A lake test method for acoustic compatibility of a bulbous bow hydroacoustic device with a towed linear array

Abstract

The present invention discloses a lake test method for acoustic compatibility of a bulbous bow hydroacoustic device with a towed linear array, which belongs to the technical field of ship acoustic compatibility design. The method of the present invention constructs a lake test environment, then formulates the emission conditions of the bulbous bow hydroacoustic device, and judges whether the front-end receiving channel of the towed linear array is saturated based on the data collected by the standard hydrophone, and finally judges whether the detection performance of the towed linear array is interfered based on the array element domain data. The method of the present invention can be used for the situation where the front-end receiving channel of the towed linear array has been encapsulated in a sheath and the front-end receiving channel cannot set a measuring point. In the design stage, the bulbous bow hydroacoustic device and the towed linear array are used to carry out an acoustic compatibility lake test, find out the acoustic interference of the bulbous bow hydroacoustic device to the towed linear array, support the analysis of the interference cause, and put forward targeted anti-interference measures to maximize the compatible use of the two devices.

Description

Technical Field

[0001] The invention belongs to the technical field of ship acoustic compatibility design, and in particular relates to a lake test method for acoustic compatibility of a bulbous bow hydroacoustic device with a towed linear array. Background Art

[0002] Submarines are the main underwater threat to surface ships. Surface ships are usually equipped with bulbous bow hydroacoustic equipment and towed linear arrays for submarine detection. The bulbous bow hydroacoustic equipment is installed in the bulbous bow of the ship, and the towed linear array is towed at a certain distance from the stern of the ship when in use. Usually, the towed linear array has a lower operating frequency and is used for long-range warning of submarines, while the bulbous bow hydroacoustic equipment has a higher operating frequency and is used for accurate tracking of submarines.

[0003] In recent years, with the continuous enhancement of submarine stealth capabilities and the increasing demand for long-range and accurate detection capabilities of submarines by surface ships, bulbous bow hydroacoustic equipment has begun to develop in the direction of low frequency, large aperture, and high power, resulting in the increasing risk of interference of bulbous bow hydroacoustic equipment with towed linear arrays. The traditional theoretical calculation method can qualitatively analyze the interference situation, but it is difficult to accurately predict the acoustic interference of bulbous bow hydroacoustic equipment with towed linear arrays, especially the out-of-band interference situation. If the acoustic compatibility test of bulbous bow hydroacoustic equipment with towed linear arrays is carried out on a real ship after the construction of the surface ship is completed, there will be problems such as the packaging of the real ship sonar equipment has been completed, and some data cannot be obtained on demand, resulting in the inability to accurately judge the acoustic interference situation, and the equipment cannot take effective anti-interference measures, resulting in the two devices being difficult to use compatibly. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a lake test method for the acoustic compatibility of a bulbous bow hydroacoustic device with a towed linear array. In the design phase, the bulbous bow hydroacoustic device and the towed linear array are used to carry out an acoustic compatibility test on the lake to find out the acoustic interference of the bulbous bow hydroacoustic device on the towed linear array, support the subsequent analysis of the cause of the interference, and propose targeted anti-interference measures to maximize the compatible use of the two devices.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a lake test method for acoustic compatibility of a bulbous bow hydroacoustic device with a towed linear array, comprising the following steps:

[0007] Step 1: Construct a test environment on the lake, and place the bow hydroacoustic equipment, acoustic baffle, towed linear array and standard hydrophone in the water at a certain depth;

[0008] Step 2: Formulate the launch conditions of the bulbous bow hydroacoustic device; the launch conditions of the bulbous bow hydroacoustic device include launch pulse width, launch range, launch frequency, launch main beam azimuth and launch power;

[0009] Step 3: Determine whether the front-end receiving channel of the towed linear array is saturated based on the data collected by the standard hydrophone;

[0010] When the bulbous bow hydroacoustic device is launched, the standard hydrophone and the towed linear array collect data synchronously, wherein the standard hydrophone data is collected by a data collector, and the towed linear array uses its own data recording device to record its time domain waveform data after AD conversion; by comparing the peak-to-peak value of the time domain waveform with the limiting voltage of each level of amplification and filtering, it is judged whether the channel is saturated. If it is greater than the limiting voltage, it is judged to be saturated, and if it is less than the limiting voltage, it is judged to be not saturated;

[0011] The AD conversion part uses the time domain data i(t) recorded synchronously by the dragging line array to determine whether the link is saturated, that is, if the peak-to-peak value of i(t) is greater than the limit voltage, it is judged to be saturated, and if it is less than the limit voltage, it is judged to be not saturated;

[0012] Step 4: Determine whether the detection performance of the towed linear array is interfered based on the array element domain data;

[0013] Interference judgment is performed using the time domain data i(t) recorded by the towed linear array. If C ≥ NL, interference is judged to occur; otherwise, no interference is judged to occur, where NL represents the background noise spectrum level when the towed linear array achieves the index.

