GB2231128A

GB2231128A - Activating a missile

Info

Publication number: GB2231128A
Application number: GB8715880A
Authority: GB
Inventors: Rainer Berthold
Original assignee: Brown Boveri und Cie AG Germany; BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1986-07-18
Filing date: 1987-07-06
Publication date: 1990-11-07
Also published as: DE3624348A1; NL8701714A; FR2642832A1; GB8715880D0; IT1228420B; IT8721314A0; SE8702900D0

Abstract

After the launch of a flying station. e.g. a missile, its distance from a base station, e.g. a tank, is continuously detected and compared with a stored distance between the base station and the target; if the two values coincide, the flying station is activated. The invention compensates for the perturbing effect of base station and target movements by determining the velocities of these at the base station and adjusting the frequency the microwave signal which is transmitted to the flying station for generation of a Doppler signal. A subtraction circuit forms the difference between the target velocity and the tank velocity. The product of the frequency of the generator on the launch of the flying station (50) and the output signal of the subtraction circuit is formed by means of a multiplier. From the voltage signal of the multiplier and a voltage signal proportional to the speed of light a divider generates a voltage signal with which the frequency of the generator is controlled.

Description

Method of and circuit for activating station.

This invention relates to a method according to the preamble of claim 1 and to a circuit for performing the method.

A method and circuit of this kind are used mainly for defence.

For defence purposes the method can, for example, be used in tanks from which missiles with electronic fuses are launched. With tanks there is only an extremely low probability of small targets being hit with the main weapon outside the direct close-up zone. For this reason, a tank of this kind fires fragmentation missiles which are detonated near the target. The hit probability is increased by the used of such fragmentation missiles. Before each missile is launched the fuse detonation time is adjusted. Various external influences to which the missile is exposed cause the missile speed to vary, so that the detonation time must be corrected before reaching the target so that the missile is not activated until it is as close as possible to the target.

Patent application P 33 08 859.4 discloses a method and a circuit for activating a flying station launched from a base station. The base station may be a tank and the flying station a missile. In this method, the distance between the base station and the target is determined and stored before the flying station is launched. After the launch of the flying station its distance from the base station is continuously detected and compared with the stored distance between the base station and the target. If the two values coincided the flying station is activated. A generator for generating electromagnetic waves is provided in the base station in order to perform the method.These electromagnetic waves are received in the flying station and, together with electromagnetic waves of the same frequency generated there, they are fed to a mixer by means of which a Doppler signal is separated and fed to an integrator. A disadvantage in this connection, however, is that the signal transmitted by the base station is falsified if the base station itself moves. A further falsification of these transmitted signals is produced if the target at which the flying station is aimed is also in movement.

The object of the invention is to provide a method and circuit by means of which these falsifying influences on the signals are precluded.

This problem is solved by the features of claim 1.

A circuit for performing the method is disclosed in claim 2.

By the use of the method according to the invention the flying station receives only signals which simulate to it that both the base station and the target are in a stationary condition. Exclusion of the interfering signal variations results in the flying station receiving only a signal which exactly indicates the distance between it and the base station without any correction having to be made in the flying station. At the same time, the signal is so devised that it transmits the distance between the base station and the target to the flying station as if the target were also stationary. This means that the distance determined between the base station and the target before the launch of the flying station and stored in the latter need not be changed during flight.

Further features essential to the invention are characterised in the sub-claims.

The invention is explained below with reference to drawings wherein: Figure 1 is a diagram of a base station.

Figure 2 is the circuit according to the invention disposed in the base station.

Figure 3 shows the circuit in the flying station.

The base station shown in Figure 1 is constructed as a tank. The essential components that the latter contains are a generator 2, a circuit 3 for changing the generator frequency, a velocity measuring means 4, a distance measuring means 5, an angle measuring means 6 for determining the deflection of the tank barrel 1R from the horizontal, a flying station 50 in the form of a missile adapted to be launched from the base station 1, and an adjusting means for adjusting the distance fuse (not shown) disposed in the missile 50.

The tank also has a transmitter and an antenna for transmitting the signals generated by the generator 2 (not shown here). The tank components shown in Figure 1 are indicated only diagramatically.

Generator 2 generates high-frequency electro-magnetic waves, preferably microwaves. Circuit 3 is required to enable the CW signals generated by the generator 2 to be changed. The circuit 3 so changes these signals that the flying station 50 launched from the tank is always transmitted the in formation as if it were coming from a stationary tank, even if the latter is in motion.

