IL258066A

IL258066A - Method for protecting a missile

Info

Publication number: IL258066A
Application number: IL258066A
Authority: IL
Inventors: Gundel Bernd; Katzenbeisser Stefan
Original assignee: Diehl Defence Gmbh & Co Kg; Gundel Bernd; Katzenbeisser Stefan
Priority date: 2017-03-14
Filing date: 2018-03-13
Publication date: 2018-04-30
Also published as: IL258066B; DE102017002446A1; EP3376154B1; EP3376154A1

Description

Method for protecting a missile The invention relates to a method for protecting a missile during its flight in the direction of a target.

For attacking ships or building complexes on land, generally long-range missiles are used, for example cruise missiles with a range of 100 km and more. They are launched from a ship or a land-based launcher and fly over a relatively great distance in the direction of their target. If possible, the target flown to by the missile attempts to attack the missile and launches one or more guided missiles or fires projectiles at the approaching missile.

An object of the present invention is to provide an efficient method for protecting a missile.

This object is achieved by a method of the type mentioned at the beginning in which, according to the invention, the missile monitors its surrounding environment to ascertain whether there is a detectable signature of an opposing missile that has been launched to combat the missile, and, depending on a detection result, starts a defensive measure.

The invention is based on the idea that, in its so-called endgame, that is to say the last part of its flight, in which it is closer to its target than a predetermined distance, a missile for attacking a ship or a building complex performs an automatic evasive manoeuvre, for example flies erratically, so that it is more difficult for it to be hit by a guided missile fired from the target or by approaching projectiles. It is also possible for decoys to be launched, for example so-called flares to be fired. However, such a method has disadvantages whenever the missile has not yet been detected at all at the time that these measures are taken. Evasive manoeuvres cause it to lose time, or the target gets more time to take its own combating measures, or the missile is only detected in the first place by the defensive measures, so that they have an adverse effect on its defence.

These disadvantages can be avoided if actions of self defence are made dependent on the detection of a signature of an opposing missile. If such a signature is detected, it can be assumed that the missile is being attacked. Evasive manoeuvres can be2 commenced and/or decoys can be fired. In this way, a loss of time or disadvantageous discovery can be avoided.

The missile may be an anti-ship missile for attacking a target at sea. Generally, a cruise missile is also possible, with a range of over 100 km, for example for attacking a bunker facility. The missile starts a defensive measure in dependence on its detection result. A defensive measure is expediently an externally visible change in behaviour of the missile, for example an evasive manoeuvre, that is to say a deviation from the trajectory of the flight towards the target, the alignment of a radar antenna on the missile, the launching, in particular firing, of a decoy and the like. It is advantageous if no defensive measure takes place before a signature of an opposing missile is detected.

In the simplest case, the missile starts the defensive measure immediately after the detection of the opposing combating measure or the signature. However, depending on the situation, it is advantageous if a defence mode, which prepares the defensive measure, is first started, in particular immediately after the detection. The defence mode may be performed by a work routine, the starting of which is triggered by the detection of the signature. A defence mode is expediently a work mode of a control unit of the missile and comprises measures that do not have to be externally visible, but may initially just comprise operations internally in the missile. Within the missile, defence-relevant data may be loaded into the control unit, a seeking optical system may be aligned with the signature and/or one or more objects are specifically investigated optically. In the defence mode, a starting time for the defensive measure is set. This is expediently dependent on the detection result and current sensor data, such as the distance of the opposing missile from the missile.

An opposing missile may be a rocket-propelled guided missile or a projectile without any propulsion of its own. The signature of the opposing missile is expediently formed by radiation emanating from combustion gases that are produced by the rocket propulsion unit or the firing operation. A signature may also be an outline of the opposing missile itself or of a gun that launches or fires the opposing missile.

In an advantageous configuration of the invention, if there is no detection of the signature, the missile remains in its cruise mode, in which it flies towards the target, for example the target at sea. A time loss or disadvantageous discovery can be avoided in3 this mode. The cruise mode is a flying mode or control mode of the missile in which the missile is guided towards the target as though it were unopposed.

After a detection of the signature, the missile advantageously changes from the cruise mode to one of a number of defence modes, the selection of the defence mode advantageously taking place in dependence on the detection result. The selection of the defence mode expediently takes place in dependence on the type of a detected opposing missile. Depending on whether the missile is opposed for example by projectiles or one or more guided missiles, the corresponding defence mode is selected and the associated control routines are carried out. A defence mode may also include that an active radar is switched over from an interval mode to a continuous mode, whereby the target, and in particular also the opposing missile, can be detected more accurately. The associated disadvantage of easy detectability of the missile is only of little relevance once opposing combating measures have already commenced.

