FR2622976A1 - METHOD AND DEVICE FOR THE NON-DISTURBED LOCALIZATION OF MISSILES - Google Patents

Abstract

Undisturbed localization of missiles against a background in strong equal parts (low frequency) by means of a reference transmitter as the transmitter of optical radiation (high frequency) which is modulated. To determine the position of the missile, an optical radiation receiver is used with a superficial receiving field which is arranged as a detector array with a large number of elements of various sizes arranged so that their size decreases with increasing frequency. we move towards the center, and each of the elements is connected to its own filter amplifier channel which only lets pass for processing the signals modulated with respect to the missile; the goal / object appears in a broken line on the representation according to the attached figure of the detector network. According to the invention, great security against jamming transmitters is obtained.

Description

METHOD AND DEVICE FOR NON-DISTURBED LOCALIZATION

MISSILES

  The present invention relates to a method of locating undisturbed missiles with respect to a background of high equal parts (low frequency) by means of a reference transmitter as a transmitter of an optical radiation (high frequency) that an undisturbed missile location device which encloses as a radiation emitter a

modulated reference transmitter.

  For the separation of the useful signal and the background signal and consequently the recognition of the displaced object, such as a missile, a whole series of solutions have already been proposed (see the level of the technique indicated in FIG. the German patent DE-PS 29 44 261

of the plaintiff).

  In DE-PS 29 44 261, on the other hand, a greater security against jammers is obtained by the fact that the missile is provided with an illuminating composition whose radiation is modulated by means of a suitable disc which comprises sectors of various spectral transparencies. We can eliminate

  jammers of the same intensity.

  However, a scenic structure may also have a disruptive effect in certain circumstances, for example if it is in the background of heat sources such as objects carried, explosions, fires or so-called "lures" . Such sources of disturbance can be in the same spectral zone as the radiation of the illuminating composition: they are then no longer

  clearly separable or recognizable as such.

  There is a description of a method of

  distinguishing the background noise from the intended purpose despite such sources of disturbance in European Patent Application EP 79,175, A1. It makes the most of the fact that, for reasons that are out of place, time plays a role in the third dimension in the formation of the image and can also be used to evaluate it. The indicated method, however, uses "tessellated sensors", that is, frames with as many small image dots as possible, which must be examined sequentially, as much as possible in real time, with respect to their various intensities of gray tones. The intensities of gray are at the same time

very prone to disturbance.

  The electronic deployment required to swiftly scan many small identical image points and evaluate them by means of intensity comparisons is enormous and very expensive. It is also necessary to take into account the congestion of a signal processing and evaluation unit required for this purpose.

effect.

  The object of the invention is a method and a device for the undisturbed and accurate localization of missiles that are feasible with a much lesser complication and at a much lower price than at the aforementioned level of the technique and which make it possible to operate at high speeds. modulation frequencies up to several kilohertz, which again increases the

security against interference.

  The method is characterized in that, for determining the position of the missile, an optical radiation receiver with a surface receiver field is used which is arranged in a detector array with a large number of elements of various sizes arranged. in such a way that their magnitude decreases as one moves towards the center and that each of the elements is connected to an own filter amplifier channel which selectively passes 4 for processing only the signals modulated by report to the missile. The device is characterized by a surface-detector radiation receiver composed of a large number of elements of different sizes decreasing as one moves towards the center, each element of the detector being connected to an own amplifier channel which only selectively amplifies the modulated signals with respect to the missile, each element being connected as regards the alternating current to its amplifier channel input, all the inputs of the amplifier channels comprising an automatic common AGC signal normalization and a tracking regulation which are connected to a bandpass filter, a rectifying diode, an analog / digital converter and a multiplexer as well as a processor with computer. The invention also relates to the use of such a device with a rigid imaging geometry of the detector array for localization (angular deviation) within the detector surface of amplitude modulated signals such as they are received and the use of this same device to bring the values obtained in the electronic evaluation unit to a control and / or signaling device for the

guidance of a missile.

  Particularly because the radiation of a transmitter linked to the missile is modulated in its amplitude, a clear identification is obtained according to the invention which makes it possible to be content with a small number of elements.

  detectors and to limit the electronic expense.

  It is no longer necessary for each element to have an amplifier and a filter channel that can, however, be integrated on one chip because of their

  particular achievement in large numbers.

  A rigid detector array with respect to the imaging geometry is sufficient for locating the received signals. Only signals that have been prescribed in signaling to each missile by their modulation are admitted by the recognition of the signals in the detector channel for the purpose of further processing and

devaluation.

