RU2788477C1 - The method for information processing in the noise direction-finding mode of the hydroacoustic complex - Google Patents

Abstract

FIELD: hydroacoustics.

SUBSTANCE: invention relates to the hydroacoustics and is designed to warn of a possible collision with a marine object detected owing to its noise field. The method is applicable for the noise direction-finding mode of a hydroacoustic system that receives the noise signal of an object with a hydroacoustic antenna, determines the ratio of the signal to interference in a set of frequency ranges, determines the directions to the object and the signal power at successive times, determines the angular velocity of the object. When implementing the method, the rate of change in signal power is determined, the number of the frequency range in which the signal-to-interference ratio is maximum is determined, and a decision is made about a dangerous approach to a sea noisy object when three conditions are met together: the frequency range number is more than the threshold, the rate of change in signal power is more than the threshold, and the absolute value of the angular velocity of the object is less than the threshold.

EFFECT: present invention enables continuous monitoring of marine noise-generating objects for their possible dangerous approach to the carrier of sonar without using an active location.

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Description

The invention relates to the field of hydroacoustics and is intended to warn of a possible collision with a marine object detected by the noise field.

Collision warning methods are important for any moving technical means. Such methods are also known for ground vehicles [Galimov A.I. Patent of the Russian Federation No. 2724044 dated 06/18/2020. Collision warning method. G08G 1/16], and for aircraft [Meyer J. et al. RF Patent No. 2597047 dated 20.00.2013. Unmanned aerial vehicle with built-in collision warning system. IPC B64C 39/00, G08G 5/04, G05D 1/12].

For marine moving technical means when using hydroacoustics, collision warning methods based on active location are used, the so-called navigation safety sonar stations [Koryakin Yu.A., Smirnov S.A., Yakovlev G.V. Shipborne hydroacoustic technology: state of the art and actual problems. St. Petersburg: Nauka, 2004, Mashoshin A.I., Pashkevich I.V. Patent of the Russian Federation No. 2725706 dated 07/30/2020. A way to survey space with a sonar to ensure the safety of navigation of an autonomous uninhabited underwater vehicle]. It is clear that the use of active agents, firstly, is energy-consuming, which can be critical for small-sized vehicles, and, secondly, negatively affects representatives of the marine fauna. It would be useful to create a way to warn of collisions at sea, based on passive location, that is, noise direction finding.

The closest analogue to the procedures to the present invention is a method for processing information in the noise direction finding mode [Handbook of hydroacoustics / A.P. Evtyutov, A.E. Kolesnikov, E.A. Korepin and others - 2nd ed., revised. and additional - L.: Shipbuilding. 1988], which can be taken as a prototype.

In the prototype method, the following operations are performed:

receive the noise signal of the object with a hydroacoustic antenna,

carry out time-frequency processing of the signal in several frequency ranges with the determination of the signal-to-interference ratio in each of the frequency ranges,

determine the directions to the object in the horizontal plane and the signal strength at successive points in time,

determine the angular velocity of the object,

listening to the signal.

In this method, there is no procedure for checking the maneuvering parameters of the observed object for a possible collision with the carrier of the direction-finding station.

The objective of the proposed method is to provide an objective check of the detected marine objects for dangerous proximity to the carrier of the direction-finding station without increasing the composition of the measured signal parameters.

To solve the problem for the method of information processing in the noise direction finding mode of the hydroacoustic complex, according to which

receive the noise signal of the object with a hydroacoustic antenna,

carry out time-frequency processing of the signal in several frequency ranges with the determination of the signal-to-interference ratio q _j in each of the frequency ranges j,

determine the directions to the object ϕ _i in the horizontal plane and the signal power S _i at successive times t _i ,

determine the angular velocity of the object V _ϕ as V _ϕ =(ϕ _i -ϕ _i-1 )/(t _i -t _i-1 ),

new signs have been introduced, namely:

determine the rate of change of signal power V _S as V _S =(S _i -S _i-1 )/(t _i -t _i-1 ),

determine the number of the frequency range N, in which the signal-to-interference ratio is maximum N=arg max _j (q _j )

and make a decision about a dangerous approach to a noisy sea object under the joint fulfillment of the three conditions N>Por _N and V _S >Por _S and |V _ϕ |<Por _ϕ , where |V _ϕ | - the absolute value of the angular velocity of the object, Por _N , Por _S , Por _ϕ - threshold values for the number of the frequency range, the rate of change of the signal power and the absolute value of the angular, respectively.

