阅读说明：本技术 一种垂直阵声压梯度波束形成与信号检测方法 (Vertical array sound pressure gradient beam forming and signal detecting method ) 是由 陈韶华 曹振宇 张恒 秦银 汶宏刚 赵冬艳 于 2020-12-16 设计创作，主要内容包括：本发明公开了一种垂直阵声压梯度波束形成与信号检测方法,涉及水声阵列处理与目标探测技术领域,本发明既能检测较近距离的目标,又可以抑制远处传来的干扰,实现远程强干扰背景下的较近距离目标检测。本发明的技术方案包括如下步骤：采用M元等距垂直阵相邻阵元接收信号依次相减,得到M-1通道声压梯度信号；M为大于1的整数。对M-1通道声压梯度信号在预定角度上形成波束,并求得波束输出功率。对一段时间的波束输出功率输出形成数据序列,对数据序列采用长时α滤波求背景均值,对数据序列采用短时α滤波求信号均值,若信号均值大于背景均值设定数值,则判决为检测到目标。(The invention discloses a vertical array sound pressure gradient beam forming and signal detecting method, and relates to the technical field of underwater acoustic array processing and target detection. The technical scheme of the invention comprises the following steps: sequentially subtracting the received signals of adjacent array elements of the M-element equidistant vertical array to obtain an M-1 channel sound pressure gradient signal; m is an integer greater than 1. And forming a wave beam on the M-1 channel sound pressure gradient signal at a preset angle, and obtaining the output power of the wave beam. And outputting the beam output power for a period of time to form a data sequence, solving a background mean value by adopting long-time alpha filtering on the data sequence, solving a signal mean value by adopting short-time alpha filtering on the data sequence, and judging that the target is detected if the signal mean value is larger than a set value of the background mean value.)

1. A vertical array sound pressure gradient beam forming and signal detecting method is characterized by comprising the following steps:

sequentially subtracting the received signals of adjacent array elements of the M-element equidistant vertical array to obtain an M-1 channel sound pressure gradient signal; m is an integer greater than 1;

forming a wave beam on the M-1 channel sound pressure gradient signal at a preset angle, and obtaining the output power of the wave beam;

and outputting the beam output power for a period of time to form a data sequence, solving a background mean value by adopting long-time alpha filtering on the data sequence, solving a signal mean value by adopting short-time alpha filtering on the data sequence, and judging that the target is detected if the signal mean value is larger than a set value of the background mean value.

2. The method according to claim 1, wherein the M-channel acoustic pressure gradient signal is obtained by sequentially subtracting the received signals of the M-element equidistant vertical array elements, specifically:

filtering and amplifying M-channel signals received by the M-element equidistant vertical array, and then sampling to obtain an M-channel discrete signal sequence x₁(n),x₂(n),……,x_M(N), where N is 0,1, … …, N-1, where N is the number of sample points of one frame of data per channel;

subtracting every two adjacent channel signals in the M-channel discrete signals to obtain an M-1 channel sound pressure gradient signal: y is_i(n)＝x_i+1(n)-x_i(n),i＝1,2,……,M-1。

3. The method of claim 2, wherein the pair of M-1 channel acoustic pressure gradient signals form a beam at a predetermined angle, in particular:

according to the depth h of the M-element equidistant vertical array and the distance r to be monitored, obtaining the angle theta of the beam to be formed: theta as arctan (r/h)

Performing conventional beam forming on the M-1 channel sound pressure gradient signal in the theta direction, wherein the beam output is u (N), N is 0,1, … …, and N-1;

calculating a beam output power of

4. The method of claim 3, wherein the forming a data sequence for a period of beamformed output is in particular:

and obtaining K frame signals in total within a set period of time, wherein each frame signal corresponds to one beam output power, namely the K frame signals in total obtain a data sequence of { z (K) }, K is 0,1, … …, K-1, and K is a K frame signal.

5. The method of claim 4, wherein the background averaging is performed by long-term alpha filtering on the data sequence, and the signal averaging is performed by short-term alpha filtering on the data sequence, specifically:

the background mean value is obtained by long-time alpha filtering on the data sequence

Averaging data sequences using short-time alpha filtering

Wherein M is_aThe short-time filtering parameter is smaller than a set short-time filtering threshold value; m_bAnd the long-term filtering parameter is larger than the set long-term filtering threshold value.

