CA2041743A1 - Autonomous acoustic detonation device - Google Patents
Autonomous acoustic detonation deviceInfo
- Publication number
- CA2041743A1 CA2041743A1 CA 2041743 CA2041743A CA2041743A1 CA 2041743 A1 CA2041743 A1 CA 2041743A1 CA 2041743 CA2041743 CA 2041743 CA 2041743 A CA2041743 A CA 2041743A CA 2041743 A1 CA2041743 A1 CA 2041743A1
- Authority
- CA
- Canada
- Prior art keywords
- signal
- fire
- microphone
- blasting cap
- sensing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
- F42D1/04—Arrangements for ignition
- F42D1/045—Arrangements for electric ignition
- F42D1/05—Electric circuits for blasting
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Fire-Detection Mechanisms (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An autonomous detonation device comprising an acoustic sensor, a logic circuit, and an output circuit.
The invention is capable of discriminating the acoustic signal of an explosion of a primary charge such that it will detonate an explosive shortly thereafter. The invention further incorporates a delay system for safety purposes.
An autonomous detonation device comprising an acoustic sensor, a logic circuit, and an output circuit.
The invention is capable of discriminating the acoustic signal of an explosion of a primary charge such that it will detonate an explosive shortly thereafter. The invention further incorporates a delay system for safety purposes.
Description
-- 2 ~ 3 AUTONOMOUS ACOUSTIC DETONATION DEVICE
FIELD OF THE I~ENTION
The present invention pertains to demolition and particularly dekonators. More particularly, the invention pertains to the simultaneous detonation of a plurality of explosi~es.
BACKGROUND OF THE INVENTION
In some situatisns during ths course of commercial and military demolition operations, it is imperative to have substantially simultaneous detonation of several explosive charges which are not in close proximity to each other. Further, it is desirable that these devices do not require any physical connections between them, that they need not require line of sight location, nor that magnetic wave~ interfere with their operation. This allows the operator to place the charges faster and conceal them better, thereby reducing the possibility of enemy detection.
In the past, if an operator wished to destroy a subject (e.g., a bridge), the operator would distribute charges throughout the supporting members of the bridge.
These charges would then be connected with a detonation cord or wire which would be strung from one charge to another. The detonation cord and wire had two negative characteristics. The first was that it took time to string the cord or wire. This forced the operator to spend an inordinate amount of time stringing the cord or wire; the operator was thereby less efficient and exposed to possible detection by unfriendly forces for a greater time period. The second detrimental characteristic was the detection of the detonation cord or wire; as the cord or wire was strung from one charge to another, it was difficult to conceal. Thus detection of the explosive before detonation became ~uite probable in military operations.
A second method of detonating devices includes remote blasting systems. ~n example of this method is in '' . :
~ ~4~7~
U.S. Patent No. 4,615,268. This method uses an electromagnetic wave to induce AC currents in the receiving unit. Upon receiving the electromagnetic wave, the receiving unit detonates a blasting cap which in turn detonates a charge. Although this method does not US2 detonation cord, it is susceptible to electromagnetic interferences. For instance, if the object the operator wishes to remove was a radio tower, it was possible that the tower itself would interfere with the detonation methodO
The U.S. Army has a de~ice designated as the Ml Concussion Detonator. The Ml Concussion Detonator is a mechanical ~iring device actuated by the concussion wave of a nearby blast. It fires several charges simultaneously without connecting them with wire or detonating cord. A single charge detonated in water or air will detonate all charges primed with the concussion detonators within a particular range of the main charge or of each other. Thi~ device has two major drawbacks. The first is that it requires line of sight betwe~n each charge in order to operate. The second is that the maximum range in air is only 25.2 feet thus severely limiting the device. Another drawback is that the Ml is unable to discriminate between particular types of signals, as the Ml is dependent upon signal strength only.
This invention overcomes the problems of the prior art. This invention does not require physical connections between each of the charges, yet allows them to detonate substantially simultaneously. Howev~r, unlike the remote blasting system, this invention is no affected by electromagnetic waves. ~his invention operates by sensing the acoustic wave generated by the explosion of a primary charge. Further, it has a much larger range than the Ml and does not require a line of sight placement due to the characteristics of an acoustic signal. Further, unlike the Ml, this invention is capable of discriminating between different signals, thus lessening the chance of a ~4 l ~4~
false detonation.
SUMMARY
This invention overcomes the problems previously described in the background through use of an acoustic sensor. This invention i6 capable of being activated by two or more pounds of high explosives such as C4 explosiv~
at a range of 150 feet. "C4" is a designator used by the Army to identify a particular explosive described in lo Military Specification MlL-C-45010A. Further, this invention does not require line of sight placement due to the characteristics of a low fre~uency acoustic signal.
