AU784786B2

AU784786B2 - Submarine

Info

Publication number: AU784786B2
Application number: AU44458/02A
Authority: AU
Inventors: Kai Wicker
Original assignee: Atlas Elektronik GmbH
Current assignee: Atlas Elektronik GmbH
Priority date: 2001-06-15
Filing date: 2002-05-30
Publication date: 2006-06-22
Anticipated expiration: 2022-05-30
Also published as: ATE361872T1; EP1266823B1; PT1266823E; EP1266823A2; DE50210101D1; DE10128973C1; AU4445802A; EP1266823A3; ES2283478T3

Abstract

The submarine has a hull (10) provided with an outer skin (12) having a number of omnidirectional reception hydrophones (16), coupled to a signal processing device (17) for location of a torpedo from the sound pulses emitted by the latter. The hydrophones are directly attached to the outer skin in a defined pattern across the hull, with location of the torpedo from the propagation time differences between the received signals.

Description

AUSTRALIA

Patents Act 1990 STN ATLAS ELEKTRON I K GIVIBAR I A-vcjS ca-c--rajajk, C- mo 1 COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Submarine The following statement is a full description of this invention including the best method of performing it known to us:- Title Submarine Technical Field The invention concerns a submarine with a device to recognise torpedoes emitting sonic pulses. The submarine is a type that has an external skin with a plurality of omnidirectionally receiving hydrophones as well as a signal processing unit to determine torpedo data from output signals of the hydrophones.

Background Art The modern, fast running, actively locating torpedo represents the greatest danger for submarines. This is valid especially for air-driven torpedoes, which are fired from surface ships in a ballistic trajectory or thrown into the water from helicopters or planes at a short distance from the target. Therefore, to survive it, it is important for a submarine to detect such torpedoes very fast on a short instance and to determine the torpedo data, such as bearing and/or distance, so that to commence defensive manoeuvres immediately and use defensive weapons effectively.

A submarine of this kind (L.Kiihnle "Classification and Identification CAI by Submarine Sonars" Naval Forces No. VII 1987, page 28) points to a so called 0Intercept-Panorama-Sonar (IPS) with an intercept base, that in addition to detection and bearings of the targets radiating sonar pulses, e.g. torpedoes, 25 also analyses the sonar pulses with regard to its frequency range, its type of modulation, the length of the pulse and rate of pulse repeat, so that to classify and identify an oncoming target. The intercept base is in the region of the bow of the submarine on the top side of the hull and on the outer skin.

30 One example of the construction of the intercept base is described in DE 196 12 503 C2. The intercept base has there, for example, an external contour in the shape of a barrel or a drum, that is divided inside by dividing walls in a star shape made of rubber-coated sheet metal into six, for example, sectors each with a 600 opening angle. There is a plurality of hydrophones provided in each sector, which are cemented in rows and columns in a matrix formed from polyurethane hard foam material. The individual hydrophones, designed for the high-frequency transmission frequency range of torpedo sonars, are connected with the signal processing unit via signal lines placed into a centrally positioned tubular passage.

Such a reception base, comprising a single module with a plurality of hydrophones, is complicated in its manufacture and is correspondingly expensive. With this reception base the bearings of an oncoming torpedo can be accurately established only if it moves in that plane in which the reception base is provided. A greater offset of the oncoming plane of the torpedo in elevation leads to inaccurate bearing angles. In addition, the reception base is "blind" against torpedoes coming steeply from above the submarine.

Summary of the Invention In a first aspect the invention provides a submarine with a hull having an external skin and with a device to recognise torpedoes emitting sonic pulses, the external skin having a plurality of omnidirectionally receiving hydrophones as well as a signal processing unit to determine torpedo data from output signals of the hydrophones, characterised in that the hydrophones are arbitrarily distributed over the hull and are directly fastened on the external skin and that the signal processing unit operates to determine torpedo data by determining the bearing of the torpedo from time delay differences between the output signals of selected hydrophones.

gig The advantage of the invention is to produce for a submarine equipped with a 25 device to identify torpedoes the necessary reception base in a cost-effective manner and so that torpedoes attacking at a large elevation angle are also detected and the torpedo data can be determined with adequate accuracy.

9999 Further the submarine according to the invention has the advantage that the hydrophones necessary to form a reception base, that is designed for the transmission frequency range of torpedo sonars, are commercially available and have a very small volume even with an integrated amplifier. These smalldimensioned hydrophones can be distributed anywhere on the surface of the submarine and directly fastened on the external skin at positions particularly suitable for this purpose. At the same time the hydrophones are arranged both in the bow and stern areas of the hull as well as in the region of the tower, so that by a suitable selection of spatially favourably positioned hydrophones alternatively a linear or planar reception base can be formed. In this case, in a manner different from the known reception bases, the adherence to specified distances between the hydrophones or groups of hydrophones and a highly accurate alignment is not necessary. The mounting of the hydrophones on the hull and the tower is very simple and can be carried out in a short time. The required ranging of the positions of the hydrophones mounted is carried out acoustically and can be accomplished in a short time using a suitable software.

