KR20170131006A - Method and apparatus for processing sound wave containing data symbols received via multipaths - Google Patents

Abstract

According to an embodiment of the present invention, provided is a method for processing a sound wave including a preamble and a data symbol received through a multi-path, which includes the steps of: (a) extracting an envelope of at least a part of the sound wave; (b) detecting a maximum peak in the extracted envelope; and (c) excluding the detected maximum peak from a maximum peak search object. The (b) and (c) steps are repeated several times. At this time, the position of the preamble of the signal received through each path is detected from each maximum peak detected in the several (b) steps. Accordingly, the present invention can improve a signal-to-noise ratio.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for processing a sound wave including data symbols received in a multi-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for processing a sound wave, and more particularly, to a method and apparatus for processing a sound wave including data symbols and receiving and processing sound waves emitted from one sound wave transmitter through multipath .

Recently, as smart devices become popular, sound communication using a built-in audio interface, that is, a speaker and a microphone, is being studied. For example, as disclosed in Korean Patent Application No. 2013-0043862 (filed on Apr. 19, 2013), when a non-audible sound wave containing specific information is inserted into a television (TV) broadcast to be broadcast to a viewer, And technologies in which a smartphone receives non-audible sound waves and provides customized advertisements to viewers based on the received non-audible sound waves.

However, in general, the sound wave communication using such a smart device is often performed in an indoor place such as a house or an office. Since the indoor environment is basically surrounded by structures such as walls and furniture, a sound wave emitted from a sound wave transmitter And reaches a sound wave receiver (for example, a smart phone). Therefore, in such a multipath environment, the sound wave receiver receives one sound wave with a plurality of sound waves having various time delays. Therefore, it is preferable that the sound wave receiver accurately overlaps the sound waves received over time to improve the signal-to-noise ratio .

According to an embodiment of the present invention, there is provided a sound wave processing method and apparatus capable of detecting and combining a plurality of sound waves along respective paths of a multipath when a same sound wave enters a sound wave receiving apparatus through a multipath, and then processing the sound waves do.

According to an embodiment of the present invention, there is provided a method of processing a multi-path sound wave including a preamble and a data symbol, the method comprising: (a) extracting an envelope of at least a part of the sound wave; (b) detecting a maximum peak in the extracted envelope; And (c) excluding the detected maximum peak from the maximum peak search object, wherein the steps (b) and (c) are repeated a plurality of times, And detecting the position of the preamble of the signal received in each path from the respective maximum peaks.

According to an embodiment of the present invention, there is provided an apparatus for processing a multi-path received sound wave including a preamble and a data symbol, the apparatus comprising: an envelope detection unit configured to extract an envelope of at least a part of a received sound wave; And repeating the operation of detecting the maximum peak in the extracted envelope and excluding the detected maximum peak from the maximum peak search object a plurality of times, and detecting the position of the preamble of the signal received on each path from each maximum peak detected in the repeated execution A peak processing unit configured to detect a peak value; And a symbol detection and demodulation unit for detecting and demodulating a data symbol in a sound wave using the detected position information of each preamble.

According to an embodiment of the present invention, there is provided a computer-readable recording medium on which a sound processing application for processing sound waves received by a multipath including a preamble and a data symbol is recorded, And the sound processing method according to any one of claims 1 to 8 is executed on the receiving apparatus. The computer-readable recording medium records the sound processing application.

According to an embodiment of the present invention, when the same sound wave enters the sound wave receiving apparatus through a multipath, a plurality of sound waves along each path of the multipath are detected, combined, and demodulated to increase the size of the received signal, : Signal-to-Noise Ratio) and improve the reception success rate.

1 is a view for explaining a sound wave processing method and an apparatus according to an embodiment of the present invention;
2 is a diagram for explaining a sound wave including a preamble and a data symbol according to an embodiment,
3 is a view for explaining a sound wave receiving apparatus according to an embodiment,
4 is a block diagram for explaining a sound wave processing method according to an embodiment.
5 is a flowchart for explaining a sound wave processing method according to an embodiment,
FIGS. 6 and 7 illustrate an exemplary envelope graph for explaining a sound wave processing method according to an embodiment,
8 is an exemplary flowchart of a method of setting a search window in a sound processing method according to an embodiment;
Figures 9 and 10 illustrate exemplary envelope graphs to illustrate an exemplary method of setting and extending a search window in accordance with one embodiment,
11 is an exemplary flowchart of a step of excluding a search target in a sound wave processing method according to an embodiment,
12 and 13 are exemplary envelope graphs for explaining the search target excluding step according to an embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and advantages of the present invention will become more readily apparent from the following description of preferred embodiments with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In this specification, when an element is referred to as being on another element, it means that it can be formed directly on the other element, or a third element may be placed therebetween.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms "comprises" and / or "comprising" used in the specification do not exclude the presence or addition of one or more other elements.

