Response type underwater acoustic ranging method

Abstract

The embodiment of the invention provides a response type underwater acoustic ranging method. The method comprises the following steps: S1, a response type measurement method: measuring and calculating sound signal propagation time in a form of calling by a host computer and responding by a slave computer, and calculating a distance through sound velocity and time; s2, depth correction: correcting the depth data read by the master and slave machines according to the uploading time of the pressure sensor; s3, sound velocity correction: correcting sound velocity differentials at different depths on the signal propagation path according to the sound velocity gradient profile map; s4, calculating a slope distance according to an iterative formula; s5, calculating a horizontal distance according to the slope distance and the relative depth; and S6, performing ten-point moving average on the distance measurement result. According to the method for accurately measuring the distance between the two responding underwater targets, more accurate distance measurement can be realized, and support is provided for underwater acoustic positioning.

Description

Technical Field

[0001] The present application relates to the field of underwater acoustic positioning and signal detection technology, and in particular to a responsive underwater acoustic ranging method. Background Art

[0002] In recent years, ranging technology has been widely used in fields such as marine development. Due to the long-distance transmission characteristics of sound waves underwater, underwater acoustic ranging technology is of great significance to underwater positioning, detection, communication and networking technologies. The basic principle of underwater acoustic ranging is to calculate the distance based on the propagation time of sound waves and the propagation speed of sound waves underwater. However, due to the unevenness of underwater sound speed, the uncertainty of the underwater acoustic channel and the position offset caused by the movement of the target, errors will be introduced into the final ranging result.

[0003] At present, there are two main methods for measuring the distance between two underwater targets: active and passive. The traditional ranging method has the following problems: 1. The propagation speed of sound waves underwater changes gradiently with increasing depth. If a single sound speed is used as the standard, it will cause deviations in the ranging results; 2. When the two targets of the measured object have relative motion, the ranging results will have a certain offset. It is very necessary to seek a ranging method that can avoid the above error factors and make real-time corrections to the variables in the distance calculation process. Summary of the invention

[0004] The purpose of the present invention is to provide a responsive underwater acoustic ranging method to solve the above-mentioned problems.

[0005] The embodiment of the present invention provides a response-type underwater acoustic ranging method, including:

[0006] Step S1, a response measurement method, using the master calling and the slave answering to measure the sound signal propagation time, and calculate the distance through the sound speed and time;

[0007] Step S2, depth correction, correcting the depth data read by the master and slave machines according to the upload time of the pressure sensor;

[0008] Step S3, sound velocity correction, correcting the sound velocity differentials at different depths on the signal propagation path according to the sound velocity gradient profile;

[0009] Step S4, calculating the slope distance according to the iterative formula;

[0010] Step S5, calculating the horizontal distance according to the slant distance and the relative depth;

[0011] Step S6, taking a ten-point sliding average of the distance measurement results.

[0012] In some embodiments, the step S1, a response measurement method, uses the form of a host calling and a slave responding to measure the propagation time of the sound signal, and calculates the distance by the speed of sound and time, including:

[0013] The host device is suspended on the shore at a fixed depth and periodically emits sound wave signals. Each time a signal is emitted, a timer is read to record the time when the signal is emitted.

[0014] The slave is at a certain point underwater, and its depth changes at a constant speed over time. After detecting the signal sent by the host, it sends a response signal to the host. After the host detects the response signal, it reads the timer again and calculates the specific time of the sound signal propagation according to the following formula:

[0015]

[0016] Among them, Tmp is the sum of the propagation time t1 of the host sending signal and the propagation time t2 of the slave machine response signal, T1CntAfter is the time when the host receives the slave machine signal, T1CntBefore is the time when the host sends the signal, the timer crystal frequency is 24000Hz, CCNT is the total number of points collected in a packet of signals, PeakNum is the position of the signal starting point in a packet of signals, the signal sampling frequency is 144000, TAU is the modulation and demodulation time between the slave machine receiving the signal and sending the signal, and Trim is the reserved delay.

[0017] In some embodiments, the step S2, depth correction, corrects the depth data read by the master and slave devices according to the upload time of the pressure sensor, including:

[0018] Slave depth calibration: After receiving the host signal and completing demodulation, the slave reads the timer count DCNT, takes the remainder of 111ms, and selects the depth data closest to the current moment from the interpolated pressure sensor data according to the obtained time, recorded as h2, and writes it into the communication data to be transmitted to the host;

[0019] Host depth calibration: After receiving the slave signal, the host reads the timer count DCNT, takes the remainder of 111ms, and selects the depth data closest to the current moment from the interpolated pressure sensor data according to the obtained time, which is recorded as h0;

[0020] The depth of the slave will change during the modulation and demodulation process. After testing, the length of this time is TAU. The depth of the slave at the moment of receiving the host signal is calculated and recorded as h1.