6. The method of claim 5, wherein taking M_aLess than 10, M_bGreater than 50.

Technical Field

The invention relates to the technical field of underwater acoustic array processing and target detection, in particular to a vertical array sound pressure gradient beam forming and signal detecting method.

Background

When the underwater vertical array detects weak target signals passing nearby, ship noise and other interference transmitted from far places in the ocean are mainly incident from the horizontal direction, as shown in fig. 1. When the target signal is weak, the sound pressure array beam forming is not enough to suppress interference and extract the signal. In order to suppress strong interference incident in the horizontal direction, an adaptive beam nulling technique is generally employed. The self-adaptive wave beam null technology is complex to realize and is not suitable for being applied to a small underwater platform powered by a battery for a long time.

How to realize the detection of a target at a short distance under the background of remote strong interference on an underwater small platform is a problem which cannot be solved by the current beam forming scheme.

Disclosure of Invention

In view of this, the invention provides a vertical array sound pressure gradient beam forming and signal detecting method, which can detect a target at a short distance, and can suppress interference from a far distance, thereby realizing the detection of the target at the short distance under the background of remote strong interference.

In order to achieve the purpose, the technical scheme of the invention comprises the following steps:

sequentially subtracting the received signals of adjacent array elements of the M-element equidistant vertical array to obtain an M-1 channel sound pressure gradient signal; m is an integer greater than 1.

And forming a wave beam on the M-1 channel sound pressure gradient signal at a preset angle, and obtaining the output power of the wave beam.

And outputting the beam output power for a period of time to form a data sequence, solving a background mean value by adopting long-time alpha filtering on the data sequence, solving a signal mean value by adopting short-time alpha filtering on the data sequence, and judging that the target is detected if the signal mean value is larger than a set value of the background mean value.

Further, the M-element equidistant vertical array adjacent array element receiving signals are sequentially subtracted to obtain an M-1 channel sound pressure gradient signal, which specifically comprises:

filtering and amplifying M-channel signals received by the M-element equidistant vertical array, and then sampling to obtain an M-channel discrete signal sequence x₁(n),x₂(n),……,x_M(N), where N is 0,1, … …, N-1, where N is the number of sample points per frame of data per channel.

Subtracting every two adjacent channel signals in the M-channel discrete signals to obtain an M-1 channel sound pressure gradient signal: y is_i(n)＝x_i+1(n)-x_i(n),i＝1,2,……,M-1。

Further, forming a beam on the M-1 channel sound pressure gradient signal at a predetermined angle, specifically:

according to the depth h of the M-element equidistant vertical array and the distance r to be monitored, obtaining the angle theta of the beam to be formed: theta as arctan (r/h)

Performing conventional beam forming on the M-1 channel sound pressure gradient signal in the theta direction, wherein the beam output is u (N), N is 0,1, … …, and N-1;

calculating a beam output power of

Further, outputting a formed data sequence for a period of time beam, specifically: and obtaining K frame signals in total within a set period of time, wherein each frame signal corresponds to one beam output power, namely the K frame signals in total obtain a data sequence of { z (K) }, K is 0,1, … …, K-1, and K is a K frame signal.

Further, the long-time α filtering is adopted for the data sequence to obtain a background mean value, and the short-time α filtering is adopted for the data sequence to obtain a signal mean value, which specifically comprises the following steps:

the background mean value is obtained by long-time alpha filtering on the data sequence

Averaging data sequences using short-time alpha filtering

Wherein M is_aThe short-time filtering parameter is smaller than a set short-time filtering threshold value; m_bAnd the long-term filtering parameter is larger than the set long-term filtering threshold value.

Further, take M_aLess than 10, M_bGreater than 50.

Has the advantages that:

according to the method for forming the vertical array boosting gradient wave beam and detecting the signal, the sound pressure gradient signal is obtained by subtracting the receiving signals of the adjacent arrays of the equal-spacing vertical array. The sound pressure gradient signal has spatial directivity, a recess is formed in the horizontal direction, the sound pressure gradient signal is subjected to beam forming processing, the obtained beam forms the recess in the horizontal direction according to the multiplication principle of beam pattern synthesis, and the energy loss at a position of 30 degrees in the appointed direction is very small, so that a target at a short distance can be detected, the interference transmitted from a far distance can be restrained, and the detection of the target at the short distance under the background of remote strong interference is realized. Compared with the sound pressure array beam forming method, the method has better interference suppression capability. Compared with the existing self-adaptive zero-trap beam forming technology, the complexity is greatly reduced, and the method is more convenient to apply in engineering.