Also, terms such as " ... part ", "module "," ... board ", "... block ", etc. used to refer to components of the invention are used herein to describe at least one function or operation Unit, which may be implemented in hardware, software, or a combination of hardware and software.

Hereinafter, the present invention will be described in detail with reference to the drawings. In describing the specific embodiments below, various specific details have been set forth in order to explain the invention in greater detail and to assist in understanding it. However, it will be appreciated by those skilled in the art that the present invention may be understood by those skilled in the art without departing from such specific details. In some instances, it should be noted that portions of the invention that are well known in the description of the invention and not significantly related to the invention do not describe confusion in describing the present invention.

1 is a view for explaining a sound wave processing method and an apparatus according to an embodiment of the present invention.

Referring to the drawings, a sound processing apparatus according to an embodiment of the present invention may be embodied in a sound wave receiving apparatus 20. The sound wave receiving apparatus 20 receives the sound wave transmitted from the sound wave transmitting apparatus 10 and the sound wave is processed by the sound wave processing apparatus in the receiving apparatus 20. [

The sound wave transmitting device 10 is a device for outputting a sound wave. In the illustrated embodiment, the sound wave output from the sound wave transmitting device 10 includes a signal modulated with digital information, and may be a signal in the non-audible or audible band.

The non-audible range refers to a frequency band that can not be heard by human hearing, and may include frequencies in the 18 to 24 KHz band, for example. In one embodiment, a sound wave in the non-audible range is generated by an auditory sound generator (not shown) and specific digital information is injected into this non-audible sound sound wave. The generation of the non-audible sound wave including the specific digital information can be performed by various modulation methods such as amplitude modulation (ASK), frequency modulation (FSK), time-varying modulation (Chirp modulation) To generate non-audible sound waves by modulating it by one of the non-audible sound waves.

As used herein, the term "sound waves" refers to those in which the vibrations of an object are propagated through the medium (air) so that a person can hear them audibly. Unless there is a particular need for distinction, Or "sound ".

For example, Korean Patent Application No. 2013-0107604 (a method of transmitting and receiving a sound wave using time-varying frequency-based symbols and a device using the same), or a method of generating and outputting a non-audible sound wave, Korean Patent Application No. 2014-0169557 (a method of generating a broadcast image file or a streaming packet including non-audible sound waves and a television broadcast system using the method) can be used.

The sound wave output from the sound wave transmitting apparatus 10 may include a signal obtained by modulating digital information, and the signal modulated by the digital information may include, for example, a preamble and a data symbol (symbol). The preamble is inserted in front of the data symbol as a signal for synchronizing the transmission timing between the sound wave transmitting device 10 and the receiving device 20 or for informing the receiving device 20 of the start of the sound wave signal transmission. The preamble can be set as a signal of a specific type predetermined between the sound wave transmitting device 10 and the receiving device 20. [ In the illustrated embodiment, the preamble is a chirp signal whose frequency is constantly increased with time, and may have a predetermined length of time.

The data symbol is, for example, a signal indicated by " 10101100 " at the rear end of the preamble in the illustrated embodiment. In general, a symbol represents a unit of data meaningful in data communication. In the present specification, information to be transmitted from the sound wave transmitting device 10 to the sound wave receiving device 20, or information to which the information is modulated (digital or analog ) Signal.

In the illustrated embodiment, for example, "10101100" is assumed as the digital information to be transmitted. In this case, the digital bit "1" is assigned to the chirp signal whose frequency increases with time, And the chirp signal is reduced. However, this is an exemplary method for explaining the present invention, and those skilled in the art will appreciate that there are various other ways of modulating digital information into analog sound wave signals.

1, the sound wave transmitting device 10 outputs the sound wave including the digital information through an output device such as a speaker. At this time, the sound wave outputted from the transmitting device 10 is a medium (air) The sound wave receiver 20 may directly reach the sound wave receiving device 20 through the route (route 1) but may also be reflected by an object (wall surface, furniture, etc.) The same sound wave signal is received several times according to various sound wave paths.

