KR101790224B1 - Method for estimating synchronization position of training sequence and receiver using the same - Google Patents

Abstract

Receiving a communication signal through a transmission channel, wherein the training sequence is included; And finding a position of a J shape in the communication signal; Estimating a position having a Jth (J) shape as a synchronization position of a training sequence; A training thermal synchronization position estimation method is disclosed. Thereby, the synchronization position of the training sequence can be reliably detected in the signal including the living noise.

Description

[0001] The present invention relates to a method for estimating a train thermal synchronization position and a receiver using the same,

The present invention relates to a training heat synchronization position estimation method and a receiver using the same.

Recently, technologies for providing information using sound waves have been utilized.

For example, Korean Patent Laid-Open Publication No. 2013-0064014 (2013.06.17) ("System, Server, Method, and Recording Medium for Providing Location-Based Services Using Sound Wave Communication" And a system for providing a service.

As another example, Korean Unexamined Patent Application Publication No. 2012-0045613 (May 05, 2012) ("Data transmission and reception system and method in audible frequency band sound wave communication, and device applied thereto") discloses a method of transmitting and receiving data in an audible frequency band, Device is disclosed.

However, when such a sound wave is transmitted through a channel, noise (for example, living noise) is included. However, there is a problem that it is not easy to find a synchronization position of a training sequence on the side of receiving a sound wave due to such living noise.

According to an embodiment of the present invention, a training heat synchronization position estimation method and a receiver using the training heat synchronization position estimation method capable of accurately estimating a synchronization position of a training sequence in a signal including a living noise can be provided.

According to an embodiment of the present invention, there is provided a method comprising: receiving a communication signal-training sequence via a transmission channel; And

Searching for a position of a J shape in the communication signal; And

Estimating a position having the J shape as a synchronization position of the training sequence; And a training-heat-synchronization-position estimating method.

According to another embodiment of the present invention, there is provided an acoustic receiver including a peak finder for estimating a synchronization position of a training sequence in a sound signal-training sequence received through a transmission channel,

Wherein the peak finder finds a position having a J shape in the sound wave signal and estimates a portion having the J shape as a synchronization position of the training sequence.

According to another embodiment of the present invention,

Receiving a communication signal through a transmission channel, wherein the training sequence is included; And

Finding a position-peak position having a value greater than or equal to a reference value in a result of correlating the communication signal or the communication signal with a training sequence; And

And estimating a position of one of the peak positions as a synchronization position of the training sequence,

Wherein the asymmetry ratio for the peak estimated as the synchronization position of the train train is larger than the asymmetry ratios for the remaining peaks.

In the above-described embodiments, the communication signal is a sound wave, and may be a chirp signal whose frequency varies with time.

In the above-described embodiments, when finding the position having the J shape,

Peak-to-peak positions having a reference value or more in a result of correlating the communication signal or the communication signal with a training sequence, and determining one of the peak positions as a J-shaped position .

In the above-described embodiments, when searching for position-peak positions with the reference value or more,

A window for peak detection can be applied to signals above a reference value in a result of correlating the communication signal or the communication signal with a training sequence.

In the above-described embodiments, when determining which one of the peak positions is a J (J) shape, among the peak positions, the following cases

- When there is substantially no signal on the left side and a plurality of signals on the right side based on the peak

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When there is substantially no signal at a portion spaced a predetermined time to the left with respect to a peak and a plurality of signals are present at the right portion

A plurality of signals within a predetermined time on the right side of the peak are larger than a second reference value and a plurality of signals within a predetermined time on the left side are smaller than a third reference value

The position of the peak satisfying at least one of the above-described conditions can be determined as a position having a J (J) shape.

In the above-described embodiments, when it is determined whether or not both sides are asymmetrical with respect to the peak, the asymmetry ratio is calculated and then it is determined whether or not the asymmetry corresponds to the asymmetry ratio,

The calculation of the asymmetric ratio may be performed,

Calculating an average value of values within a predetermined time on the basis of a peak, a peak surrounding average value, calculating an average value of values within a predetermined time of the left part of the peak - an average value of peak left position -

Asymmetry ratio = (peak mean value) / (peak left mean value)

. ≪ / RTI >

In the above-described embodiments, the calculation of the peak left position average value may be performed by,

And to obtain an average value for the portions spaced a predetermined time from the peak to the left.

