GB2346751A

GB2346751A - Torpedo guidance system

Info

Publication number: GB2346751A
Application number: GB8331479A
Authority: GB
Inventors: John Critchton Barlow; Peter Hugh Dickinson; Douglas Albert Gregory; John O'TOOLE; Leo Ewart Arthur Summers
Original assignee: British Aerospace PLC; Matra Bae Dynamics UK Ltd
Current assignee: BAE Systems PLC; Matra Bae Dynamics UK Ltd
Priority date: 1983-11-25
Filing date: 1983-11-25
Publication date: 2000-08-16
Anticipated expiration: 2003-11-25
Also published as: GB2346751B; GB8331479D0

Abstract

A dual mode guidance system for a torpedo includes a sonar sub-system 1, 2 for long range guidance and a 'close-in' sub-system including a laser beam generator, scanning means for scanning the beam over the target, and a processor 5 for analysing the laser return signals with a view to determining a best hit position on the target, say the mid-hull position of a submarine, and for then guiding the torpedo onto that position.

Description

GUIDANCE SYSTEMS This invention relates primarily to a method of guiding torpedoes and in particular to a dual mode guidance system therefor.

It is common practice for a single sonar guidance system to be used for torpedo guidance when attacking a submarine. This practice has several drawbacks.

(a) Sonar systems become inaccurate at close range due to the finite pulse width of their output and the large target area of the submarine causing multiple echoes.

(b) Sonar decoys are becomina more sophisticated.

(c) Navies are tending to apply anechoic coatinas to their submarines to reduce their return echo.

(d) With the high speed and the increased hull strength of modern submarines the"close-in" manoeuvres have to be accurate in order to secure a high kill probability.

It is an object of the present invention to provide a torpedo guidance system incorporating means whereby these drawbacks are overcome.

According to one aspect of this invention, there is provided a guidance arrangement for a submersible vehicle which includes a radiation guidance system, including radiation beam producing means, radiation deflecting means arranged to deflect the radiation beam in a predetermined pattern over a field of view, radiation detector means arranged to receive radiation reflected from a potential target in the field of view, signal processing means for processing signals produced by the radiation detector means, thereby to determine the location of a potential target in the field of view and means to direct the vehicle towards a predetermined part of the perceived region of the target.

Preferably, the radiation bear. producing means comprise a laser device.

Preferably, the deflecting means are arranged to deflect the radiation beam in azimuth and elevation.

The guidance arrangement advantageously further includes a scnar guidance system including sound producing means, sound pick-up means arranged to receive sound reflected from a potential target, further signal processing means/processing signals produced by the -0% sound pick-up means thereby to determine the range and bearing of a potential target and means to direct the vehicle towards said potential target.

This arrangement preferably also includes switch means arranged to effect actuation of the radiation guidance system when the determined range of a potential target falls below a pre-set threshold value, so that at relatively large distances from a potential target the submersible vehicle is guided by said sonar guidance system whilst at relatively small distances said vehicle is guided by said radiation guidance system, either alone or in conjunction with said sonar auidance system.

In one form the present invention provides a dual mode system using sonar for guidance at long range and for laser guidance at short range, said system being characterised by the employment of switching means controlled by range finding means associated with said sonar system and operable to switch from the sonar system to the laser system at a predetermined range, said laser system being adopted to scan in a vertical plane and thereby establish the mid-point of the hull toward which thetorpedo is then guided.

In another form the laser guidance means may scan the target in both the horizontal and vertical planes, in a manner enabling the profile of the hull of the submarine to be established, the information so obtained being utilised to determine the desired point of impact.

In yet another form a combination of signals from both sonar and laser systems is employed.

As an example, and with reference to Fig. l, the sonar system consists of an active sonar array 1 on the front face of the torpedo.

The elements of this array are both transmitters and receivers of sonar energy and are arranged in a pattern suitable for producing the required sonar beam directivity.

The laser system consists of a laser beam 2 with a forward point of exit 3, which is directed in its scanning mode by a suitable deflector. The laser scans in both azimuth and elevation to give the maximum probability of striking the submarine in mid ship and at 90 to the hull. Interspersed among the sonar elements are the laser receivers 4 whose optical output is fed by fibre optic or electronic links 5 to a central detector 6.

With reference to Fig. 2 which shows a block schematic diagram, the sonar array 1 supplies the sonar processor 2 with the information which is needed to enable it to tell the central computer 3 (through the changeover switch 4) the direction in which the torpedo must be heading. The changeover switch would be activated either by range or received laser signals or a combination.