This invention comprises an acoustically sealed box containing an acoustic sensor means, a logic means and an output means. The acoustic sensor means comprises a microphone, a band pass filter and a detector. The microphone senses the acoustic signal generated by the detonation of a primary explosive and passes this signal to a band pass filter. The band pass filter then passes a predetermined freguency band to the detector. I~ the signal is of sufficient strength, the detector then passes the signal to the logic means. The logic means comprises a pair of oscillators, a pair of counters, a self check means and an output control. The power source can either be primary batteries such as carbon zinc or alkaline or can be a reserve battery where the electrolyte is stored in a glass ampule internal to the battery until it is broken at activations. When electrical power is applied to the electronics, both counters begin counting out the predetermined time from signals provided by the oscillators. The self check means determines whether both oscillators are operating at similar frequencies thereby increasing the safety of the invention. Upon both counters reaching the predetermined time and the self check means giving a positive signal to the output control, a signal from the detector may pass to the output means. This allows the operator a predatermined time from ' 2 ~
when he activates the invention, to the time that th~
detonator will actually operate. Further, the logic means has a second predetermined time counted by the counter, where upon the counter reaching the second predetermined time, passes a fire signal to the output means. This prevents a failure of the primary charge from preventing the device from eventually detonating.
The output means for this invention is common in this class of art and operates simply by applying the energy from the energy source to a blasting cap.
Line of sight location is not required for this invention due to the characteristic~ of a low frequency acoustic signal. A low frequency signal is able to travel around objects. It is therefore not necessary for physical connections between the devices as the acoustic sensor will sense the detonation of the primary explosive if it is located within a specific range. Further, electromagnetic waves will not affect the device, thus avoiding the major faults of the related art.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l demonstrates how a detonation device is utilized for the destruction of a bridge.
Figure 2 is an embodiment of the invention.
Figure 3 is a schematic block diagram of the invention.
Figure 4 is a schematic of the sensor means.
A DESCR_PTION OF THE PREFERRED EMBO~IMæN?
The development of the present invention, an acoustic detonation system, was in response to a need at the Engineers' School at Ft. Leonardwood, Missouri. The detonation system was designed to be activated by the detonation of 2 lbs. of C4 explosive at a distance of up to 150 feet. Secondly, it does not reguire a line of sight between the primary charge datonation and the system. Thirdly, the system is immune from false activation from the normal background environment.
Fourth, since broadcast towers, radat, and microwave facilities are potential targets, the device can operate in high RF (Radio Frequency) environments.
Figure 1 demonstrates how the present invention may be utilized in the destruction o~ a bridye 110.
Invention or autonomous detonation device 120 having at least 2 lbs. of the C4 explosive is placed on numerous supporting structures o~ the hridge 110, making sure that 10 each device 120 is within the 300-foot diameter 125 of a second device 120. This insures that each device 120 will be detonated substantially simultaneously with explosion of a primary charge 130. A main primary charge 130 having at least 2 lbs. of the C4 explosive is located within the 15 300-foot diameter 125 of a second charge 120. Thus, upon the detonation of primary charge 130, all of the explosives on the bridge will be detonated either by the devices 120 sensing the initial primary explosion, or by sensing a secondary explosion within its 300-foot diameter 20 or 150-foot range 125.
Embodiment 120 of the present invention was specifically designed to work with the explosive C4 as it is a standard explosive used by military demolition units.
Particularly, it was designed to detonate upon sensing a minimum of 2 lbs. of C4 explosive being detonated within a 150 foot radius; however, device 120 may be used with other powerful explosives. It was found that powerful explosives upon detonation, have a specific acoustic freguency which can be detected. For C~ that frequency range is between .2 hertz and 500 hertz having a specific acoustic threshold level which can be calculated from acoustic measurements of the C4 explosive when detonated.
Embodiment 120 was tested to ensure that it would properly discriminate between the C4 explosive and small arms fire, such as a 30-06 rifle or a 12-gauge shotgun at 30 and 100 feet respectively. Secondly, the invention was tested to insure that a medium caliber weapon such as 25mm r and 30mm automatic cannons fired at 30 and 100 feet, respectively, and a large gun, (e.g., a 155mm Howitzer), Pired at a 130 feet would not induce a false detonation.
Due to the different acoustic frequencies and the threshold levels, this invention is able to distinguish each of these noise signals. Because th~ C4 explosive has a low frequency acoustic signal upon detonation, line of sight location for device 120 detonation is not required.
This is due to low frequency signals being able to traverse obstacles more efPectively than high frequencies.
Figure 2 is a drawing o~ embodiment 120 the present invention as a finished product. The basic device i6 encased in an acoustically sealed box 200 with a microphone (not shown) located directly behind a sintered porous metal filter 205. Porous metal filter 205 functions as a barrier to the environment, for example, rain, dust, sand, insects and items that could damage the electronics. Further, metal filter 205 is an acoustic attenuator, attenuating the acoustic pressure wave created by the explosion of the primary charge. A Pacific Metals (located in hos Angeles, California) FCR-25 porous metal filter is used in this embodiment. The openings in the metal filter vary from .0005 to .001 inch.
By incorporating acoustiGally sealed box 200 and porous metal filter ~05 (e.g., having the form of a metal diaphragm), seismic pressure waves are attenuated at a 10 to 1 level. Seismic pressure waves are signals that are passed through solid materials (e.g., the ground) and, unless attenuated, they may cause false detonation.
Porous metal filter 205 diminishes the possibility of false detonation.
