KR101790221B1 - Method of data demodulating using reliability of symbol and sound wave receiving apparatus using the same method - Google Patents

Abstract

According to an embodiment of the present invention, there is provided a data demodulating method for demodulating data in a symbol unit of a predetermined length of time by receiving an acoustic signal packet including data, the method comprising the steps of: (K) is an integer equal to or greater than 2, and k is an integer equal to or greater than 1 and equal to or less than K), for a kth received symbol, (a) the magnitude of the first sound wave signal in the first frequency band, Calculating reliability of a symbol for the first sound wave signal by comparing magnitudes of the two sound wave signals; (b) determining a data bit corresponding to the received symbol based on the calculated reliability; And (c) updating the undone data based on the determination of the data bit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of demodulating data using symbol reliability,

The present invention relates to a demodulation method for demodulating a sound wave signal and a sound wave receiving apparatus to which the method is applied. More particularly, the present invention relates to a demodulation method for demodulating a sound wave signal, And a sound wave receiving apparatus using the same.

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, Techniques for receiving a non-audible sound wave from a sound wave receiving device (for example, a smart phone) and providing contents such as customized advertisements to a viewer based on the received non-audible sound waves are being studied.

However, in order for the sound wave receiver to receive the sound wave signal well, it is preferable that there is no noise around it. However, in the real life, since various kinds of sound wave noise occurs, it is necessary to receive the sound wave signal in the sound wave communication, Uneasy.

According to an embodiment of the present invention, there is provided a data demodulation method and a sound wave receiving apparatus using the same, which can demodulate data with higher accuracy by performing data demodulation on a symbol-by-symbol basis and reflecting a weight based on the reliability of a symbol can do.

According to an embodiment of the present invention, data is demodulated on a symbol-by-symbol basis and an error check is performed. If it is determined that there is no error in the data after demodulation of the specific symbol, the subsequent symbol is not demodulated and data is output And a sound wave receiving apparatus using the data demodulating method.

According to an embodiment of the present invention, there is provided a data demodulating method for demodulating data in a symbol unit of a predetermined length of time by receiving an acoustic signal packet including data, the method comprising the steps of: (K) is an integer equal to or greater than 2, and k is an integer equal to or greater than 1 and equal to or less than K), for a kth received symbol, (a) the magnitude of the first sound wave signal in the first frequency band, Calculating reliability of a symbol for the first sound wave signal by comparing magnitudes of the two sound wave signals; (b) determining a data bit corresponding to the received symbol based on the calculated reliability; And (c) updating the undone data based on the determination of the data bit.

According to an embodiment of the present invention, there is provided a sound wave receiving apparatus for receiving a sound wave signal packet including data and demodulating data in symbol units of a predetermined time length, the apparatus comprising: K is an integer equal to or greater than 2, and k is an integer equal to or greater than 1 and equal to or less than K) symbols for a kth received symbol, a magnitude of a first sound wave signal in a first frequency band, A reliability calculating unit configured to calculate a reliability of a symbol for the first sound wave signal by comparing magnitudes of the first sound wave signals; A data demodulator configured to determine a data bit corresponding to the received symbol based on the calculated reliability; And a data combining unit for updating the undone data based on the determination of the data bits.

According to an embodiment of the present invention, data demodulation can be performed with higher accuracy by reflecting the weight based on the reliability of the symbol when performing data demodulation on a symbol-by-symbol basis.

According to an embodiment of the present invention, when data is demodulated on a symbol-by-symbol basis and an error check is performed, it is determined that there is no error in the data after demodulating the specific symbol, the subsequent symbols can be output without demodulating There is an advantage that data demodulation can be performed quickly.

1 is a view for explaining a sound wave receiving apparatus according to an embodiment of the present invention;
2 is a view for explaining an acoustic signal packet according to an embodiment,
3 is an exemplary block diagram of a sound wave receiving apparatus according to an embodiment.
4 is an exemplary spectrogram for explaining the reliability of an in-band sound wave signal,
5 is a flowchart illustrating a data demodulation method according to an embodiment,
6 is a flow chart illustrating an exemplary method for determining data bits based on a weight in accordance with one embodiment;
7 is a diagram for explaining a method of determining a data bit of a symbol based on a weight-reflected similarity.

