KR101539992B1 - Method for detecting saturation signals beyond dynamic range in underwater wireless distributed sensor networks - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sound navigation ranging (Sonar), and more particularly, to a sound navigation ranging method in which, when a signal having a different signal magnitude such as a direct wave or a target reflected wave is input to a receiving node The present invention relates to a saturated signal detecting apparatus and method capable of stably detecting a signal without adjusting gain when a gain of a receiving node is adjusted due to saturation resulting in signal distortion due to clipping.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for detecting a saturated signal outside a dynamic range in an underwater distributed sensor network,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sound navigation ranging (Sonar), and more particularly, to a sound navigation ranging method in which, when a signal having a different signal magnitude such as a direct wave or a target reflected wave is input to a receiving node The present invention relates to a saturation signal detection method capable of stably performing detection without adjusting a gain when a signal distortion due to clipping is saturated to adjust a gain of a receiving node.

In general, an underwater distributed sensor network is composed of a plurality of transmitting nodes and receiving nodes and is a system for detecting objects in the water.

A view showing such an underwater dispersion sensor network is shown in FIG. Referring to FIG. 1, the water dispersion sensor network shown in FIG. 1 corresponds to a multi-sta- tionary sonar in which the positions of the transmitting nodes 110 and 111 and the receiving nodes 120 to 129 are different.

A signal in the underwater dispersive sensor network includes a direct wave signal 150 directly inputted from the transmitting node 110 to the receiving node 124 and a radio wave signal 140 propagating from the transmitting node 110 to the target 130, And a target reflected signal 131 that is incident on the receiving node 124 by colliding with the target 130.

The direct wave signal 150 is important for estimating information such as the pulse transmission period at the receiving node 124 and / or calculating the time difference with respect to the target reflected signal 131, and the target reflected signal 1310 is important for the presence Which is an important factor.

However, since the magnitude of the direct wave signal 150 is larger than that of the target reflected wave signal 131, in general, a signal attenuation according to the distance is obtained by using a method such as a time varying gain (TVG) So that a direct wave and a target signal can be stably obtained.

However, since the receiving nodes 120 to 129 of the underwater dispersive sensor network operate independently with respect to the transmitting nodes 110 and 111, the receiving node is able to detect the generation time of the transmitting pulses emitted from the transmitting node, , And a repetition period (Pulse Repetition Interval).

Therefore, there is a problem that it is difficult to directly apply a method such as TVG. To solve this problem, a method of automatically adjusting the gain according to the magnitude of the input signal can be considered.

However, since the gain is adjusted so that the signal is not saturated based on a relatively large direct wave, a relatively small target reflected signal passes through an analog-digital converter due to a low gain, Can be lost.

Also, even if the gain is fixed, signal saturation occurs as shown in Fig. In this case, since harmonic components appear in the frequency domain as shown in FIG. 3, there is a possibility that the false alarm rate may increase.

1. Korean Published Patent No. 10-2012-0003326 2. Korean Patent Publication No. 10-2011-0045627

The present invention has been proposed in order to solve the problem according to the above background art. When a signal having different signal magnitudes such as a direct wave and a target reflected wave is incident on a receiving node in an underwater dispersion sensor network, a relatively large signal is saturated The present invention provides a saturated signal detection method deviating from a dynamic range in an underwater distributed sensor network in which detection can be performed stably without adjusting gain when a gain of a receiving node is adjusted due to signal distortion due to clipping. have.

In order to achieve the above-described object, when a signal having a different signal magnitude such as a direct wave or a target reflected wave is incident on a receiving node in an underwater dispersion sensor network, a relatively large signal is saturated and signal distortion due to clipping The present invention provides a method for detecting a saturated signal out of a dynamic range in an underwater distributed sensor network that can perform detection without adjustment of gain when the gain of the receiving node needs to be adjusted.