Acoustically sealed box 200 has been demonstrated to protect device 120 Prom damage due to a blast of as much as 10 lbs. of C4 within 20 ~eet. Thus, the sensor has the capability to survive and perform its primary function of detection, and has the feasibility of a reusable device for training purposes provided that the . i , :
training unit is designed to utilize replaceable batteries.
Figure 3 is a schematic of the electrical aomponents of the present invention. ~his schematic i6 divided into three major part--a sensor means 310, a logic means 340 and an output circuit 370. Additionally, there is a blasting cap 395, two crystal oscillators 343 and 345, an energy supply 305, being two AA size batt2ries, and an initializing switch 306. The two A~ size batteries 305 supply energy for the entire circuit used to detonate blasting cap 395.
The sensor circuit comprises a microphone 320, a bia~ circuit 325, a gain means 323, a ~ilter 327, and a detection circuit 335. Microphone 320 is placed directly behind porous metal filter 205 of ~igure 2. Microphone 320 senses the initial explosion of the primary charge or a secondary charge. Upon sensing the detonation of the primary charge, microphone 320 passes a first signal to bias circuit 325. B-las circuit 325 provides feedback to microphone 320 in order to keep microphone 320 operating at its optimum level. Bias circuit 325 passes the signal from microphone 320 to gain circuit 323 and filter circuit 327. Gain circuit 323 increases the level of the signal sensed by microphone 320 to an adequate level which is usable by the remainder of the circuit. Filter 327 is a bandpass filter 327 which permits sound having a frequency from 0.2 hertz to 500 hertz to pass to detector 335.
Detector 335, upon sensing tha signal from filter 327, determines whether the signal is above a set threshold level. If the signal is above the set threshold, detector 335 continues to process the signal to output control 355 of logic means 340. Sensor circuit 310 is described in greater detail below in conjunction with Figure 4.
Logic means 340 comprises an output control 355, two counters 350 and 352, two low power oscillators 342 and 344, a self-check 365, a slow-check 362 and a fast-check 360. Logic means 3~0 has two primary functions.
First, logic means 340 passes the fire signal from sensor means 310 to output circuit 370. Second, logic means functions as a safety feature to prevent premature ~iring of blasting cap 395.
Logic means 340 is incorporated into a LSIC
tlarge scale integrated circuit) in order to decrease the overall size and weight of the unit. In connection with the large scale integrated circuit, two crystal oscillators 343 and 345 have been provided. Upon initiation by initiating switch 306, crystal oscillators 343 and 345 oscillate and pass their signals to low power oscillators 342 and 344. ~irst and second low power oscillators 3~2 and 344 are utilized to ensure that proper timing functions exist. First low power oscillator 344 is a primary time base. The output of primary time base 344 is provided to a first counter 352, slow-check means 362 and fast-check means 360. Second low power oscillator 342 is a test time base. The output of second low power oscillator 342 is provided to a second counter 350, slow-check 362 and fast-check means 360. First and second counters 350 and 352 are utilized to count out a first event time and a second event time. The first event time occurs approximately ten minutes after the initializa~ion by switch 306. The first event time trigger prevents output control 355 from passing a fire signal from sensor means 310 to output circuit 370 until the 10 minute tims period has elapsed. This first event time trigger is incorporated for the purposes of safety for the operator.
Thus, by preventing the device from firing within the first ten minutes a~ter initialization, the operator is able to place the entire system on the object to be destroyed and still have an adequate time to leave the area before the device is capable of detonating.
Counters 350 and 352 further count out a second event time. The second event time is several hours and upon the elapse of the second event time, output control 355 sends a fire signal to output circuit 370. The 2 ~ ri' purpose of the second event time is to ensure that the device activates after a predetermined period of time in order to remove any explosives which may be harmful to friendly forces.
Further, logic means 340 incorporates a self-check means. The self-check means has a fast-check means 360, a slow-check means 362 and an overall sel~-check 365.
Fast-check means 360 detects the output from both primary time base 34~ and test time baæe 342. Fast-check means 360 compares both signal~ and determines whether either signal is oscillating at an unacceptably high level.
Slow-check means 362 detects the signal from both primary time base 344 and test time base 342 and ensures that both signals are 06cillating at an appropriate level. Outputs from both slow-check means 362 and fast-check means 360 are input into self-check 365. Self-check 365 receives signals from slow-check means 362, fast-check means 360, a battery check 307 and a capacitor sense 308. Battery check 307 ensures that the batteries 305 have a sufficient energy level. Capacitor sense 208 ensures that output circuit 370 is not energized prematurely. Upon receiving an adequate signal from battery check 307, capacitor sense 308, slow check means 362 and fast-check means 360, self-check 365 passes a signal to output control 355 and thus allows output control 355 to pass the fir~ signal.
Without the presence of a positive signal from self-check 365, output control 355 can not pass the fire signal.
Further, upon receiving the signals ~rom cap sense 308, battery check 307, slow-check means 362 and fast-check 30 means 360, self-check 365 provides a signal to a light emitting diode 368 which informs the operator that the device passed the self-check. This occurs within the first ~ew minutes after initiation by initiation switch 306.