FIG. 3 is a diagram for explaining a sound wave receiving apparatus 20 according to an embodiment, and illustrates components of the sound wave receiving apparatus 20 by way of example. Here, the 'sound wave receiving apparatus' may be, for example, a portable computer such as a smart phone, a tablet PC, a wearable computer, or a desktop PC.

3, the computer includes a microphone 21 capable of receiving a sound wave, an A / D converter 22 for converting the received sound wave into a digital signal, a memory (not shown) A computer processor 25 for loading and executing an application in the memory 23 and other hardware and software resources 26 required to operate the sound wave receiving apparatus 20.

The microphone 21 receives the sound wave and converts it into an electrical signal of an analog form. At this time, the sound wave received by the microphone 21 may be a sound file including the preamble and digital information described with reference to FIG.

The A / D converter 22 converts the electrical signal output from the microphone 21 into a digital signal by a predetermined sampling rate and a quantization level. For example, the predetermined sampling rate may be any of 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, and 192 kHz, and the predetermined quantization level may be 8 bits, 16 bits, 20 bits, 24 bits, and 32 bits. < / RTI >

The application 24 is one or a plurality of computer programs that are executed to process sound waves, and may perform, for example, operations of detecting, demodulating, and / or decoding digital information from sound waves. In one embodiment of the present invention, the application 24 may perform at least some functions of an envelope detection unit 230, a multipath acoustic wave processing unit 240, and the like, which will be described later with reference to FIG.

4 is a block diagram for explaining a sound wave receiving apparatus 20 according to an embodiment. 3 is a block diagram of the sound wave receiving apparatus 20 viewed from a hardware point of view, and Fig. 4 shows a functional block of the sound wave receiving apparatus 20 in terms of a function of processing a sound wave.

4, the sound wave receiving apparatus 20 may include a microphone 210, an A / D converter 220, an envelope detection unit 230, and a multipath sound processing unit 240.

The microphone 210 receives a sound wave and converts it into an analog type electrical signal, which is the same as or similar to the microphone 21 shown in FIG. In one embodiment, the microphone 210 may be configured to receive acoustic wave signals of a predetermined intensity or higher.

The A / D converter 220 converts the electrical signal output from the microphone 210 into a digital signal according to a predetermined sampling rate and a quantization level, and is the same as or similar to the A / D converter 22 shown in FIG. 3 Detailed explanation is omitted.

The envelope detection unit 230 can extract an envelope of at least a part of the received sound wave. In one embodiment, the envelope detector 230 can extract at least the envelope of the preamble portion of the received sound wave. Techniques for detecting an envelope of a part or all of a sound wave are well known and are disclosed, for example, in Korean Patent Application No. 2013-0107604. As an exemplary method for extracting an envelope, an A / D converter 220 converts a preamble of a sound wave signal into a digital signal, and then performs a correlation process (for example, a received preamble in a matched filter) (FFT) and multiplies it by a fast Fourier transform (FFT) of a previously stored time-inverted preamble), then performs a zero-filling and an inverse fast Fourier transform (IFFT) to obtain an envelope.

An example of the envelope of the preamble extracted by the envelope detection unit 230 is shown in the lower end of FIG. It can be seen that there are four peaks (indicated by dotted lines) in the exemplary envelope of FIG. 4, where each of these four peaks represents the position of the preamble and one sound wave is transmitted to the sound wave receiver 20 4 < / RTI >

The multi-path sound processing unit 240 receives a plurality of sound waves when it is received a plurality of times by the receiving apparatus 20 through the multipath, and detects and demodulates the data symbols from the sound waves. In one embodiment, the multi-path sonic wave processor 240 may include a peak processing unit 241 and a symbol detection and demodulation unit 242.

The peak processing section 241 may repeat the operation of detecting the maximum peak in the envelope line and excluding the detected maximum peak from the next peak search object a plurality of times. Further, the peak processing section 241 can detect the position of each preamble from each maximum peak detected in this repetitive execution.

In one embodiment, the peak processing section 241 can determine how long to repeat the detection and exclusion of the maximum peak for the envelope. For example, when the peak processing unit 241 detects the maximum peak, it is determined whether or not the detected maximum peak is less than a predetermined threshold value, and if it is less than the predetermined threshold value, such repeated execution can be stopped. The threshold value may be set based on at least one of a noise level when receiving the sound wave signal that does not include the data symbol and a signal level of the first detected maximum peak.