The technical result of the invention is the provision of continuous monitoring of marine noisy objects for their possible dangerous approach to the carrier of hydroacoustic means without the use of active location.

We will show the possibility of achieving the specified technical result by the proposed method.

The basis of the method is to check the joint fulfillment of three conditions, which together make it possible to make a decision about a dangerous approach to a noisy object without using an active location:

- N>Por _N - analysis of the number of the frequency range in which the maximum value of the signal-to-interference ratio is observed;

- |V _ϕ |<Por _ϕ - analysis of the absolute value of the angular velocity of the object;

- V _S >Por _S - analysis of the rate of change of signal power.

In the first condition, the number of the frequency range is analyzed, in which the maximum value of the signal-to-interference ratio is observed. It is known [Marasev S.V., Mashoshin A.I. Optimum operating frequency of hydroacoustic detection devices in a real oceanic waveguide // Fundamental and applied hydrophysics. 2016. V. 9, No. 4. S. 85-92] that for objects that are close, the maximum value of the signal-to-interference ratio will be observed in the highest frequency range. Therefore, comparing the corresponding number of the frequency range with the threshold allows you to limit the distance to the observed noisy object and select those objects, the distance to which is critically small for the implementation of an evasive maneuver. However, objects that are at a short distance may not pose a collision hazard if their motion trajectories do not intersect with the motion trajectory of the direction-finding station carrier. This requires checking the second condition.

In the second condition, the analysis of the absolute value of the angular velocity of the object is carried out. Known [Fundamentals of maneuvering ships. Under the general editorship. M.I. Skvortsova. Military publishing house Min. Defense of the USSR. M.: 1966] that a necessary condition for the close approach of two maneuvering objects is the equality to zero of the value of the angular velocity of one object, observed by the means of another object, in our case, observed by means of the carrier of the direction-finding station. Therefore, determining the absolute value of the angular velocity of an object and comparing it with the threshold allows you to select those objects whose trajectory intersects the trajectory of the direction-finding station carrier. At the same time, the specified second condition, being necessary, is also not sufficient, since the observed object and the carrier of the direction-finding station can move away, and the point of intersection of their trajectories is hypothetical. For the final choice of objects dangerous for collision, it is necessary to check the third condition.

In the third condition, the rate of change of the signal power is analyzed. It is known [Volkova A.A., Nikulin M.N. Observation time interval required for estimating the parameter "value of signal change" in order to classify the source // Hydroacoustics. 2014. Issue. 20(2). P. 53-60] that when the noisy object and the carrier of the direction-finding station approach each other, the signal power increases, and the value of the signal power change rate should be positive. Therefore, determining the rate of change in signal power and comparing it with the threshold allows you to select those objects, the distance to which decreases.

The fulfillment of all three conditions together implies a dangerous, up to a collision, approach of the observed object with the carrier of the direction-finding station:

- firstly, the object and the carrier are close,

- secondly, the trajectories of the movement of the object and the carrier intersect,

- thirdly, the object and the carrier are moving towards convergence.

Thus, the analysis of the parameters measured in the noise direction finding mode of the hydroacoustic complex allows continuous monitoring of observed marine objects for their possible dangerous approach to the carrier of sonar means without using active location.

The essence of the invention is illustrated in Fig. 1, which shows a block diagram of a device that implements the proposed method.

The device (Fig. 2) contains blocks connected in series: an antenna 1, a block 2 for determining the parameters of the received signal (Processing), a decision block 3 (Decision), a block 4 indicating the decision made (Indication).