[0021] In some embodiments, the step S3, sound velocity correction, corrects the sound velocity differentials at different depths on the signal propagation path according to the sound velocity gradient profile, including:

[0022] According to the sound velocity gradient map obtained by CTD measurement, the sound velocity c is divided into N micro-elements at a depth of 1m. Assuming that the sound velocity in each micro-element is constant, when the depth variation range is (a, b), the sound wave propagation distance is calculated according to the following formula:

[0023]

[0024] In some embodiments, the step S4, calculating the slope distance according to the iterative formula, includes

[0025] The one-way slant distance x2 between the two targets is calculated by an iterative algorithm. The iterative process is as follows:

[0026] c0=1500,

[0027] D=c0*Tmp=c0*(t1+t2)

[0028]

[0029] x2=D-x1

[0030]

[0031] When |D ′ -When D|≤ε, stop iteration.

[0032] In some embodiments, the step S5 of calculating the horizontal distance according to the slant distance and the relative depth includes:

[0033] Calculate the horizontal distance d according to the formula:

[0034]

[0035] In some embodiments, the step S6, performing a ten-point sliding average on the ranging result, includes:

[0036] Every ten frames of data are grouped together and their average is taken.

[0037] The responsive method for accurately measuring the distance between two underwater targets of the present invention can achieve more accurate distance measurement and provide support for underwater acoustic positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings illustrate generally, by way of example and not limitation, various embodiments discussed herein.

[0039] Figure 1 This is a system structure diagram of the response ranging method;

[0040] Figure 2 It is a flow chart of the answering ranging method;

[0041] Figure 3 is the depth interpolation process;

[0042] Figure 4 It is the depth change process of the slave;

[0043] Figure 5 It is the sound velocity gradient diagram. DETAILED DESCRIPTION

[0044] In order to enable a more detailed understanding of the features and technical contents of the embodiments of the present application, the implementation of the embodiments of the present application is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present application.

[0045] In the embodiments of the present application, it should be noted that, unless otherwise specified and limited, the term "connection" should be understood in a broad sense. For example, it can be an electrical connection or a connection between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0046] It should be noted that the terms "first\second\third" involved in the embodiments of the present application are only used to distinguish similar objects, and do not represent a specific order for the objects. It is understandable that the specific order or sequence of "first\second\third" can be interchanged where permitted. It should be understood that the objects distinguished by "first\second\third" can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0047] The embodiment of the present invention provides a response-type underwater acoustic ranging method, using Figure 1 The answering ranging method system shown in the figure includes a host and two slaves, such as Figure 2 As shown, the distance measurement includes the following steps:

[0048] Step S1, a response measurement method, using the host calling and the slave responding to measure the sound signal propagation time, and calculate the distance through the sound speed and time.

[0049] The host device is suspended on the shore with a fixed depth. It periodically transmits sound wave signals. Each time a signal is transmitted, the timer is read to record the time when the signal is sent. The slave device is at a point underwater. The depth changes uniformly with time. After detecting the signal sent by the host, it sends a response signal to the host. After detecting the response signal, the host reads the timer again and calculates the specific time of the sound signal propagation according to the following formula.

[0050]

[0051] Wherein, Tmp is the sum of the propagation time t1 of the host sending signal and the propagation time t2 of the slave response signal, as shown in Figure 4 As shown in the figure; T1CntAfter is the moment when the host receives the slave signal, T1CntBefore is the moment when the host sends the signal, the timer crystal frequency is 24000Hz; CCNT is the total number of points collected in a packet of signals, PeakNum is the position of the signal starting point in a packet of signals, and the signal sampling frequency is 144000; TAU is the modulation and demodulation time between the slave receiving the signal and sending the signal; Trim is the reserved delay, which can be fine-tuned through the serial port input.

[0052] Step S2: depth calibration, calibrating the depth data read by the master and slave machines according to the upload time of the pressure sensor.

[0053] (1) Depth calibration of slave machine: Figure 3 As shown, after receiving the host signal and completing demodulation, the slave reads the timer count DCNT, takes the remainder of 111ms, selects the depth data closest to the current moment from the interpolated pressure sensor data according to the obtained time, records it as h2, and writes it into the communication data to be transmitted to the host;

[0054] (2) Host depth calibration: After receiving the slave signal, the host reads the timer count DCNT, takes the modulus of 111ms, and selects the depth data closest to the current moment from the interpolated pressure sensor data based on the obtained time, which is recorded as h0.

[0055] In addition, the depth of the slave will change during the modulation and demodulation process. After testing, the length of this time is TAU. The depth of the slave at the moment of receiving the host signal can be calculated according to the formula, which is recorded as h1.

[0056] Step S3, sound velocity correction, correcting the sound velocity differentials at different depths on the signal propagation path according to the sound velocity gradient profile.