As explained above, output control 355 provides the fire signal to output circuit 370. Further, output control 355 provides the supply voltage for output circuit 370 from battery 305. Output control 355 will provide a fire signal to output circuit 370 if one of two following conditions is met. The first condition is that a first event trigger has been received from both first and second counters 350 and 352, a positive sel~-check has been received ~rom self-check 365 and a fire signal has been received from sensor means 310. The second condition is that a positive self-check has been received from self-check 365 and the second event trigger has been received from fir6t and second counters 350 and 352.
Output circuit 370 of this device is common in the art. The output circuit comprises a transistor power switch 380 and an RC charging and eneryy storage circuit 376. Output control 355 provide power to a capacitor in filter 376 after the 10 minute ~irst event time. Then output control 355 provides a fire signal to txansistor switch 380. ~nergy from the capacitor in filter 376 is then passed through circuit 380 into blasting cap element 395 which detonates. Detonation of the blasting cap 395 causes the detonation of an explosive means, not shown in Figure 3.
Another safety feature is imposed with FETS 385 and 390. A release signal from first counter 352 to first FET 385 (approximately 10 minutes after initialization of the device) must be received and a release signal from second counter 350 to second FET 390 must also be received. If these signals are not present, the system will not fire. This further protects the operator from an accidental firing.
Figure 4 is a more detailed schematic of the sensor means 310 shown in Figure 3. Sensor means 310 comprises a microphone 420, a bias circuit 430, a filter 427, gain circuit 450, integrating circuit 460, and a detector means 435. Microphone 420 is a BL1785 microphone manufactured by Knowles Microphone Company (located in Franklin ParX, IL). Microphone 420 receives a positive supply voltage from battery 405 and has both an input 421 ,:
20~ r~
and an output 422. Output 422 of microphone 420 iz provided to gain and bias circuit 430.
Bias circuit 430 incorporates a voltage limiting circuit. ~he voltage limiting circuit is comprised o~ t~Jo pairs of lN4148 diodes 431, 432, 433 and 434, respectively. The first pair, 431 and 432, are electrically connected cathode-to anode with the anode of fir3t diode 431 connected to output 422 of microphone 420, the cathode of first diode 431 connected to the anode of second diode 432 and the cathode of second diode 432 connected to the case ground 49g. A~ to the second diode pair, the cathode of first diode 433 is connected to output 422 of microphone 420, the anode of first diode 433 is connected to the cathode of second diode 434 and the anode of second diode 434 is connected to case ground 499.
Gain circuit 450 for sensor means 310 comprises a non~inverting amplifier 452 with the positive input of operational amplifier 452 receivi~g a signal directly from the output of microphone 420. The negative intput of operational amplifier 452 is electrically connected to a voltage divider. Resistors 455 and 456 are connected in series from the positive supply voltage to the negative supply voltage. The junction of resistors 455 and 456 is connected to the negative input of operational amplifier 452. Operational amplifier 452 further has a negative feedback resistor 457~ The output of operational amplifier 452 is electrically provided to integrating amplifier 460 and passive bandpass filter 427.
Integrating amplifier 460 is used as a feedback network to 3U microphone 420. The output of integrating amplifier 460 is feed through resistor 462 back to microphone 420. This feedback provides the biasing noted above. Further, the output of integrating ampli~ier 460 is fed back to the positive input of non-inverting amplifier 452, thereby reducing the DC offset and centering the output of non-inverting amplifier 452.
Passive bandpass filter 427 comprise~ a network , 2 0 ~ 3 with terminals A, B and C and the circuit is made up o~ a pair of resistors 470 and 471 and a pair of capacitors 473 and 474. Resistor 470 is electrically connected between terminals A and B and second resistor 471 is electrically 5 connected between terminals B and C. Capacitsr 473 is electrically connected between terminals B and ground and second capacitor 474 is electrically connected between terminals C and ground. The input terminal for passive filter 427 is terminal A, which is connected to the output 10 of non-inverting amplifier 452. Terminal C, being the output of the passive filter 427, is input into detection means 435. Detection means 435 comprises a comparator amplifier 480 and resistors 481, 482 and 483. Resistor 483 is a hysteresis resistor, which is electrically 15 connected between the positive input of comparator amplifier 480 and the output of comparator amplifier 480.
The threshold level is set by connecting resistors 481 and 482 in series ~rom case ground 499 to system ground 498.
The junction of resistors 481 and 482 is conncted to the 20 negative input of comparator amplifier 480. In this manner, if the output of passive filter 427 is of sufficient strength, it will trigger comparator amplifier 480 to output a fire signal to logic means 340 of Figure 3.
As has been shown, the present invention overcomes the limitations of the prior art. By incorporating the acoustic sensor, this device no longer requires the physical connections, such as detonation cord, and further is not susceptible to electromagnetic interference which affected prior art devices. Further, due to the specific characteristics of the acoustic signals of an explosive, the present invention is capable of discriminating normal background noises from the specific signal of the primary explosive. This enables the operator to quickly place the system on the object to be destroyed with a reduced chance of detection, thereby eliminating the dangers of prior art devices.
,
FIELD OF THE I~ENTION
The present invention pertains to demolition and particularly dekonators. More particularly, the invention pertains to the simultaneous detonation of a plurality of explosi~es.