  The small number of detector elements in the invention makes such a network inexpensive, the simple evaluation and frequency of the signal to be used (and therefore the signal-to-noise ratio) can be chosen very high, which further improves security. and the stability of recognition and possibly regulation. The electronics used is highly

  integrable and the device is compact.

  The invention will be better understood using the

  detailed description of a mode of realization taken as

  non-limiting example and illustrated schematically in the accompanying drawing, in which: Figure 1 represents as a surface network elementary sensor device with the purpose / object in broken lines; Figure 2 shows the evaluation electronics for better goal / object recognition; FIG. 3a gives the detail of an automatic signal normalization (regulation) circuit; FIG. 3b shows a control circuit with the same simplified effect compared with that of FIG. 3a; Figure 4a shows a tracking control with controlled band filters (variable frequency); Figure 4b is an operating diagram of the band filter; FIG. 4c gives an example of connection of the

band filter.

  The invention relates to a method for the undisturbed localization of missiles with respect to a background of high equal parts (low frequency) by means of a reference transmitter as a transmitter of an optical radiation (high frequency) that we modulate, process in which we use,. to determine the position of the missile, an optical radiation receiver having a surface receiver field which is arranged in a detector array with a large number of elements of various sizes arranged so that their magnitude decreases as one goes goes towards the center and each of the elements is connected to an own filter amplifier channel which selectively passes for processing only the modulated signals as to their

  - frequencies relative to missiles.

  The method according to the invention differs from the general methods of image processing and recognition in that a goal / object / image can not be separated from the background simply by scanning a surface in network and by differences between black and white but that is selected from the outset and then let pass for processing and evaluate signals in a predetermined modulation, different

from one missile to another.

  In a preferred embodiment of the invention, the modulation is associated with the transmitter in the missile. The

  receiver is adapted to each coded modulation (in time).

  In the case of modulation with regard to the signals, or pulses, to be transmitted, amplitude modulation is mainly preferred because of the small bandwidth, that is to say when one has to work in a zone of length.

narrow wave.

  The optical transmitter may be a light source of a specific wavelength, for example a xenon lamp. In the simplest case, a modulator (ray) is used as a modulator, such as for example

  rotating chopper disk of a kind known per se.

  The device according to the invention is used to achieve the aims thereof and to apply the method of certain recognition of missiles. This device contains as an optical radiation transmitter a modulated reference transmitter. It is characterized by a surface-detector radiation receiver composed of a large number of elements of different sizes decreasing as one moves towards the center, each element of the detector being connected to an own amplifier channel which selectively amplifies only modulated signals relative to the missile, and, as regards the alternating current, to its amplifier channel input and all the inputs of the amplifier channels comprising a common AGC signal normalization and a tracking regulation which are connected to a bandpass filter, a rectifying diode, an analog / digital converter and a

  a multiplexer as well as a processor with computer.

  We look separately at all the coherent image elements that fulfill the threshold value condition, that is to say that for each object the calculation of the center of gravity is done by limiting it to these coherent image elements. . The assignment of the correct object to the missile is accomplished by distance comparisons between the position of the missile in the previous images and the positions of the object in the current image. If we denote by v the velocity vector acquired from the missile in the image, the expected missile position Pn + i in the new image is written: Pn + 1 = Pn + vT (T = image period), expression in which Pn is the position of the missile in the previous image. It is estimated that the missile -5 the object-whose center of gravity is the closest to

the expected position Pn + i.

  The electronic evaluation circuit still has the following features, explained below: - automatic signal control (AGC); - tracking regulation (NLR) for the filter

  switched capacitor filter SCF).

  Automatic Signal Normalization (AGC): The role of "AGC" is to standardize the signal levels present on the Multiplexer. The standardization criterion used is a statistical measure of these signals, for example: the sum of all the signals; - the maximum value of the signals;

- the variance of the signals.

  The "AGC" then sets the input amplifiers so that the corresponding statistical measurement is maintained at a given value in advance. All these input amplifiers are at the same time subjected to the same regulation voltage. Figure 3a shows the control circuit. A measuring circuit M gives the chosen statistical measurement, which is extracted from a given set value. The regulation difference thus obtained is converted in the regulation and positioning element R into a regulation voltage which regulates the amplification of the detector signals. The regulating and positioning member R determines the time behavior of the control circuit. he

  contains in any case an integrating component.