Circuit 3 is shown in detail in Figure 2. The velocity measuring means 4, distance measuring means 5 and angle measuring means 6 are directly connected to this circuit 3. They are also shown in figure 2. The velocity of the tank 1 is determined by the velocity measuring means 4, more particularly a tachometer. The velocity measuring means 4 is connected to a converter 10 whose output is connected to a first multiplier 11. Multiplier 11 receives the voltage signal of a converter 12 whose input is connected to the angle measuring means 6. The distance between the tank 1 and target (not shown here) is determined by means of the distance measuring means 5. The latter is preferably constructed as a laser range finder.It is connected to a circuit 5A for determining the vectorial velocity of the target = rVZI.COS i)Circuit 5A is a state-of- the-art arrangement which determines the target velocity from the range as determined and its variation in time, or is a laser Doppler velocity measuring means. The output signal of circuit 5A is connected to a converter 13 which generates a voltage signal UZ from the vectorial velocity signal. The converter 13 is connected to the input of a subtraction circuit 14, whose second signal input is connected to the multiplier 11. The output of subtraction circuit 14 is connected to the first input of a second multiplier 15, whose second input is connected to a memory 16. By means of a univibrator 17 the information contained in the memory 16 is transmitted to the multiplier 15. The univibrator 17 is triggered by the signal at the output of the subtraction circuit 14 and opens the output of memory 16 when the subtraction operation in progress is completed. The information input of memory 16 is connected to a third converter 18.

It is connected to the output of generator 2 and generates a voltage signal UF from the output signal of the generator. The output of the multiplier 15 is connected to a divider 19 connected to a set-value selector 20. By means of the voltage signal UG obtained at the output of the divider 19 the frequency of the voltage-controlled generator 2 is changed.

Figure 3 shows in detail the circuit in the station 50, which can be launched from the base station 1. A superhet receiver is Disposed inside the station 50 which is constructed -as a missile. The superhet receiver, for example, comprises an antenna 52, a mixer 53, a generator 54 for generating electromagnetic waves, frequency converters 55 and 56, analog switches 57, 58 and 59, a phase detector 60, a filter 61 and a filter 62. In the exemplified embodiment illustrated here the generator used is a VC0 54 which generates electromagnetic waves in the HF range. It will readily be seen that the phase detector 60, filter 61 and oscillator 54 form a phase locked loop (PLL). The microwaves coming from the antenna 52 must be matched to the phase locking circuit in the frequency converters 55 and 56.The antenna 52 of the missile 50 and the generator 54 are so connected to a mixer 53 that their output signals are fed to the mixer 53 (partly after frequency conversion). A filter 62 and an analog switch 59 are connected to the output 53A of the mixer 53.

Just before the missile 50 is launched the phase locked loop provides synchronisation between the generator 2 of the tank 1 and The generator 54 of the station 50.

The analog switches 57 to 59 ensure that no signals are fed to the integrator (counter) 64 before launch and during synchronisation.

They are switched by the acceleration converter 63.

The output 53A of mixer 53 is connected to a counter 64 serving as an integrator. A comparator 65 is connected to the output 64A of the integrator 64. The second input of comparator 65 is connected to a memory 67 which is connected to a programming means 67 via which information data is written into the memory 66 by radio. The output 65A of comparator 65 is connected to a trigger 67 used to detonate the missile 50.

The method according to the invention and the operation of the circuit will be explained below: The fuse of the missile 50 launched from the tank 1 is required to be activated as close as possible to the target to obtain optimum hit reliability. To this end, generator 2 generates microwaves emitted in the direction of missile 50. After the latter has been launched the microwaves generated by generator 2 are received by means of antenna 52 and fed to the mixer 53. At the same time mixer 53 receives the microwaves from the oscillator 54 after conversion in the frequency converter 56. The mixer 53 and the filter 62 are so constructed that they generate Doppler signals from the microwaves fed to the them from the antenna 52 and the oscillator 54. - The switches 57 and 58 are open in these conditions. Switch 59 is closed.If the tank is stationary during launch of the missile 50 and during its flight, and if the same applies to the target aimed at, the Doppler signal obtained at the output 62 of filter 62 is directly proportional to the velocity of the missile 50. If the pulses of this signal are integrated by means of integrator 64, the value of the signal obtained at the output 64A of integrator 64 is an exact index of the distance covered by the missile 50. The output signal of integrator 64 is compared with the contents of memory 66. Just before the missile 50 is launched the distance existing at that time between the tank and the target is written into the memory 66 via the antennas 68 and 69 with the aid of the programming means 67. If the comparator 65 finds that the two signals fed to it are equal, it actuates the trigger 67.

If the tank 1 from which the missile 50 is launched is not stationary, contrary to what was assumed above, but has a certain velocity Vp, the signal emitted by the tank generator 2 must be adapted to this state of affairs. Assuming that the tank and the target are at rest, the missile 50 receives a microwave signal at the frequency f = f'. (1- (We/C)).

fq stands for the frequency of the microwave signal generated by the generator 2 and VG is the velocity of the missile 50.