[0014] Furthermore, the deployment depth of the bulbous bow hydroacoustic device is the minimum value required for it to transmit at full power; a sound baffle is deployed at the rear end of the bulbous bow hydroacoustic device, suspended in the water and perpendicular to the towed linear array, and the size, shape, shielding performance and relative position relationship of the sound baffle with the bulbous bow hydroacoustic device are consistent with those of the actual ship; the towed linear array is deployed underwater, and the standard hydrophone is deployed at the position where the distance between the towed linear array and the bulbous bow hydroacoustic device is minimum, and the deployment depth is basically the same as the depth of the towed linear array.

[0015] Further, in step 2, the parameters of the launch condition of the bulbous bow hydroacoustic device are as follows:

[0016] a. Transmitting pulse width: at least including two situations: less than the integration time of the towed linear array and greater than the integration time of the towed linear array;

[0017] b. Transmitting range: the minimum range that meets the transmitting pulse width requirements;

[0018] c. Transmitting frequency: including the transmitting frequencies of the bulbous bow hydroacoustic equipment and their corresponding waveforms;

[0019] d. Azimuth of the main beam: At this design stage, when it is to be installed on a real ship, the bulbous bow hydroacoustic equipment can detect the critical angle azimuth of the field of view, the critical angle azimuth of the field of view with guaranteed accuracy, the 0° azimuth, and some azimuths between the above azimuths;

[0020] e. Transmitting power: including full power and minimum power. If both cause interference or no interference to the towed linear array, there is no need to increase the power between the two. Otherwise, it is necessary to increase the power between the two.

[0021] Furthermore, in step 3, the calculation method is shown in formula (1) to formula (4):

[0022] I A1 (f) = FFT (i s (t)) / As(f)*(S t (f) / S s (f))*A1(f)(1)

[0023] I F1 (f) = I A1 (f)*Filter1(f)(2)

[0024] I A2 (f) = I F1 (f)*A2(f)(3)

[0025] I F2 (f) = I A2 (f)*Filter2(f)(4)

[0026] where i s (t) represents the time domain waveform of interference collected by the data collector, S s (f) represents the receiving sensitivity of the standard hydrophone, As(f) represents the amplitude-frequency response of the amplifier in this acquisition system; S t (f) represents the receiving sensitivity of the towed linear array hydrophone, A1(f), Filter1(f), A2(f), and Filter2(f) represent the amplitude-frequency response characteristics of the first-stage amplification, the first-stage filtering, the variable gain, and the second-stage filtering, respectively. A1 (f) I F1 (f) I A2 (f) I F2 (f) represent the output spectrum of the first-stage amplification, first-stage filtering, variable gain, and second-stage filtering of the front-end receiving channel of the towed linear array, where FFT (.) represents the fast Fourier transform, which converts the time domain waveform into a spectrum; A1 (f) I F1 (f) I A2 (f) I F2(f) They are transformed into time domain waveforms after inverse Fourier transform.

[0027] Furthermore, in step 4, the element domain time domain data i1(t), i2(t), and i3(t) of the hydrophones at the front, middle, and rear positions of the towed linear array are selected for interference judgment. Then, the output interference intensity C of the towed linear array at the φ position is:

[0028] (5)

[0029] C1=FFT(i1(t))+DI-D(θ,φ)(6)

[0030] C2=FFT(i2(t))+DI-D(θ,φ)(7)

[0031] C3=FFT(i3(t))+DI-D(θ,φ)(8)

[0032] Where DI represents the array gain of the towed linear array, D(θ, φ) represents the sidelobe suppression in the azimuth when the main beam of the towed linear array points to the azimuth of θ, when θ=φ, D(θ, φ)=0, when judging the interference of the bulbous bow hydroacoustic equipment to the towed linear array, θ=0°, C1, C2, and C3 are the interference intensities output by the array elements at the front, middle, and rear positions of the towed linear array, respectively.

