Method for decoding distorted radio signals in multichannel audio signals

Technical field

0001The invention relates to a method for decoding multi-channel audio program, especially from two-channel stereo audio broadcasts, with a respective useful signal per channel, for each of the useful signals transmitted 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, according to the preamble of claim 1.

State of the art

0002Radio receiver for multi-channel audio signals, such as stereo broadcasts, are at different signal levels, with level variations of high-frequency carrier signal and the low frequency in radio interference (Audio) signal originating reflect as realistically as possible. Among them, the spatial arrangement of the various understood reproduced sound sources. This spatial arrangement is also referred to as location information. In a multi-channel audio broadcast, particularly two-channel stereo audio program, is to a respective useful signal per channel, said of each the useful signals transmitted 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. some Reception conditions deteriorate the audio quality of a Multi-channel signal, for example at low Nutzsignalpegeln and shrinkage or multipath reception. To these situations an acceptable Sound quality continue to be able to provide, is to remedy the situation in conventional Receivers reduces the channel separation, 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 as far least disruptive action under difficult reception conditions accepted.

0003The strategy described above is particularly promising, when the obtained one-channel signal due to the modulation method used a lower susceptibility to the aforementioned interference having. This is particularly the widespread frequency modulated FM broadcasting (Multplexsignal on the pilot tone) the case. Here, the mono information in the low, systemic less affected parts of the useful transfer.

0004Further methods are known to process a mono signal to that the impression of a spatial distribution of signal sources is obtained. For this purpose, the mono signal is broken down into several frequency ranges. These Areas are to varying degrees and / or with different delay 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 and closer Frequency segments can be distinguished. Always further Splitting ultimately lead while continuous functions Damping-over-frequency and delay-over-frequency, each one own function for each signal path. For discrete frequency ranges can be the width of 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).

0005Conventional stereo decoder are relatively simple and thus constructed inexpensive. The date when stereo receivers with such a stereo decoders used method with mono-stereo blend is based, such as previously explained, solely on the control channel separation. at occurring disorders is remapped very early single-channel, not reproduced whereby a possibly still existing location information becomes. The known simple stereo decoder have with noisy thus stereo signals only the choice of the location information throughout or partially to reject.

SUMMARY OF THE INVENTION, OBJECT, SOLUTION, benefits

0006It is an object of the present invention, an improved method and an improved receiver of the above kind available questions to which significantly reduces the disadvantages mentioned above.

0007This object is achieved by a method of the aforementioned type having the in claim 1 marked features and by a receiver of the type described above the features characterized in claim 12 dissolved.

0008For this it is inventively provided that during the reception the multichannel audio transmission in time periods in which the reception is disrupted such that a direct multi-channel playback no longer is possible, the location information is extracted from the useful signals, and with this current location information from a the useful signals of all channels Mono signal containing an artificial surround sound by spreading different frequency bands to the channel number of the multi-channel audio transmission appropriate channels, each with different temporal Delay and / or different damping of the levels in the different channels is generated.

0009This has the advantage that, although a multi-channel decoder according to the prior art no multichannel decoding with acceptable quality more can make that still existing in the disturbed useful signals Location information is extracted and a reproduction with a corresponding "artificial" surround sound, whereby this "artificial" generated surround substantially corresponds to the original surround sound.

0010Preferable further developments of the method are described in claims 2 to 11 described.

0011In a preferred embodiment, spectral distributions of 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 various channels together compared. are from the comparison for each channel for at least two or more different spectral parameters for signal attenuation and / or a signal delay so determined, and the corresponding containing spectral components of a the useful signals of all channels delayed channel signal according to the determined parameters and / or attenuated to the channel number of the multi-channel audio broadcast corresponding Channels distributed such that for a listener for the corresponding Spectral a spatial sound impression is generated, which essentially a spatial sound impression of directly reproduced Audio signals of the channels corresponds. This has the advantage that not switched to single channel mode during a reception interference must be 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 sound appears to the listener less disruptive than a falsification by mono operation. Short disturbances are no longer perceived by the listener. One can use shorter time constants and delays for multichannel operation return as a pulsation (appears in the periodic disturbances Signal source quickly jump between different locations) not or occur to a much lesser degree.

