GB2057733A - Transmitting information to explosive etc. devices - Google Patents

Abstract

A method of transmitting information is transmitted seismically and/or acoustically to an explosive or pyrotechnic device wherein the information is not operation-initiating information. The device is preferably a mine, in which case the signals may be arming or disarming signals, and may be provided with an electronic evaluator to evaluate the information.

Description

SPECIFICATION A method of transmitting information The invention relates to a method of transmitting information to an explosive or pyrotechnic device, or to explosive or pyrotechnic devices, also to such a device itself.

There has long been a demand for the possibility of influencing for example explosive mines in a controlled manner, even after they have been laid in water or on land, preferably, however, underground, in order to convert them for example from a live state into a safe state or vice versa. Above all, this demand may relate to the creation in a mine-field of a safe lane which is passable on foot and by vehicle and to the overall operating period of the mine-field, i.e the maximum time that the mines may remain in a live condition. In order to satisfy this demand it is preferable to be able to control the mines by externally arriving coded signals after the mines have been laid in any type of terrain or in water.

It is known for these information signals to be transmitted on an electromagnetic basis, whereby, with regard to mines lain underground, this method mostly uses relatively long electromagnetic waves. A disadvantage of this electromagnetic information transmission is the relatively large expense on the transmitter end and also on the receiver end in the mines.

This type of subsequent transmission of information is also desirable for other types of device, for example for pyrotechnic flare charges for lighting airfield approaches, pyrotechnique smoke-screen generating devices, or pyrotechnic incendiary devices for setting terrain alight.

Also, subsequent transmission of information may be used with automatic bombardment installations, i.e. stationary blast units triggerable by the approaching target, in order to change these from, for example, the safe condition into the live condition.

According to the present invention there is provided a method of transmitting information to an explosive or pyrotechnic device, or to explosive or pyrotechnic devices, wherein the information is not operation-initiating information and is transmitted seismically and/or acoustically.

A preferred method according to the invention may provide a method of transmitting information to devices, more particularly mines, after they have been laid, which in particular need not involve the above-mentioned disadvantages and which may be put into practice with little expense.

In this connection, in the case of mines, advantageous use may be made of the fact that modern mines have sensors for identifying targets, which sensors operate in the same way as a geophone or a pressure sensor on, for example, a piezoelectric basis and which are capable of identifying the targets by their typical ground vibrations, engine noises etc.

For this purpose, these sensors are provided, for example, with an electronic evaluator which makes a selection via a frequency filter for example, and transmits to the subsequently-connected elements only those electrical oscillations which are in a frequency range which is characteristic for the respective targets. These sensors may now be used also to obtain control information input additional to the required triggering of the mine, and thus a control of the mine behaviour may be achieved.

When the devices are not built with such sensors, suitable simply contructed oscillation receivers may be provided.

In a method according to the invention the information may be transmitted by mechanical oscillations or pulses in the ground, in the air and/or in water, which can be produced in numerous ways. For example, in a limited area containing the devices to be controlled the ground can be set into vibrations for this purpose by locally defined vibratory stresses.

For example, oscillation generators operated mechanically or by gas pressure can be used for this purpose. For example, spring tension operated impact devices which act on the ground at prescribed intervals of time by means of ram-type impact members which are driven by varying spring forces and which may be successively actuated in a defined manner. Suitable impact devices driven, for example, by compressed air or the reaction of a propellant may also be used. Also, generators operated mechanically or by gas pressure, producing suitably defined impact or acoustic shocks or suchlike are suitable for producing acoustic oscillations. Thus, it is also possible to use impact equipment provided with suitable hammer and anvil devices or an ultrasonic whistle which enable air oscillations interrupted by prescribed intervals to be produced in a predetermined manner.Acoustic shocks in the air may be produced, for example, by a predetermined sequence of pistol shots.

As a general principle these discrete information oscillations or pulses, i.e. succeeding each other at intervals, may each have, for example, the same frequency characteristic as the signals emitted by a target. Of course, care must then be taken, particularly when a live mine is to be converted to the safe condition, that the information pulses themselves cannot inadvertently trigger the mine.

The evaluator assigned to the respective mine sensor must for this purpose be constructed, for example, so that it can distinguish the signals emitted by the targets and lasting for a longer period from the discrete information pulses separated from each other by pauses.

On the other hand, therefore, for the required triggering of the mine the evaluator should be provided with, for example, an electrical delay member which only allows the triggering electrical signal to be transmitted after a period of time which is greater than the longest possible duration of an information pulse. On the other hand, for the required information transmission the evaluator could be provided, for example, with a store arrangement and an information code contained therein for changing the state of the mine, with a registering device for the information pulses received and also with a comparator between the stored code and the registration, which allows the electrical signal to be transmitted for signal processing and thus effects the required change of the mine state only when these correspond.

