DE3201069C1 - Doppler-radar proximity fuse preferably for anti-aircraft missile - Google Patents

Abstract

Air-speed-dependent reference signals are applied to a voltage-controlled phase comparator (6) via a Doppler signal amplitude threshold comparator (5). An AND gate (7) triggers a detonation signal via a flip-flop (12) and another AND gate (13) whose second input is supplied by a NOR gate (8) from the same three-bit register (11). Detonation is instigated only when the Doppler echo amplitude exceeds a predetermined level (with interruptions of less than 3 ms) continuously, a time-of-flight-dependent "detonation Doppler frequency" is not attained e.,g. three times in succession.

Description

The invention relates to a proximity fuse according to the preamble of claim 1. comes as a target preferably a destination.

The invention has for its object a generic Proximity detonators specify the cheaper and smaller than ago conventional proximity fuse. He won't be a direct hit aims, then the detonation should take place in such a way that a possible large proportion of the fragments hits the target flying past.

With an already proposed (P 24 48 898.0) Doppler proximity ignition fuse, which is based on an ignition criterion determining the ignition criterion  law works, the one that occurs shortly after the target is acquired maximum Doppler frequency (i.e. the detection frequency far from Target, therefore called Farabdoppler frequency) measured and from it the ignition frequency and thus the optimum according to the following equation Ignition point calculated:

f _ignition = f _Dmaxcos ϕ _Z
f _Ignition = Doppler frequency at the optimal ignition point
f _Dmax = = wide Doppler frequency
v _r = V _G + V _target = relative speed
V _G = bullet speed
V _target = target speed
λ = wavelength of the transmission frequency
ϕ _Z = arc tan
v _Sp = splinter speed

Falls below the current double when approaching the target the calculated ignition frequency, then the detonation takes place.

This system is arranged as a coupled control loop executed.  

The above-mentioned Doppler signal is the reference fre quenzgenerator, the interference barrier and the phase comparator fed simultaneously. The reference frequency generator is with a additional input of the interference barrier interconnected. The end This interference barrier is applied to the phase comparator couples.

Disadvantages of this already proposed igniter are for small caliber projectiles, in particular points:

• 1. To determine the ignition frequency, the wide-spread doubler frequency are measured, this requires a large one Transmit power.
• 2. The antenna may be used for the far Doppler frequency measurement have no zero in the direction of flight.
• 3. The known system is too expensive.

These requirements require one for small-caliber projectiles mostly unacceptable space requirement for the detonator.

The invention is based on the premise that when using relatively small-caliber projectiles (z. B. 35 mm ⌀) a proximity ignition in most applications is only effective if the projectile flies no more than a few meters past the target. With this small permissible hit error, according to the basic idea on which the invention is based, the target speed V _target can be neglected when determining the ignition criterion, that is to say the optimum ignition frequency, so that the wide-frequency Doppler frequency no longer has to be measured. Nevertheless, in this case there is a sufficient triggering. This omission of the measurement of the wide-frequency Doppler frequency enables a greatly reduced construction volume in the case of the fuse according to the invention, for example because of the reduction in the necessary transmission power, which has a favorable volume and weight effect on the power supply (battery).

The invention can be found in claim 1. The sub Claims contain advantageous refinements and further formations of the invention.

It is very advantageous in the implementation of the invention to provide a time function generator for the generator of the first airspeed-dependent reference signal, which controls a voltage-controlled, digitally operating phase comparator in such a way that the "detection" or "ignition Doppler frequency" which changes as a result of the projectile speed changing one poses. In practice, approximately 80% of the wide-range Doppler frequency f _{Dmax of} a standing target are expediently chosen as the detection Doppler frequency. This curve is labeled f _{D (max-20%)} in Figure 1.

In the case of the invention, the ignition only takes place in the example then, when:

• 1. From detection of the target to ignition, the ampli tude of the Doppler signal a predetermined value (except for drops in amplitude <3 ms) steps.
• 2. The "acquisition double" specified by the function generator ler frequency "is exceeded; it is flight time dependent.
• 3. The "acquisition Doppler frequency" in succession zend z. B. 4 half waves is present.
• 4. The "Zünddopplerfre quenz "consecutively e.g. 3 times under is taken.

In the case of the invention, faults (e.g. ECM) which Ignition criteria mentioned 1st to 4th consecutively not meet all ignition criteria in a further failure attempt compliance (amplitude monitoring).

In the case of the invention, the voltage-controlled measures in the example Phase comparator amplifies the "detection Doppler frequency" dependent (small amplitude in the far range) and the "ignition fre quenz "depending on the amplitude (large amplitude in the near range) what ECM measures difficult.