If a signature has been detected and assigned to an opposing missile, the missile may change from a cruise mode to a defence mode. In this mode, defence-relevant data are expediently loaded in a control unit of the missile. These data expediently include a reaction time, at which a defensive measure is started. The reaction time may be dependent on the type of opposing missile. If, for example, projectiles are fired at the missile, it expediently takes evasive action more quickly than if a guided missile is approaching the missile. Since projectiles are generally not fired until the missile is within firing range, the period of time in which the projectiles fly from the gun to the missile remains as the time for taking evasive action. At a distance of 3000 m and with a projectile velocity of 1000 m/s, this would be 3 seconds. By this time, the missile should make a controlled evasive movement. However, with a guided missile coming towards it, evasive action should be taken as late as possible, so that a collision is just avoided, and then it should expediently move away as much as possible.

The position and distance of the target from the missile are advantageously detected.

This allows the defensive measure to be controlled by using the position and distance of the target. For instance, it may be advantageous to increase the flying speed in dependence on the distance from the target, in order for example to reach the target as quickly as possible in order to pre-empt opposing combating measures.

For flying to the target, the missile expediently has a seeker, for example in a seeker head of the missile, with a seeking optical system and a detector, expediently a matrix detector for recording images of the target. However, it may be advantageous for the4 detection of a signature of an opposing missile to use a second seeker with a second seeking optical system of the missile. This allows the detection to be provided with properties that make signature detection easier in comparison with the first seeking optical system. For example, the two seeking optical systems are provided with different sizes of the field of view. In this way it is possible for example that, at a great distance, the target can be sighted by the seeker with the higher resolution, so that the target can be sufficiently monitored for a signature even at great distances. When the missile comes closer to the target, it may be that the target appears to fill the entire image in the seeker with the higher resolution, and as a result becomes increasingly difficult to fly to or monitor. Then the approach flight and/or the monitoring can be continued by the seeker with the lower resolution, so that the missile can be reliably guided to the target.

Another possibility is that the seeker with the higher resolution is used for flying the missile to the target and the seeker with the lower resolution is used for monitoring the surrounding space for the signature. This allows a very large field of view to be monitored for the signature. If, for example, the opposing missile is not fired from the target at sea at all but from another ship in a convoy of ships or even from land, it is highly likely that this will be missed by the seeker with the higher resolution. The seeking optical system with the larger field of view can however pick this up. The signature can be detected and the defensive measure can be initiated.

It is particularly advantageous if one of the two seeking optical systems is pivotable. It can be aligned correctly with the location of the signature, so that the signature can be investigated in detail and in this way for example a type of opposing missile can be determined.

Depending on the distance from the target, it may be advantageous if, after discovery of a signature, the seeking optical system with the field of view of the greater size is pivoted back and forth between the target and the signature. If, for example, it is clear that the signature is at a great distance and there is the risk that a second opposing missile will be launched from the target, both the first signature, and the target may continue to be monitored, so that more dependable engagement/combating of the target can be achieved.

If suspicious radiation is detected, it should be checked as to whether it is a signature of an opposing missile. One possibility for the investigation is to investigate the frequency spectrum of the signature. The frequency spectrum of a rocket propulsion5 unit or of a firing flash generally differs significantly from ambient radiation, which usually occurs spectrally continuously. Another possibility is that of investigating a change over time of the signature, for example in position, size and/or form. While a luminous part of a jet from a rocket propulsion unit becomes longer after firing, moves spatially and is more or less constant in its size thereafter over a relatively long time period, a firing flash from a gun is much shorter and visible in a different form. In this way, on the one hand suspicious radiation can be detected as a signature of an opposing missile and on the other hand it is possible to distinguish between different missile types. For example, the type of opposing missile can be concluded from a variation over time of the brightness of the signature, the size and/or form or the spatial position.

It is also advantageous if a flying status of the opposing missile is determined from one or more of the aforementioned variables, that is to say whether the missile was launched upwards or was fired in a way that it was already directed towards the missile, or after being launched vertically has already been turned towards the missile.

Not only does the series of multiple flashes also indicate that ballistic projectiles have been fired, but also the type of projectiles can be determined from the frequency of the flashes. The development of the brightness and/or of the form of a plume, and in particular also its direction, can also provide valuable data for determining the type of the opposing missile. The flying speed of the opposing missile, in particular when flying upwards, and also a launch acceleration may also be characteristic of a type of an opposing missile.

The control unit or a memory connected thereto of the missile may comprise data on a number of signature categories, with which detected signature characteristics can be compared. The signature may be allocated to one of a number of signature categories, to which in turn an opposing missile type is assigned. In this way, the opposing missile type can be concluded from the signature.

It is advantageous for effective defence if the signature is assigned to one of a number of signature categories and flying data assigned to this category are loaded into a control unit that controls the flight of the missile. In this way, an explicit defensive measure can be specifically tailored to the opposing missile flying towards it, and consequently act effectively. When detecting the signature and assigning it to a signature category, corresponding assigned defence algorithms may be loaded into the control unit and a change of the defence mode may take place, for example from a6 general defence mode, in which the missile type is determined, to a type-related defence mode. This does not mean that the missile immediately takes a controlled defensive measure, since it presumably first continues flying unchanged. Depending on the advantageous time for defensive action, the suitable defensive measure is started at a suitable point. For example, flying capability data of the opposing missile assigned to the opposing missile type are loaded into the control unit and used for controlling the flying trajectory of the missile.