BACKGROUND OF THE INVENTION
In some situatisns during ths course of commercial and military demolition operations, it is imperative to have substantially simultaneous detonation of several explosive charges which are not in close proximity to each other. Further, it is desirable that these devices do not require any physical connections between them, that they need not require line of sight location, nor that magnetic wave~ interfere with their operation. This allows the operator to place the charges faster and conceal them better, thereby reducing the possibility of enemy detection.
In the past, if an operator wished to destroy a subject (e.g., a bridge), the operator would distribute charges throughout the supporting members of the bridge.
These charges would then be connected with a detonation cord or wire which would be strung from one charge to another. The detonation cord and wire had two negative characteristics. The first was that it took time to string the cord or wire. This forced the operator to spend an inordinate amount of time stringing the cord or wire; the operator was thereby less efficient and exposed to possible detection by unfriendly forces for a greater time period. The second detrimental characteristic was the detection of the detonation cord or wire; as the cord or wire was strung from one charge to another, it was difficult to conceal. Thus detection of the explosive before detonation became ~uite probable in military operations.
A second method of detonating devices includes remote blasting systems. ~n example of this method is in '' . :
~ ~4~7~
U.S. Patent No. 4,615,268. This method uses an electromagnetic wave to induce AC currents in the receiving unit. Upon receiving the electromagnetic wave, the receiving unit detonates a blasting cap which in turn detonates a charge. Although this method does not US2 detonation cord, it is susceptible to electromagnetic interferences. For instance, if the object the operator wishes to remove was a radio tower, it was possible that the tower itself would interfere with the detonation methodO
The U.S. Army has a de~ice designated as the Ml Concussion Detonator. The Ml Concussion Detonator is a mechanical ~iring device actuated by the concussion wave of a nearby blast. It fires several charges simultaneously without connecting them with wire or detonating cord. A single charge detonated in water or air will detonate all charges primed with the concussion detonators within a particular range of the main charge or of each other. Thi~ device has two major drawbacks. The first is that it requires line of sight betwe~n each charge in order to operate. The second is that the maximum range in air is only 25.2 feet thus severely limiting the device. Another drawback is that the Ml is unable to discriminate between particular types of signals, as the Ml is dependent upon signal strength only.
This invention overcomes the problems of the prior art. This invention does not require physical connections between each of the charges, yet allows them to detonate substantially simultaneously. Howev~r, unlike the remote blasting system, this invention is no affected by electromagnetic waves. ~his invention operates by sensing the acoustic wave generated by the explosion of a primary charge. Further, it has a much larger range than the Ml and does not require a line of sight placement due to the characteristics of an acoustic signal. Further, unlike the Ml, this invention is capable of discriminating between different signals, thus lessening the chance of a ~4 l ~4~
false detonation.
SUMMARY
This invention overcomes the problems previously described in the background through use of an acoustic sensor. This invention i6 capable of being activated by two or more pounds of high explosives such as C4 explosiv~
at a range of 150 feet. "C4" is a designator used by the Army to identify a particular explosive described in lo Military Specification MlL-C-45010A. Further, this invention does not require line of sight placement due to the characteristics of a low fre~uency acoustic signal.
This invention comprises an acoustically sealed box containing an acoustic sensor means, a logic means and an output means. The acoustic sensor means comprises a microphone, a band pass filter and a detector. The microphone senses the acoustic signal generated by the detonation of a primary explosive and passes this signal to a band pass filter. The band pass filter then passes a predetermined freguency band to the detector. I~ the signal is of sufficient strength, the detector then passes the signal to the logic means. The logic means comprises a pair of oscillators, a pair of counters, a self check means and an output control. The power source can either be primary batteries such as carbon zinc or alkaline or can be a reserve battery where the electrolyte is stored in a glass ampule internal to the battery until it is broken at activations. When electrical power is applied to the electronics, both counters begin counting out the predetermined time from signals provided by the oscillators. The self check means determines whether both oscillators are operating at similar frequencies thereby increasing the safety of the invention. Upon both counters reaching the predetermined time and the self check means giving a positive signal to the output control, a signal from the detector may pass to the output means. This allows the operator a predatermined time from ' 2 ~
when he activates the invention, to the time that th~
detonator will actually operate. Further, the logic means has a second predetermined time counted by the counter, where upon the counter reaching the second predetermined time, passes a fire signal to the output means. This prevents a failure of the primary charge from preventing the device from eventually detonating.
The output means for this invention is common in this class of art and operates simply by applying the energy from the energy source to a blasting cap.
Line of sight location is not required for this invention due to the characteristic~ of a low frequency acoustic signal. A low frequency signal is able to travel around objects. It is therefore not necessary for physical connections between the devices as the acoustic sensor will sense the detonation of the primary explosive if it is located within a specific range. Further, electromagnetic waves will not affect the device, thus avoiding the major faults of the related art.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l demonstrates how a detonation device is utilized for the destruction of a bridge.
Figure 2 is an embodiment of the invention.
Figure 3 is a schematic block diagram of the invention.
Figure 4 is a schematic of the sensor means.