However, in order to simplify distinguishing between them, it is preferable for each of the information pulses also to have a different characteristic to the signals emitted by the targets. In an advantageous development of the invention according to Claim 2 this is provided by using as information signals seismic and/or acoustic oscillations or pulses which are triggered by detonation and which preferably, in comparison with the target signals, particularly of mines, have a much higher frequency with correspondingly steep rising edge.These information frequencies may be distinguished from the target frequencies in a simple manner, for example by means of a further frequency filter associated with the sensors which forms a window only for these information frequencies, i.e. it allows only these frequencies to pass to the subsequent members of the evaluator relating to the information transmission.

The most varied, associated parameters may be used as information contents of the pulses or pulse sequences respectively. Preferably, however, according to claim 3 the pulse times, and/or the pulse pause times and/or the number of pauses occuring in a specific period of time or the number of pulses respectively equivalent to this in the expression are used as the information contents. Of these, in their turn, the combination of pause time and number of pauses or pulses respectively is particularly preferable for the information transmission and its evaluation, especially when very brief, needle-shaped pulses are involved, in order to obtain a coding by very simple means but in very many possible variations.

There are various possibilities for producing the information pulses by detonated reaction.

For example, two or more instantaneous blast detonators may be used, triggered electrically at prescribed intervals by means of a suitable electrical circuit. Instead of these, delayed action blast detonators incorporating pyrotechnic delay action compositions of varying burnup time may be used, so that a sequence of detonations with prescribed pause times is also achieved again here. Another possibility involves the use of a relatively slow burning powder fuse with detonating caps and/or powdered explosive charges arranged therebetween, the length of the powder fuse between, for example, two detonating caps determining here the pause time between pulses. However, a method according to claim 4 is preferred.By means of a succession of fuse sections or explosive charges and blast refardants it is possible in a very simple and reliable manner to transmit coded information to the device or devices by seismic and/or acoustic means and to control the behaviour of the device or devices accordingly. In this connection, additional detonating caps or even blast charges may be provided if necessary in the fuse or explosive charge region to strengthen the detonation pulses of the fuses or fuse sections or explosive charges respectively which react by detonation and the discrete oscillations thereby triggered in the ground, water or in the air.

In order to ensure in the case of mines, which, for example, are to be converted from the live to the safe state in order to create a safely navigable passage, that the information pulses have actually been received by the relevant mine and processed, i.e. that subsequently the mine is no longer in the live state, it is advantageous to provide in a known manner a so-called answering signal. For example, this may consist in that upon or after an interruption of the detonating circuit of the mine, an adjustment of the detonating mechanism to the safe position or suchlike, a colour marker, more particularly for submarine mines, or a cartridge with a marking flag which can be driven through the earth covering, are automatically ejected with the aid of a pyrotechnic charge.

The evaluator for information processing may be composed of known electrical or electronic structural components in the same way as that for the target identification.

However, in place of a discrete circuit it is preferable to use a commercially available microprocessor which is programmed according to the software to be used in each case and which then controls all the operating sequences accordingly.

For a more detailed explanation of a method according to the invention, the single figure shows an example, in a basic representation, for a possible electronic evaluator relating to the information transmission, which makes an evaluation in respect of the pulse pause time and the number of pauses and which consists of commercial components.

Connected after a sensor S of an explosive or pyrotechnic device, which responds to seismic and/or acoustic, i.e. mechanical, oscillations, is a filter F which selects, i.e. allows through to a subsequent comparator K, from all signals received by the sensor S those which, in terms of frequency, are typical for the information pulses which are preferably produced by detonated reactions. Approximately needle-shaped electrical pulses with correspondingly undefined edges are obtained at the filter output at prescribed intervals of time, i.e. separated by the pause time. These pulses are converted in the comparator K into rectangular pulses with defined switch-on and switch-off edges.

An amplifier V connected after the comparator K on the one hand amplifies the relatively weak pulses from the comparator K and on the other hand inverts them, i.e. with the voltage applied to the amplifier intput, zero voltage is obtained at its output and with zero voltage at the input of the amplifier, a correspondingly amplified voltage is obtained at the output. By means of this inverting amplifier, therefore, amplified rectangular pulses corresponding to the pause times between the original information pulses are obtained instead of the relatively weak rectangular pulses of the comparator K which correspond to the information pulses received by the sensor S.