Assuming that the tank 1 is not stationary but has 8 velocity VPl 0, the missile 50 receives a signal of frequency: fe = fs (1 -(VG - Vp) /C) This equation is identical to: f + #f = fs (1 - (VG - Vp)/c) If the influence of the tank velocity is to be compensated in the frequency received by the missile 50, the frequency fF of the generator 2 must be reduced until f is zero.The last equation can also be represented as follows: (f + # f) = (fs - # fs) . (VG - Vp)/c) If, in this equation, f is allowed to go to zero and if the equation is resolved in accordance with f@@ the following equation applies: 6 f3 o fas Vp C (1 -(VG - Vp)/c) Since the quotient: VG - Vp : c is very much less than 1, the following applies for iX #fs = fs . Vp c This # f represents the frequency change by which the frequency generator 2 must be changed to eliminate the velocity of the tank Vp from the signal transmitted by the tank 1 to the missile 50.

If the missile 50 is not launched in such a way that the direction of missile flight is situated on an extension of the direction of movement of the tank, this must also be allowed for in the above equation. The velocity must then be written: Vp . COS # h The following equation then applies to Af: f3 = fs . Vp . COs C The above equation assumes that the target at which the missile 50 is aimed is at rest. If that is not the case, the target velocity must also be taken into account. The equation then applicable to #f@ is then: # fs = fs (Vp . COS #h - Vz cos # ) C Vz stands for the velocity of the triggered target (not shown here).

is the angle between the tank gun barrel and the direction of target movement.

The circuit 3 shown in Figure 2 is provided to generate the voltage signal required for the change of the generator frequency f. With the velocity measuring means 4 the tank velocity is measured, the measurement signal is converted by converter 10 into a voltage signal UP and fed to the multiplier 11. The velocity of the target is determined by the distance measuring means 5 and circuit 5a.

Converter 13 generates the voltage signal UZ. The angle of deflection Sh of the tank barrel 1R in the horizontal is detected by the angle measuring means 6. From this measurement a voltage signal UW is generated and fed to the second input of the multiplier 11. If the deflection of the tank barrel 1R from the horizontal is 0 degrees, the value 1 is obtained at the input of multiplier 11. The output signal of multiplier 11 then corresponds to its input signal, i.e. UP = UM. The voltage signals UZ and UM obtained at the output of the converter 13 and at the output of the first multiplier 11 are fed to the two inputs of the subtraction circuit 14.If the target at which the missile 50 is directed is stationary, the voltage signal at the output of the circuit 14 is identical to the output signal of the multiplier 11. When the missile 50 is launched the frequency of the generator 2 is converted to a voltage signal UF by means of convertor 18 and fed to a memory 16. The contents of the latter can be fed to the second multiplier 15. If the signal UD is obtained at the output of subtraction circuit 14, the univibrator 17 is triggered as a result and causes the memory 16 to dellver its contents to the second multiplier 15, to which the voltage signal UD of subtraction circuit 14 is also fed. From the voltage signal UD and the voltage signal UF resulting from the frequency of the generator 2 the multiplier 15 forms the product UM and delivers it to the input of the divider 19.A voltage signal UC proportional to the speed of light is fed to the divider 19 by the set-value selector 20. From the voltage signal UM and UC the divider 19 forms the quotient representing the voltage signal UG. This signal is fed to the control, input of generator 2. It is proportional to the frequency variation #fs by which the frequency f5 of the generator 2 must be changed so that the signal transmitted to the missile 50 simulates the stationary state of the tank and target. The signal generated by generator 2 is transmitted via transmission amplifier 21 and antenna 22.To prevent interference with missile 50 by microwave beams of frequency f reflected from the ground or somewhere else the transmission antenna 22 on the tank and the reception antenna 52 in the missile are constructed as anticlockwise or clockwise rotating circularly polarised antennas. The antenna 22 of tank 1 can, for example, be installed near the distance measuring means 5 on the stabilisation platform. If antenna 22 is installed at or on the tank barrel 1R, the barrel recoil velocity VÇR must be measured and be taken into account in accordance with the above considerations in connection with the formation of the voltage signal UG controlling the generator 2. In that case circuit 3 must be expanded by at least one measuring device for VR and one frequency/voltage converter (not shown).

Claims

1. A method of activitating a flying station (50) launched from a stationary or a moving base station (1) to a target and which1 when it reaches the target, is activated by the signals transmitted by the base station (1), characterised in that the moving base station (1) generates and transmits only signals of the kind by which the flying station (50) is given the information that the base station (1) and the target are at rest even when the base station and/or the target are in movement.