By virtue of the stated type of configuration of the signal processing unit not only an arbitrary distribution of the hydrophones over the surface of the submarine is possible by making use of surface areas which are particularly advantageous from the point of view of positioning, but by a two-dimensional arrangement of the hydrophones on the curved surface of the submarine accurate bearing angles are obtained both in azimuth and in elevation. The more hydrophones are used, the more accurate the bearing result obtained. If the number of hydrophones used is greater than the degrees of freedom to be measured, then the use of a least squares assessing method is necessary to determine the bearing angle. Measuring of distances can be realised by cross bearing with hydrophones or groups of hydrophones which are preferably far from one another, for example at the front and the rear of the hull.

According to an advantageous embodiment of the invention a plurality of hydrophones are combined into a girdle of hydrophones at a distance from one 25 another and several such hydrophone girdles are distributed on the surface of the submarine. By this orderly arrangement of the hydrophones the calculatory effort to determine the torpedo data in the azimuth and elevation is reduced, particularly when the girdle-like arrangement of the hydrophones is done in an equidistant manner. The vertically aligned enclosed hydrophone girdles in the bow and stern areas are selected to obtain the torpedo data in elevation and the horizontally aligned open hydrophone girdles on the flanks of the hull to determine the torpedo data in the azimuth.

Brief Description of the Drawings The invention is explained in detail in the following based on an embodiment illustrated in the drawing. For this purpose the drawing shows a schematic perspective view of a submarine in conjunction with a device to recognise actively locating torpedoes.

Best Modes of the Invention The submarine, schematically illustrated in the drawing, has an elongated, quasi-cylindrical hull 10 having a conning tower 11 and an external skin 12, on the stern of which a propeller 13 is provided to drive the submarine. On the stern and laterally on the conning tower 11 rudders 14, 15 are provided.

The submarine is equipped with a device to detect and locate the so called actively locating torpedoes, which emit high-frequency sonic pulses by means of a so called torpedo sonar. The device has a plurality of omnidirectionally receiving hydrophones 16 as well as a signal processing unit 17, that for the purpose of obtaining the torpedo data determines from the output signals of the hydrophones 16 at least the bearing of the torpedoes. The hydrophones 16 are designed for the typical transmission frequency range of torpedo sonars and preferably have integrated amplifiers. Such hydrophones 16 can be obtained commercially and are characterised by a construction having a very small volume. The hydrophones 16 are arbitrarily distributed over the surface of the submarine and are directly fastened on the external skin 12 of the submarine in o a manner that is decoupled from the noise of the hull. The electric output signals of the hydrophones 16 are connected with the signal processing unit 17 installed in the interior of the hull 10 by signal lines 18 only symbolically indicated here and passing through the external skin 12 of the interior of the 25 submarine. For the sake of a simplified illustration the signal processing unit 17 is illustrated outside of the submarine.

In the drawing the hydrophones 16 and their arrangement are only schematically shown. As it can be seen there, a plurality of hydrophones 16 are combined into a girdle of hydrophones 16 at a distance from one another and several such hydrophone girdles are distributed on the surface. At the same time two enclosed hydrophone girdles 19 are provided in the region of the bow and two enclosed hydrophone girdles 19 in the region of the stern of the hull while the hydrophone girdles 19 completely encircle the hull 10 transversely to the longitudinal axis of the ship. Furthermore, an open hydrophone girdle is provided on the port and starboard sides of the hull 10 parallel to the longitudinal axis of the ship. Of these two hydrophone girdles 20 only the hydrophone girdle 20 on the starboard side can be seen in the drawing. At the same time each hydrophone girdle 20 can be so arranged that hydrophones 16 from the four enclosed hydrophone girdles 19 extend the hydrophone girdle at the ends. Further two open hydrophone girdles 21 are arranged on the lateral walls of the conning tower 11 parallel to the longitudinal axis of the ship.

Once again, in the drawing only the hydrophone girdles 21 arranged parallel to one another on the starboard side of the conning tower 11 are shown. Between the hydrophone girdles 21 additional individual hydrophones 16 can be so arranged that they form, together with the selected hydrophones 16 from the hydrophone girdles 21, a vertical row.