[0033] The beneficial effects of the present invention are:

[0034] The present invention provides a method for testing the acoustic compatibility of a bulbous bow hydroacoustic device with a towed linear array on a lake, which can improve the situation in the prior art where the front-end receiving channel of the towed linear array is encapsulated in a sheath and the front-end receiving channel cannot be set with a measuring point. During the design phase, the bulbous bow hydroacoustic device and the towed linear array are used to carry out an acoustic compatibility test on a lake, and the acoustic interference of the bulbous bow hydroacoustic device to the towed linear array is understood, which effectively solves the problem of being unable to fully obtain data for acoustic compatibility analysis in the case of a real ship, and can effectively support the subsequent analysis of the cause of interference, and put forward targeted anti-interference measures, so as to achieve the purpose of compatible use of the two devices.

[0035] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0037] Figure 1This is a schematic diagram of the acoustic compatibility test environment on the lake of the present invention;

[0038] Figure 2 The present invention provides a method for arranging a towed linear array in a lake test;

[0039] Figure 3 This is a schematic diagram of the launch position of the bulbous bow hydroacoustic equipment;

[0040] Figure 4 This is a schematic diagram of the standard hydrophone receiving system used in the experiment;

[0041] Figure 5 This is a typical front-end receiving channel flow chart of a towed linear array;

[0042] Figure 6 This is a typical digital signal processing flow chart of a towed linear array. DETAILED DESCRIPTION

[0043] The present invention provides a lake test method for acoustic compatibility of a bulbous bow hydroacoustic device with a towed linear array, comprising the following steps:

[0044] Step 1: Build the test environment on the lake;

[0045] The bulbous bow hydroacoustic equipment is lowered into the lake by the fixed lifting device on the pontoon through the measuring well, and the laying depth is the minimum value that satisfies its full power emission; a sound baffle is laid at the rear end of the bulbous bow hydroacoustic equipment, and the sound baffle is lowered into the water by the fixed lifting device on the pontoon, and is perpendicular to the towed linear array. Its size, shape, shielding performance and relative position relationship with the bulbous bow hydroacoustic equipment are consistent with those of the actual ship; the towed linear array is laid at a depth of about 10-20m underwater through the pontoon, slope, tow cable, buoy, towing rope, etc., see the attached Figure 2 ; The standard hydrophone is placed at the position where the distance between the towed linear array and the bulbous bow hydroacoustic equipment is the smallest. The placement depth is basically the same as the depth of the towed linear array. For details, see the attached Figure 1 .

[0046] Step 2: Formulate the launch conditions of the bulbous bow hydroacoustic equipment

[0047] The launch conditions of the bulbous bow hydroacoustic equipment include the following parameters:

[0048] a. Transmitting pulse width: at least including two situations: less than the integration time of the towed linear array and greater than the integration time of the towed linear array;

[0049] b. Transmitting range: the minimum range that meets the transmitting pulse width requirements;

[0050] c. Transmitting frequency: including the transmitting frequencies of the bulbous bow hydroacoustic equipment and their corresponding waveforms;

[0051] d. Azimuth of the main beam: At this design stage, when it is to be installed on a real ship, the bulbous bow hydroacoustic equipment can detect the critical angle azimuth of the field of view, the critical angle azimuth of the field of view with guaranteed accuracy, the 0° azimuth, and some azimuths between the above azimuths, such as the attached Figure 3 As shown;

[0052] e. Transmitting power: including full power and minimum power. If both cause interference or no interference to the towed linear array, there is no need to increase the power between the two. Otherwise, it is necessary to increase the power between the two.