According to one or more embodiments of the present invention, it is possible to reliably estimate the synchronization position of a training sequence even when receiving a signal containing a living noise. In particular, it is possible to reliably estimate the synchronization position of a training sequence in a receiver that receives a sound wave including life noise.

FIG. 1 is a view for explaining a method of estimating a training thermal synchronization position according to an embodiment of the present invention.
FIG. 2 is a view for explaining a method of finding a position having a J shape according to an embodiment of the present invention.
FIGS. 3 and 13 are diagrams for explaining a method of finding a position having a J shape according to another embodiment of the present invention.
FIG. 4 is a diagram for explaining a receiver according to an embodiment of the present invention to which a method of estimating a training pulse synchronization position according to an embodiment of the present invention is applied.
5 is a view for explaining a sound wave receiver according to another embodiment of the present invention to which a method of estimating a training heat synchronization position according to an embodiment of the present invention is applied.
FIGS. 6 and 7 are other views for explaining the shape of a J (J) according to an embodiment of the present invention.
8 and 9 are views for explaining a method of calculating an asymmetric ratio according to an embodiment of the present invention.
FIGS. 10 to 12 are views for explaining an asymmetric ratio according to an embodiment of the present invention. FIG.
14 to 18 are diagrams for explaining a method of finding a peak position according to an embodiment of the present invention.
Figure 19 is an illustration of the coexistence signals that may be used in the present invention.

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 transmission channel synchronization method according to the present invention finds a J (J) shape in a signal received from a transmission channel. Hereinafter, various embodiments according to the present invention will be described with reference to the drawings.

FIG. 1 is a view for explaining a method of estimating a training thermal synchronization position according to an embodiment of the present invention.

Referring to FIG. 1, a method for estimating a training thermal synchronization position according to an exemplary embodiment of the present invention includes receiving a communication signal-training sequence (S100). In step S100, A step S300 of finding a position having a J-shape from the correlation result of step S200, and a step S400 of estimating a synchronization position of the training sequence from the correlation result of step S200 .

The step of performing the correlation operation (S200) may be a step of performing a correlation operation with the communication signal received in the step S100 and the training sequence of the same kind as that included in the communication signal. For example, when the communication signal is a sound wave whose frequency is temporally changed, step (S200) of performing the correlation operation may be to perform the correlation operation using the concatenation signals exemplarily shown in Fig. 19 have.

The step (S300) of finding the position having the J shape is a step of finding the J shape from the correlation result which is the result of performing the step S200. In the present specification, the term " correlation result " is used to mean not only a direct result of performing step S200, but also a result of performing additional processing on a direct result of step S200. Here, " additional processing " may mean, for example, an operation of detecting an envelope. That is, the step S300 may be a step of finding the position of the J shape from the result of performing the correlation or the result of performing the correlation.

The step of estimating the synchronization position of the training sequence (S400) is a step of estimating the shape of the J (J) found in the step S300 as the synchronization position of the training sequence. Specifically, the position of the peak included in the J shape can be estimated as the synchronization position of the training sequence.

As described above, in the embodiment described with reference to FIG. 1, the description has been made to include the step S200 (the step of performing the correlation operation). However, as an option, the training thermal synchronization position estimation method according to another embodiment of the present invention includes: And performing steps S300 and S400 without performing step S200.

6 is a view for explaining a shape of a jaw J according to an embodiment of the present invention.

Referring to FIG. 6, the envelope of the correlation result of the training sequence is shown, and it can be seen that there is a J shape based on the position at which the peak exists. It can be seen that there are substantially no signals in the left-temporal peak portion with respect to the position where the peak exists, and there are many signals in the right-temporal peak portion after the position with the peak.

According to one embodiment of the present invention, the J shape includes a peak, and the left side of the peak and the right side of the peak are asymmetric with respect to each other. The graph of FIG. 6 shows the envelope of the correlation result of the sound waves, and it is determined that there are many signals on the right side based on the peaks because the sound waves have a large delay spread in comparison with the electromagnetic waves.

The J shape to be found in step S300 includes a peak having a reference value - a first reference value - or more, and may correspond to at least one of the following cases.