When the threshold value is determined based on the noise level, for example, an arbitrary value that is larger than the average value (or maximum value) of the noise of the sound wave signal that does not include the data symbol can be set as the threshold value.

When a threshold value is determined based on the signal level of the maximum peak, for example, if the first maximum peak is detected, an arbitrary value (for example, a value smaller by 4 dB) smaller than the signal level of the first detected maximum peak can be set as a threshold value have.

Alternatively, the peak processing section 241 may determine how long to repeat the maximum peak detecting and excluding operations based on the maximum number of detected peaks. For example, when the maximum number of peak detection times is set to five, if the maximum peak is detected five times, the detection and exclusion of the maximum peak can be terminated thereafter.

In another alternative embodiment, at least two combinations of the noise level, the signal level of the maximum peak, and the maximum number of peak detections may be considered. For example, the noise level and the signal level of the maximum peak may be respectively calculated, and a larger value (or a smaller value) may be set as a threshold value.

On the other hand, the peak processing section 241 detects the maximum peak within a predetermined time interval ("search window") when detecting the maximum peak. In one embodiment, the peak processing unit 241 may detect a first maximum peak in an envelope, and then set a search window up to a predetermined time interval around the first maximum peak in the time domain of the envelope. Thus, when the search window is set based on the first maximum peak, this search window can be used as it is when detecting the second and subsequent maximum peaks.

In one embodiment, up to a predetermined time interval is set as a search window around the first detected maximum peak. However, in an alternative embodiment, when the boundary value of the search window is set to a certain condition, the search window is extended. When the maximum peak is detected after the second search, the maximum peak is detected using the extended search window It is possible. This will be described later with reference to FIG. 8 to FIG.

The peak processing section 241 can exclude an envelope of a predetermined time width from the search object centered on the maximum peak in the time domain of the envelope in order to exclude the maximum peak from the search target. At this time, the predetermined time width to be excluded may be a preset value. However, in an alternative embodiment, it may be possible to extend this time width to exclude according to certain circumstances, and to exclude the maximum peak of the envelope and its surroundings from the search target with this extended time width. This will be described later with reference to FIG. 11 to FIG.

The symbol detection and demodulation unit 242 is a functional unit for detecting and demodulating a data symbol from the received sound wave signal. The symbol detection and demodulation unit 242 can detect and demodulate data symbols in the sound wave using the position information of each preamble detected by the peak processing unit 241. [

When the position of each preamble detected by the peak processing unit 241 is detected, the starting position of the data symbol can be known from this. Therefore, the symbol detection and demodulation unit 242 can identify and detect the data symbols corresponding to the respective preambles using the positional information of the respective preambles. For example, when one sound wave is transmitted to the sound wave receiving apparatus 20 through four different paths, the peak processing section 241 sequentially detects the four maximum peaks and detects the position information of the preamble corresponding to each maximum peak , The symbol detection and demodulation unit 242 detects data symbols corresponding to the respective maximum peaks.

In one embodiment, the symbol detection and demodulation unit 242 may weight each detected data symbol, combine them, and demodulate the combined data symbols to extract information. The configuration for weighting and combining the respective data symbols can be implemented using, for example, an MRC (Maximal Ratio Combining) method. The configuration for demodulating (bit detecting) the data symbols inserted in the sound wave signal and extracting information is described in For example, Korean Patent Application Nos. 2012-0038120, 2012-0078410, 2013-0107604, 2015-0118809, etc.

An exemplary method of processing sound waves received in multiple paths will now be described with reference to FIGS. 5-7.

FIG. 5 is a flowchart for explaining a sound wave processing method according to an embodiment, and FIGS. 6 and 7 illustrate an envelope of an exemplary preamble for explaining a sound wave processing method.

Referring to FIG. 5, it is assumed that a sound wave is received by the microphone 210 of the sound wave receiving apparatus 20 before the step S110, and the sound wave signal is converted into a digital signal by the A / D converter 220. Thereafter, in step S110, the envelope detector 230 extracts at least a portion of the envelope of the sound wave. In one embodiment, the envelope detector 230 extracts at least the envelope of the preamble of the received sound wave. In this regard, Figure 6 shows a portion of the extracted envelope.