Once the changeover has occurred the laser processor 5 then controls the direction of the torpedo.

The changeover switch can be made to activate also in the presence of sonar decoys and if a re-run is required after a first attack has missed the target.

The transmitter is a dye laser operating at a wavelength of approximately 480 nm with a pulse width of 50 ns, pulse energy joule and PRF of 25 per second. The design is such that its size and weight are minimised for a short operational life of about 30 seconds.

The actual laser may be placed at virtually any position in the torpedo body and its beam brought to the output point by a suitable optical relay. The diameter of this laser beam is about 10 mm with a divergence total angle of about 10 3 radians. This is deflected in both azimuth and elevation between the limits 1 25 by means of a deflector controlled by a suitable driving voltage obtained from the laser processor. The output window is about 2 cms diameter and is suitably corrected to produce minimum bearing distortion.

The laser receiver consists of short focal length lenses of 2 cm diameter, with suitable commercially obtained fibre-optic or electronic links delivering the received energy from their focus to a suitable commercially obtained fibre optic adding system. The maximum number of these receivers is used depending on the sonar transducer geometry.

The sequence of operations in the attack mode is as follows.

1. Assume that the sonar has acquired the submarine at a range exceeding 200 metres.

2. Switch on the laser whilst monitoring sonar contact and make a trial acquisition at 150 m using range and bearing information from the sonar.

3o If no acquisition within 1 second shut down laser and continue with sonar.

4. Repeat 2 and 3 at 100 m.

5. If no acquisition at 100 m continue with sonar.

6. Switch to laser at 50 m and shut down sonar either after acquisition or minimum sonar operating range.

Claims

CLAIMS: 1. A guidance arrangement for a submersible vehicle which includes a radiation guidance system, including radiation beam producing means, radiation deflecting means arranged to deflect the radiation beam in a predetermined pattern over a field of view, radiation detector means arranged to receive radiation reflected from a potential target in the field of view, signal processing means for processing signals produced by the radiation detector means, thereby to determine the location of a potential target in the field of view and means to direct the vehicle towards a predetermined part of the perceived region of the target.
2. An arrangement according to claim 1, wherein the radiation beam producing means comprise a laser device.
3. A vehicle according to claim 1 or 2 including switch means arranged to effect actuation of the first guidance system when the determined range of a potential target falls below a pre-set threshold value, so that at relatively large distances from a potential target the submersible vehicle is guided by said second guidance system whilst at relatively small distances said vehicle is guided by said first guidance system, either alone or in conjunction with said second guidance system.
4. A submersible vehicle substantially as hereinbefore described with reference to the accompanying drawings.

3. An arrangement according to claim 1 or 2, wherein the deflecting means are arranged to deflect the radiation beam in azimuth and elevation.

4. An arrangement according to claim 1,2 or 3, further including a sonar guidance system including sound producing means, sound pick-up means arranged to receive sound reflected from a potential target, further signal processing means for processing signals produced by the sound pick-up means thereby to determine the range and bearing of a potential target and means to direct the vehicle towards said potential target.

5. An arrangement according to claim 4 including switch means arranged to effect actuation of radiation guidance system when the determined range of a potential target falls below a pre-set threshold value, so that at relatively large distances from a potential target the submersible vehicle is guided by said sonar guidance system whilst at relatively small distances said vehicle is guided by said radiation guidance system, either alone or in conjunction with said sonar guidance system.

6. A guidance arrangement for a submersible vehicle substantially as hereinbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed as follows 1. A submersible vehicle having thereon a first guidance system which includes laser beam producing means, radiation deflecting means arranged to deflect the laser beam in a predetermined pattern over a field of view, radiation detector means arranged to receive laser radiation reflected from a potential target in the field of view, signal processing means for processing signals produced by the radiation detector means, thereby to determine the location of a potential target in the field of view and means to direct the vehicle towards a predetermined part of the perceived region of the target, the vehicle also having thereon a second guidance system which includes sound producing means, sound pick-up means arranged to receive sound reflected from a potential target, further signal processing means for processing signals produced by the sound pick-up means thereby to determine the range and bearing of a potential target and means to direct the vehicle towards said potential target.

2. A vehicle according to claim 1, wherein the radiation deflecting means are arranged to deflect the laser radiation beam in azimuth and elevation.