0012An undesirable impression of a quick change of location of the audio signal reproduced signal source when the frequencies of these Source a range boundary between adjacent spectral exceed, is avoided in that the parameters for attenuation and / or delay as a constant function of the level / time delay difference determined in function of the frequency will.

0013For digital signal processing, it is especially 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 be considered weighted differently. Here, the disturbing impression of a spatially bouncing source reliable avoided that the predetermined spectral components in the Frequency partially overlap and the frequencies of a spectral component lower in the overlap area to an adjacent spectral are weighted. Advantageously, the distribution of spectral components dynamically depending on the analysis of the useful signals changed.

0014To prevent short-term events in the useful signal a surround sound inappropriately strong influence, once certain parameters supplemented over time by means of a weighting function. in this connection takes place for example as a weighting function, a communication on predetermined Periods or a summary of a predetermined Period with greater consideration younger certain parameters.

0015To noise components in the payload of the design of an artificial keep room sound remotely, be in determining the parameters only those spectral components considered is a predetermined level threshold exceed or a frequency-dependent threshold function. The spectral component within a frequency range or existing signal components, thereby impairing a localization by comparing the useful signals of the various channels no longer dominant signal.

0016A good prediction of a future spatial location of a signal source is achieved by the fact that for such spectral components, in which a Determination of the parameters is not possible to use these from adjacent Spectral interpolated previously possibly weighted certain parameters used further, predetermined parameters or parameter functions used and / or random parameters are used.

0017Further, a receiver of the above-mentioned type is characterized according to the invention by an analysis module which spectral distributions of the useful signals of the various channels and / or propagation time differences or Delay time differences of two or more different spectral components in the respective useful signal of the various channels with one another compares, from the comparison for each channel for at least two or more different spectral parameters for signal attenuation and / or determines a signal delay such and a surround sound module Which the corresponding spectral components of a the useful signals of all channel signal containing channels in accordance with the specific delayed and / or attenuated to the channel number of the parameter Multi-channel audio broadcast corresponding channels distributed such that a Listeners for the corresponding spectral components a spatial Receives sound impression, which is essentially a spatial Sound impression of directly reproduced audio signals of the channels corresponds.

0018With this receiver, the advantages already mentioned above of achieved inventive method.

0019Preferable further developments of the receiver are in the claims 12 described to 17th

0020In a preferred embodiment, the analysis module for each channel a filter assembly in which the respective useful signal or parts of the useful signal into a plurality, in particular four spectral decomposed. The analysis module has to be evaluated for each spectral component a level detector and a number of spectral components corresponding number of Pegelvergleichern, with each level comparator the levels of an associated spectral component in several, optionally all channels compares. Each level is a comparator Signalumformerstufe downstream, which 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 certainly. The surround sound module has a filter assembly on which a useful signals of all channels containing mono signal in several, particularly five, separated spectral components, wherein for at least one spectral component of a number of processing Kanläle corresponding number of Abschwächerbaugruppen and / or Delay stages is provided, wherein Abschwächerbaugruppen and / or a delay stage according to this channel and this Spectral component provided by the analysis module parameters verzögerts produce and / or attenuated output signal. For each channel the artificial surround sound combined each an adder the so obtained spectral component signals.

0021A time offset between the multi-channel information signal which just analyze segment and manipulated using this information segment of Mono signal has the advantage that one only during the course of the signal segment clearly salient spatial information already on the design the surround sound can act earlier this signal segment.