Thereafter, in step S120, the peak detecting section 241 detects the first maximum peak in the extracted envelope. Referring to FIG. 6, the maximum peak ("first maximum peak") around 1304 ms is detected. In this step S120, the peak detecting section 241 can set a "win _search " which is a range for searching for the maximum peak. For example, the peak processing section 241 may detect the first peak in the envelope, and then set the search window up to a predetermined time interval around the first peak (about 1304 ms) in the time domain of the envelope. In the example of FIG. 6, a win _search having a size of 40 ms is set up including 20 ms before and after. Thus, when the search window is set based on the first maximum peak, this search window can be used as it is when detecting the second and subsequent maximum peaks.

Next, in step S130, it is determined whether or not the detected maximum peak is less than a predetermined threshold value. As described with reference to Fig. 4, the threshold at this time can be set based on at least one of the noise level when receiving the sound wave signal that does not include the data symbol and the signal level of the first detected maximum peak.

As a result of the determination in step S130, if it is less than the predetermined threshold value (S130_Yes), it is determined that the maximum peak is noise other than the sound signal including the data symbol, and no further sound processing is performed.

As a result of the determination in step S130, if it is greater than or equal to the predetermined threshold value (S130_No), the process proceeds to step S140, and information on the maximum peak is obtained. The information at this time may include, for example, the time at which the maximum peak appears, from which the position of the preamble can be known and the start position of the data symbol can be known. The obtained information is temporarily stored in a storage means such as a memory, and when the symbol detection and demodulation unit 242 detects and demodulates each data symbol from the sound wave signal, the information indicating the start position of each data symbol Can be used.

Then, in step S150, the maximum peak detected (i.e., the "first maximum peak" in Fig. 6) is excluded from the maximum peak search target. As an example for excluding the maximum peak, an envelope of a predetermined time width (2 ms in Fig. 6) around the maximum peak can be excluded, as shown in Fig.

In this case, "excluded from the search target" may mean, for example, that the envelope signal of the predetermined time width (2 ms) is actually removed (deleted) in the time domain of the envelope in FIG.

In addition, in the alternative embodiment, "excluded from the search target" means that instead of actually removing the envelope of the predetermined time width (2 ms) in the time domain, the envelope signal within the predetermined time width at the maximum peak search is not considered can do. In this alternative embodiment, in the execution of the step S120 of detecting the maximum peak, instead of the search target excluding step S150 and the subsequent maximum peak detecting step S120 as independent steps, It is to be understood that the maximum peak is detected while excluding the predetermined time width region from the detection target regardless of the value of the envelope in the time width.

Thereafter, the peak processing unit 241 repeatedly executes the maximum peak detection (S120), the comparison with the threshold value (S130), the maximum peak information acquisition (S140), and the search target excluding (S150). For example, FIG. 7 shows a case where the second peak detection (S120) is performed for the second time. Referring to FIG. 7, since the first maximum peak is already detected in the preceding steps and is excluded from the next peak search target, the maximum peak ("second maximum peak") in the vicinity of approximately 1306 ms .

Next, it is determined whether or not the second maximum peak detected in step S130 is less than a predetermined threshold value. If it is determined to be equal to or greater than the predetermined threshold value (S130_No), information on the second maximum peak is obtained (S140) The peak is excluded from the search target at the next maximum peak search (S150).

As described above, the peak processing section 241 repeatedly executes the step of detecting and excluding the maximum peak a plurality of times, and the symbol detection and demodulation section 242 detects the peak Detects the data symbols corresponding to each of the maximum peaks of the detected data symbols, weights each of the detected data symbols, and combines them to demodulate the data symbols.

An exemplary embodiment for setting a search window will now be described with reference to Figures 8-10.

FIG. 8 is an exemplary flowchart for setting a search window in a sound processing method according to an embodiment, and FIGS. 9 and 10 are views for explaining an exemplary method of expanding a window when setting a search window.

Referring to FIG. 8, step S160 of setting a search window may be performed between detecting the first maximum peak ("first S120") and detecting the second maximum peak ("second S120"). The dotted line between the "first S120" and the "second S120" at this time indicates that the window setting step S160 can be executed at any point between the first S120 and the second S120 steps. For example, the search window setting step S160 may be executed immediately after the first step S120 in FIG. 5, or alternatively, between steps S130 and S140, or between steps S140 and S150.