A DESCR_PTION OF THE PREFERRED EMBO~IMæN?
The development of the present invention, an acoustic detonation system, was in response to a need at the Engineers' School at Ft. Leonardwood, Missouri. The detonation system was designed to be activated by the detonation of 2 lbs. of C4 explosive at a distance of up to 150 feet. Secondly, it does not reguire a line of sight between the primary charge datonation and the system. Thirdly, the system is immune from false activation from the normal background environment.
Fourth, since broadcast towers, radat, and microwave facilities are potential targets, the device can operate in high RF (Radio Frequency) environments.
Figure 1 demonstrates how the present invention may be utilized in the destruction o~ a bridye 110.
Invention or autonomous detonation device 120 having at least 2 lbs. of the C4 explosive is placed on numerous supporting structures o~ the hridge 110, making sure that 10 each device 120 is within the 300-foot diameter 125 of a second device 120. This insures that each device 120 will be detonated substantially simultaneously with explosion of a primary charge 130. A main primary charge 130 having at least 2 lbs. of the C4 explosive is located within the 15 300-foot diameter 125 of a second charge 120. Thus, upon the detonation of primary charge 130, all of the explosives on the bridge will be detonated either by the devices 120 sensing the initial primary explosion, or by sensing a secondary explosion within its 300-foot diameter 20 or 150-foot range 125.
Embodiment 120 of the present invention was specifically designed to work with the explosive C4 as it is a standard explosive used by military demolition units.
Particularly, it was designed to detonate upon sensing a minimum of 2 lbs. of C4 explosive being detonated within a 150 foot radius; however, device 120 may be used with other powerful explosives. It was found that powerful explosives upon detonation, have a specific acoustic freguency which can be detected. For C~ that frequency range is between .2 hertz and 500 hertz having a specific acoustic threshold level which can be calculated from acoustic measurements of the C4 explosive when detonated.
Embodiment 120 was tested to ensure that it would properly discriminate between the C4 explosive and small arms fire, such as a 30-06 rifle or a 12-gauge shotgun at 30 and 100 feet respectively. Secondly, the invention was tested to insure that a medium caliber weapon such as 25mm r and 30mm automatic cannons fired at 30 and 100 feet, respectively, and a large gun, (e.g., a 155mm Howitzer), Pired at a 130 feet would not induce a false detonation.
Due to the different acoustic frequencies and the threshold levels, this invention is able to distinguish each of these noise signals. Because th~ C4 explosive has a low frequency acoustic signal upon detonation, line of sight location for device 120 detonation is not required.
This is due to low frequency signals being able to traverse obstacles more efPectively than high frequencies.
Figure 2 is a drawing o~ embodiment 120 the present invention as a finished product. The basic device i6 encased in an acoustically sealed box 200 with a microphone (not shown) located directly behind a sintered porous metal filter 205. Porous metal filter 205 functions as a barrier to the environment, for example, rain, dust, sand, insects and items that could damage the electronics. Further, metal filter 205 is an acoustic attenuator, attenuating the acoustic pressure wave created by the explosion of the primary charge. A Pacific Metals (located in hos Angeles, California) FCR-25 porous metal filter is used in this embodiment. The openings in the metal filter vary from .0005 to .001 inch.
By incorporating acoustiGally sealed box 200 and porous metal filter ~05 (e.g., having the form of a metal diaphragm), seismic pressure waves are attenuated at a 10 to 1 level. Seismic pressure waves are signals that are passed through solid materials (e.g., the ground) and, unless attenuated, they may cause false detonation.
Porous metal filter 205 diminishes the possibility of false detonation.
Acoustically sealed box 200 has been demonstrated to protect device 120 Prom damage due to a blast of as much as 10 lbs. of C4 within 20 ~eet. Thus, the sensor has the capability to survive and perform its primary function of detection, and has the feasibility of a reusable device for training purposes provided that the . i , :
training unit is designed to utilize replaceable batteries.
Figure 3 is a schematic of the electrical aomponents of the present invention. ~his schematic i6 divided into three major part--a sensor means 310, a logic means 340 and an output circuit 370. Additionally, there is a blasting cap 395, two crystal oscillators 343 and 345, an energy supply 305, being two AA size batt2ries, and an initializing switch 306. The two A~ size batteries 305 supply energy for the entire circuit used to detonate blasting cap 395.
The sensor circuit comprises a microphone 320, a bia~ circuit 325, a gain means 323, a ~ilter 327, and a detection circuit 335. Microphone 320 is placed directly behind porous metal filter 205 of ~igure 2. Microphone 320 senses the initial explosion of the primary charge or a secondary charge. Upon sensing the detonation of the primary charge, microphone 320 passes a first signal to bias circuit 325. B-las circuit 325 provides feedback to microphone 320 in order to keep microphone 320 operating at its optimum level. Bias circuit 325 passes the signal from microphone 320 to gain circuit 323 and filter circuit 327. Gain circuit 323 increases the level of the signal sensed by microphone 320 to an adequate level which is usable by the remainder of the circuit. Filter 327 is a bandpass filter 327 which permits sound having a frequency from 0.2 hertz to 500 hertz to pass to detector 335.