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 receiving apparatus according to an embodiment of the present invention.

Referring to the drawings, a sound wave receiving apparatus 200 can receive an acoustic wave signal generated in an arbitrary sound wave generating apparatus 100. In one embodiment, the sound generator 100 may be a multimedia playback means including a speaker or a speaker, e.g., a device such as a TV, a computer, a smart phone, a tablet, or the like.

The sound wave receiving apparatus 200 can receive a sound wave signal transmitted from the sound wave generator 100 and including predetermined data, and can demodulate data from the received sound wave signal.

The data included in the sound wave signal may be data including arbitrary information, and may be composed of digital bits of a predetermined length, for example.

In one embodiment, such data may be included in the non-audible range of the sound wave signal. 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.

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 ".

In one embodiment, a non-audible sound generator (not shown) can generate sound waves in the non-audible range and can be injected with data having specific information in the non-audible sound waves. For example, digital data may be modulated by one of various modulation schemes such as amplitude modulation (ASK), frequency modulation (FSK), chirp modulation, or phase modulation (PSK) To generate non-audible sound waves containing the data.

Techniques for inserting arbitrary specific data into non-audible sound waves can be implemented using known techniques. For example, Korean Patent Application No. 10-1448823 (a method for transmitting and receiving sound waves using time-varying frequency-based symbols and a device using the same) Or 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.

2 is a diagram for explaining an acoustic wave signal according to an embodiment.

In the present specification, a sound wave signal of one unit including data is referred to as a " packet "or an" sound wave signal packet ". Referring to the drawings, the sound wave generator 100 can repeatedly generate and send the same sound wave signal packet. At this time, each sound wave signal packet may be composed of, for example, a training sequence and digital bit data of a predetermined length.

The training sequence is inserted in the sound wave signal so that the sound wave receiving apparatus 200 can detect the starting point of data in the sound wave signal, and is located at the first part of the packet in the form of a preamble as shown in FIG. Or may be included in the last part of the packet in an alternative embodiment or divided into small training sequences in the form of a pilot.

In one embodiment, the training sequence may comprise a sound wave signal having a characteristic that the frequency varies with time. For example, in the illustrated embodiment, the training sequence consists of a frequency up signal whose frequency increases with time.

In one embodiment, the digital bit data is composed of an 8-bit data bit string of "10101100" in the example of FIG. 2 as a bit string of a predetermined length. In this case, each digital bit may be time-varying-modulated, and may be composed of a frequency up time signal having a characteristic that the frequency increases with time and a frequency down time signal having a characteristic that the frequency decreases with time. For example, the frequency up signal represents a digital bit "1" in the illustrated embodiment and the frequency down time signal represents a digital bit "0 ".

A symbol (an analog signal waveform representing a bit) may contain one or more bits of information. In the embodiment shown in FIG. 2, one symbol includes 1-bit data. That is, the symbols (i.e., the frequency down signal and the frequency up signal) correspond to the digital values "0" and "1 ". However, in an alternative embodiment, for example, one symbol may represent 2-bit data (i.e., four digital values of "00", "01", "10", "11"

Therefore, according to one embodiment, a demodulation operation can be performed on a symbol basis when demodulating a sound wave signal packet. For example, when a symbol of one unit includes 2-bit data, demodulation is performed on a symbol-by-symbol basis, so that digital bit data can be extracted by 2 bits.

Referring again to FIG. 1, the sound wave receiving apparatus 200 can receive a plurality of sound wave signal packets continuously transmitted from the sound wave generating apparatus 100 and demodulate data therefrom.

The sound wave receiving apparatus 200 may be any device such as, for example, a smart phone, a tablet PC, a notebook computer, a desktop computer, and the like.