Referring again to FIG. 8, in step S161, a win _search is set up to search for a maximum peak. In one embodiment, up to a certain time interval back and forth around the first detected maximum peak can be set as the search window.

For example, assuming that a win _search is set as shown in FIG. 9, as the boundary value of the right boundary of the win _search in the envelope of FIG. 9 goes out of the search window (that is, As you go to the right of the graph, you can see that the envelope continues to increase. That is, the boundary of the search window is located during the rise of the peak, and the envelope peaks outside the window boundary. Therefore, the middle point where the envelope increases (that is, the shoulder) is caught by the boundary of the search window and the value is too large to be recognized as a peak, so that it may be misrecognized even if it is not the preamble position. Therefore, in order to prevent such a shoulder from being mistaken as a peak, it is desirable to extend the search window to the first-ever peak outside the boundary just when the boundary value of the search window corresponds to the shoulder.

To this end, in step S163, it is determined whether the boundary value of the search window corresponds to the shoulder of the envelope. For example, it is determined whether the boundary value of the search window gradually increases toward the outside of the window. If the boundary value increases (S163_Yes), the win _search is extended until the boundary value reaches the peak of the envelope (S165). That is, as shown in FIG. 10, the right boundary of the win _search was extended to the peak just outside the boundary of the first search window. As described above, the maximum peak can be detected using the extended window from the step of detecting the second and subsequent maximum peaks after extending the win _search in step S165.

If it is determined in step S163 that the boundary value of the win _search does not increase as the window goes beyond the window (S163_No), there is no problem that the shoulder is mistaken as a peak, so the search window set in step S161 is maintained (S167), and the maximum peak is detected using the search window from the step of detecting the second and subsequent maximum peaks.

Meanwhile, the above-described method of expanding a search window can be applied to either or both of the left and right boundary values of the search window.

An alternative embodiment of step S150 of excluding the maximum peak from the search target will now be described with reference to FIGS. 11 to 13. FIG.

FIG. 11 is an exemplary flowchart of a step of excluding a search target in the sound processing method according to an embodiment, and FIGS. 12 and 13 show an exemplary envelope for explaining a search target excluding step.

Referring to the example envelope of FIG. 12, the envelope of the predetermined time width ("win _erase " in FIG. 12) centered around the maximum peak is removed to exclude the detected maximum peak from the maximum peak search target . In this example, the shoulder region of the removed maximum peak remains, and when the boundary value of the broken portion of this shoulder region is higher than the surrounding peaks, the boundary value of this shoulder portion There is a possibility of being detected as the maximum peak. Therefore, in order to prevent such a case, it is preferable to exclude the remaining shoulder portion of the maximum peak that has already been removed from the maximum peak search target.

To this end, according to the flowchart shown in FIG. 11, the envelope of the predetermined time width is excluded from the search target in the step S151 (that is, the envelope of the predetermined time width (win _erase ) Then, in step S153, it is determined whether or not the boundary value of the excluded time width decreases further from the maximum peak. As a result of the determination, if the boundary value of the excluded time width decreases as the distance from the maximum peak decreases (S153_Yes), the flow advances to step S155 to select a valley immediately left and / or right , The point at which the boundary value of the excluded time width does not decrease any more, or the slope of the envelope becomes zero) is excluded from the maximum peak search object (see FIG. 13).

If the boundary value of the excluded time width does not decrease even if the boundary value of the excluded time width deviates from the maximum peak (S153_No), it means that the valley around the maximum peak has already been excluded from the search target in step S151, (win _erase ).

Thus, according to the embodiment of Figs. 11 to 13, the range to be excluded from the search target is further expanded according to whether or not the shoulder area remains on the left and right sides of the envelope excluded from the search target, And then searching for the maximum peak can be repeated.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Therefore, the scope of the present invention should not be limited by the described embodiments, but should be determined by the scope of the appended claims, as well as the appended claims.