The voltage control can advantageously be used in the invention Measure the phase comparator every half-wave. He will be with everyone Half wave restarted. This means that there is no phase error.  

The ignition frequency f _ignition results from the ignition law defined in the igniter when it was designed.

The actual frequency f _Dist is the currently measurable Doppler frequency; This means that it can only be evaluated from a technical point of view only when it exceeds the 80% limit, ie f _{D (max-20%)} and becomes practically equal to the ignition airspeed-dependent f _Dmax . In picture 1 you can see in the upper part in the range of a sub-interval of the detonator flight time between 6 and 7 s the detonator working time from its launch, which is shown enlarged between 6.5 and 6.7 s in the lower part of picture 1. The ignition is triggered when the actual frequency f at the time Z falls below the 80% limit f _{D (max 20%),} the ignition frequency reaches _Dzünd.

The embodiment of the invention according to Figures 2 to 5 will now be described in more detail.

A transmit / receive stage 1 emits electromagnetic vibrations via a transmit / receive antenna 2 and receives reflected vibrations via the same, which, after frequency conversion and after amplification, enter a selective amplifier 3 and 4 .

They are then input signals of a first amplitude comparator 5 , which checks the amplitude of the Doppler signal for exceeding a first threshold value and gives comparison signals to a voltage-controlled phase comparator 6 during the exceeding intervals. These signal sequences can be found in the pulse diagram in the lower part of Figure 3. This phase comparator compares these aforementioned comparison signals with the airspeed-dependent reference signals.

In the upper part of Figure 3, a particularly advantageous scarf device for the realization of a comparator, for example, can be used as a phase comparator 6 in the subject of the invention. This embodiment of the comparator has at its input for the airspeed-dependent reference signals, which are referred to in FIG. 3 as control voltage, a voltage-controlled resistor N1, the resistance value of which, with reference signals which decrease in amplitude with the airspeed, as is assumed in FIG speed of the voltage applied to it decreases. This voltage-controlled resistor also includes an ohmic resistor R12 and one side of a current mirror circuit composed of the semiconductor components P1 and P2. At the series connection of this side of the current mirror circuit, the semiconductor device N1 and the ohmic resistor R12 is a fixed voltage source V _DD . The other side of the current mirror circuit is connected in series with a capacitor C via a changeover switch, which is formed, for example, by the semiconductor arrangement P3, N2. This switch is controlled by the output signal f _{D of} the first amplitude comparator 5 , in such a way that during the exceeding intervals, during which the amplitude comparator outputs comparison signals to the phase comparator, the capacitor C can be charged and that during the interval breaks the capacitor via the switch N2, P3 is discharged again. A second amplitude comparator, for example consisting of the semiconductor elements P4 and N3, then gives a signal to a first logic operation, in the example an AND circuit 7 , and to a second logic operation, in the example a NOR circuit 8 if the capacitor voltage U _{C of} the capacitor C exceeds a second predetermined threshold value (gate threshold). The output signal ZI then has the pulse shape of the lower line of the picture 3. The dashed voltage profiles result from a small control voltage, ie at the beginning of the flight phase, and the dotted voltage profiles result from a large control voltage.

It is expedient to provide a common generator 9 for the first and the second reference signal, which are fed to the phase comparator in succession, which generator always generates the first reference signal and is connected to the phase comparator 6 via a resistance network 10 . In the example, this resistance network in the signal channel, which lies between the generator 9 and the comparator 6 , during the time in which the comparator 6 is supplied with the first reference signal, has no attenuation or only a basic attenuation, while supplying the second reference signal on the comparator 6 in the network, an appropriate attenuation in the signal channel is switched on, so that the generator circuit, consisting of generator 9 and network 10 , after switching the network instead of the first gives the second reference signal to the phase comparator 6 .

To the logic operations 7 and 8 , a 3-bit register 11 is still functionally associated in the example. The first logic operation 7 releases in the example of a memory in the form of a flip-flop 12, the ignition by applying one input of an AND circuit 13 as soon as a first predetermined plurality, for example 3 times, the frequency of the Doppler signal is that of the exceeds the first reference signal. The second input of the AND circuit 13 is then acted upon by the second logic link 8 as soon as, after the ignition has been released by the logic link 7 , a second predetermined plurality in succession the frequency of the Doppler signal falls below that of the second airspeed-dependent reference signal.

When both inputs of the AND circuit 13 are acted upon, the same outputs a signal to an OR circuit 14 , which controls a thyristor 15 for passage and switches the battery voltage U of the supply source through to the actual ignition means 16 .