The saturation signal detecting method includes:

A method for detecting a saturated signal outside a dynamic range in an underwater distributed sensor network,

A windowing step of generating a plurality of windows for the received signal;

An active signal determination step of determining presence or absence of an active signal in a plurality of windows;

Converting the signal into a frequency domain signal if the active signal exists;

A saturation determining step of determining whether the window is a saturated signal by using the converted frequency domain signal;

A comparison step of comparing frequency information in another window not including the saturation signal with frequency information in the window;

A storing step of holding a frequency value having the same value as a result of the comparison and separately storing the received signal having the same value; And

And a step of recognizing the target signal as a target signal when the number of received signals separately stored is greater than a predetermined set value.

Here, the presence or absence of the active signal may be determined by using signal energy between neighboring windows.

The determination of the saturation signal may be performed by converting a signal in the corresponding window into a frequency domain signal to calculate a harmonic frequency value and determining whether a harmonic wave having a predetermined number or more exists.

Further, the transformation may be a Fourier transform.

The saturation determination step may include: searching for a harmonic component excluding the transmission frequency component if information on the transmission frequency exists; And determining that the received signal is saturated if the harmonic components are more than the set number.

The saturation determination step may include: searching for a frequency component having a maximum magnitude value in a frequency domain if information on the transmission frequency is not present; And a step of obtaining a frequency value of a high frequency corresponding to the estimated transmission frequency and comparing the obtained frequency value with a reference frequency value to determine saturation of the received signal.

The storing step may further include excluding a value corresponding to a harmonic component of a significant frequency component greater than a threshold value in the corresponding window.

( Further, the signal energy may be expressed by Equation

(

이고,

이다)으로 정의되는 것을 특징으로 할 수 있다.here,

ego,

) Is defined as < EMI ID = 1.0 >

(여기서

는 문턱 값 (Threshold)을 의미한다)으로 정의되는 것을 특징으로 할 수 있다.In addition, the discrimination equation for determining whether the active signal is present is expressed by Equation

(here

Is defined as a threshold (Threshold).

(여기서

이고, fc는 송신 주파수이다)에 의해 산출되는 것을 특징으로 할 수 있다.Further, the frequency value of the harmonic is expressed by the following equation

(here

, And fc is a transmission frequency).

In addition, the determination of saturation may be made based on the following equation

,(

, (

은 n번째 판별식의 참/거짓 여부를 저장하는 변수이며, 수학식here

Is a variable for storing true / false of the n- th discrimination expression,

. 로 정의되며, 여기서,

는 해당 주파수의 스펙트럼 크기 값을, 그리고

는 주파수에 따른 문턱값을 의미한다)에 의해 이루어지는 것을 특징으로 할 수 있다.

. Lt; RTI ID = 0.0 >

Is the spectral magnitude value of the corresponding frequency, and

Is a threshold value according to the frequency).

는 주파수 별로 상이한 값 또는 동일한 값이 사용되는 것을 특징으로 할 수 있다.In addition,

A different value or the same value may be used for each frequency.

According to the present invention, when a strong signal is input to the receiving sensor and the signal is clipped, the detection can be continuously performed without adjusting the dynamic range, thereby preventing the loss of the detection information due to the dynamic range change.

Another advantage of the present invention is that since harmonics can be decomposed even when signal clipping occurs, stable performance of the receiving sensor can be assured.

1 is a view showing an example of a general underwater dispersion sensor network.
2 is a graph showing an example in which the active signal received by the sensor is saturated and clipped.
3 shows an example of a frequency spectrogram of a clipped signal.
4 is a diagram showing an example of a signal received in an underwater dispersion sensor network.
5 is a flowchart illustrating a process of detecting a saturated signal out of a dynamic range in an underwater dispersion sensor network according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method of detecting a saturated signal out of a dynamic range in an underwater dispersive sensor network according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, prior to describing the saturated signal detection method, signals received in an underwater dispersion sensor network will be described with reference to FIG.

4 is a diagram showing an example of a signal received in an underwater dispersion sensor network. 4, a first window 411, a second window 412, and a third window 413 for windowing a received signal, which is a direct wave signal 420 and / or a target reflected wave signal 131, Are shown.