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- When there is substantially no signal on the left side and a plurality of signals on the right side based on the peak

When there is substantially no signal at a portion spaced a predetermined time to the left with respect to a peak and a plurality of signals are present at the right portion

A plurality of signals within a predetermined time on the right side of the peak are larger than a second reference value and a plurality of signals within a predetermined time on the left side are smaller than a third reference value

A step S300 of finding a position having a J shape is a step of finding a part having at least one of the characteristics as described above in the correlation performed in the step S200.

With continued reference to FIG. 6, there are few signals on the left side, in particular on the peaks (for the purposes of the present invention, the positions with peaks on the time axis are denoted by " 0 & It can be seen that there is substantially no signal at a portion spaced apart by a predetermined time. It can be seen that there are a plurality of signals on the right side based on the position of the peak.

7 is another view for explaining a shape of a jaw J according to an embodiment of the present invention.

FIG. 7 exemplarily shows the result of the step S200 (only the envelope is shown), and correlation characteristics for the training sequence and the noise can be known. That is, the correlation portion with respect to the training sequence has a J (J) shape, but the correlation portion with respect to noise has no J (J) shape. The inventor of the present invention paid attention to this fact and tried to estimate the portion where the J shape appears in the correlation result as the portion where the training train exists, and in fact, a reliable result was obtained.

FIG. 2 is a view for explaining a method of finding a position having a J shape according to an embodiment of the present invention.

Referring to FIG. 2, a method of finding a position having a J shape according to an embodiment of the present invention includes a position-peak position that is equal to or greater than a first reference value in a result of performing step S200 (correlation result) (S301), calculating (S303) an asymmetric ratio for each of the peaks found in step S301, and calculating a peak position having the largest asymmetry ratio calculated in step S303 as a position having a J shape (Step S305).

In this embodiment, the step S303 of calculating the asymmetry ratio is performed by calculating the average value of the values within a predetermined time based on the peak position-the peak surrounding average value-and calculating the values of the values Average value - peak left position average value ") is calculated, and the following Equation (1)

Asymmetry ratio = (peak mean value) / (peak left mean value)

. ≪ / RTI >

The asymmetry ratio is a parameter indicating the degree of asymmetry with respect to the peak. The above Equation (1) is an example, and the parameter indicating the degree of asymmetry may be calculated by another equation.

FIGS. 8 and 9 are views for explaining asymmetric ratios according to an embodiment of the present invention. FIG. 8A is for explaining an asymmetric ratio of a portion including a training sequence, FIG. (B) is to explain the asymmetric ratio of the portion including the noise.

Referring to FIG. 8 (a), the reference value-reference value can be determined by a person engaged in the technical field to which the present invention belongs-within a predetermined time (Δt1) based on the ideal peak P1, Lt; RTI ID = 0.0 > a < / RTI > That is, the average value around the peak P1 is obtained. Then, an average value of values belonging to a predetermined time (? T3) from a position separated from the peak P1 by a predetermined time (? T2) in the leftward direction is calculated. That is, the average value of the left position of the peak P1 is calculated. With respect to these average values, the asymmetry ratio can be calculated using Equation (1).

Referring to FIG. 8B, an average value of values belonging to a predetermined time Δt1 is calculated on the basis of a peak P2 that is equal to or greater than a reference value in the same manner as FIG. 8B. That is, the average value around the peak P2 is obtained. Then, an average value of values belonging to a predetermined time? T3 from a position separated from the peak P2 by a predetermined time? T2 in the leftward direction is calculated. That is, the average value of the left position of the peak P2 is obtained. With respect to these average values, the asymmetry ratio can be calculated using Equation (1).

9 shows an asymmetric ratio calculated for peaks having a reference value or more in the same or similar manner as that described with reference to Figs. 8 (a) and 8 (b).

Referring to FIG. 9, the largest value among the asymmetric ratios calculated for the respective peaks is 6. 57, and the asymmetric ratios for the remaining peaks are 2.0 or less. In this case, the step (S300) of finding a position having a J shape according to an embodiment of the present invention determines that a portion having an asymmetric ratio of 6,57 is a J shape. Since the asymmetry ratio of the training column portion and the noise portion is more than three times, even if the asymmetry ratio of 6,57 is determined as the training column synchronization position, a reliable result can be obtained have.