Techniques for extracting specific information from a sound wave signal are well known. For example, Korean Patent Application No. 2013-0107604 (method of transmitting and receiving sound waves using time-varying frequency-based symbols and apparatus using the same) or Korean Patent Application No. 2015-0118809 (Training thermal synchronization position estimation method and receiver using the same), and the like can be used.

3 is an exemplary block diagram of a sound wave receiving apparatus according to an embodiment.

The sound wave receiving apparatus 200 according to an embodiment may include a microphone 10, an analog / digital (A / D) converter 20, and a data extracting unit 30.

The microphone 10 converts the received sound wave signal into an electrical signal of an analog form. At this time, the analog type electrical signal may include, for example, the sound wave signal packet described with reference to FIG. The A / D converter 20 converts an electrical signal received and output by the microphone 10 into a digital signal.

The data extracting unit 30 extracts a digital bit stream from the digital signal output from the A / D converter 20. [ The data extracting unit 30 includes a frequency converting unit 310, a training sequence detecting unit 320, a data demodulating unit 330, a reliability calculating unit 340, and a data combining unit 350 can do. At this time, each of the components 310, 320, 330, 340, and 350 may be implemented as hardware, software, or a combination of hardware and software, respectively.

The frequency converter 310 may convert the digital signal output from the A / D converter 20 into a frequency domain signal. In one embodiment, the frequency transform unit 310 may perform a Fast Fourier Transform (FFT) operation to convert a digital signal into a frequency domain.

At this time, the operation of the sound wave receiving apparatus 200 to receive the sound wave signal through the microphone 10 and to process the sound wave signal in the A / D converter 20 and the frequency converting unit 310 may be performed in units of chunks of the sound wave signal . That is, the sound wave signal received through the microphone 10 can be cut at predetermined time intervals, A / D converted and frequency-converted, and transmitted to the training heat detector 320. In the embodiment shown in FIG. 2, the chunk has a time length corresponding to, for example, two symbol lengths. However, it goes without saying that the chunk unit may vary depending on the specific embodiment.

The training heat detector 320 detects the position of the training sequence in the sound wave signal packet converted by the frequency conversion unit 310 and separates the sound train signal in the sound wave signal packet and provides the sound wave signal packet in which the training sequence is separated to the data demodulation unit 330 can do. In one embodiment, the training heat detector 320 may also provide the confidence calculator 340 with the sound wave signal packets from which the training sequence has been separated.

The data demodulator 330 demodulates the sound signal packet received from the training-heat detector 320 and extracts the digital bit data. In one embodiment, the data demodulator 330 may include an envelope detector and a bit detector for data demodulation.

The envelope detector is a functional unit that quantitatively computes a signal demodulated on a symbol-by-symbol basis to a digital value among the digital values that the symbol can represent. The envelope detection unit exists as many as the number of kinds of symbols. If the symbol represents a 1-bit digital value (i.e., one symbol includes one of the digital values "0" and "1" A first envelope detector for calculating a degree of similarity (hereinafter also referred to as "similarity"), and a second envelope detector for calculating the degree to which the received symbol is close to the digital value "1 ".

In an alternative embodiment, for example, if the symbol represents a two-bit digital value, the received symbol is quantitatively computed to quantitatively approximate each of the digital values "00 "," 01 ", & Envelope detection unit.

When each envelope detector quantitatively calculates the degree of similarity between each digital value and the received symbol, the bit detector compares these similarity values and determines which bit corresponds to the received symbol.

The reliability calculation unit 340 calculates the reliability of each received symbol of the sound wave signal packet. Here, the reliability of the symbol may be a value quantitatively indicating how reliable each symbol received is valid data.

In one embodiment, assuming that a frequency band including data in the sound wave signal is referred to as a first frequency band and a band in which data is not included is a second frequency band, the magnitude of the sound wave signal in the first frequency band and the magnitude of the second frequency band The reliability of the symbol can be calculated. In this case, a frequency band of interest including data is referred to as an " in-band signal "and a frequency other than the frequency band of the in-band signal is referred to as an" out- Signal "

For example, when the data is transmitted by being inserted into the sound wave signal of the non-audible frequency band, the sound wave signal of the predetermined band in the entire non-audible frequency band or the non-audible frequency band is an in-band signal, A sound wave signal of a frequency band other than the band or a predetermined band within the frequency band may be defined as an out-of-band signal. The reliability of the symbol at this time can be quantitatively calculated as a ratio of the signal size of the in-band signal to the signal size of the out-of-band signal or a value proportional to the ratio. In one embodiment, the reliability of the symbol may be defined as a value proportional to the logarithm of the ratio of the signal size of the in-band signal to the signal size of the out-of-band signal.