According to another aspect of the present invention, there is provided a method of detecting an active signal, the method comprising: determining whether an active signal is present in the received signal; Determining whether the active signal is saturated; And excluding the estimated harmonic components and performing the detection.

FIG. 5 is a view showing such a structure for easy understanding. That is, FIG. 5 is a flowchart illustrating a process of detecting a saturated signal out of a dynamic range in an underwater sensor network according to an exemplary embodiment of the present invention.

5, in the signal processing unit (not shown) of the receiving node (120 to 129 in FIG. 1), the receiving signal s ( n ) as shown in FIG. 4 is windowed Windowing), the energy of a signal included in the k -th window is obtained as shown in the following Equation (S510).

이고,

이다.here,

ego,

to be.

4, assuming that the energy of the window A 412 including the active signal 420 and the energy of the window B 413 that does not include the energy and the active signal are the same under different conditions, 0.0 > 412) < / RTI > Therefore, the discrimination equation for determining the presence or absence of the active signal using this can be defined as follows (step S520).

는 문턱 값 (Threshold)을 의미한다. here

Means a threshold value.

If it is determined in step S520 that there is an active signal in the current window, the signal of the corresponding window is transformed into a frequency domain signal through a Fourier transform to determine whether the signal is saturated (step S530).

이 발생하게 되며, 이 때 발생하는 고조파의 주파수 값은 다음식과 같다.If the received signal is saturated if clipping occurs, the harmonic component of the transmission frequency f _c

And the frequency value of the harmonics generated at this time is as follows.

이다.here

to be.

을 탐색하여 해당 고조파 성분들이 설정된 개수 m이상 존재하는 경우 수신 신호가 포화된 것으로 판단하며, 이를 식으로 표현하면 다음과 같다(단계 S540).If there is information on the transmission frequency, the harmonic component excluding the transmission frequency component

And determines that the received signal is saturated when the harmonic components are present in the number m or more, and the equation is expressed as follows (step S540).

은 n번째 판별식의 참/거짓 여부를 저장하는 변수이며 다음과 같이 정의된다.here

Is a variable that stores true / false of the nth discriminant and is defined as follows.

는 해당 주파수의 스펙트럼 크기 값을, 그리고

는 주파수에 따른 문턱 값을 의미한다. 단,

는 반드시 주파수 별로 상이한 값을 사용해야 하는 것은 아니며 동일한 값이 사용될 수도 있다. here,

Is the spectral magnitude value of the corresponding frequency, and

Means a threshold value according to frequency. only,

Does not necessarily have to use a different value for each frequency, and the same value may be used.

If there is no information on the transmission frequency f _c , it is also possible to determine whether the signal is saturated by searching for a frequency component having a maximum magnitude in the frequency domain and obtaining a harmonic frequency value corresponding to the estimated transmission frequency.

과 일치하는 값을 배제한 후, 포화 신호가 포함되지 않은 다른 윈도우에서 판단된 주파수 정보와 비교하여 같은 값을 가지는 주파수 값은 계속 유지하고, 그 외의 값을 가지는 신호는 별도로 저장한다(단계 S550,S560). If it is determined that the signal of the current window is saturated, the harmonic component of a significant frequency component greater than the threshold value in the current window

And then the frequency value having the same value is kept as being compared with the frequency information judged in the other window not including the saturation signal and the signal having the other value is stored separately (steps S550 and S560 ).

If there is no active signal thereafter, if the stored signal is detected for a predetermined time or longer, the frequency is regarded as target signal frequency information, and if not, the signal is discarded (step S570).

By acquiring information about harmonic components generated by clipping using the steps described above, it is possible to distinguish frequency components and harmonic components due to actual signals in the frequency domain, so that it is possible to discriminate whether or not a high frequency component is a target signal You can. It is thus possible to maintain the detection performance without adjusting the gain according to the active signal by excluding the frequency from the detection information.