It is also advantageous if a time at which the missile will be engaged by the opposing missile is determined from the signature. The time of engagement provides a good temporal starting basis for calculating a suitable time for taking defensive action, for starting an explicit defensive manoeuvre or a defensive measure. The time of engagement may be determined from the type of the opposing missile, the distance from the opposing missile and a flying speed of its own. The speed of the opposing missile and its future flying trajectory can be derived from the known type of the opposing missile, since they usually fly with a determined trajectory and speed.

Depending on the time of opposing combating engagement, there may be only little time left for initiating defensive measures. It is therefore advantageous if an opposing missile is detected as early as possible. This can be achieved if the location of the signature is determined within an image produced of the target, for example a ship, and from it a type of the opposing missile. If, for example, it is known at which point of the target/ship various guns or launchers for opposing missiles are located, it can already be concluded from the location of the signature on the target/ship which type of opposing missile is being launched.

An opposing missile can be detected even earlier if a movement at the target is detected and an imminent threat by an opposing missile is detected from the type and/or location of the movement. If, for example, the seeking optical system can resolve a gun on a target at sea or on another ship and it can be detected that this gun is moving, for example is being aimed at the missile, it can consequently be expected that an opposing missile will shortly be launched. The outline of the gun may be used as a signature from which it is also possible to conclude the type of the opposing missile not yet launched.

A defensive measure may be the controlling of an evasive flight of the missile. The firing of at least one decoy is likewise advantageous. This is expediently fired out in front, since an opposing missile usually approaches from the front. The decoy may be7 a smoke grenade. This obscures the view of the missile, so that it becomes more difficult for the missile to be hit by the opposing missile. Moreover, the missile may leave its previous flight path, and thereby start an evasive manoeuvre initially undetected.

Likewise advantageous as a defensive measure is the firing of a decoy, for example an illumination grenade, which is expediently fired out in front on the flight path of the missile. The opposing missile can be dazzled by the bright light, or deceived with respect to its target, so that there is the possibility of the missile starting an evasive manoeuvre undetected.

The invention is also directed to a missile with a seeker head comprising an imaging detector and a seeking optical system. In order to achieve effective defence of the missile, it is proposed that the missile has according to the invention a control unit which is prepared for detecting a signature of an opposing missile and, depending on a detection result, taking a controlled defensive measure.

The imaging detector may be a matrix detector. It is expediently sensitive in imaging terms in the infrared or visible spectral range. The seeking optical system is expediently pivotable, so that even in the case of a small field of view combined with high resolution, a great range of investigation can be achieved for detecting an opposing missile in the surrounding environment. For good orientation in the surrounding environment, it is advantageous if the missile has a passive radar with a radar receiver. Surrounding ships or other craft can be detected on the basis of actively emitted or reflected radar radiation.

An advantageous embodiment of the invention provides that the seeker head comprises a second seeking optical system, the two seeking optical systems having different sizes of the field of view. Likewise expedient is a different spatial resolution of the two seekers, which respectively comprise a seeking optical system and the associated detector. It will generally be the case that the seeker with the field of view of the smaller size has the higher spatial resolution.

Very good monitoring of a great range of spatial angles can be achieved if the second seeking optical system produces images of a number of spatial sectors with an edge length of at least 3° in each case on a single detector element. Each detector element is consequently assigned to this sector, so that with a relatively small number of detector elements a very great range of spatial angles can be scanned with very high8 sensitivity. If a suspicious signature is detected in a sector, the first seeking optical system can be directed to this sector for recording an image of this sector or a part thereof. The signature may be monitored in form, size, variation over time and other parameters, so that a type of an opposing missile can be determined from the signature. A number of detector elements that are in each case sensitive in different spectral ranges may be understood as equivalent to a single detector element. In this way, a spectral investigation of the signature can be performed.

The description given so far of advantageous configurations of the invention includes numerous features that are in some cases reproduced together in a number of dependent claims. However, the features may expediently also be considered individually and combined into appropriate further combinations, in particular where claims have dependency references, so that a single feature of one dependent claim can be combined with a single feature or a number of features or all of the features of another dependent claim. Furthermore, these features can be respectively combined individually and in any suitable combination both with the method according to the invention and with the device according to the invention according to the independent claims. Thus, method features may also be regarded as worded in substantive terms as properties of the corresponding device unit and functional device features also as corresponding method features.

The properties, features and advantages of this invention described above and the manner in which they are achieved will be more clearly and distinctly comprehensible in conjunction with the following description of the exemplary embodiments, which are explained in greater detail in conjunction with the drawings. The exemplary embodiments are used to explain the invention and do not restrict the invention to the combination of features, including functional features, that is specified therein. For this purpose, it is furthermore also possible for suitable features of each exemplary embodiment to be considered explicitly in isolation, removed from one exemplary embodiment, introduced into another exemplary embodiment in order to supplement the latter and/or combined with any one of the claims.