Drawings

FIG. 1 is a schematic diagram of a vertical array in an embodiment of the present invention for detecting a long-range interference background;

FIG. 2 is a schematic diagram of the vertical directivity of the sound pressure gradient in an embodiment of the present invention;

FIG. 3 is a schematic diagram of acoustic pressure gradient beamforming interference nulling in an embodiment of the present invention;

FIG. 4 is a schematic diagram of the beam output and signal detection results of the acoustic pressure array and the acoustic pressure gradient array according to the embodiment of the present invention;

fig. 5 is a flowchart of a vertical array acoustic pressure gradient beam forming and signal detecting method according to an embodiment of the present invention.

Detailed Description

The invention is described in detail below by way of example with reference to the accompanying drawings.

The invention provides a vertical array sound pressure gradient beam forming and signal detecting method, the flow of which is shown in figure 5, the method comprises the following steps:

s1, sequentially subtracting the received signals of adjacent array elements of the M-element equidistant vertical array to obtain an M-1 channel sound pressure gradient signal; m is an integer greater than 1.

In the embodiment of the invention, M-channel signals received by M-element equidistant vertical arrays are filtered and amplified and then sampled to obtain M-channel discrete signal sequences x₁(n),x₂(n),……,x_M(N), where N is 0,1, … …, N-1, where N is the number of sample points of one frame of data per channel;

subtracting every two adjacent channel signals in the M-channel discrete signals to obtain an M-1 channel sound pressure gradient signal: y is_i(n)＝x_i+1(n)-x_i(n),i＝1,2,……,M-1。

And subtracting the received signals of the adjacent arrays of the equidistant vertical array to obtain a sound pressure gradient signal. The sound pressure gradient signal has spatial directivity, forming a notch in the horizontal direction, as shown in fig. 2.

And S2, forming a beam on the M-1 channel sound pressure gradient signal at a preset angle, and obtaining the output power of the beam.

According to the depth h of the M-element equidistant vertical array and the distance r to be monitored, obtaining the angle theta of the beam to be formed: theta as arctan (r/h)

Performing conventional beam forming on the M-1 channel sound pressure gradient signal in the theta direction, wherein the beam output is u (N), N is 0,1, … …, and N-1;

calculating a beam output power of

The sound pressure gradient signal is subjected to beamforming processing, and the resultant beam is depressed in the horizontal direction according to the multiplication principle of beam pattern synthesis, while the energy loss is small at 30 ° in a given direction, as shown in fig. 3.

S3, forming a data sequence for the beam output power output of a period of time; and obtaining K frame signals in total within a set period of time, wherein each frame signal corresponds to one beam output power, namely the K frame signals in total obtain a data sequence of { z (K) }, K is 0,1, … …, K-1, and K is a K frame signal.

And S4, adopting long-time alpha filtering to solve the background mean value of the data sequence, and adopting short-time alpha filtering to solve the signal mean value of the data sequence.

Wherein the short-term alpha filtering and the long-term alpha filtering refer to filtering parameters applied in the alpha filtering, wherein M is different_aThe short-time filtering parameter is smaller than a set short-time filtering threshold value; m_bAnd the long-term filtering parameter is larger than the set long-term filtering threshold value.

The background mean value is obtained by long-time alpha filtering on the data sequence

Averaging data sequences using short-time alpha filtering

In the embodiment of the invention, M is taken_aLess than 10, M_bGreater than 50.

And S5, judging the size of the background mean value and the signal mean value, judging that the target is detected if the signal mean value is larger than the set value of the background mean value, and returning to S1 to continue the next detection if the target is not detected.

I.e. ifThe target is judged and detected, and the delta is the set value, and the selection can be determined according to the judgment effect, and can be generally 2-5.

The method for forming the vertical array sound pressure gradient wave beam and detecting the signal has been verified by sea test data, as shown in figure 4.

In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.