Brief Description of Drawings

0022The invention will be with reference to the accompanying drawings explained in more detail. These show in<dl tsize="6"><dt>Fig. 1</dt><dd>a graphical Visu ung channel separation function on the reception quality of a received signal for different decoding methods,</dd><dt>FIG. 2</dt><dd>a graph of the 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 function on the reception quality of a received signal for various 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 Reception quality of a received signal for different decoding,</dd><dt>Fig. 5</dt><dd>a schematic block diagram of a preferred embodiment an inventive receiver,</dd><dt>Fig. 6</dt><dd>a schematic block diagram of a preferred embodiment an analysis module of the present invention Receiver of FIG. 1,</dd><dt>Fig. 7</dt><dd>a schematic block diagram of a preferred embodiment a surround sound module of erfindungsgemäβen Receiver of FIG. 1 and</dd><dt>Fig. 8</dt><dd>different spectral weighting funct Onen.</dd></dl>

BEST MODE FOR CARRYING OUT THE INVENTION

0023According to the invention during the reception of multi-channel transmissions Useful signals of different channels of multi-channel audio signal analyzed in their spectral distribution. By comparing the Analyzes of different channels is determined which spectral components where in space originate. This invention determined data describing the original signal are referred to as "location information" below. While impaired Reception times is switched to an artificial surround or remapped, the reference to the disturbed current from the Merkanal signal determined location information is designed so that Spectral components of the mono signal distributed to the various channels, so that the impression is created that the spectral components would continue their Originating at this determined location. After the end of the disturbance is on returns or -geblendet multichannel operation. The parameters such as eg cut-off frequencies of sub-frequency bands, and control signals for Design of artificial room sound are referred to as "Surround Parameter" means. Depending on the technical realization can be identical to the location information surround sound parameters. The location information and / or surround parameters take data Single frequencies or signal components together in frequency ranges. The detection of the location information takes place at specific time points or a desired time period.

0024The determination of the location information of the multi-channel signal and / or the Surround parameters for the design of surround sound, for example, as continuous functions of the level as a function of the realized frequency. A continuous function of the level as a function of the frequency prevents the impression of a fast The temporary movement of a signal source, if the frequency of the source a range limit exceeds.

0025The frequencies of common processed region flow optional with different weighting in the calculations (frequency-dependent Evaluation function). The weighting can be at the location information be chosen differently than for the surround parameters. It will Parts of the spectrum analyzed or processed, the accrued fixed are or partially overlap. In this digital signal processing more appropriate allocation in the frequency ranges are adjacent detected frequencies with a lower weighting, so that here the disturbing impression of a jumping signal source reliable is avoided.

0026In addition to or in place of the analysis of signal levels, the time difference the spectral (time differences) in the different Channels according to the procedures described above in the location information adopted. In various useful signals (eg accented rhythm Pop) provides the time difference between the channels, a more reliable Statement about the place of the signal generation and is therefore better than initial information for the simulation of artificial Surround sound.

0027Once unrecognized destination alternatively be the next replaced measurement, but supplemented with a weighting function, as averaged over longer periods of time or with greater consideration recent measurements summarized. Thus, the detection the location information or continuously. With a weighting function can prevent you that brief events affect the useful signal the surround inappropriately strong

0028In determining the location information option, only those Spectral considered that a certain level threshold exceed or a frequency-dependent threshold function. Noise components in the useful signal are thus on the design of artificial Surround sound kept. The within a frequency range existing small signal components further affect not more location determination of the dominant signal.

0029For frequency ranges, their analysis does not provide sufficient information provides on the location of the signal origin, the necessary location information or surround parameters from adjacent frequency ranges interpolated previously established values ​​used further (possibly weighted) predefined values ​​or functions used (eg those gaps treated as a single, that is to all channels equally distributed) and / or (if appropriate partially) replaced by random parameters. The re-use of recently determined from useful signal components parameters and the interpolation from adjacent frequency ranges allow often good prognosis on the future location of the signal source.

0030The division into frequency ranges (eg range limits), the evaluation functions and / or threshold functions are, for example, variable designed, in particular, they are based on the analysis of the useful signal dynamically changed. This method enables individual edit spectral priorities of the useful signal as a whole, it prevents splitting and spatial separation of such areas. Moreover, the smaller Nutzsignalanalyse in quiet passages Detect signal amplitudes. The timing may be better adapted to the characteristics the current interference situation, for example, frequency of fading dips be adjusted. When disturbances in the single-channel information signal, such as noise, can be individually responsive, eg reduction of signal level and / or the channel separation in the range of high frequencies, so that the unused noise components in the straight for the treble Channel are particularly strongly audible.