In the drawings: FIG 1 shows an anti-ship missile in an approach flight to a ship, FIG 2 shows the anti-ship missile in a schematic view from above,9 FIG 3 shows a time-based diagram of an approach flight of the anti-ship missile to a target at sea, FIG 4 shows a time-based diagram of an approach flight in which the signature of an opposing missile that is flying towards the anti-ship missile is detected and FIG 5 shows a military ship with a number of items of equipment for firing opposing missiles for combating an incoming anti-ship missile.

FIG 1 shows a missile 2 in the form of an anti-ship missile in the approach flight to a target 4, which in this exemplary embodiment is a target at sea 4 in the form of a military ship, which is prepared for combating the missile 2. For this purpose, the ship has launched an opposing missile 6a, which is an anti-aircraft missile. This flies towards the anti-ship missile 2 to a point of engagement 8, at which the anti-ship missile 2 and the opposing missile 6a will meet if they continue on their flight paths 10, 12.

The target at sea 4 has also fired one or more projectiles in the direction of the anti ship missile 2 from a gun 14. This or these further opposing missile(s) 6b will likewise hit the anti-ship missile 2 if it flies further in the direction of the ship or target at sea 4 on a continuous flight path 10. In the following, a distinction is made between the two different opposing missiles 6a, 6b. If the reference numeral 6 without the reference letter is mentioned, both opposing missiles 6a, 6b are meant.

In FIG 2, the anti-ship missile 2 is shown in more detail in a schematic representation.

It is an unmanned aircraft with a propulsion unit 16, which may be a rocket propulsion unit or an air-breathing turbine propulsion unit. If the anti-ship missile 2 is a cruise missile with a range of over 100 km, the propulsion unit 16 is a turbine propulsion unit.

The anti-ship missile 2 also includes an active part 18 with an explosive for detonation at or within the target at sea 4. Fins 20 enable the anti-ship missile 2 to be guided with very agile response at a speed of for example 1000 km/h in spite of its great weight of over 500 kg.

The control of the flight is controlled by a control unit 22, which for this evaluate signals from a front seeker head. The seeker head is provided with two seekers 24, 26. The seeker 24 has a pivotable seeking optical system 28, the field of view 30 of which is two-dimensionally pivotable over more than ± 90° in each of both dimensions, as10 indicated by the two arrows in FIG 2. As a result, the entire front half-space can be covered by the pivotable field of view 30. The seeker 26 is provided with a rigid seeking optical system 32, which is divided into a number of sectors 34. The entirety of the sectors 34 forms a field of view 36, which likewise covers the entire front half-space in front of the anti-ship missile 2, and in addition also a viewing range laterally a little to the rear, as indicated in FIG 2 by the dashed lines of the field of view 36.

While the seeker 24 is an imaging seeker 24, the seeking optical system 28 of which produces an image on a matrix detector 38, the seeker 26 is not an imaging detector, the seeking optical system 32 of which only produces an image of each sector 34 on a single detector element of a radiation spectrum. Since each sector 34 has an edge length of at least 3° in both dimensions, the signals from their detector elements can only be used as a directional indication, without being able to conclude by means of image-processing methods from which object the light signals were emitted. However, because of the relatively large sectors 34, the seeker 26 has a very high light-gathering power, so that even weak signals can be clearly distinguished from background noise.

Depending on the number of monitored spectra or frequency bands, per sector 34 a signal for only one frequency band or for a number of frequency bands respectively generates a signal, so that the sectors 34 in each case produce a spectrally resolved monitoring result. The seeker 26 is an IR seeker, the detector elements of which are sensitive in one or more different infrared spectral ranges. The seeker 24 is sensitive in the visible spectral range.

FIG 3 shows a time-based diagram of an approach flight of the anti-ship missile 2 flying towards the target at sea 4. As a difference from the example from FIG 2, it is assumed in this exemplary embodiment that the seeker 26 is also an imaging seeker, but with a fixed and larger field of view 36 than the field of view 30 of the first seeker. The field of view 30 of the optical system 28 may in this case be pivotable or not.

The approach flight 40 of the anti-ship missile 2 to the target at sea 4 takes place during the entire flight in a cruise mode or normal flying mode, which has been programmed for a normal approach flight to the target at sea 4 without the anti-ship missile 2 being opposed by combating measures by the target at sea 4. At the time t3, the anti-ship missile 2 hits the target at sea 4 and detonates, as indicated by the rectangle on the right in FIG 3, which stands for the detonation 42. During the first part of the approach flight - the launching of the anti-ship missile 2 is not represented in FIG 3 - the anti-ship missile 2 is still so far away from the target at sea 4 that neither of11 the two seekers 24, 26 can detect the target at sea 4 as such, whether because of lack of resolution or because the target at sea 4 is still below the horizon for the anti-ship missile 2 flying just above the surface of the water. The anti-ship missile 2 is flying in the direction of the target at sea 4 purely on a coordinate-controlled basis.