2. A circuit for performing the method according to claim 1, characterised in that that to form the difference between the velocities of the target and of the base station (1) a subtraction circuit (14) is provided1 whose output is connected to a second multiplier (15), to the second signal input of which there is connected a memory (16) which stores the instantaneous frequency (f)of a generator (2), the output of the second multiplier (15) is connected to a divider (19) connected to a set-value selector (20) in which a voltage signal UC proportional to the speed of light is stored1 and the voltage signal UG generated by the divider (19) is fed to the generator (2).

3. A circuit according to claim 2, characterised in that a velocity measuring means (4) is provided to determine the tank velocity and is followed by a first converter (10) to form a voltgage signal (UP) proportional to the tank velocity (Vp).

4. A circuit according to clairn 2 or 3, characterised in that an angle measuring means (6) is provided to determine the horizontal deflection A of the tank barrel (1R), the output signal thereof being fed to a second converter (12), the output of the second converter (12) is connected to a first multiplier (11) whose second input is connected to the first converter (10).

5. A circuit according to any one of claims 2 to 4, characterised in that a distance measuring means (5) is connected to a circuit (5A) for determining the velocity of a moving target and the velocity signal is fed to a third converter (13), the outputs of the third converter (13) and of the first multiplier (11) are connected to the signal inputs of the subtraction circuit (14).

6. A circuit according to any one of claims 2 to 5, characterised in that a fourth converter (18) is connected to a signal input of the generator (2) and its voltage signal UF is fed to a memory (16), the output of the memory (16) is connected to the second multiplier (15) and a univibrator (17) is connected to the control input of the memory (16), the voltage signal (UD) generated by the subtraction circuit (14) being obtained at the signal input of the univibrator (17).

7. A circuit according to any one of claims i to 6 characterised in that at least one other velocity measuring means and a frequency/voltage converter are provided to allow for the barrel recoil velocity VR 8. A circuit according to any one of claims 1 two~7, characterised in that at least the reception antenna (52) and the transmission antenna (22) are constructed as anti-clockwise or clockwise rotating circularly polarised antennas.

Amendments to the claims have been filed as follows 1. A method of activating a flying station launched from a base station to a target and which, when it reaches the target, is activated by signals transmitted by the base station, in which method the base station transmits an oscillatory signal to the flying station which is compared in the latter with a locally generated oscillatory signal to generate a Doppler signal, The Doppler signal is integrated at the flying station, and the integrated value is compared with a target distance previously stored at the flying station; the base station determines its own velocity of movement and adjusts the frequency of its transmitted oscillatory signal in such a manner that the signal received at the flying station is compensated for the perturbing effect on the Doppler signal of base station movement; and the base station determines the velocity of movement of the target and adjusts the frequency of its transmitted oscillatory signal in such a manner that the signal received at the flying station is compensated for the perturbing effect on the Doppler signal of target movement.

2. A circuit for performing the method according to claim 1; comprising, at the base station, on oscillatory signal generator of variable frequency, means for measuring the velocity of the base station, means for measuring the velocity of the target, a subtraction circuit having inputs connected to receive respective signals representing the target and base station velocities, to form the difference between the velocities of the target and of the base station, the subs traction circuit output being connected to a multiplier to the second signal input of which there is connected a memory which stores the instantaneous frequency of the signal generator, the output of the multiplier being connected to a divider connected to a set-value selector in which a voltage signal UC proportional to the speed of light is stored, and the voltage signal UG generated by the divider is fed to the generator for adjusting the generator frequency.

3. A circuit according to claim 2, characterised in that a velocity measuring means is provided to determine the base station velocity and is followed by a first converter to form a voltage signal (UP) proportional to the base station velocity.

4. A circuit according to claim 3, for use in a tank, characterised in that an angle measuring means is provided to determine the horizontal deflection Çh of the tank barrel, the output signal thereof being fed to a second converter, the output of the second converter is connected to a further multiplier whose second input is connected to the first converter.

5. A circuit according to claim 4, characterised in that a target distance measuring means is connected to a circuit for determining the velocity of a moving target and the target velocity signal is fed to a third converter, the outputs of the third converter and of the further multiplier are connected to the signal inputs of the subs tracti on circuit.

6. A circuit according to any one of claims 2 to 5, characterised in that a converter is connected to a signal output of the generator and its voltage signal UF is fed to the memory, the output of the memory is connected to the first-mentioned multiplier and a univibrator is connected to the control input of the memory for releasing the contents of the memory, the voltage signal (UD) generated by the subtraction circuit being applied to the signal input of the univibrator.

7. A circuit according to any one of claims 2 to 6 characterised in that at least one other velocity measuring means and a frequency/voltage converter are provided to allow for the barrel recoil velocity VR.

8. A circuit according to any one of claims 2 to 7, characterised in that at least the signal transmission antenna of the base station is an anti-clockwise or clockwise rotating circularly polarised antenna.

9. Apparatus for activating a missile, substantially as described with reference to the accompanying drawings.