0031Even with good reception signals is optional temporarily or permanently the artificial surround maintained. is in these periods overlapping in time and / or alternatively, the determination of the location information and surround parameters and the creation of surround sound performed. 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.

0032All variants have in common that the distortion components of a no longer influence the disturbed signal, the signal amplitude and thus the signal to noise ratio reduced, but it suffers only the location information in poor werdendem signal. A complete multi-channel audio signal contains at any time or the smallest time interval and for each frequency information on the location of the signal generation or a spatial arrangement of various signal sources Fairs. Recording a microphone and thus with respect to the listener. The human ear is not capable of this wealth of information is complete evaluate. Fast switching from one channel to another usually come not before and would moreover in full Speed ​​is not detected by the ear. Now, when the multi-channel audio signal, for example, by noise components becomes weaker at Signal losing information, there remains enough yet for a long time Residual information left to an acceptable spatial impression of the ear provide. The invention uses this information to artificially rest a surround sound restore.

0033According to the invention, even during a fault condition still information recovered from the distorted signal to the "artificial" surround sound effect to customize according to the actual transmitted location information. For critical reception situations reaches only the mono signal to the Speakers, which is subjected to an artificial surround sound. It a detection is still present in the disturbed signal even in the times when the signal so greatly disturbed location information is that it is no longer suitable for multi-channel playback, but again not so greatly disturbed than that the location information had been distorted to a great extent. Thus, the information is to Design of artificial surround sound effect from the continued available, even if poor-quality multi-channel audio signal recovered.

0034In periods particularly poor reception, the search for this Method detectable residues of spatial information is not sufficient to to make an artificial surround sound. In these times, the detection the spatial information is temporarily interrupted and the further worked most recently calculated values ​​or to Umblendung Mono operation performed.

0035Expediently carried out with sufficient reception quality a Averaging the measurements over longer periods of time or frequency ranges, to eliminate the noise components in the disturbed signal. this relationship graphically show Figs. 1 to 4.

0036In Figs. 1 to 4 respectively on the horizontal axis 10, a reception quality a multi-channel audio broadcast on one plotted normalized. When "1" is the optimal reception quality, whereas in the direction the origin of the coordinate system to the reception quality always more declines until at "0" no reception is recorded. On the respective vertical axis 12 is a separation channel (Fig. 1), a Time resolution (Fig. 2), a frequency resolution (Fig. 3) and a quality the reproduction of the current location information or the room sound each applied to one normalized. The dashed line 14 shows the respective Characteristic of a conventional decoder with fading from stereo to mono when signal interference occurs (mono-stereo blend). The crossed, solid line 16 shows the respective characteristics 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 respective Characteristic at extracting the location information even from the disturbed Signal, according to the invention.

0037The location information or the location information may be distorted in three parameters be, namely in the channel separation, the time resolution and the frequency resolution. The channel separation (Fig. 1) corresponding to the spatial Separation of signal sources. The time resolution (Fig. 2) shows, for example, in the maximum speed at which a signal source their location changes. The frequency resolution (Fig. 3) indicates the extent to which localized in frequency similar signal sources at different locations can be. The quality of the reproduction of spatial information (Fig. 4) is in simple terms, the product of the three parameters. In this representation remains unconsidered that human Hearing the parameters evaluated very differently, and this in turn with the frequency, the level and other parameters of the signal varies.

0038Figures 1 to 4 show for various decoding principle Correlations for the three parameters (FIGS. 1 to 3) and the overall quality the reproduction (Fig. 4) depending on the quality of the received signal, which on the horizontal axis 10 in the previously described manner is applied. This quality can be used as N ratio be applied in other sturgeon species, such as Fading or multipath reception could be a different scale be useful. Conventional stereo decoder are relatively simple and thus inexpensive constructed. The previously used in stereo receivers Method with mono-stereo blend is based solely on the controller the channel separation (line 14). If problems occur is quite remapped early single-channel mode, the remaining location information will no longer be reproduced.