During the entire flight, the surrounding environment of the anti-ship missile 2, at least the front half-space, is investigated by the seeker 26 with the large field of view 36 for an optical signature that could indicate an opposing missile 6. This monitoring 44 takes place during the entire flight independently of a detection of the target at sea 4, since the anti-ship missile 2 could also face opposing combating measures from elsewhere, for example from another ship, or land-based measures.

At the time t1, the seeker 24 with the smaller field of view 30, which however is provided with a higher image resolution than the seeker 26, has detected the target at sea 4 to the extent that an image processing of the control unit 22 has detected the target at sea 4 as such. The optical system 28 remains directed towards the target at sea 4 and the signals of the seeker 24 are likewise used for monitoring 46 for a suspicious signature and in addition for controlling the flight of the anti-ship missile 2 to the target at sea 4. The activity of the seeker 24 with the higher resolution for monitoring the target at sea 4 is schematically indicated in FIG 3 by the vertically hatched zone.

In this exemplary embodiment, the approaching anti-ship missile 2 is not detected by the target at sea 4, or the target at sea 4 does not respond with combating measures against the anti-ship missile 2 for other reasons. The anti-ship missile 2 is not attacked from elsewhere either. To this extent, the monitorings 44, 46 of the two seekers 24, 26 remain unsuccessful. The anti-ship missile 2 approaches ever closer to the target at sea 4. With a size of the field of view longitudinally of for example 3.8°, the target at sea 4, with an extent by way of example of 150 m, will completely fill the field of view 30 in the longitudinal direction as from a distance of a little over 2000 m. From this time, complete monitoring of the target at sea 4 over its entire length is no longer possible with the seeker 24. This is represented in FIG 3 by the time t2. Therefore, the monitoring 46 and flight control are set by the seeker 24 and only the monitoring 44 and flight control on the basis of image data from the seeker 26 with the lower resolution and the larger field of view 36 are continued, as indicated in FIG 3. The seeker 26 also takes over the last stretch of the flight control of the anti-ship missile 2 to the target at sea 4.12 If there are no opposing combating measures, the anti-ship missile 2 therefore flies to the target at sea 4 in its normal flying mode or cruise mode 40, so that this approach flight takes place without being delayed by defensive measures. To this extent, it dispenses with a defensive measure, such as an evasive flight on an evasive trajectory or the firing of a decoy, even though the anti-ship missile 2 is designed for such an evasive or defensive flight or the firing of a decoy. This however only happens in dependence on the monitoring result or result of a detection of a signature. Since no signature has been detected, the detection result is of such a kind that a defensive measure is prevented.

A further time-based diagram of an approach flight of the anti-ship missile 2 to the target at sea 4 is represented in FIG 4. The approach flight 40 takes place initially as explained in relation to FIG 3, the monitorings 44, 46 being performed by both seekers 24, 26, in other words the target at sea 4 already being within reconnaissance range.

The seekers 24, 26 are assumed to be designed as described in relation to FIG 2. For combating the anti-ship missile 2, the target at sea 4 however launches an opposing missile 6a, which first rises and then turns in the direction of the anti-ship missile 2, as represented in FIG 1, or is already directed at the anti-ship missile 2 by a movable launching platform and is then launched while already aimed at the anti-ship missile 2.

The launch of the opposing missile 6a is accompanied by a strong signature 48. This signature 48 is clearly visible both in the visible spectral range and the infrared spectral range and is detected by at least one of the two seekers 24, 26.

In this very simple exemplary embodiment, the signature 48 can be detected by both seekers 24, 26. This is so because the seeker 26 is directed at the entire front half space and detects the signature 48 as a result of its high sensitivity and for example by a spectral evaluation, in the infrared spectral range, since the signature 48 is very distinctive in the infrared spectral range and stands out clearly against all of the infrared radiation from the background. Since the opposing missile 6a is launched from the target at sea 4 and also the seeker 24 with high resolution is directed at the target at sea 4, the seeker 24 can also detect the signature 48 and for example evaluate it with regard to the development over time of its size and form. The detection of the signature 48 by the anti-ship missile 2 takes place at the time t1. Up to this time, the anti-ship missile 2 is in cruise mode 50, in which it stays if there is no detection of a signature or of an opposing missile 6. With the detection of the opposing missile 6 or the signature 48, the cruise mode 50 ends and a defence mode 52 begins, in which the anti-ship missile 2 performs defensive routines. It can be seen from the upper bar that the13 normal approach flight 40 continues unchanged, in other words there is no externally visible sign from the anti-ship missile 2 of the detection of the signature 48 or of the opposing missile 6a. It flies unchanged, in the same way as in the cruise mode 50, towards the target at sea 4.