The reason why the ratio of the signal sizes of the in-band signal and the out-of-band signal to each received symbol is considered as a main factor of the reliability of the symbols is that the data is transmitted in a specific frequency band Band) and is not present in the rest of the frequency bands, while noise, which generally includes high frequencies, exists over the entire audio frequency band, so that the sound wave signal at a specific time is divided into the in- If the ratio of the two signals is calculated by dividing them into out-of-band signals, it is possible to know how much of the noise signal received at this time is affected by the noise.

As an example, FIG. 4 illustrates the reliability of an in-band sound wave signal. The upper graph in the drawing shows an example of noise (a sound in blue) Green color) is shown as a graph of amplitude with time. 4 is a spectrogram representing the intensity of the sound wave signal in the time (X axis) and the frequency band (Y axis) in the graph in color, and the larger the signal size from blue to yellow it means.

According to the graph of FIG. 4, it can be seen that noise in general real-life noise such as a sound generated when a plastic bag is knocked or knocked on the door exists over the entire frequency band during the time when the noise occurs, In the case of a sound wave signal containing data in a band, since the signal is present only in the non-audible band (the "In-band" band in the drawing), the signal will be displayed in yellow only in this in-band band. Thus, for example, in the case of a large amount of noise, the ratio of the sizes of the in-band signal and the out-of-band signal approaches approximately 1, and in the case of no noise, the ratio of the sizes of the in- It has a large value.

Accordingly, when receiving the sound wave signal and comparing the sizes of the in-band signal and the out-of-band signal of the sound wave signal received every predetermined period of time (for example, a time length of a symbol), the reliability of each received symbol is quantitatively And based on this reliability, it is possible to determine, for example, whether the demodulated data of the corresponding symbol is to be recognized as valid data, or to ignore the data and consider the symbol of the next sound wave signal packet as valid data, or the like.

Referring back to FIG. 3, the reliability calculator 340 may calculate reliability for each received symbol and transmit the reliability value to the data demodulator 330 as described above, and the data demodulator 330 It is possible to demodulate the data of the corresponding symbol in consideration of each reliability received. For example, the data demodulator 330 calculates weights for the symbols based on the reliability, and based on the calculated weights and the weights calculated for the corresponding symbols of the previously received sound signal packet, Lt; / RTI > can be determined. This operation of the data demodulator 330 will be described later with reference to FIGS. 5 and 6. FIG.

As described above, the data demodulator 330 demodulates data on a symbol-by-symbol basis (i.e., determines a data bit for the symbol), and transmits the demodulated data to the data combiner 350. [ The data combining unit 350 may update the undone data based on the demodulated data bits and output the finally updated digital bit data.

In one embodiment, the data combining unit 330 may determine whether the updated data is erroneous each time the data is demodulated and updated on a symbol-by-symbol basis. For example, the digital bit data included in the sound wave signal may be configured to include an error correction code or error detection code, and the data combination unit 350 may perform an error correction or error detection procedure each time the data is updated have.

2, the sound wave receiving apparatus 200 may include, in addition to the above-described components, a memory that stores and executes various types of applications, a memory Or other software and / or software resources needed to operate the sound wave receiving device 200, such as a processor that loads and executes an application on the computer 200. In FIG. 2, for the convenience of description of the present invention, I will understand.

5 is a flowchart illustrating a data demodulation method according to an embodiment. 5 may be executed in any one of the data demodulator 330, the reliability calculator 340, and the data combiner 350 shown in FIG. 3, for example.