10: Sound wave transmitter
20: sound wave receiver
21, 210: a microphone
22, 220: A / D converter
230: envelope detection unit
240: Multi-path sound wave processor
241:
242: Symbol detection and demodulation unit

Claims (17)

CLAIMS 1. A method for processing a received sound wave in a multipath including a preamble and a data symbol,
(a) extracting an envelope of at least a part of the sound wave;
(b) detecting a maximum peak in the extracted envelope; And
(c) excluding the detected maximum peak from the maximum peak search target,
Wherein the steps (b) and (c) are repeated a plurality of times, and the position of each preamble is detected from each of the maximum peaks detected in the step (b). 2. The method according to claim 1, further comprising, between the step (b) of the first execution of the step (b) and the step of the step (b)
And setting a search window at predetermined time intervals around the maximum peak in the time domain of the envelope. The method according to claim 1,
Determining whether the detected maximum peak is less than a predetermined threshold value or whether the number of detected maximum peaks has reached a predetermined number after the step (b) of detecting the maximum peak,
And when it is determined that the predetermined number is less than the predetermined threshold value or when the predetermined number is reached, repeats the repeated execution. The method of claim 3,
Wherein the predetermined threshold value is set based on at least one of a noise level when receiving a sound wave not including a data symbol and a signal level of a first detected maximum peak. 3. The method of claim 2, wherein the setting of the search window comprises:
Determining whether at least one of the left and right boundary values of the search window increases toward the outside of the search window; And
And expanding the search window until the boundary value reaches a peak of an envelope when the boundary value increases as a result of the determination. The method of claim 1, wherein the step (c) of excluding the maximum peak from the maximum peak search target comprises:
And removing an envelope having a predetermined time width centered on the detected maximum peak in the time domain of the envelope. The method of claim 1, wherein the step (c) of excluding the maximum peak from the maximum peak search target comprises:
Determining whether the boundary value of the excluded time width decreases with increasing distance from the maximum peak; And
And excluding the envelope from the maximum peak search object to a point where the boundary value of the excluded time width does not decrease any more when the determination result is decreased. The method according to claim 1,
Detecting a data symbol corresponding to each of the plurality of detected maximum peaks using the detected position information of each preamble;
Weighting and combining the detected data symbols; And
And demodulating the combined data symbols. ≪ Desc / Clms Page number 22 > An apparatus for processing a sound wave received by a multipath including a preamble and a data symbol,
An envelope detector configured to extract an envelope of at least a part of the received sound wave;
A peak detector configured to detect the maximum peak in the extracted envelope and to exclude the detected maximum peak from the maximum peak search object a plurality of times and to detect the position of each preamble from each maximum peak detected in the repeated execution; A processor; And
And a symbol detection and demodulation unit for detecting and demodulating data symbols in a sound wave using the detected position information of each preamble. 10. The method of claim 9,
Wherein the peak processing unit is configured to set a search window at a predetermined time interval around the maximum peak in the time domain of the envelope after detecting the first peak of the plurality of times. 10. The method of claim 9,
The peak processing unit determines whether or not the detected maximum peak is less than a predetermined threshold value or whether or not the number of detected maximum peaks has reached a predetermined number, and when it is determined that the detected maximum peak is less than a predetermined threshold value, When the number of the sound waves reaches a predetermined number, repeats the repeated execution. 12. The method of claim 11,
Wherein the predetermined threshold value is set based on at least one of a noise level when receiving the sound wave signal not including the data symbol and a signal level of the first detected maximum peak. 11. The method of claim 10,
The peak processing unit, when setting the search window,
Determining whether at least one of the left and right boundary values of the search window increases as it goes out of the search window, and when the boundary value increases as a result of the determination, expanding the search window until the boundary value reaches a peak of an envelope Characterized in that it comprises: 10. The method of claim 9,
Wherein the peak processing unit removes an envelope having a predetermined time width centered on the detected maximum peak in the time domain of the envelope so as to exclude the maximum peak from the maximum peak search target. 15. The method of claim 14,
The peak processing section, when excluding the maximum peak from the maximum peak search target,
Determining whether the boundary value of the time width to be excluded decreases as the distance from the maximum peak is decreased; and, when the determination result indicates that the boundary value of the excluded time width is decreased, And excluded from the search target. 10. The method of claim 9,
The symbol detection and demodulation unit detects data symbols corresponding to each of the plurality of maximum peaks using the detected position information of each preamble, assigns weights to the detected data symbols, combines them, And demodulate the received data symbols. A computer-readable recording medium storing a sound processing application for processing a sound wave received by a multipath including a preamble and a data symbol,
Characterized in that the sound processing application is loaded in a memory of a sound wave receiving device and executes on the receiving device the sound wave processing method according to any one of claims 1 to 8. A computer- Lt; / RTI >

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