0039Continuing to use previous location information before the fault (line 16) is already at slightly disturbed signals, the time resolution is reduced to zero (Fig. 2), so that while maintaining a spatial impression, this but when prolonged disturbances greatly from the original information may differ. The reception interference is apparent with information bridged with the assumption that this bogus information the actual Signal comes very close initially. In contrast, shows in itself Application of the method (line 18) even at strong interference, good spatial sound impression (Fig. 4), the possible largely reflects the original signal itself.

0040The 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 Hearing and the computing power of the signal processing modules. In general, the temporal resolution is first, because of the inertia hearing hardly cause audible loss of quality. The abstract limited but discernible in frequency bands for simple systems Falsification of location information (arrow 20, fine resolution requires great computing power). A fading information content you have to reduce one or both resolutions on. The channel separation will only be withdrawn if the available signal in the remaining information is no longer sufficient for an acceptable audio quality. The The method is particularly suitable for decoding of weak but largely stable signals, ie below the conventional "Mono" level Decoder. shows this portion of the gain in location information Arrow 22nd

0041Figure 5 shows a section of a block diagram of an FM stereo radio receiver as a preferred embodiment for an inventive Receiver. An antenna 1010 receives RF signals of broadcasting stations and forwards 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 both stereo channels L + R (left plus right). Another output 1022 includes the difference signal of the two channels LR. A third output 1023 indicates the extent to which the signal reception Interference is subjected, either by too low or rapidly fluctuating signal strength, multipath reception or other events. The sum signal 1021 is applied to a module 1100 for generating an artificial surround sound. Both the sum signal 1021, as well as the difference signal 1022 are supplied to a stereo decoder 1030, the resulting two output signals 1031 to the right channel R and 1032 generates the left channel L. These two signals are applied to an analysis module 1300 for determining the parameter space. The Assembly 1300 is also connected to the signal 1023rd The determined Space parameters for signal attenuation and signal delay are several lines in 1301 and 1302 to the surround assembly 1100 passed. They serve as surround parameters for the realistic Reproduction of surround sound.

0042About two signals 1101 and 1102 reach two artificially from the single-channel signal 1021 generated signals Rs (right synthetically) and Ls (left synthetic) to a superimposing unit 1040. The signals 1031 and 1032 will be led to the superimposing unit 1040th The signal 1023 to Information about reception problems is also to superimposing unit 1040 forwarded. Depending on this signal 1023 at worse werdendem reception of the signals 1031 and 1032 the synthetic signals 1101 and 1102 remapped. Two signals 1041 and 1042 result in the outputs of the cross-fading 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 digital signal processor (DSP) 1500 are combined, wherein formed the functions described in particular as software are.

0043Figure 6 shows an exemplary embodiment of the surround assembly 1100th The mono signal (L + R) 1021 is a filter assembly 1110 in five spectral partial signals 1111-1115 disassembled, with the highest frequency components be delivered 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 arrives at a first summing junction or adder 1141. A second path carries the signal 1111 via a second Abschwächerbaugruppe 1122 and a second delay stage 1132 to a second Summing or adder 1142. The signals 1112, 1113 and 1114 each have two paths through the attenuator 1123 to 1128 and delay stages from 1133 to 1138 to the summing points and adder 1141 and 1142 performed. Output lines 1143 and 1144 the 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 1131-1138 are signal buses 1129 and 1139 controlled, each consisting of eight lines, each one line per to be controlled assembly. Since man is not able to Origin seen from deep or low-pitched sound is in this frequency range a signal splitting required. The signal 1115 is therefore directly to the two summation points or adder 1141 and 1142 passed.