Particularly, in the underwater sensor network according to an embodiment of the present invention, the saturated signal detection method out of the dynamic range is implemented in the form of a program command code that can be executed through various computer means and is recorded in a computer- .

The computer-readable storage medium may include program instructions, data files, data structures, etc., alone or in combination.

The program instructions recorded on the computer-readable storage medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software.

Examples of computer-readable storage media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs and DVDs, floppy disks, Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like.

Also, examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In addition, one embodiment of the present invention may be implemented in hardware, software, or a combination thereof. (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microprocessor, and the like, which are designed to perform the above- , Other electronic units, or a combination thereof.

In a software implementation, it may be implemented as a module that performs the functions described above. The software may be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means well known to those skilled in the art.

110, 111: transmitting node
120 to 129: Receiving node
130: Target
131: target reflected wave signal
140: radio signal
150: direct wave signal
420: active signal
411 to 413: Window

Claims (12)

A method for detecting a saturated signal outside a dynamic range in an underwater distributed sensor network,
A windowing step of generating a plurality of windows for the received signal;
An active signal determination step of determining presence or absence of an active signal in a plurality of windows;
Converting the signal into a frequency domain signal if the active signal exists;
A saturation determining step of determining whether the window is a saturated signal by using the converted frequency domain signal;
A comparison step of comparing frequency information in another window not including the saturation signal with frequency information in the window;
A storing step of holding a frequency value having the same value as a result of the comparison and separately storing the received signal having the same value; And
Whether the target signal is detected as a target signal if the number of received signals separately stored is greater than a predetermined set value;
Wherein the saturation signal is out of dynamic range in an underwater dispersion sensor network.
The method according to claim 1,
Wherein the determination of the presence or absence of the active signal is made using signal energy between neighboring windows.
The method according to claim 1,
Wherein the determination of the saturation signal is performed by converting a signal in the corresponding window into a frequency domain signal to calculate a harmonic frequency value and determining whether a harmonic wave having a predetermined number or more exists. A method for detecting a saturated signal out of range.
The method according to claim 1,
Wherein the conversion is a Fourier transform. The method of detecting a saturated signal out of a dynamic range in an underwater distributed sensor network.
The method of claim 3,
The saturation determining step may include:
If the information on the transmission frequency is found, searching for a harmonic component excluding the transmission frequency component; And
And determining that the received signal is saturated if the harmonic components are greater than a predetermined number.
The method of claim 3,
The saturation determining step may include:
Searching for a frequency component having a maximum magnitude value in the frequency domain if there is no information about the transmission frequency; And
Determining a saturation of the received signal by comparing the obtained frequency value with a reference frequency value; and determining a saturation of the received signal by comparing the obtained frequency value with a reference frequency value. Detection method.
The method according to claim 1,
Wherein,
And excluding a value corresponding to a harmonic component among a significant frequency component greater than a threshold value in the corresponding window, wherein the saturation signal is out of dynamic range in the underwater dispersive sensor network.

3. The method of claim 2,
The signal energy is expressed by the following equation

(
here,

ego,

Wherein the saturation signal is defined as the saturation signal of the sensor network.
9. The method of claim 8,
The determination equation for determining whether the active signal is present is expressed by Equation

(here

Is defined as a threshold (Threshold). The method of detecting a saturated signal out of dynamic range in an underwater dispersive sensor network.
The method of claim 3,
The frequency value of the harmonic is given by Equation

(here

, And fc is a transmission frequency). ≪ / RTI >
9. The method of claim 8,
The determination as to whether or not the saturation has occurred can be made by determining the frequency value of the harmonic of the equation

, (
here

Is a variable for storing true / false of the n- th discrimination expression,

. Lt; RTI ID = 0.0 >

Is the spectral magnitude value of the corresponding frequency, and

Wherein the saturation signal is a threshold value according to frequency.
12. The method of claim 11,
remind

Wherein a different value or the same value is used for each frequency.

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