FIGS. 10 to 12 are views for explaining an asymmetric ratio according to an embodiment of the present invention. FIG.

Hereinafter, a method of obtaining the correlation result (only the envelope is shown) as shown in FIG. 10 as a result of performing the step S200 will be described, and a method of obtaining the asymmetric ratio will be described.

Referring to FIG. 10, there are P1, P2, and P3 peaks having a first reference value or more, and a process of calculating an asymmetry ratio with respect to the peak P1 will be described first.

The peak surrounding average value for the peak P1 is calculated by averaging over the values contained in the window W1 defined such that the peak P1 is at the center and the peak left position average value for the peak P1 is calculated as the peak value (I.e., the values included in the window W2) from the position at a predetermined time (t2) from the position P1 at a predetermined time (t3). Thereafter, the asymmetric ratio can be calculated by applying Equation (1) exemplarily described.

Referring to FIG. 11, a process for calculating the asymmetry ratio with respect to the peak P2 will be described.

The peak surrounding average value for the peak P2 is calculated by averaging the values contained in the window W1 defined such that the peak P2 is at the center and the peak left position average value for the peak P2 is calculated by the average value (I.e., the values included in the window W2) from the position at the predetermined time interval? T2 from the position P2 at the predetermined time interval? T3. Thereafter, the asymmetric ratio can be calculated by applying Equation (1) exemplarily described.

Referring to FIG. 12, a process for calculating the asymmetric ratio with respect to the peak P3 will be described.

The peak surrounding average value for the peak P3 is calculated by averaging the values contained in the window W1 defined such that the peak P3 is at the center and the peak left position average value for the peak P3 is calculated as the peak (I.e., the values included in the window W2) from the position at the predetermined time? T2 from the position P3 at the predetermined time? T3. Thereafter, the asymmetric ratio can be calculated by applying Equation (1) exemplarily described.

When the asymmetric ratios are calculated for the peaks having the reference value or more in the above manner, the portion having the largest asymmetric ratio will be determined as the portion having the J shape defined in the present invention.

As described above, the sizes of the predetermined times (? T1,? T2,? T3) and the windows (W1, W2), which have been described with reference to Figs. 10 to 12, are exemplary and can be suitably changed by those skilled in the art . Here, it is also possible to set Δt2 time to zero (O).

FIGS. 3 and 13 are diagrams for explaining a method of finding a position having a J shape according to another embodiment of the present invention.

3 and 13, among the features of the J shape,

A plurality of signals within a predetermined time on the right side of the peak are larger than a second reference value and a plurality of signals within a predetermined time on the left side are smaller than a third reference value,

(J) shape using a feature called " J ".

Referring to FIGS. 3 and 13, a method of finding a position having a J shape may include a step S302 of finding position-peak positions having a first reference value or more in the result of step S200, , A peak position corresponding to a case where all the signals within a predetermined time on the left side from the peak position have a value smaller than the third reference value are found in the right portion of the peak position The step S304, and the step S306 of determining the peak position found in the step S304 as a position having a J shape.

Referring to FIG. 13, the result of step S200 is illustrated as an example, and a first reference value, a second reference value, and a third reference value are set. In step S304, it is determined whether there is a portion having a value higher than the second reference value on the right side based on the peak, and whether there is a portion having a value lower than the third reference value on the left side based on the peak. The example shown in Fig. 13 will be judged as J (J) because it satisfies the above condition.

On the other hand, when comparing the values of the left part with the third reference value on the basis of the peak, the values of the part within the predetermined time (? T3) with the peak are compared with the third reference value. Also, when comparing the values of the right portion with the second reference value with respect to the peak, the values of the portion within the predetermined time (? T4) with the peak are compared with the second reference value.

The training thermal synchronization position estimation methods described above with respect to one or more embodiments can be used as a method of estimating the synchronization position of training sequences included in a sound wave signal.

In addition, the method for estimating the training thermal synchronization position according to the embodiment of the present invention can be used as a method of estimating the synchronization position of the training sequence included in the sound signal whose frequency changes with time. It is needless to say that the training thermal synchronization position estimation methods according to the embodiment of the present invention can be applied to a method of estimating synchronization positions of training sequences included in other types of signals as well as sound waves.

