RU2303806C1 - Method for forming of control signals in single-pulse homing heads - Google Patents

Abstract

FIELD: homing heads with single-pulse direction finders installed on missiles.

SUBSTANCE: partial neutralization of the negative influence of the target angular noise on the trajectory of the missile-to-target approach is attained due to the refusal from pursuit by the missile of the target phase control "wandering" far beyond the limits of the geometric dimensions of the target proper, and transition to a regular shift of the missile trajectory towards the increase of the amplitude of the received signal, as a results, the missile trajectory acquires a smoother shape thus decreasing the missile misses. To this end, the autopilot control signal is formed as sum η=Kα+β, where main signal α of the single-pulse direction finder regulated in amplitude is used as the first component, and auxiliary signal β of the single-pulse direction finder is used as the second component, and coefficient K is selected by a monotonically diminishing function of the modulus of auxiliary single |β|.

EFFECT: partially neutralized negative influence of the target angular noise on the missile-to-target approach trajectory.

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Description

The invention relates to monopulse radar, and more specifically to homing mounted on missiles (GOS) with monopulse direction finders (MP).

Known methods for generating control signals in GOS with MP / 1, p.66-89; 2, p. 303-328; 3 /. According to them, the signals α _x and α _y are generated in the MP that characterize the angular deviation of the target phase center (FC) from the axis of the MP antenna in the direction finding plane XZ and YZ, respectively, and are proportional to the derivatives of the phase distribution φ (x, y, z) of the received target signal :

In the future, the signals α _x and α _y are used to track the movement of the target's FC by affecting the MP antenna control system and to control the rocket’s trajectory by affecting the rocket’s autopilot.

The lack of analogues / 1, p. 66-89; 2, pp. 303-328 / consists in the low information content of the signals α _x , α _{in the} MP due to the existence of the so-called angular noise of targets / 1, pp. 128-135 /, the essence of which is the deviation of the target's FC from its energy center (EC) . When the target’s FC moves far beyond its geometrical dimensions, the rocket’s trajectory differs significantly from that determined by the missile’s homing method and acquires a “wandering” character due to random changes in the target’s angle. In addition, the axis of the tracking antenna of the MP noticeably deviates from the direction of the target's EC and, therefore, the accuracy of tracking the target in angular coordinates decreases sharply. The negative effect of angular noise is especially noticeable at short distances to the target. Partial neutralization of the negative effect of angular noise on the rocket trajectory is achieved by weighting the samples of the output signals α _x and α _{at the} MP with their subsequent accumulation, when the samples of the amplitude A of the received signal / 3 / are selected as weight coefficients. At the same time, it is implicitly assumed in / 3 / that the angle of the target changes rather quickly, as a result of which the number of goniometric readings with weak correlation during the accumulation of the output signal of the MP turns out to be quite large (≥10). However, in a situation where the target’s FC extends far beyond its geometrical dimensions and maintains its position relative to the EC for a long time, comparable to or greater than the accumulation interval (the target’s angle remains unchanged), the analogue / 3 / is also characterized by low information content of the signals α _x , α _at .

Closest to the proposed method is / 4 /, in which, in addition to the main signals α _x , α _y , the MP generates auxiliary signals β _x and β _y ). In work / 5 /, the physical content of the signals β _{x (y)} was revealed - their proportionality to the normalized derivatives of the amplitude distribution A (x, y, z) of the received signal:

The pairs of signals {α _x , β _x } and {α _y , β _y } in each of the direction finding planes are called complex signal MP.

The disadvantage of the prototype is the low information content of the MP signals when exposed to angular noise of the target.

The aim of the invention is to partially neutralize the negative effect of angular noise of the target on the path of approach of the rocket with the target.

To achieve the goal in the prototype method, which consists in isolating in the XZ (YZ) direction-finding plane the main signal α _{x (y)} proportional to the derivative ∂φ / ∂x (∂у) of the phase distribution φ (x, у, z) taken signal, auxiliary signal β _{x (y)} proportional to the normalized derivative (1 / A) ∂A / ∂x (∂y) of the amplitude distribution A (x, y, z) of the received signal, the amplitude of the main signal α _{x is} additionally adjusted _y) according to the law K _{x (y)} α _{x (y)} , the signal K _{x ( y)} α _{x (y)} , and the total signal η _{x (y)} = β _{x (y)} + K _{x (y)} α _{x (y)} is selected as the signal for controlling the trajectory of the rocket, and the coefficient K _{x (y)} is selected decreasing function of the auxiliary signal module | β _{x (y)} |.