For convenience of explanation, as shown in Fig. 2, the sound wave signal packets of the same information can be successively received, the sound wave signal packet is composed of N bit digital bit data, and this N bit data is represented by K symbols Lt; / RTI > Assuming that the training sequence of the sound signal is already separated and removed from the training sequence detector 320 and demodulated only for N bits of digital bit data, for example, in the case of FIG. 2, the sound signal packet includes 8 bits N = 8) data, and one symbol includes 1-bit information, 8-bit data can be extracted by sequentially demodulating 8 symbols (i.e., K = 8).

In the case of demodulating the kth symbol of the K symbols constituting the sound wave signal packet (where K is an integer of 2 or more and k is an integer of 1 or more and K or less) symbols, steps (S110) to (S150) may be performed.

Specifically, in step S110, reliability of this symbol is calculated for the received k-th symbol. This operation can be performed, for example, in the reliability calculating section 340. As a method for calculating the reliability of a symbol, there is a method of calculating the reliability of a symbol by comparing the signal size of an in-band signal (for example, a signal in an invisible band when data is inserted and transmitted in an invisible band) - The reliability value can be calculated by comparing the signal amplitude of the band signal.

Next, the weight of the symbol can be calculated based on the calculated reliability. This operation may be performed, for example, in the reliability calculation unit 340 or the data demodulation unit 330. [

The method for calculating the weight can be variously implemented according to the concrete embodiment. For example, the reliability value and weight can be mapped linearly or non-linearly so that the weight value has a value between 0 and 1 corresponding to the numerical range that the reliability value can have.

Alternatively, steps S110 and S120 may be combined to calculate the direct weights in the ratio of the signal size of the in-band signal of the received symbol to the signal size of the out-of-band .

Thereafter, in step S130, a data bit corresponding to the received symbol is determined based on the calculated weight. This step S130 may be performed in the data demodulator 330, for example. In one embodiment, when determining the data bits in step S130, the data bits of the kth symbol may be determined by considering only the weights calculated in the immediately preceding step S120, and in another embodiment, The data bits of the k-th symbol can be determined by considering the weight, i.e., the weight calculated for the k-th symbol of the previously received sound signal packet.

Next, in step S140, based on the determination of the data bit in step S130, the data of the undone bit stream (stored in the register or memory) is updated. This operation can be performed in the data combining unit 350, for example.

As a specific example for updating, if the data bit of the kth symbol determined in step S130 is different from the data bit of the kth symbol of the undone data, the data bit of the undone kth symbol is stored in step S130. K < / RTI >

Thereafter, in step S150, it is determined whether or not the updated N-bit data is erroneous. This operation can be performed in the data combining unit 350, for example. In step S150, for example, a CRC check can be performed. If there is no error as a result of the determination (S150_No), the updated N-bit data is output. If an error is detected (S150_Yes) (Step S170), for the (k + 1) th received symbol, in step S170.

FIG. 6 shows an exemplary method of determining data bits based on weights, with step S130 of FIG. 5 being a specific embodiment.

First, in step S210, the degree of similarity, which indicates how similar the received k-th symbol is to each of the digital values that the symbol can represent, is measured. This step (S210) may be performed by, for example, an envelope detection unit of the data demodulation unit (330).

Next, in step S230, a weight is applied to each similarity. Here, the weight is, for example, a weight calculated based on the reliability calculated by the reliability calculating unit 340 in step S120 of FIG. Thus, the "current weighted-reflected similarity" can be calculated by reflecting the weight based on the reliability to the similarity to each digital value.

 Then, in step S250, based on the "current weight-reflectance similarity" calculated in step S230 for the k-th symbol and the "old weight-reflect similarity" calculated according to the previously calculated weight, Can be determined.

A specific example of applying the method of steps S210 to S250 described above will be described with reference to FIG. 7 is a diagram for explaining a method of determining a data bit of a symbol based on a weight-reflected similarity.