As has already been mentioned, the orderly, girdle-like arrangement of the hydrophones 16 with preferably constant distance between the hydrophones 16 is only one of the possible executions of fitting the hydrophones on the external skin 12 of the submarine.

In principle and advantageously for the mounting the fitting of the hydrophones i: can be arbitrary, while such areas of the submarine should be chosen which 20 are not in the region of traversing, so that the hydrophones 16 cannot be mechanically damaged. The distances of the hydrophones 16 from one another do not have to be periodic or regular and are not subjected to any conditions either, like, for example, to be smaller than where X is the wavelength of the received signals.

Hydrophones 16 may also be provided on the end face 22 of the bow of the hull so that a linear hydrophone arrangement is present altogether by virtue of the hydrophone girdles 20 and 21, a two-dimensional hydrophone arrangement by the hydrophone girdle 19 on the cylindrically curved surface of the hull 30 and a hydrophone arrangement on the front face of the bow.

After fitting the hydrophones 16 on the external skin 12 of the submarine, the positions of the individual hydrophones 16 are acoustically ranged relative a hull-related coordinate system, and the positional coordinates are stored in the signal processing unit 17.

The signal processing unit 17 symbolised in the drawing by a block circuit diagram is so constructed, that it determines the torpedo data, namely the bearing angle, from the time delay differences between the output signals according to the selected hydrophones 16. Depending from the arrangement of the selected hydrophones 16, the bearing angle is determined only in the azimuth, only in elevation or both in azimuth and elevation. A signal processing method that determines the bearing in the azimuth and elevation from the difference in time delays between the output signals of a multisensor array, is described in Berdugo, Doron Rosenhouse, Azhari "On direction finding of an emitting source from time delays", The Journal of the Acoustical Society of America, Vo1.105, No.6, June 1999, pages 3355-3363. In brief, the algorithm described there is based on an extension of a Maximum Likelihood Estimator 24 by an algorithm to determine the signal time delays (Time Delay Estimator) between the combination of the hydrophones 16 to be selected depending on the geometry. The Time Delay Estimator 23 calculates from the electric output signals Si of the hydrophones 16 the vector of the signal time delays T and the Maximum Likelihood Estimator 24 determines from it an assessed value for the incident vector k and consequently the azimuth angle 6 and the elevation angle of the incident wave front, which are illustrated in a display unit 25 as the bearing of the torpedo. With the bearing angles, determined by various groups of hydrophones that are situated preferably at a great distance from one another on the hull 10, the distance of the torpedo can be geometrically calculated, what is generally known as "cross bearing".

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Claims

1. A submarine with a hull having an external skin and with a device to recognise torpedoes emitting sonic pulses, the external skin having a plurality of omnidirectionally receiving hydrophones as well as a signal processing unit to determine torpedo data from output signals of the hydrophones, characterised in that the hydrophones are arbitrarily distributed over the hull and are directly fastened on the external skin and that the signal processing unit operates to determine torpedo data by determining the bearing of the torpedo from time delay differences between the output signals of selected hydrophones.

2. A submarine according to claim 1 with a conning tower placed on the hull, characterised in that a plurality of hydrophones is arbitrarily distributed on the conning tower and is fastened directly on the wall of the tower.

3. A submarine according to claim 1 or 2, characterised in that in each case a plurality of hydrophones are combined into girdles of hydrophones at a distance from one another.

4. A submarine according to claim 3, characterised in that at least one enclosed hydrophone girdle is provided in the region of the bow and at least one *o enclosed hydrophone girdle in the region of the stern of the hull, encircling the hull transversely to the longitudinal axis of the ship. goD* A submarine according to claim 3 or 4, characterised in that at least one open hydrophone girdle each is provided on the port and starboard sides of the conning tower approximately parallel to the longitudinal axis of the ship.

6. A submarine according to any one of claims 3 to 5, characterised in that at least one open hydrophone girdle each is provided on the port and starboard sides of the hull parallel to the longitudinal axis of the ship.

7. A submarine according to any one of claims 1 to 6, characterised in that a plurality of hydrophones is provided on the front face of the bow of the hull. 9

8. A submarine according to any one of claims 1 to 7, characterised in that the fastening of the hydrophones is carried out in a manner that is decoupled from the noise of the hull.

9. A submarine according to any one of claims 1 to 8, characterised in that the positions of the hydrophones are acoustically ranged relative to a hull-related coordinate system and the positional coordinates are stored on the signal processing unit..

10. A submarine as substantially herein described with reference to the accompanying drawing. DATED this thirty-first day of March 2006 STN ATLAS ELEKTRONIK GMBH Patent Attorneys for the Applicant: F.B. RICE CO. 9 *99o *9 9