The drawing shows a functional diagram of the GOS, representing one of the possible options for implementing the proposed method in the same direction finding plane (XZ). It is indicated here: 1 - amplitude-type MP antenna; 2 - total-difference antenna converter; 3 - antenna control system; 4, 5 - receiver with an amplifier of intermediate frequency (UPCH); 6 - block automatic gain control; 7 - phase shifter on π / 2; 8, 9 - phase detector; 10 - autopilot; 11 - adjustable attenuator; 12 is a control diagram; 13 is a diagram of a module allocation; 14 - adder.

The MP circuit included in the GOS in the drawing differs from the original MP functional diagram that implements the prototype method / 6 /, by the presence of additional elements 11, 12, 13 and 14, the presence of communication 8-14 and, in addition, in the prototype circuit, the output of element 9 directly connected to the input of element 10.

It should be noted that relations (1), (2) remain true not only for the implementation of the GOS with MP shown in the drawing, but also for other options for constructing the MP, because irrespective of the type of magnetic field, the local characteristics of the amplitude-phase distribution of the received signal within the aperture of the magnetic field antenna are rather accurately approximated by an inhomogeneous plane wave, which is completely characterized by the local derivatives indicated in (1), (2) (in addition to amplitude A). Note that the physical content of the signal β _{x (y)} / 5 / resulting from (2) is fundamental for understanding the essence of the proposed method.

The justification of the proposed method is convenient to start with a review of the main results of a theoretical analysis of the properties of signals reflected by objects of complex shape, which are almost all real goals. In addition to the physical content of complex MP signals, these results are as follows (only one direction-finding plane is considered) / 5; 7 /:

a) the average value of the signal α coincides with the direction to the target EC α ₀ , i.e. α = α ₀ + ξ, where ξ is the angular deviation of the target FC from the target EC (angular noise), the average value of which is zero: <ξ> = 0;

b) the average value of the signal β is equal to zero: <β> = 0;

c) the absence of correlation between the noise component ξ of signal α and signal β: in 50% of cases, the signs of ξ and β coincide, and in the other 50% of cases they are opposite. At the same time, there is a strong correlation between their absolute values | ξ | and | β |: the more | β |, the more | ξ | and vice versa;

d) there is a strong correlation of the amplitude A of the received signal with the absolute values | ξ | and | β |, i.e. almost always an increase in | ξ | and | β | accompanied by a decrease in the amplitude of the reflected signal;

d) the coincidence of the variances of the signals α and β in each of the direction finding planes XZ or YZ.

These results allow us to draw the following practical conclusion: for large values of | β | the information content of the signal α in the sense of its coincidence with α ₀ drops sharply and the signal α cannot be used either to control the MP antenna or to control the autopilot of the rocket. In this regard, the problem arises of generating new, non-α, control signals of the MP antenna and autopilot at time intervals when large spikes in the absolute value of the signal | β | are observed.