  We will also briefly describe, being particularly distinguished by its simplicity, a variant to this version. Instead of the control circuit, a simple control circuit according to FIG. 3b is used. The law of decrease of the radiation intensity of the missile with the time being approximately known, one reproduces this law in a voltage generator which

  adjusts the amplification accordingly.

  The disadvantage of this simpler solution lies in the fact that this regulation does not eliminate fluctuations, for example due to smoke, as well as atmospheric influences, so that one can lose

earlier the missile.

  Track Control (NLR): The purpose of track control is to tune the bandpass filter to the existing modulation frequency each time. If one can maintain stable said modulation frequency, one can also suppress

said tracking regulation.

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  The input signal used is the output of the

  bands. It is necessary to act so that the input signal contains the modulation frequency. This is achieved by selecting the channel with the largest amplitude or summation of all channels. This last method has the advantage of eliminating a corresponding selection circuit for the search of the maximum. See figure

explanatory 4a.

  If one controls the band-pass filters (SCF) (see, for example, the Maxim MF 10 filter of the Maxim Firm), according to the preferred formula, by a frequency, the control variable must be a variable frequency designated here by fR. It is generated by a voltage controlled oscillator (VCO). This generates two further frequencies -fa and fu which, constantly, are respectively greater than and less than fR by a predetermined value, so that the corresponding average frequencies are placed symmetrically with respect to fR. The control voltage of the "VCO" is obtained as follows: As mentioned above, the output signals of the band-passes are summed. This is accomplished in the "Sum" block. To see the direction in which the modulation frequency deviates, two additional band pass are used

  BPI and BP2, each with output rectifier circuit.

  Their average frequencies are at a predetermined value above (BP1) or below (BP2) of the

  average frequency of the bandpass of the detector channels.

  If, for example, the modulation frequency then rises, BP1 gives a higher output level than BP2. This difference is brought to the "regulator" which controls the "VCO" so that fR, and therefore also f0 and fu, increase correspondingly until the output levels of BP1 and BP2 are equalized. The "regulator" is an integral regulator, that is, an integrator. Since the average frequencies of BP1 and BP2 are symmetrically located with respect to the average frequency of the pass-band in the detector channels, an exact tuning of the modulation frequency is obtained precisely when the output levels of BP1 and BP2

are equal to each other.

  FIGS. 4b and 4c show the second-order controlled bandpass filter as a variable state filter. Each of the two partial filters uses two integrators (RC) and an operational amplifier to generate the second-order function. Two to four external resistors (for stability of the Q coefficient) and one clock (VCO) for the adjustment of the Q-factor are used.

  the average frequency (for example at 2-20 kHz).

  The invention is not limited to the embodiments described above. They can of course be modified without departing from the scope of the invention. This is also not limited to the tracking control (NLR) or signal normalization (AGC) described above, nor to the aforementioned filter. Instead of a variable frequency filter (SCF), it is also possible to use a variable voltage filter (VTF). The network may consist of a plurality of "n" (photoelectric) elements decreasing as one moves towards the center, and the multiplexer may be set for a selected number of

even at will of "n" channels.

Claims (4)

  1. A method of undisturbed location of missiles with respect to a background of high equal parts (low frequency) by means of a reference transmitter as a transmitter of an optical (high frequency) radiation that is module, characterized in that a receiver of the optical radiation having a surface receiving field which is arranged in a detector array with a large number of elements of various sizes arranged in such a way that their magnitude decreases as one moves towards the center and by the fact that each of the elements is connected to an own filter amplifier channel which selectively passes for processing only the signals modulated by report to the missile.   2. Non-perturbed missile locating device, which contains as optical radiation transmitter a modulated reference transmitter, characterized by a surface detector radiation receiver composed of a large number of elements of various sizes decreasing in size as one moves towards the center, each detector element being connected to an own amplifier channel which selectively amplifies only the modulated signals relative to the missile and being connected as regards the alternating current to its amplifier channel input, all the inputs of the amplifier channels comprising a common AGC signal normalization and a tracking control which are connected to a bandpass filter, a rectifying diode, an analog / digital converter and a multiplexer as well as a processor with calculator.   3. Use of a device according to claim 2 with a geometry of rigid images of the detector array for localization (angular deviation) inside the detector surface of the modulated signals   in amplitude as they are received.   4. Use of a device according to one of   Claims 2 to 3 to bring the values obtained   in the electronic evaluation unit to a control and / or signaling apparatus for the guidance of a missile.