0044Figure 7 shows a Ausführgungsbeispiel for the analysis assembly 1300th The coming out of the stereo decoder 1030 signals 1031 and 1032 the right and left audio channels are in two filter assemblies 1310 and 1320 to four in spectral partial signals 1311-1314 and 1321 1324 broken down, with the lowest, not localized by the human ear Frequencies are not considered. The amplitude of the Signal line 1311 with the highest frequency components of the right channel is determined with a level detector 1331st A resultant signal 1351 reached a level comparator 1371. Here it is with the appropriate level of the left channel compared, the signal via 1321 and a detector 1341 and line 1361 also at the level in 1371 has come. A signal conditioning stage 1381 generated from the result of the comparison, four control signals 1401-1404 for controlling the attenuator 1123-1128 and delay stages from 1133 to 1138 in the Surround sound module 1100. Corresponding signals and processing stages are available for the signals of the other three spectral components.

0045In order to analyze the transmitted signals in different channels alternatively no filter 1310/1320 used for one frequency, but one determined for each channel is a function of the level above the Frequency, from a list of a parameter set with characteristic frequencies and corresponding level values. The frequencies between can be obtained, for example, by interpolation. artificially for each for generating channel in place of assembly 1100, for example, an analog multistage filter, for example, operational amplifiers, is controlled such that it accordingly the accessing mono signal these functions / parameters transforms.

0046When filtering and determination of the parameters for signal attenuation and Signal delay is, for example, the frequency spectrum in different divided parts, which according to the illustrated in Fig. 8 different Weighting functions are weighted. As a direct of FIG. 8 shows some areas overlap. further be in some areas, frequencies in the peripheral regions less weighted as frequencies in the middle of such areas.

0047Alternatively, the levels in the frequency sub-segments are one measured long period and these courses, for example in a stored ring buffer and supplied to a correlation stage. This stage determined by different time shifts and subsequent Comparison of the channels for which time shift a pronounced Compliance is detected. This time difference is the information used about the origin of the signal. The above-described simple level comparison may continue to be, a subsequent Stage decides which of the two localization strategies in this case, better information (credible, pronounced, constant or other criterion) results and is processed further.

0048In a preferred development for averaging and weighting of Won ennen Location information is in assembly in 1371 and corresponding Assemblies en lowpass provided.

0049The frequency ranges generated in steps 1310 and 1320 (for example, 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 again to signals which after the first Frequency allocation (eg 1311) correspond.

0050If a gap in the local signal occurs, so for this spectral portion in all Channels temporarily present a sufficient level, the in DSP digital calculated low-pass function is stopped for this measurement. In an implementation in digital hardware, for example, be the various measurements written into a shift register. Each new Measurement generates a clock signal and shifts in the transmission of the oldest from the register. A weighted addition of all components Register gives the surround parameters. For the duration of a gap in the Local signal is interrupted to the shift register of the clock. alternative first all frequency ranges with sufficient information calculated and then the gaps linear in other frequency ranges interpolated from the neighboring areas.

0051The levels in the frequency sub-segments are in an alternative Embodiment, measured over a longer period of time and this Curves stored in a ring buffer. At the start of a disturbance from this recording of the level curve, a signal rise or drop calculated that for the duration of the disruption continued in the surround parameters is incorporated.

0052In a continuation of the invention, the highest peaks in Frequency spectrum determined. These are known as center frequencies of the filters 1110 used for spectral division.

0053The signal at the input 1023 of the module 1040, alternatively only in the shifting direction of stereo switched immediately to surround sound. at the rear glare from surround sound to stereo, however a out low-pass, so that in this case there is a delay and thus to limited period and at times good reception even of artificial Surround sound remains active.

0054At the signal input in 1021 leading the surround assembly 1100 can be added to a delay element, for example in the form of a digital FIFO memory. This closes the straight at the antenna 1010 incoming signal sequence processed in the analysis module 1300 the results of the analysis but act on a signal segment has already been received earlier, according to the offset by the Time Delay. A clearly worked out only in the course of analysis Location information can thus on the entire signal sequence from the beginning Act. In order to skew the Umblenden from artificial surround sound to compensate for the reproduction of the original signals, are also two inputs of Umblendeinheit 1040, the signals 1031 and lead 1031, equipped with delay stages same time behavior.