In the dynamics of a typical noise direction finding station, the proposed method is implemented as follows.

The object's signal is received by antenna 1, enters block 2, where typical noise direction finding procedures are performed: frequency-time processing of the signal is carried out in several frequency bands with the determination of the signal-to-interference ratio q _j in each of the frequency bands j, directions to the object ϕ _i in the horizontal plane and power of the signal S _i at successive times t _i determine the angular velocity of the object as V _ϕ =(ϕ _i -ϕ _i-1 )/(t _i -t _i-1 ). In addition, in block 2, the rate of change of signal power is determined as V _S =(S _i -S _i-1 )/(t _i -t _i-1 ) and the number of the frequency range in which the signal-to-interference ratio is maximum N=arg max _j (q _j ), and also determine the absolute value of the object's angular velocity |V _ϕ |.

Further, the generated signal parameters N, V _S and |V _ϕ | arrive at block 3, in which they are compared with the thresholds.

Thresholds can be set based on the known method of obtaining errors in indirect measurements in such a way as to provide the required probability of a correct decision [Taylor J. Introduction to the theory of errors. Per. from English. M.: Mir. 1985]. If necessary, the thresholds can be refined experimentally.

The threshold for the number of the frequency range can be formed on the basis of the known dependence of the optimal noise direction finding frequency on the distance to the object [Marasev S.V., Mashoshin A.I. Optimum operating frequency of hydroacoustic detection devices in a real oceanic waveguide // Fundamental and applied hydrophysics. 2016. V. 9, No. 4. S. 85-92]. The distance to the object, which can be considered critically dangerous, is chosen, the optimal frequency corresponding to it and the number of the frequency range for the division into ranges inherent in a particular direction-finding station are determined.

The threshold for the signal power change rate can be formed on the basis of the known dependence of the signal power change rate error on the observation time interval, taking into account the signal power measurement error in a particular direction-finding station. The error in the rate of change of the signal power is determined, and a value of two to three errors is used as a threshold to provide the required probability of a correct decision.

The threshold for the absolute value of the angular velocity can be formed in a similar way based on the dependence of the error of the angular velocity on the observation time interval, taking into account the measurement error of the direction in a specific direction-finding station. The angular velocity error is determined, and a value of two to three errors is used as a threshold. To fulfill the condition when analyzing the angular velocity, it is important that the value of the quantity tends to zero at any sign, therefore, the absolute value is calculated, which is compared with the threshold.

When the conditions N>Por _N and V _S >Por _S and |V _ϕ |<Por _ϕ are met together, a decision is made about a dangerous approach to a noisy object, which enters block 4 for indication.

All of the above allows us to consider the problem of the invention solved. A method for preventing a collision with a marine object based on passive location is proposed, which can be used in the noise direction finding mode of a hydroacoustic complex to objectively check the detected marine objects for dangerous approach to the carrier.

Claims (1)

A method for processing information in the noise direction finding mode of a hydroacoustic complex, through which the noise signal of an object is received by a hydroacoustic antenna, frequency-time processing of the signal is carried out in several frequency ranges with the determination of the signal-to-interference ratio q _j in each of the frequency ranges j, directions to the object ϕ _i in horizontal plane and signal power S _i at successive times t _i determine the angular velocity of the object V _ϕ as V _ϕ =(ϕ _i -ϕ _i-1 )/(t _i -t _i-1 ), characterized in that the speed is determined changes in the signal power V _S as V _S =(S _i -S _i-1 )/(t _i -t _i-1 ), determine the number of the frequency range N, in which the signal-to-interference ratio is maximum N=arg max _j (q _j ), and make a decision about a dangerous approach to a noisy marine object under the joint fulfillment of the three conditions N>Por _N and V _S >Por _S and |V _ϕ |<Por _ϕ , where |V _ϕ | - the absolute value of the angular velocity of the object, Por _N , Por _S , Por _ϕ - threshold values for the number of the frequency range, the rate of change of the signal power and the absolute value of the angular, respectively.

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