In the proposed method, the task of controlling the antenna of the MP is solved as follows. With emissions | β | it is advisable not to swing the MF antenna of the random component ξ, but to keep it in the same position that existed before the release of | β | and wait for the moment when | β |, and therefore | ξ | will not become sufficiently small (less than the value corresponding to the half-width of the direction-finding characteristic of the magnetic field) and α will not become close to α ₀ . In the circuit, this is achieved by adjusting the amplitude of the signal α using elements 11 and 12, as a result of which the output signal of the phase detector 9 becomes equal to Kα, where K is the transmission coefficient of element 11. The resulting adjustment characteristic (PX) of the pair of elements 11, 12 is the dependence of K on | β | - depends on the PX of element 11 and the transfer characteristic of element 12 and is selected such that K is a monotonically decreasing function of the absolute value | β |, and when | β | = 0, K takes its maximum value equal to unity. In one of the simplest versions, the resulting PX has the form K (| β |) = exp {- | β |}. The best form of the dependence of K on | β | can be found by modeling the proposed homing system. A pair of elements 11, 12 performs the same function as a pair 4, 6 or a pair 5, 6, and can be implemented using well-known circuit solutions traditional for automatic gain control systems / 8, p. 220-227 /. In particular, element 11 can be made in the form of a passive attenuator or, as elements 4 and 5, in the form of an amplifier. In the latter case, in order to restore the equality of the dispersions of the output signals 8 and 9 (when the connection between the elements 12 and 13 is broken), the attenuator must be switched on at the output of the amplifier, the attenuation of which must coincide with the maximum gain of this amplifier. The control circuit 12 performs the function of non-linear transformation of the input quantity | β |. By selecting its non-linear transfer characteristic, the resulting PX K (| β |) of pair 11, 12 can be reduced to the desired form. Element 12 can be implemented on the basis of an operational amplifier with non-linear resistance included in it. To answer the main question: how to generate an autopilot control signal in a situation of large emissions of | β | - it is necessary to use the obvious recommendation - to minimize the time interval for the existence of large emissions | ξ | and | β |. Taking into account the physical interpretation (2) of the signal β and the output "g", it seems appropriate to use the signal Kα as the main component in the rocket autopilot control signal, and the auxiliary signal β as the additional component, which, although it does not contain information about the angular position of the target, but it is useful for the process of pointing the missile at the target. Exposure to the autopilot of the total signal η = β + Kα leads to normal autopilot control by the main signal α for small values of | β | ≈0, when K≈1, and, at the same time, for large emissions | β | the rocket will change its trajectory in the direction of increasing the amplitude A of the received signal and, thus, will tend to get into the region of large values of the amplitude A in the shortest time and, therefore, the correct measurements of the angle α ₀ . Of course, with large emissions | β | the rocket can also be controlled by the signal α, which in the end will move it to the region of correct angular measurements, but this will happen in a longer time interval and along a longer path, because according to the conclusion “to”, the target FC is only in half the cases located in the region with a higher amplitude A.

Thus, as a result of the refusal to pursue the FC missile with a target “wandering” far beyond the geometrical dimensions of the target itself and the transition to a regular shift of the missile trajectory towards an increase in the amplitude of the received signal, the missile trajectory acquires a smoother appearance, thereby reducing missile misses.

Information sources

1. Leonov A.I., Fomichev K.I. Monopulse radar. - M .: Radio and communications, 1984

2. The basics of radio control. Ed. V.A. Weitel and V.N.Tipugin. M .: "Sov. Radio", 1973

3. USSR copyright certificate No. 854161, cl. G01S 13/34, 1981

4. Sherman. Comprehensive estimates of the angular coordinates of unsolvable targets when using monopulse radars. - Foreign Radio Electronics, 1972, No. 1.

5. Bakulev P.A., Simonov V.I. The possibility of using estimates of the complex error signal in monopulse radars. - Statistical modeling and optimal integration of autonomous measuring instruments for navigation parameters of flight. Thematic collection of scientific works of the Moscow Aviation Institute. - M .: MAI, 1981

6. Simonov V.I. Recognition of spatially extended objects according to the goniometer channel of monopulse devices. - Adaptive information processing devices in radar and radio navigation systems. Thematic collection of scientific works of the Moscow Aviation Institute. - M .: MAI, 1984

7. Stager E.A., Chaevsky E.V. Wave scattering on bodies of complex shape. - M .: "Sov. Radio", 1974

8. Radio receivers. Ed. A.G. Zyuko. M .: "Communication", 1975

Claims (1)

The method of generating control signals in monopulse homing heads, which consists in isolating in the direction-finding plane XZ (YZ) the main signal α _{x (y)} proportional to the derivative ∂φ / ∂х (∂у) of the phase distribution φ (x, у, z) received signal, auxiliary signal β _{x (y)} proportional to the normalized derivative (1 / A) ∂A / ∂x (∂y) of the amplitude distribution A (x, y, z) of the received signal, characterized in that the amplitude of the main signal α _{x (y)} according to the law K _{x (y)} α _{x (y)} , as the signal of controlling the antenna of the monopulse direction finder selects the signal K _{x (y)} α _{x (y)} , and as the control signal of the rocket path selects the total signal η _{x (y)} = β _{x (y)} + K _{x (y)} α _{x (y )} , and the coefficient K _{x (y)} is selected by a monotonically decreasing function of the auxiliary signal module | β _{x (y)} |.