A more complex opposing combat situation exists if the opposing missile 6a is not launched from the target at sea 4, but from another ship or even from land. In this case, the signature 48 is generally not detected by the seeker 24 with the smaller field of view 30, since the signature 48 lies outside the field of view 30. The signature 48 is however discovered by the seeker 26 with the larger field of view 36. It is evident from the detection in which sector 34 the signature 48 lies. The seeker 24 is then pivoted in the direction of this sector 34. As a result, the signature 48 comes to lie in the field of view 30 of the seeker 24, so that the anti-ship missile 2 can then also investigate the signature 48 from data of the seeker 24, for example by means of image processing algorithms. This somewhat more complex example is represented in FIG 4. After detecting the signature 48 or the opposing missile 6a at the time t1, the seeker 24 is pivoted to the corresponding sector and the signature 48 appears in the field of view 30 of the seeker 24. This pivoting is indicated in FIG 4 by an upward shift of the vertical hatching. Hatched regions above the solid line indicate an alignment of the seeker 24 with the opposing missile 6a or the signature 48 thereof and hatched regions under the solid line indicate an alignment of the seeker 24 with the target at sea 4. The seeker 24 is initially directed towards the target at sea. Shortly after the time t1, the seeker 24 is pivoted and is then no longer aligned with the target at sea 4, but with the signature 48.

The defence mode 52 is, for example, a general defence mode 52, since it is not yet known which type of opposing missile 6a is concerned. In order to determine this, the anti-ship missile 2 or its control unit 22 performs, for example, three steps, which are represented in FIG 4 by three small boxes. First of all, an investigation 54 of the signature 48 is performed. The investigation may be performed with regard to the spectral distribution of the signature 48, the form, size and development of these parameters over time. Other investigation parameters described below may also be used.

The investigation data are then sent to a categorization 56, it also being possible for steps 54 and 56 to overlap one another. The investigation data are thereby compared with stored data and then allocated to one of a number of categories, so that finally the signature 48 is categorized, that is to say is assigned to one of a number of categories.14 Each category is assigned at least one type of opposing missile 6, so that the signature 48 is then assigned to this type.

In the third step of finalizing the specific defence 58, data on the opposing missile type are loaded into the control unit 22, and one or more defensive measures are planned.

For this purpose, for example, defensive measures stored for the opposing missile type are selected in dependence on the distance of the anti-ship missile 2 from the target at sea 4, the flying stage of the opposing missile 6, technical properties of the opposing missile 6 and/or the distance of the opposing missile 6 from the anti-ship missile 2 or the distance of the anti-ship missile 2 from a calculated point of engagement 8. A reaction time at which an explicit defensive measure is started may also be determined. This time is the time t3 in FIG 4.

After this finalizing of the specific defence 58, the anti-ship missile 2 or its control unit 22 changes to a type-related defence mode 60, which in comparison with the general defence mode 52 is therefore specifically finalized with regard to the type of opposing missile. In this type-related defence mode 60 too, the anti-ship missile 2 remains in its normal flight 40, that is to say still no defensive trajectory is flown or decoy fired.

Independently of the change of modes, the investigation 54, the categorization 56 and the finalizing of the specific defence 58, the seeker 24 with high resolution repeatedly changes its position. This is indicated in FIG 4 by the changing of the vertically hatched regions. It alternately focusses on the target at sea 4 and on the signature 48, in order both to graphically investigate the signature 48 and to continue to monitor the target at sea 4, since a further opposing missile 6 could also be launched from the latter. In this case, it would be necessary to defend itself against a number of opposing missiles 6 simultaneously. In the case of the example from FIG 4, this is not the case, so that the anti-ship missile 2 only has to defend itself against the opposing missile 6a in the form of the anti-aircraft missile.

The more the opposing missile 6a approaches the anti-ship missile 2, or the closer the anti-ship missile 2 comes to the point of engagement 8, the more important it becomes to determine the exact position of the opposing missile 6a in relation to the anti-ship missile 2. Since the seeker 24 follows the opposing missile 6a, in order to detect the flight and position of the latter as accurately as possible, the proportion of the alignment of the seeker 24 with the opposing missile 6a as a percentage becomes increasingly directed at the opposing missile 6a as the distance between the two missiles becomes15 less, as is represented in FIG 4. As an alternative or in addition, it is possible to detect the distance of the two missiles 2, 6 from one another and their relative speed with an active radar of the anti-ship missile 2.