[0057] The sound velocity gradient diagram obtained by CTD measurement is as follows Figure 5 As shown in the figure, the sound velocity c is divided into N micro-elements at a depth of 1m. Assuming that the sound velocity in each micro-element is constant, when the depth range is (a, b), the sound wave propagation distance can be calculated according to the following formula:

[0058]

[0059] Step S4, calculating the slope distance according to the iterative formula;

[0060] Step 4: Given Tmp, h0, h1, and h2, the one-way slant distance x2 between the two targets can be calculated through an iterative algorithm. The iterative process is as follows:

[0061] c0=1500,

[0062] D=c0*Tmp=c0*(t1+t2)

[0063]

[0064] x2=D-x1

[0065]

[0066] When |D′-D|≤ε, stop the iteration.

[0067] Step S5, calculating the horizontal distance according to the slant distance and the relative depth;

[0068] Calculate the horizontal distance d according to the formula:

[0069]

[0070] Step S6: perform a ten-point sliding average on the distance measurement results.

[0071] Because the host sends a signal every 5.9 seconds, that is, a frame of distance data is obtained every 5.9 seconds, and every ten frames of data are grouped together and the average is taken. This method can obtain a smoother trajectory.

[0072] The technical solutions described in the embodiments of the present application can be combined arbitrarily without conflict.

[0073] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A responsive underwater acoustic ranging method, characterized in that: include: Step S1, a response measurement method, using the master calling and the slave answering to measure the sound signal propagation time, and calculate the distance by the sound speed and time; Step S2, depth correction, correcting the depth data read by the master and slave machines according to the upload time of the pressure sensor; Step S3, sound velocity correction, correcting the sound velocity differentials at different depths on the signal propagation path according to the sound velocity gradient profile; Step S4, calculating the slope distance according to the iterative formula; Step S5, calculating the horizontal distance according to the slant distance and the relative depth; Step S6, taking a ten-point sliding average of the distance measurement results.

2. The responsive underwater acoustic ranging method according to claim 1, characterized in that: The step S1, a response measurement method, uses the form of a host calling and a slave responding to measure the propagation time of the sound signal, and calculates the distance by the speed of sound and time, including: The host device is suspended on the shore at a fixed depth and periodically emits sound wave signals. Each time a signal is emitted, a timer is read to record the time when the signal is emitted. The slave is at a certain point underwater, and its depth changes at a constant speed over time. After detecting the signal sent by the host, it sends a response signal to the host. After the host detects the response signal, it reads the timer again and calculates the specific time of the sound signal propagation according to the following formula: Among them, Tmp is the sum of the propagation time t1 of the host sending signal and the propagation time t2 of the slave machine response signal, T1CntAfter is the time when the host receives the slave machine signal, T1CntBefore is the time when the host sends the signal, the timer crystal frequency is 24000Hz, CCNT is the total number of points collected in a packet of signals, PeakNum is the position of the signal starting point in a packet of signals, the signal sampling frequency is 144000, TAU is the modulation and demodulation time between the slave machine receiving the signal and sending the signal, and Trim is the reserved delay.

3. The responsive underwater acoustic ranging method according to claim 2, characterized in that: The step S2, depth correction, corrects the depth data read by the master and slave machines according to the upload time of the pressure sensor, including: Slave depth calibration: After receiving the host signal and completing demodulation, the slave reads the timer count DCNT, takes the remainder of 111ms, and selects the depth data closest to the current moment from the interpolated pressure sensor data according to the obtained time, recorded as h2, and writes it into the communication data to be transmitted to the host; Host depth calibration: After receiving the slave signal, the host reads the timer count DCNT, takes the remainder of 111ms, and selects the depth data closest to the current moment from the interpolated pressure sensor data according to the obtained time, which is recorded as h0; The depth of the slave will change during the modulation and demodulation process. After testing, the length of this time is TAU. The depth of the slave at the moment of receiving the host signal is calculated and recorded as h1.

4. The responsive underwater acoustic ranging method according to claim 3, characterized in that: The step S3, sound velocity correction, corrects the sound velocity differentials at different depths on the signal propagation path according to the sound velocity gradient profile, including: According to the sound velocity gradient map obtained by CTD measurement, the sound velocity c is divided into N micro-elements at a depth of 1m. Assuming that the sound velocity in each micro-element is constant, when the depth variation range is (a, b), the sound wave propagation distance is calculated according to the following formula:

5. The responsive underwater acoustic ranging method according to claim 4, characterized in that: The step S4, calculating the slope distance according to the iterative formula, includes The one-way slant distance x2 between the two targets is calculated by an iterative algorithm. The iterative process is as follows: c0＝1500, D=c0*Tmp=c0*(t1+t2) x2=D-x1 When |D ′ -When D|≤ε, stop iteration.

6. The responsive underwater acoustic ranging method according to claim 5, characterized in that: The step S5, calculating the horizontal distance according to the slant distance and the relative depth, comprises: Calculate the horizontal distance d according to the formula:

7. The responsive underwater acoustic ranging method according to claim 1, characterized in that: The step S6, performing a ten-point sliding average on the distance measurement result, comprises: Every ten frames of data are grouped together and their average is taken.

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