Detector 335, upon sensing tha signal from filter 327, determines whether the signal is above a set threshold level. If the signal is above the set threshold, detector 335 continues to process the signal to output control 355 of logic means 340. Sensor circuit 310 is described in greater detail below in conjunction with Figure 4.
Logic means 340 comprises an output control 355, two counters 350 and 352, two low power oscillators 342 and 344, a self-check 365, a slow-check 362 and a fast-check 360. Logic means 3~0 has two primary functions.
First, logic means 340 passes the fire signal from sensor means 310 to output circuit 370. Second, logic means functions as a safety feature to prevent premature ~iring of blasting cap 395.
Logic means 340 is incorporated into a LSIC
tlarge scale integrated circuit) in order to decrease the overall size and weight of the unit. In connection with the large scale integrated circuit, two crystal oscillators 343 and 345 have been provided. Upon initiation by initiating switch 306, crystal oscillators 343 and 345 oscillate and pass their signals to low power oscillators 342 and 344. ~irst and second low power oscillators 3~2 and 344 are utilized to ensure that proper timing functions exist. First low power oscillator 344 is a primary time base. The output of primary time base 344 is provided to a first counter 352, slow-check means 362 and fast-check means 360. Second low power oscillator 342 is a test time base. The output of second low power oscillator 342 is provided to a second counter 350, slow-check 362 and fast-check means 360. First and second counters 350 and 352 are utilized to count out a first event time and a second event time. The first event time occurs approximately ten minutes after the initializa~ion by switch 306. The first event time trigger prevents output control 355 from passing a fire signal from sensor means 310 to output circuit 370 until the 10 minute tims period has elapsed. This first event time trigger is incorporated for the purposes of safety for the operator.
Thus, by preventing the device from firing within the first ten minutes a~ter initialization, the operator is able to place the entire system on the object to be destroyed and still have an adequate time to leave the area before the device is capable of detonating.
Counters 350 and 352 further count out a second event time. The second event time is several hours and upon the elapse of the second event time, output control 355 sends a fire signal to output circuit 370. The 2 ~ ri' purpose of the second event time is to ensure that the device activates after a predetermined period of time in order to remove any explosives which may be harmful to friendly forces.
Further, logic means 340 incorporates a self-check means. The self-check means has a fast-check means 360, a slow-check means 362 and an overall sel~-check 365.
Fast-check means 360 detects the output from both primary time base 34~ and test time baæe 342. Fast-check means 360 compares both signal~ and determines whether either signal is oscillating at an unacceptably high level.
Slow-check means 362 detects the signal from both primary time base 344 and test time base 342 and ensures that both signals are 06cillating at an appropriate level. Outputs from both slow-check means 362 and fast-check means 360 are input into self-check 365. Self-check 365 receives signals from slow-check means 362, fast-check means 360, a battery check 307 and a capacitor sense 308. Battery check 307 ensures that the batteries 305 have a sufficient energy level. Capacitor sense 208 ensures that output circuit 370 is not energized prematurely. Upon receiving an adequate signal from battery check 307, capacitor sense 308, slow check means 362 and fast-check means 360, self-check 365 passes a signal to output control 355 and thus allows output control 355 to pass the fir~ signal.
Without the presence of a positive signal from self-check 365, output control 355 can not pass the fire signal.
Further, upon receiving the signals ~rom cap sense 308, battery check 307, slow-check means 362 and fast-check 30 means 360, self-check 365 provides a signal to a light emitting diode 368 which informs the operator that the device passed the self-check. This occurs within the first ~ew minutes after initiation by initiation switch 306.
As explained above, output control 355 provides the fire signal to output circuit 370. Further, output control 355 provides the supply voltage for output circuit 370 from battery 305. Output control 355 will provide a fire signal to output circuit 370 if one of two following conditions is met. The first condition is that a first event trigger has been received from both first and second counters 350 and 352, a positive sel~-check has been received ~rom self-check 365 and a fire signal has been received from sensor means 310. The second condition is that a positive self-check has been received from self-check 365 and the second event trigger has been received from fir6t and second counters 350 and 352.
Output circuit 370 of this device is common in the art. The output circuit comprises a transistor power switch 380 and an RC charging and eneryy storage circuit 376. Output control 355 provide power to a capacitor in filter 376 after the 10 minute ~irst event time. Then output control 355 provides a fire signal to txansistor switch 380. ~nergy from the capacitor in filter 376 is then passed through circuit 380 into blasting cap element 395 which detonates. Detonation of the blasting cap 395 causes the detonation of an explosive means, not shown in Figure 3.
Another safety feature is imposed with FETS 385 and 390. A release signal from first counter 352 to first FET 385 (approximately 10 minutes after initialization of the device) must be received and a release signal from second counter 350 to second FET 390 must also be received. If these signals are not present, the system will not fire. This further protects the operator from an accidental firing.