For convenience of explanation, as shown in FIG. 2, the sound wave signal receiver 200 receives the sound wave signal packet of the same information in which the 8-bit data of "10101100" is inserted into the non-audible band in the sound wave generator 100 It can be assumed. In addition, data demodulation has already been completed for the first one of the successive sound signal packets, which has been demodulated into 8-bit data of "10001100 " as shown in FIG. 7, , And thus is currently performing data demodulation for the second packet, specifically demodulating up to the second symbol to determine the digital bit stream "10 " and now trying to demodulate the third (k = 3) It is.

In this state, according to step S210 of FIG. 6, the reliability calculation unit 340 (or the data demodulation unit 330) determines how close the received third symbol is to each of the digital values that the symbol can represent (Degree of similarity) is measured. Referring to the example of FIG. 7, in this step S210, the similarity to the digital value "0" is calculated to 0.3 and the similarity to the digital value "1 " is calculated to 0.4 for the third symbol of the second packet .

Then, in step S230 of FIG. 6, the weight based on the reliability of the symbol is reflected in the similarity to calculate the current weight-reflectance similarity roll. Referring to the example of FIG. 7, the weight is calculated as 0.8 based on the reliability of the symbol in step S230, and the current weight-reflected similarity to the digital value "0 " is calculated as 0.8 * 0.3 = 0.24 , And the current weighted-reflected similarity to the digital value "1 " is 0.8 * 0.4 = 0.32.

Next, in step S250 of FIG. 6, the digital bits of the third (k = 3) symbol are determined based on the current weight-reflected similarity and the past weight-reflected similarity. 7, it is assumed that the weight of the third symbol in the first packet demodulation is 0.5, the similarity to the digital value "0" is 0.4, and the similarity to the digital value "1 & .

Then, the past weighted-reflected similarity for the digital value "0" is 0.5 * 04 = 0.20 and the past weighted-reflected similarity for the digital value "1 "

Thus, for example, the final similarity for the digital value " 0 "is 0.24 + 0.2 = 0.44 and the final similarity for the digital value" 1 " is 0.32 + 0.15 = 0.47. As a result, in step S250, it is determined that the digital bit indicated by the third (k = 3) symbol is "1 ".

As described above, according to the embodiment of the present invention, data demodulation can be performed with higher accuracy by reflecting the weight based on the reliability of symbols when data demodulation is performed for each symbol.

According to the present invention, since data is demodulated and error check is performed on a symbol-by-symbol basis, for example, in FIG. 7, the third symbol of the second packet is demodulated into a digital bit "1 & N bits of data can be immediately output without performing demodulation for the fourth and subsequent symbols of the second packet. Therefore, data demodulation can be performed more quickly than demodulation and error checking on a whole N bit column basis have.

While the embodiments of the present invention have been described with reference to the drawings, those skilled in the art will appreciate that various modifications and changes may be made by those skilled in the art without departing from the scope of 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.

100: sound wave generator
200: sound wave receiver
10: microphone
20: A / D converter
30: Data extraction unit
310: Frequency converter
320: training heat detector
330: Data demodulator
340: reliability calculating section
350: Data combination part

Claims (16)