Shortly before reaching the point of engagement 8, which is continually corrected by the control unit 22 on the basis of the data of the seeker 24 and/or of the radar, the anti-ship missile 2 or the control unit 22 changes to an active defence mode 62. In the active defence mode 62, one or more explicit defensive measures take place, such as leaving the cruise trajectory 10 by taking a controlled defensive trajectory and/or firing one or more decoys. This interrupts the normal flight 40 and a defensive flight 64 is adopted. For example - as shown in FIG 1 - the point of engagement 8 is evaded, in particular by a maximum deviation in flight, so that the anti-ship missile evades the opposing missile 6a just before colliding. The active defence 66 is performed for as long as it is detected that combating measures are being undertaken in the form of an opposing missile 6. In the case of the exemplary embodiment from FIG 4, for example, the opposing missile 6a has missed the anti-ship missile 2 and the distance between the two is so great that the opposing missile 6a can no longer catch up with the anti ship missile 2 before it strikes the target at sea 4. The combat is to this extent recognized as ended and the anti-ship missile 2 or the control unit 22 changes back to the cruise mode 50, in order to reach the target at sea 4 as quickly as possible. It is alternatively possible to take a controlled escape mode, in which the anti-ship missile 2 is brought to maximum speed, in order to reach the target at sea 4 as quickly as possible. It is also possible to already initiate such an escape or acceleration mode before, in order to make the distance from the target at sea 4 smaller as quickly as possible.

The activities of a defence mode 52, 60, such as the investigation of the signature 48, 68, its categorization and the finalizing of a specific defence, are actions preparing for the defensive measure. A defensive measure itself is an action taken specifically in defence against the opposing combat on its own or in combination with further actions, such as for example a defensive flight and the firing of decoys. A general defence mode 52 may be started independently of the detection result of the signature 48, 68. A specific, type-related defence mode 60 and also an active defence mode 62 are started in dependence on the detection result, in particular in dependence on the detected type of the opposing missile 6, from a plurality of modes resulting from the various types.16 In the case of the exemplary embodiment from FIG 1, it can be seen that not only the opposing missile 6a is flying towards the anti-ship missile 2, but also opposing missiles 6b in the form of projectiles from the gun 14. The anti-ship missile 2 reacts to such opposing missiles 6b earlier than to propelled or guidable opposing missiles 6a. This is represented in FIG 1, in that after the defensive flight 64 a straight flight path 10 corresponding to the cruise mode 50 or escape mode is adopted again. The reason for this is that the gun 14 only begins the opposing combating measures when the anti ship missile 2 is within range. Until then, the anti-ship missile 2 continues to fly straight.

If then the muzzle fire is detected as a signature 68 and assigned to the gun 14, the anti-ship missile 2 reacts different in comparison to the detection of the missile 6a, since only a few seconds then remain for an evasive manoeuvre. An active defence mode 62 is again activated, this time tailored to the other type of opposing missile 6b, for example an erratic defensive flight 64 is performed, or short lateral "jumps”, as indicated by the dashed line in FIG 1. In this way it is attempted to evade the projectiles.

For carrying out an efficient defensive measure, it is necessary to detect the type of the opposing missile 6. The firing of a decoy out to the front, for example a smoke grenade or a flash grenade, is largely ineffective when facing opposing projectiles. In the case of a guidable opposing missile 6a, on the other hand, concealment by smoke or a dazzling flash can have an effect, allowing the anti-ship missile 2 to perform an evasive manoeuvre that is not discovered by the opposing missile 6a, or discovered too late, just before the point of engagement 8, so that the two missiles 2, 6a miss each other, or a distance of engagement is so great that a detonation of the opposing missile 6a does not decisively damage the anti-ship missile 2. The detection takes place by an evaluation of the signature 48. There are several possibilities for this. The signature 48 may be investigated for its frequency spectrum, a change over time, size, form and/or a variation over time of these parameters. In the case of the example from FIG 1, it is clear that the signature 48 from a rocket propulsion unit is significantly different from a firing flash, that is to say a signature 68 of a gun 14. Such a difference concerns not only the form and size, but also a spectral radiation distribution and especially a variation over time. While the signature 48 moves along with the flight of the opposing missile 6a, the signature 68 from a gun occurs only briefly and in one place, but is generally repeated, since a multiplicity of projectiles are fired one after the other at the anti-ship missile 2. For this reason, such a signature 68 can be easily identified as a projectile signature.17 A further possibility for investigating signatures 48, 68 is explained on the basis of the representation from FIG 5. FIG 5 shows a military ship 70 with a number of firing units.

There is, for example, an anti-aircraft gun 72, a rocket launcher 74 for anti-ship missiles, a multiple launcher 76 for anti-aircraft missiles, a medium-calibre gun 78, for example for a calibre of 30 mm, and/or a large-calibre gun 80, for example a 100-mm gun. All of these units are fixed installations on the military ship 70, and consequently are definitively fixed by their position. If it is thus detected at which location the signature 48, 68 occurs on the military ship 70, the type of firing unit can be concluded from this location. The location parameter in relation to, for example, a point of reference of the military ship 70 is consequently a parameter which can be used on its own to determine the type of the opposing missile 6. Particularly advantageously, this parameter can of course be combined with one or more of the aforementioned parameters in order to arrive at a particularly reliable result of the type detection.