The output of the amplifier V is connected on the one hand to a pulse generator IG and on the other hand to one of the inputs of an AND-gate G1, the other input of which is connected to the output of the pulse generator IG. The output of the gate G, is connected to a pulse group comparator IV.

The pulse generator IG is actuated by a pulse of the amplifier V and then continuously produces precise rectangular pulses which, in comparison with the pause rectangular pulses are very brief and pass the AND-gate G, so long as the rectangular pulse of the amplifier V characterising the pause time is simultaneously applied at this gate. At the output of the gate G1, therefore, groups of precise rectangular pulses are obtained at intervals, the number of rectangular pulses of, for example, four, six or more per group being an exact measure for the pause time. These successive pulse groups are compared in the pulse group comparator IV with stores and the code groups fed into these for the pause times.If -the respective pulse group entering the pulse group comparator IV is identical in terms of the number of its pulses and the sequence in the pulse groups as a whole to the code groups programmed in, then a counting pulse for this pulse group which is recognized as correct is sent to a subsequent pulse group counter IZ. If, on the other hand, a deviation in respect of the number of the rectangular pulses and/or the temporal sequence is established in even one pulse group in the pulse group comparator IV from the code and thus from the prescribed pause programme, i.e.

the information transmission is recognized as faulty, then no counting pulse is sent to the pulse group counter IZ, but a command is transmitted to an automatic reset device R.

This reset device is connected to both the pulse generator IG and to the pulse group counter IZ, and after receiving a corresponding command it moves the evaluator back into the initial state in which it is ready for a new information transmission.

The counting pulses entering the pulse group counter IZ from the pulse group comparator IV within a prescribed period of time are added and the final result is transferred to a store SP,. In a next stage, the contents of this store are then compared with the code programme relating to the number of pulse pauses and located in a further store SP2. For this purpose the outputs 1 to n of the two stores Sup, 2 are linked via AND-gates Gsi for the same number of pauses in each case. The drawing shows only the outputs 1, 3 and n and their linkages by way of example. Additional outputs are merely indicated in broken lines.The AND-gates Gsi in their turn are again all combined via an OR-gate G2 at the output of which the required function signal FS for the required device control is then obtained when it has also been established through the relevant AND-gate Gsi that the number of pulse pauses registered by the sensor S agrees with the rated number of pauses fed into the store SP2.

In order to reset the evaluator to the initial state when these numbers do not correspond and thus the function signal FS is not produced, all the outputs 1 to n of the store SP, are furthermore connected with an OR-gate G3, the output of which is connected to an AND-gate G4. The other inverting input of this AND-gate is connected with the output of the OR-gate G2. If now no agreement is established between the respective store contents of SP1.2 then a signal appears at the relevant output 1 to n of the store SP, which is switched via the OR-gate G3 to the AND-gate G4 but no function signal is produced. Following this, as a result of the inverting input, the AND-gate G4 switches through and sends a corresponding command to the reset device R so that the entire evaluator is again converted to the initial state.

The connections from and to the reset device are represented in broken lines in order to indicate that these remain inactive during correct information transmission.

Claims (8)

1. A method of transmitting information to an explosive or pyrotechnic device, or to explosive or pyrotechnic devices, wherein the information is not operation-initiating information and is transmitted seismically and/or acoustically.

2. A method according to claim 1, wherein the information is transmitted with the aid of seismic and/or acoustic oscillations or pulses triggered by one or more predeter mined detonations.

3. A method according to claim 1 or 2, wherein the information is determined on the basis of the duration of pulses and/or the pause between each two successive pulses and/or the number of pauses and pulses respectively occuring in a predetermined interval of time, each discrete oscillation representing one pulse.

4. A method according to claim 2 or 3, wherein the oscillations or pulses are produced with the aid of fuses or explosive charges and the pauses between the oscillations or pulses are produced by blast retarders arranged therebetween and having a predetermined delay time.

5. A method of transmitting information to an explosive or pyrotechnic device or to explosive or pyrotechnic devices, which information is not operation-initiating information, the method being substantially according to any one of the methods hereinbefore described.

6. An explosive or pyrotechnic device which is adapted for receiving and reacting to information transmitted by a method according to any one of the preceding claims, the device comprising an electronic evaluator operable to evaluate the information in the form in which it is transmitted.

7. A device according to claim 6, wherein the electronic evaluator is substantially as hereinbefore described with reference to the single Figure of the accompanying drawing.

8. A method according to any one of claims 1 to 5, or a device according to claim 6 or 7, wherein the or each device is a mine.