14 to 17 are diagrams for explaining a method of finding a peak position according to an embodiment of the present invention. Specifically, FIG. 14A shows a correlation result (only an envelope is shown), FIG. 14B shows a window used for finding a peak position according to an embodiment of the present invention (The window for peak detection has a width of [Delta] t and is intended to remove the signal included in [Delta] t time), and Figs. 15 to 17 illustrate examples in which windows are sequentially applied This is to explain the process.

A method of finding a peak position according to an embodiment of the present invention is a method of finding a position of a peak by applying a 'window for peak detection' to signals having a value equal to or greater than a reference value in a correlation result, May also be used in step S301 or S302 described above with reference to FIG.

Referring to FIG. 14, it can be seen that there are a number of signals having a reference value or more, and a random signal ('P1' in this embodiment) is selected and stored as a position of a peak. Next, in the correlation result, a 'window for finding a peak' is applied to the position of the peak P1. FIG. 15 shows the result of applying the 'window for peak detection' to the position of peak P1.

As a result of applying the 'window for peak search' to the position of the peak P1, an arbitrary signal ('P2' in this embodiment) is selected from the signals having the reference value or more and stored as the position of the peak. Next, a 'window for peak search' is applied to the position of peak P2. 16 shows the result of applying the window for peak detection to the position of peak P2.

As a result of applying the window for peak search to the position of the peak P2, an arbitrary signal ('P3' in this embodiment) is selected from the signals having the reference value or more and stored as the position of the peak. Next, 'window for peak search' is applied to the position of peak P3. FIG. 17 shows the result of applying the 'window for peak detection' to the position of peak P3.

As a result of applying the 'window for peak search' to the position of the peak P3, an arbitrary signal ('P4' in this embodiment) is selected from the signals having the reference value or more and stored as the position of the peak.

Next, a 'window for peak search' is applied to the position of peak P4. FIG. 18 shows the result of applying the 'window for peak detection' to the position of peak P4.

Referring to FIG. 18, it can be seen that there are no more signals than the reference value, so that the peaks found through the above processes become P1, P2, P3, and P4. Thereafter, it is determined whether there is a J (J) shape at the position of these peaks.

4 is a diagram for explaining an example in which a method of estimating a training thermal synchronization position according to an embodiment of the present invention is applied to a receiver according to an embodiment of the present invention.

4, a receiver 5 according to an embodiment of the present invention receives a sound wave transmitted from a transmitter 1 through a sound wave channel 3 and includes a microphone 7, an A / D converter 9, A peak finder 14, and a data demodulating unit 18. [0030]

4, the microphone 7 converts a sound wave received through the sound wave channel 3 into an electrical signal, and the A / D converter 9 converts the electric signal converted by the microphone 7 into a digital signal .

The sound wave received by the microphone 7 may be a chirp signal whose frequency varies with time, for example.

Referring to Fig. 19, exemplary signals that may be used in the present invention are shown. According to an embodiment of the present invention, an up chirp signal whose frequency increases with time and a down chirp signal whose frequency decreases with time can be used.

Meanwhile, since the frequency change rate and phase of the coherent signals shown in FIG. 19 are exemplary, the present invention can be easily understood by those skilled in the art to which the present invention belongs.

The peak finder 14 finds a position where the J (J) shape is present in the signal converted by the A / D converter 9. [ For example, the peak finder 14 can find the position having the J (J) shape by finding the J (J) shape described with reference to Figs. 1, 2, 3 and 7 to 18 have.

The peak finder 14 finds peaks having a reference value or more in the signal converted by the A / D converter 9, and finds a J shape based on the found peaks.

The data demodulator 18 demodulates the data using the position of the J (J) shape found by the peak finder 14. For example, the data demodulator 18 demodulates data from the positions of the peaks included in the J (J) shape.

5 is a view for explaining an example in which a method of estimating a training thermal synchronization position according to an embodiment of the present invention is applied to a receiver according to another embodiment of the present invention.

5, a receiver 105 according to an exemplary embodiment of the present invention includes a microphone 107, an A / D converter 109, a fast Fourier transformer 111, and a microphone 106. The microphone 107 receives sound waves transmitted through a sound channel, A training heat trimmer 113, a peak finder 114, a channel estimator 115, a channel equalizer 117, a data demodulator 118, and an envelope detector 119.