With 17 an impact sensor and with 18 a self-supply circuit are designated, which are known per se and connected to the remaining inputs of the OR circuit 14 . Finally, a device for system activation 19 is provided, which enables the ignition release signal to be stored in the memory 12 only after the safety time τ 1 calculated by the detonator launch to achieve adequate fore-pipe safety. To increase occupational safety, in the exemplary embodiment of the invention according to FIG. 2, furthermore, an erasing device 20 is provided for the memory 12 , which erases the same initially and whenever the first amplitude comparator 5 has not given any comparison signals to the phase comparator 6 for a predetermined time and which resets register 11 under the same condition. This quenching device 20 preferably consists of an integrator, which is additionally located on the input side at the output of the first amplitude comparator 5 .

The mode of operation is explained in more detail below with reference to Figures 4 and 5 :
After the launch, the battery activates. The capacitor C7 is charged via R16. Until reaching the log. 1 on gate IS11, flip-flops IS 8, 9, 10 and 17 are reset via gate IS12 and gate IS13 (front pipe security).

If, during target acquisition, the selected and amplified Doppler signal exceeds an amplitude threshold specified in the comparator (any frequency in the evaluation range) for longer than 0.5 ms, the integrator (Gr1 - R14 - C6 - gate IS11) outputs the shift register via IS12, IS13 IS 8, 9, 10 and the flip-flop 17 free. The comparator consists of the two wired linear IC's IS1 and IS2, the gates IS3 to IS6 and the D flip-flop IS7. The subject of patent application P 24 51 729.1 is hereby comparable. The voltage-controlled phase comparator compares the simply rectified double frequency with the frequency f _D controlled by the function generator _{(max. 20%)} . The function generator consists of R8, C4 and R9. The voltage drop U _R9 , which changes over time, controls the P-MOS transistor Ts3. The phase comparator control voltage for the "detection Doppler frequency" is set at the resistor R10 and the control voltage for the "ignition Doppler frequency" is set at the resistor R11 (see Figure 1 f _{D (max-20%)} and f _{D Zünd} ).

The FF IS17, which was reset during fore-pipe safety, has closed the C-MOS switch S1 (detection Doppler frequency). The control voltage passes through switch S1 to the N-MOS transistor Ts4, which together with R12 forms a source follower. If the resistance of R is at least one order of magnitude above the forward resistance of Ts4, then the current through R12 depends linearly on the control voltage. This current also flows through P-MOS transistor Ts5, which together with P-MOS transistor Ts6 forms a current mirror. The current mirror ensures that the current through Ts6 is independent of the drain-source voltage at Ts6. It is approximately equal to the current through Ts5. This is the case as long as Ts6 is operated in the saturation range. This requirement is fulfilled in the circuit shown (see Figure 3).

As long as the Doppler signal does not exceed the comparator threshold steps (no useful signal), is at the comparator output (gate IS3) log. 1. The inverter Ts1 / Ts2 inverts the signal. about C-MOS switch S3 the signal reaches the transistors Ts7, Ts8 and Ts9. The P-MOS transistor Ts7 is now low-resistance and the N-MOS transistors Ts8 and Ts9 are high-resistance. The con capacitor C5 is charged with constant current via Ts6 and Ts7.  

If the Doppler signal exceeds the comparator threshold, then the MOS transistors Ts7, Ts8 and Ts9 log appear at the gates. 1 a. Ts7 becomes high-resistance Ts8 and Ts9 become low-resistance. The capacitor C5 discharges in about 1 μs via the transistors Ts8 and Ts9 connected in parallel. If the Doppler signal falls below the comparator threshold (e.g. half-wave change), then capacitor C5 is charged with the constant current set by the function generator in the known way. If the capacitor voltage U _C5 exceeds the switching threshold of the MOS transistors Ts10 and Ts11, then log turns out. 0 at data input D of flip-flop IS8. Below the Doppler signal again the comparator threshold, then the flip-flops IS 8, 9, 10 and 17 get a positive clock pulse. The outputs Q keep the log. 0 at.

If the signal change occurs so quickly that the Doppler frequency is d _{D (max-20%)} , then the capacitor voltage U _C5 no longer exceeds the switching thresholds of Ts10 / 11. At the data input D (IS8) is then log during the positive clock pulses. 1. Three consecutive periods (Doppler frequency f _{D (max-20%)} set the gates IS14 and IS15 via IS8, IS9 and IS10 in such a way that log. 1 is established at data input D (IS17). With the fourth period (Doppler frequency f _{D (max-20%)} becomes Q (IS17) log. 1.

If the amplitude monitoring does not switch off until the ignition, flip-flop IS17 holds over Q-gate IS15-D (IS17). Flip-flop IS17 switched on C-MOS-switch S1, the "detection" (f _D f _{D (max 20%))} function from, and via switch S2 the function "ignition" (f _D f _zünd) that switch S3 opens and switch S4 closes.

