively, appear only in the shifting direction from stereo to surround sound immediately. however, In the rear glare from surround sound to stereo via a low-pass, so that in this case there is a delay and therefore remains active for a limited period even at times good reception even the artificial surround sound.

p0055On the signal input 1021 leading the surround assembly 1100, a delay element may be added, for example in the form of a digital FIFO memory. In this way, although the incoming just at the antenna 1010 signal sequence is processed in the analysis assembly 1300, the results of the analysis but act to a signal segment that has already been received earlier, in accordance with the offset by the time delay. A only in the course of the analysis clearly worked out location information can then act on the entire signal sequence from the beginning. To compensate for the time lag when Umblenden from artificial surround sound to playback of the original signals, are also the two inputs of Umblendeinheit 1040, the 1031 and 1031 lead the signals to equip with delay stages same time behavior.