[0053] Step 3: Determine whether the front-end receiving channel of the towed linear array is saturated based on the data collected by the standard hydrophone

[0054] When the bulbous bow hydroacoustic device is transmitting, the standard hydrophone and the towed linear array collect data synchronously. The standard hydrophone data is collected by the data collector, and the towed linear array uses its own data recording device to record its time domain waveform data after AD conversion. The schematic diagram of the standard hydrophone receiving system in the test is shown in the attached figure. Figure 4 As shown, where i s (t) represents the time domain waveform of interference collected by the collector, S s (f) represents the receiving sensitivity of the standard hydrophone, and As(f) represents the amplitude-frequency response of the amplifier in this acquisition system. The typical front-end receiving channel flow chart of the towed linear array is shown in the attached figure. Figure 5 As shown, S t (f) represents the receiving sensitivity of the towed linear array hydrophone, A1(f), Filter1(f), A2(f), and Filter2(f) represent the amplitude-frequency response characteristics of the first-stage amplification, the first-stage filtering, the variable gain, and the second-stage filtering, respectively. A1 (f) I F1 (f) I A2 (f) I F2 (f) respectively represent the frequency spectrum output after the first-stage amplification, first-stage filtering, variable gain, and second-stage filtering of the front-end receiving channel of the towed linear array. The calculation method is shown in equations (1) to (4):

[0055] I A1 (f) = FFT (i s (t)) / As(f)*(S t (f) / S s (f))*A1(f)(1)

[0056] I F1 (f) = I A1 (f)*Filter1(f)(2)

[0057] I A2 (f) = I F1(f)*A2(f)(3)

[0058] I F2 (f) = I A2 (f)*Filter2(f)(4)

[0059] Among them, FFT (.) represents the fast Fourier transform, which converts the time domain waveform into a spectrum; A1 (f) I F1 (f) I A2 (f) I F2 (f) The inverse Fourier transform is used to convert the waveforms into time domain waveforms. The peak-to-peak value of the time domain waveform is compared with the limiting voltage of each stage of amplification and filtering to determine whether the channel is saturated. If it is greater than the limiting voltage, it is determined to be saturated; if it is less than the limiting voltage, it is determined not to be saturated.

[0060] The AD converter uses the time domain data i(t) synchronously recorded by the dragging linear array to determine whether saturation occurs in this link. That is, if the peak-to-peak value of i(t) is greater than the limiting voltage, it is judged to be saturated, and if it is less than the limiting voltage, it is judged to be not saturated.

[0061] Step 4: Determine whether the detection performance of the towed linear array is disturbed based on the array element domain data

[0062] The time domain data i(t) recorded by the towed linear array is used for interference judgment. The element domain time domain data i1(t), i2(t), and i3(t) of the hydrophones at the front, middle, and back positions of the towed linear array are selected for interference judgment. The output interference intensity of the towed linear array at the φ position is:

[0063] (5)

[0064] C1=FFT(i1(t))+DI-D(θ,φ)(6)

[0065] C2=FFT(i2(t))+DI-D(θ,φ)(7)

[0066] C3=FFT(i3(t))+DI-D(θ,φ)(8)

[0067] Where DI represents the array gain of the towed linear array, and D(θ, φ) represents the sidelobe suppression at φ when the main beam of the towed linear array points to θ. See the attached diagram for details. Figure 6 , when θ=φ, D(θ, φ)=0. When judging the interference of the bulbous bow hydroacoustic equipment to the towed linear array, θ=0°. C1, C2, and C3 are the interference intensity of the array element outputs at the front, middle, and rear positions of the towed linear array respectively. If C≥NL, it is judged that interference occurs, otherwise it is judged that no interference occurs, where NL represents the background noise spectrum level when the towed linear array achieves the index.