Data for demodulating data in symbol units of a predetermined length of time by receiving an acoustic signal packet including a first sound wave signal of a first frequency band in which data is inserted and a second sound wave signal of a second frequency band in which the data is not inserted, As a demodulation method,
(K is an integer of 2 or more and k is an integer of 1 or more and K or less) symbols of K symbols constituting the sound wave signal packet, for a k-th received symbol,
(a) comparing the magnitude of the first sound wave signal and the magnitude of the second sound wave signal to calculate a reliability of the symbol for the first sound wave signal (Sl 10);
(b) determining, based on the calculated reliability, a data bit corresponding to the received symbol (S120 to S130); And
(c) updating (S140) the undone data based on the determination of the data bit. The method according to claim 1,
Wherein the first sound wave signal is a sound wave signal of a predetermined band within an inaudible frequency band and the second sound wave signal is a sound wave signal of a predetermined band within a frequency band other than the frequency band of the first sound wave signal / RTI > 3. The method of claim 2,
Data is inserted into the non-audible frequency band of the first sound wave signal and transmitted. The method according to claim 1,
Wherein reliability of the symbol is proportional to a logarithm of a ratio of a magnitude of the first sound wave signal to a magnitude of the second sound wave signal. 2. The method of claim 1, wherein (b)
(b-1) calculating a weight for a symbol based on the reliability (S120); And
(b-2) determining (S130) a data bit corresponding to the received symbol based on the calculated weight and a pre-calculated weight for the k-th symbol of the previously received sound signal packet; And demodulating the data. 6. The method of claim 5, wherein (b-2) determining a data bit based on the calculated weight and the pre-
(S210) measuring a degree of similarity indicating how similar the received symbols are to each of the digital values that the symbol (b-2-1) may represent;
(b-2-2) calculating the current weight-reflectance similarity of the received symbols for each of the digital values that the symbol can represent by applying the calculated weight to each of the similarities (S230); And
(b-2-3) determining a digital bit corresponding to the k-th symbol based on the past weight-reflected similarity calculated based on the current weight-reflected similarity and the previously calculated weight for the k-th symbol (S250). ≪ / RTI > 2. The method of claim 1, wherein the updating (c)
If the data bit of the k-th symbol determined in the step (b) of determining the data bit is different from the data bit of the k-th symbol of the undone data, ≪ RTI ID = 0.0 > k) < / RTI > The method according to claim 1,
(d) determining whether the updated data is erroneous after the updating step (c); And
(e) outputting the updated data if there is no error as a result of the determination,
(A) to (e) for the (k + 1) -th received symbol of the sound wave signal packet if there is an error as a result of the determination. A sound wave signal packet for receiving a sound wave signal packet including a first sound wave signal of a first frequency band in which data is inserted and a second sound wave signal of a second frequency band in which the data is not inserted, As a receiving apparatus,
In order to demodulate the kth symbol of the K symbols constituting the sound wave signal packet (K is an integer of 2 or more and k is an integer of 1 or more and K or less) symbols, for the kth received symbol, A reliability calculation unit (340) configured to compare the size of the first sound wave signal with the magnitude of the second sound wave signal to calculate reliability of the symbol for the first sound wave signal;
A data demodulator (330) configured to determine a data bit corresponding to the received symbol based on the calculated reliability; And
And a data combining unit (350) for updating the undone data based on the determination of the data bit. 10. The method of claim 9,
Wherein the first sound wave signal is a sound wave signal of a predetermined band within an inaudible frequency band and the second sound wave signal is a sound wave signal of a predetermined band within a frequency band other than the frequency band of the first sound wave signal . 11. The method of claim 10,
Data is inserted into the non-audible frequency band of the first sound wave signal and transmitted. 10. The method of claim 9,
Wherein reliability of the symbol is proportional to a logarithm of a ratio of a magnitude of the first sound wave signal to a magnitude of the second sound wave signal. 10. The method of claim 9,
Wherein the reliability calculation unit is configured to calculate a weight for a symbol based on the reliability,
Wherein the data demodulation unit is configured to determine a data bit corresponding to the received symbol based on the calculated weight and a pre-computed weight for the k-th symbol of the previously received sound signal packet, Receiving device. 14. The method of claim 13,
In order to perform an operation of determining a data bit based on the calculated weight and the pre-calculated weight,
For each of the digital values that the symbol can represent, the degree of similarity indicating how similar the received symbols are,
Calculating the current weight-reflected similarity of the received symbols for each of the digital values that the symbol can represent by applying the calculated weight to each of the similarities, and
And to determine a digital bit corresponding to the k-th symbol based on the past weight-reflected similarity calculated based on the current weight-reflected similarity and the previously calculated weight for the k-th symbol, Device. 10. The method of claim 9,
Wherein if the data bit of the k-th symbol determined by the data demodulator is different from the data bit of the k-th symbol of the relief data, the data combining unit adds the data bits of the undone k- To a data bit of the k-th symbol determined by the k-th symbol. 10. The method of claim 9,
Wherein the sound wave receiver is configured to determine whether the data updated by the data demodulator is erroneous, and to output the updated data if there is no error.

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