DE3225474C2 - Method of target recognition - Google Patents

Abstract

The invention relates to a method for target recognition of a missile flying with an active seeker head, which is flying in a predetermined direction, height and speed, the laser beam of which is pivoted perpendicular to the direction of flight by a certain angle by means of a scanner at a certain scanning speed, in which the seeker head sensor predictively and independently detects a ground target within its scanning field of view at long distances with high resolution, in which a target discrimination takes place based on the shape of the return pulses of the laser transmitter received after reflection on horizontal background or vertical target surfaces, in such a way that the laser beam receiver of the seeker head two ideally occurring return pulse shapes has adapted filters, so that the signal level at the output of the filter enables a statement to be made as to whether vertical or horizontal surfaces were hit by the scanning laser beam.

Description

On the horizontal floor there is now with these Data an almost elliptical light spot or »Ab-

35 pressure «of the beam R 1.73 m in length in the direction of flight

seen (Fig.3c). The width of this "footprint" is

The invention relates to a method for target detection 0.3 m. By means of a known scanner in the direction, height and speed of a seeker head, the laser light beam R is now perpendicular to the speed predetermined flying missile with a flight direction by an angle φ * ± 2 ° (± 35 mrad) seeker head according to the upper handle of claim 1. 40 pivoted with respect to the missile longitudinal axis. In

Such methods are known per se. Thus, a 70 m long strip is disclosed 1 km away DE-OS 30 00 007 a combat vehicle Abwehrsy- detected transversely to the direction of flight, as the F i g. 2 look at which light to hit from one above one

In order to achieve almost complete area coverage from above down onto the combat vehicle, the scanning speed t _{x must} be capable of being fired accordingly the above-mentioned overflight sensor in e: uses a missile or missile covered during a strip scan, which only detects the target when it is of the same order of magnitude as the stripe projectile is already over the target or is approaching it.

A target detection over long distances - see below for the sampling time on which the example is based for example 1 km - looking ahead, with the of- of 3 ms for a strip, one achieves an over The specified procedure is not possible, and there is also a 90% area coverage of the soil. From the point of time when the target is detected, until the weapon is delivered and the target is recognized, methods that work with the direct time only for a short period of time for receiving flight maneuvers can be used, as can methods with to disposal. This procedure works on the basis of optical overlay reception. Principle of determining the transit time of the laser pulse If there are no targets in front of the echo pulse in the scanned area and if it differs, then the search beam is generally on the half basically of the method according to the invention. hit flat ground, except when there is

DE-OS 30 41 765 is a proximity ignition of forest edges, groups of trees, etc. By the which is known, but this is also based on a distance measurement of a small aspect angle of 10 °, from which the target is then synthesized. edge of the light spot a difference in distance of

The object of the present invention is to d _H · cos · & = 1.7 m to the seeker head. The resultiegrunde from this, a method of the type mentioned to create rendc transit time difference is, whose sensor predictively and independently a target within its scanning field of view to 65 Δ & = 2 d _H · cos t? / C = 11.3 ns. detects long distances with high resolution and works without any distance measurement. This means that a transmitted laser pulse with

This task is due to the low rise time of r _A = 5 ns after the reflection in claim 1

a horizontal target with a »smoothed« rise time

te = i / 7V + AiP = 12.4 ns

5 is received.

A temporal change in this fact now forms a criterion for the detection of a target, the will always have some areas that deviate significantly from the horizontal. If the search trail captures a sol- ίο Before the surface, another »imprint« (light spot) is created on the target with an almost constant distance to the Seeker head. The backscattered laser pulse is therefore without any significant »run-time smear« receive.

In order to now both expected backscatter pulse forms, namely the reflection on the horizontal surface (generally the background) and the reflection on more vertical. To be able to evaluate areas (generally a target), the receiver has two in the seeker head matched filters. Depending on the signal level at the two filter outputs it is now judged which pulse shape has been received

The laser pulse is now emitted at a pulse rate of 80 kHz, so that the center points of the Light spots from two consecutive pulses due to the scanning movement approx. 30 cm (at a distance of 1 km) are distant from each other. If the signal evaluation determines that only one or two consecutive Return impulses are "narrow", d. H. have been reflected from almost vertical surfaces, so if this is an indication that a tree trunk or mast has been illuminated, a check is carried out automatically during the next scanning movement, during which the laser pulse is about 1 m further in the direction of flight Gciändestrcifen or the perceived goal at almost the same Spot

The receipt of an unstretched impulse is a first sign of a perceived goal, which is in the subsequent scanning movements are discriminated against, what happens when the for the expected target characteristic silhouette results from the evaluation. Since the entire detection and evaluation process at a great distance from the target, the aforementioned or vorbeschriehene method creates both Time for the evaluation as well as for the execution of the flight maneuvers to combat the target.

A system has now been created by the method described above, which by means of a predictive Sensor an independent target determination within the scanning field of view over long distances with high resolution, whereby the pulse shape discrimination, i.e. the discrimination of the temporal The course of the "echo pulses" (run-time smear), which is the essential characteristic of the process.

For this purpose 2 sheets of drawings

60

65

Claims (3)

ι 2 laid measures in flawless and temporal patent claims: solved more quickly The further embodiment he is from the subclaims. In the following 1. Method for target recognition by one In the description, an exemplary embodiment is described - direction, altitude and speed are given in advance. For a better understanding are in the drawing true flying missile with a seeker head, schematic sketches attached. It shows whose laser beam is perpendicular to the direction of flight around F i g. 1 a schematic view across the flight direction a certain angle by means of a scanner with indication of the irrelevant for the procedure a certain scanning speed is panned, route information, this seeker laser beam with a certain io F i g. 2 a schematic plan view of the scanning device Beam divergence in the direction of flight in the passage to be overflown or strip scanning transverse to the direction of flight in the ground at a certain horizontal distance and two missile positions, Illuminated in a certain aspect angle, that Fig.3a is a timing diagram of the applied search characterized in that on the basis of the beam, received pulse shapes upon reflection at hon- 15 Fig. 3b a time diagram of the backscattered search zontal background or vertical target areas in the beam in the absence of targets, the evaluation unit of the seeker head a target discrimination F i g. 3c schematic representation of the light spot minimization takes place, with the laser beam receiver measured state according to FIG. 3b, of the seeker head two the return pulse forms Fig.3d a timing diagram and the corresponding adapted filters are assigned 20 light spots when they hit a target 2. The method according to claim J. characterized according to the situation illustrated in Fig. 1 eizeichnet that the scanning speed (t _x ) corresponding missile with seeker head and laser light beam L corresponding to the airspeed (V _F ) is selected so the missile flies in a pre-assigned direction that during a strip scan (1) return with an altitude which, to explain the flight path that has been laid, is of the same order of magnitude as driving with a calculation example with H = 170 man the strip width (d _h ) . The airspeed should be Mach 1 3. The method according to claims 1 or 2, and the divergence of the seeker beam characterized in that for detection and output θ = 03 mrad this seeker beam R illuminates in the evaluation of target signatures methods with a direct distance R = 1 km Floor under a reception and / or with an optical overlay angle Φ of 10 °. With R the distance can be used. see the laser homing head and the point of impact designated