[0068] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A lake test method for acoustic compatibility of a bulbous bow hydroacoustic device with a towed linear array, characterized in that: The following steps are involved: Step 1: Construct a test environment on the lake, and place the bow hydroacoustic equipment, acoustic baffle, towed linear array and standard hydrophone in the water at a certain depth; Step 2: Formulate the launching conditions of the bulbous bow hydroacoustic equipment; The transmitting conditions of the bulbous bow hydroacoustic equipment include transmitting pulse width, transmitting range, transmitting frequency, transmitting main beam azimuth and transmitting power; Step 3: Determine whether the front-end receiving channel of the towed linear array is saturated based on the data collected by the standard hydrophone; When the bulbous bow hydroacoustic device is launched, the standard hydrophone and the towed linear array collect data synchronously, wherein the standard hydrophone data are collected by a data collector, and the towed linear array uses its own data recording device to record its time domain waveform data after AD conversion; the AD conversion part uses the time domain data i(t) synchronously recorded by the towed linear array to determine whether the link has been saturated, that is, the peak-to-peak value of the time domain waveform is compared with the limiting voltage of each level of amplification and filtering. If the peak-to-peak value of i(t) is greater than the limiting voltage, it is determined that saturation has occurred, and if it is less than the limiting voltage, it is determined that no saturation has occurred; Step 4: judging whether the detection performance of the towed linear array is interfered based on the array element domain data of the towed linear array; Interference judgment is performed using the time domain data i(t) recorded by the towed linear array. If C≥NL, it is judged that interference occurs, otherwise it is judged that no interference occurs, where NL represents the background noise spectrum level when the towed linear array achieves the index, and C represents the interference intensity output by the towed linear array in the φ direction; The placement depth of the bulbous bow hydroacoustic device is the minimum value that satisfies its full power transmission. A sound baffle is placed at the rear end of the bulbous bow hydroacoustic device. The sound baffle is suspended in the water and is perpendicular to the towed linear array. The size, shape, shielding performance and relative position relationship of the sound baffle with the bulbous bow hydroacoustic device are consistent with those of the actual ship. The towed linear array is placed underwater, and the standard hydrophone is placed at the minimum distance between the towed linear array and the bulbous bow hydroacoustic device. The placement depth is basically the same as the depth of the towed linear array. In step 2, the parameters of the launch condition of the bulbous bow hydroacoustic device are as follows: a. Transmitting pulse width: at least including two situations: less than the integration time of the towed linear array and greater than the integration time of the towed linear array; b. Transmitting range: the minimum range that meets the transmitting pulse width requirements; c. Transmitting frequency: including the transmitting frequencies of the bulbous bow hydroacoustic equipment and their corresponding waveforms; d. Azimuth of the main beam: At this design stage, when it is to be installed on a real ship, the bulbous bow hydroacoustic equipment can detect the critical angle azimuth of the field of view, the critical angle azimuth of the field of view with guaranteed accuracy, the 0° azimuth, and some azimuths between the above azimuths; e. Transmitting power: including full power and minimum power. If both of them cause interference or no interference to the towed linear array, there is no need to increase the power between the two. Otherwise, it is necessary to increase the power between the two. In step 3, the calculation method is shown in formula (1) to formula (4): I A1 (f)=FFT(i s (t)) / As(f)*(S t (f) / S s (f))*A1(f)(1) I F1 (f)= I A1 (f)*Filter1(f)(2) I A2 (f)= I F1 (f)*A2(f)(3) I F2 (f)= I A2 (f)*Filter2(f)(4) where i s (t) represents the time domain waveform of interference collected by the data collector, S s (f) represents the receiving sensitivity of the standard hydrophone, As(f) represents the amplitude-frequency response of the amplifier in this collector; S t (f) represents the receiving sensitivity of the towed linear array hydrophone, A1(f), Filter1(f), A2(f), and Filter2(f) represent the amplitude-frequency response characteristics of the first-stage amplification, the first-stage filtering, the variable gain, and the second-stage filtering, respectively. A1 (f) I F1 (f) I A2 (f) I F2 (f) represent the output spectrum of the first-stage amplification, first-stage filtering, variable gain, and second-stage filtering of the front-end receiving channel of the towed linear array, where FFT (.) represents the fast Fourier transform, which converts the time domain waveform into a spectrum; A1 (f) I F1 (f) I A2 (f) I F2 (f) They are transformed into time domain waveforms after inverse Fourier transform.

2. The lake test method for acoustic compatibility of a bulbous bow hydroacoustic device with a towed linear array according to claim 1 is characterized in that: In step 4, the element domain time domain data i1(t), i2(t), and i3(t) of the hydrophones at the front, middle, and rear positions of the towed linear array are selected for interference judgment. The output interference intensity C of the towed linear array at the φ position is: （5） C1=FFT(i1(t))+DI-D(θ,φ)(6) C2=FFT(i2(t))+DI-D(θ,φ)(7) C3=FFT(i3(t))+DI-D(θ,φ)(8) Where DI represents the array gain of the towed linear array, D(θ, φ) represents the sidelobe suppression in the azimuth when the main beam of the towed linear array points to the azimuth of θ, when θ=φ, D(θ, φ)=0, when judging the interference of the bulbous bow hydroacoustic equipment to the towed linear array, θ=0°, C1, C2, and C3 are the interference intensities output by the array elements at the front, middle, and rear positions of the towed linear array, respectively.

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