A further helpful parameter for type determination is a movement of a firing unit. If, for example, the medium-calibre gun 78 is turned in the direction of the anti-ship missile 2, this can under some circumstances already be detected as such by the seeker 24.

Since the location of the moved firing unit on the military ship 70 provides a clear indication of the type of the opposing missile 6, it can be classified before it is fired or launched. A reaction or a type-related defensive measure can be started very quickly.18 List of designations 2 Anti-ship missile 4 Target at sea 6a Opposing missile 6b Opposing missile 8 Point of engagement Flight path 12 Flight path 14 Gun 16 Propulsion unit 18 Active part Fins 22 Control unit 24 Seeker 26 Seeker 28 Seeking optical system Field of view 32 Seeking optical system 34 Sector 36 Field of view 38 Matrix detector 40 Approach flight 42 Detonation 44 Monitoring 46 Monitoring 48 Signature 50 Cruise mode 52 Defence mode 54 Investigation 56 Categorization 58 Finalizing of specific defence 60 Type-related defence mode 62 Active defence mode 64 Defence flight 66 Defensive action 68 Signature 70 Military ship19 Anti-aircraft gun 72 74 Rocket launcher 76 Multiple launcher Medium-calibre gun 78 Large-calibre gun 80 20 258066/2

Claims

CLAIMED IS:

1. Method for protecting a cruise missile (2) during its flight in the direction of a target (4, 70) to be combated, in which the cruise missile (2) monitors (44, 46) its surroundings to see whether a signature (48, 68) of a missile (6) that has been launched to combat the cruise missile (2) is detected and, depending on a detection result, begins a defensive measure (64).

2. Method according to Claim 1, characterized in that in the absence of the detection of the signature (48, 68), the cruise missile (2) remains in its cruise mode (50), in which it flies towards the target (4, 70), and changes to one of several defensive modes (52, 60, 62) only in the event that a signature (48, 68) is detected, wherein the selection of the defensive mode (52, 60, 62) depends on the detection result.

3. Method according to Claim 1 or 2, characterized in that in the event that the signature (48, 68) is detected, the cruise missile (2) changes to a defensive mode (58), in which defence-relevant data is loaded into a control unit (22) of the cruise missile (2), and which includes a reaction time (t ), 3 at which a defensive measure (64) is begun.

4. Method according to one of the preceding claims, characterized in that the position of and distance to the target (4, 70) of the cruise missile (2) are measured, and the defensive measure is controlled by using the position and distance of the target (4, 70). 21 258066/2

5. Method according to Claim 4, characterized in that the speed of flight is increased as a function of the distance to the target (4, 70).

6. Method according to one of the preceding claims, characterized in that the cruise missile (2) has two different sets of search optics (28, 32) with two different visual field sizes, and the target (4, 70) is firstly targeted by the search optics (28) with the smaller visual field (30) and controlled with image data obtained therefrom, and is then targeted by the search optics (32) with the larger visual field (36) and controlled with image data obtained therefrom.

7. Method according to one of the preceding claims, characterized in that the cruise missile (2) has two different sets of search optics (28, 32) with two different visual field sizes, and the signature is detected by the search optics (32) with the larger visual field, and the search optics (28) with the smaller visual field is pivoted in the direction of the signature (48, 68).

8. Method according to one of the preceding claims, characterized in that the signature (48, 68) is examined for its frequency spectrum, a time change, size, shape and/or time profile of its brightness, and a type of combat missile (6) is determined therefrom.

9. Method according to one of the preceding claims, characterized in that the signature (48, 68) is assigned to one of a plurality of signature categories, and flight data associated with this category is loaded into a 22 258066/2 control unit (22), which controls the flight of the cruise missile (2).

10. Method according to one of the preceding claims, characterized in that a time (8) at which the combat missile (6) will be encountered is determined from the signature (48, 68).

11. Method according to one of the preceding claims, characterized in that the location of the signature (48, 68) within an image of the target (4, 70) is determined and a type of the combat missile (6) is determined therefrom.

12. Method according to one of the preceding claims, characterized in that a movement on the target (4, 70) is detected, and an imminent threat from a combat missile (6) is detected from the type and/or the location of the movement.

13. Method according to one of the preceding claims, characterized in that the defensive measure (64) includes the launching of at least one decoy, wherein the decoy is a fog grenade or an illuminating grenade, which is launched forwards, wherein the cruise missile (2) then deviates from its flight path (10) in order to fly past the combat missile (6a).

14. Cruise missile (2) having a search head comprising an imaging detector (38), search optics (28) and a control unit (22), which is prepared to detect a signature (48, 68) of a combat missile (6) and to control a defensive measure (64) depending on a detection result. 23 258066/2

15. Cruise missile (2) according to Claim 14, characterized in that the search head comprises a second set of search optics (32), and the two sets of search optics (28, 32) have different visual field sizes. Geoffrey Melnick Patent Attorney G.E. Ehrlich (1995) Ltd. 11 Menachem Begin Road 5268104 Ramat Gan