As the target approaches, the Doppler amplitude increases. In order to increase the interference immunity of the device, the criterion "Exceeding the comparator threshold for the time, the ignition time specified by the function generator ()" was selected for the ignition frequency measurement. (When comparing the frequency f _Doppler f _{D (max-20%)} , the signal size above the response threshold is not taken into account.)

In order to fly even with the closest flyby (fast Doppler frequency from acquisition) to enable ignition works at the "ignition frequency compare "the comparator IS1, IS2, IS3, IS4 via switch S4 as a full-wave rectifier.

If the Doppler frequency falls below the specified ignition frequency, then the capacitor C5 until the positive clock pulse (Half-wave change) charged so far that the switching threshold is exceeded by the inverter Ts10 / Ts11. The data input D from flip-flop IS8 and two more in a row the frequency underruns are also D (IS9) and (IS10) log. 0. The outputs Q (IS8, IS9 and IS10) turn on log. 0 on. Gate IS16 gives log. 1 from. Via Gr4 and R17 the thyristor Thy1 switched through, which the ignition means ZM ignites.

Claims (8)

1. Proximity fuse, in which a generator is designed to generate an airspeed-dependent reference signal that controls a phase comparator, an explosive charge igniting when approaching a target object by evaluating the retroreflectivity measurements using the Doppler effect, characterized in that two defined reference signals are generated are, which emulate the airspeed-dependent characteristics of the own missile, for example by means of one or more generators, that one of the reference signals is optionally supplied to a phase comparator via a network, that the phase comparator compares the Doppler signal obtained from the retroreflectivity measurements with the first reference signal, that a first logical combination (AND) is connected to the Phasenkompara gate output, which releases the ignition as soon as a first predetermined plurality ( 11 ), for example three times, the frequency of the Doppler signal in succession that of the first reference signal exceeds that a second logic operation (NOR) triggers the ignition as soon as a second predetermined plurality after the ignition release has been made, the frequency of the Doppler signal falls below that of a second speed-dependent reference signal. That is 2. Proximity fuse according to claim 1, characterized in that provided as the phase comparator, a voltage controlled phase comparator (6) that the senkomparators an input of Pha a first magnitude comparator (5) is tet pre scarf which exceed the amplitude of the Doppler signal on the transfer a first threshold value checks and gives comparison signals on the phase comparator during the exceeding intervals. 3. proximity fuse according to claim 1, characterized in that the voltage-controlled phase comparator ( 6 ) at its input for the airspeed-dependent reference signals has a voltage-controlled resistor (N1, R12) whose Wi derstandswert at with the airspeed decreasing amplitude reference signals ( Figure 1) in Dependence on the applied voltage becomes smaller that the voltage-controlled resistor (N1, R12) is connected in series with one side of a current mirror circuit (P1, P2) to a fixed voltage source (V _DD ), that the other side of the current mirror circuit has a To switch (P3, N2) in series with a capacitor (C) is that the switch is controlled by the output signal (f _D ) of the first Ampli tudenkomparators ( 5 ), such that the capacitor is rechargeable during the exceeding intervals and that during the interval breaks the capacitor (C) over the switch (N2, P3) discharge again and that a second amplitude comparator (P4, N3) outputs a signal to the first (7) and the second (8) logic gates when the capacitor voltage (U _C ) exceeds a second predetermined threshold value (gate threshold) ( Image 3). 4. proximity fuse according to one of claims 1 to 3, characterized in that a common generator ( 9 ) is provided for the first and the second reference signal, which generates the first reference signal and supplies a switchable resistor network ( 10 ), which instead of switching instead which he emits the second reference signal. 5. proximity fuse according to claim 4, characterized in that a memory, for example a flip-flop ( 12 ), is provided for the ignition enable signal and that the output signal of the memory controls the switching of the resistance network ( 10 ) and the ignition signal channel ( 13 ) switches the ignition signal permeable . 6. Proximity fuse according to claim 5, characterized in that a device for system activation ( 19 ) is provided, which allows the ignition release signal to be stored in the memory only after a safety time calculated by the detonator launch (τ₁). 7. proximity fuse according to claim 5 or 6, characterized in that an erasing device ( 20 ) for the memory ( 12 ) is provided, which initially and always erases when the first amplitude comparator ( 5 ) over a predetermined time no comparison signals has given to the phase comparator ( 6 ). 8. proximity fuse according to claim 7, characterized in that an integrator is provided as the quenching device ( 20 ), the input side additionally at the output of the first ampli tudenkomarators ( 5 ).