The A / D converter 109 converts the electrical signal output by the microphone 107 into digital data and outputs the data.

The fast Fourier transformer 111 performs a fast Fourier transform (FFT) operation to convert the digital data output from the A / D converter 109 into the frequency domain.

The peak finder 114 can locate the training sequence according to the method according to one embodiment of the present invention. The peak finder 114 finds a position where the J (J) shape exists in the signal converted by the A / D converter 109, for example. The peak finder 14 can find a position having a J shape by means of finding the J shape described with reference to Figs. 1, 2, 3 and 7 to 18.

The envelope detector 119 detects an envelope of the signal converted by the fast Fourier transformer 111, converts the envelope to a time domain, and provides the envelope to the training heat trimmer 113 and the peak finder 114.

The training heat trimmer 113 refers to the position of the training train provided from the peak finder 114 and separates training train from the signal converted by the fast Fourier transforming unit 111. [

The channel estimator 115 estimates the distortion effect due to the channel from the training sequence provided from the training heat trimmer 113.

The channel equalizer 117 removes the distortion effect due to the channel provided from the channel estimation unit 115 on the data converted by the FFT unit 111 and then outputs the data to the data demodulation unit 118.

The data demodulator 118 calculates digital bit data from the data supplied from the channel equalizer 117. At this time, the data demodulator 118 uses the position of the training sequence provided from the peak finder 114. [

For a more detailed description of the receiver in the embodiment described with reference to FIG. 5, please refer to Korean Patent Registration No. 10-1448823 (Apr. All the contents disclosed in Korean Patent Registration No. 10-1448823 (Jan. 201, 2014) are incorporated herein by reference to the extent not inconsistent with the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Various modifications and variations are possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by equivalents to the scope of the appended claims, as well as the appended claims.

1: Transmitter 3: Sound wave channel
5, 105: Receiver 7, 107: Microphone
9, 109: A / D converter 14, 114: peak finder
18, 118: Data demodulation unit 111: Fast Fourier transform unit
113: training heat trimmer 115: channel estimation unit
117: channel equalizer 119: envelope detector

Claims (8)

A sound wave receiver including a peak finder for estimating a synchronization position of a training sequence in a sound wave signal received through a transmission channel, wherein the training sequence is included,
The peak finder performs an operation of finding a position having a J shape in a correlation result with the training sequence,
The operation of finding the position of the jaw J
Peak positions with a reference value or more in the result of correlation with the training sequence, calculates an asymmetric ratio with respect to the peak positions found, and calculates a peak position having the largest asymmetry ratio as a synchronization position Respectively,
The asymmetry ratio is calculated by the peak surrounding average value and the peak left position average value,
Wherein the peak surrounding average value is an average value of values within a predetermined time based on a peak and the peak left position average value is an average value for portions spaced a predetermined time from the peak to the left. The method according to claim 1,
Wherein the sound wave signal is a chirp signal whose frequency varies with time. The method according to claim 1,
The peak finder
When searching for position-peak positions having a value greater than or equal to the reference value,
And performing a search operation by applying a 'window for peak detection' to signals having a reference value or higher in a result of correlating the sound signal or the sound signal with a training sequence. delete Receiving a communication signal through a transmission channel, wherein the training sequence is included; And
A step of finding a position of a J shape from a result of correlating the communication signal or the communication signal with a training sequence; And
And estimating the training sequence as a synchronization position,
The step of finding a position having the J shape is a step of finding position-peak positions having a reference value or more in correlation with the training sequence in the communication signal,
Wherein the estimating step comprises estimating a position of one of the peak positions as a synchronization position of the training sequence,
The asymmetry ratio for the peak estimated as the synchronization position of the training sequence is calculated by the peak surrounding average value and the peak left position average value,
Wherein the peak surrounding average value is an average value of values within a predetermined time based on a peak, the peak left position average value is an average value of portions separated from the peak by a predetermined time to the left,
The step of finding the peak positions comprises:
And searching for a peak search window for the signals above the reference value in the communication signal. delete delete 6. The method of claim 5,
Wherein the communication signal is a chirp signal whose frequency varies with time.

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