Figure 4 is a more detailed schematic of the sensor means 310 shown in Figure 3. Sensor means 310 comprises a microphone 420, a bias circuit 430, a filter 427, gain circuit 450, integrating circuit 460, and a detector means 435. Microphone 420 is a BL1785 microphone manufactured by Knowles Microphone Company (located in Franklin ParX, IL). Microphone 420 receives a positive supply voltage from battery 405 and has both an input 421 ,:
20~ r~
and an output 422. Output 422 of microphone 420 iz provided to gain and bias circuit 430.
Bias circuit 430 incorporates a voltage limiting circuit. ~he voltage limiting circuit is comprised o~ t~Jo pairs of lN4148 diodes 431, 432, 433 and 434, respectively. The first pair, 431 and 432, are electrically connected cathode-to anode with the anode of fir3t diode 431 connected to output 422 of microphone 420, the cathode of first diode 431 connected to the anode of second diode 432 and the cathode of second diode 432 connected to the case ground 49g. A~ to the second diode pair, the cathode of first diode 433 is connected to output 422 of microphone 420, the anode of first diode 433 is connected to the cathode of second diode 434 and the anode of second diode 434 is connected to case ground 499.
Gain circuit 450 for sensor means 310 comprises a non~inverting amplifier 452 with the positive input of operational amplifier 452 receivi~g a signal directly from the output of microphone 420. The negative intput of operational amplifier 452 is electrically connected to a voltage divider. Resistors 455 and 456 are connected in series from the positive supply voltage to the negative supply voltage. The junction of resistors 455 and 456 is connected to the negative input of operational amplifier 452. Operational amplifier 452 further has a negative feedback resistor 457~ The output of operational amplifier 452 is electrically provided to integrating amplifier 460 and passive bandpass filter 427.
Integrating amplifier 460 is used as a feedback network to 3U microphone 420. The output of integrating amplifier 460 is feed through resistor 462 back to microphone 420. This feedback provides the biasing noted above. Further, the output of integrating ampli~ier 460 is fed back to the positive input of non-inverting amplifier 452, thereby reducing the DC offset and centering the output of non-inverting amplifier 452.
Passive bandpass filter 427 comprise~ a network , 2 0 ~ 3 with terminals A, B and C and the circuit is made up o~ a pair of resistors 470 and 471 and a pair of capacitors 473 and 474. Resistor 470 is electrically connected between terminals A and B and second resistor 471 is electrically 5 connected between terminals B and C. Capacitsr 473 is electrically connected between terminals B and ground and second capacitor 474 is electrically connected between terminals C and ground. The input terminal for passive filter 427 is terminal A, which is connected to the output 10 of non-inverting amplifier 452. Terminal C, being the output of the passive filter 427, is input into detection means 435. Detection means 435 comprises a comparator amplifier 480 and resistors 481, 482 and 483. Resistor 483 is a hysteresis resistor, which is electrically 15 connected between the positive input of comparator amplifier 480 and the output of comparator amplifier 480.
The threshold level is set by connecting resistors 481 and 482 in series ~rom case ground 499 to system ground 498.
The junction of resistors 481 and 482 is conncted to the 20 negative input of comparator amplifier 480. In this manner, if the output of passive filter 427 is of sufficient strength, it will trigger comparator amplifier 480 to output a fire signal to logic means 340 of Figure 3.
As has been shown, the present invention overcomes the limitations of the prior art. By incorporating the acoustic sensor, this device no longer requires the physical connections, such as detonation cord, and further is not susceptible to electromagnetic interference which affected prior art devices. Further, due to the specific characteristics of the acoustic signals of an explosive, the present invention is capable of discriminating normal background noises from the specific signal of the primary explosive. This enables the operator to quickly place the system on the object to be destroyed with a reduced chance of detection, thereby eliminating the dangers of prior art devices.
,
Claims (19)
1. An autonomous detonation device adapted to be connected to a blasting cap so as to detonate same, said device comprising:
(a) an acoustic sensor comprising a microphone, a bandpass filter and a detector, said microphone comprising means for sensing an explosion of a primary charge and for producing a first signal, said acoustic sensor further comprising conditioning means for receiving and conditioning said first signal and for applying a conditioned first signal to said bandpass filter, said bandpass filter comprising means for passing a predetermined frequency band of said conditioned first signal, thus forming a second signal, said predetermined frequency band being characteristic of an acoustic signal produced by the explosion of said primary charge, said second signal being provided to said detector, said detector comprising means for sensing said second signal and for producing a third signal; and (b) an output circuit comprising an energy source and a fire circuit adapted to be connected to said blasting cap, wherein said third signal is input into said fire circuit, said fire circuit comprising means for applying energy from said energy source to said blasting cap.
(a) an acoustic sensor comprising a microphone, a bandpass filter and a detector, said microphone comprising means for sensing an explosion of a primary charge and for producing a first signal, said acoustic sensor further comprising conditioning means for receiving and conditioning said first signal and for applying a conditioned first signal to said bandpass filter, said bandpass filter comprising means for passing a predetermined frequency band of said conditioned first signal, thus forming a second signal, said predetermined frequency band being characteristic of an acoustic signal produced by the explosion of said primary charge, said second signal being provided to said detector, said detector comprising means for sensing said second signal and for producing a third signal; and (b) an output circuit comprising an energy source and a fire circuit adapted to be connected to said blasting cap, wherein said third signal is input into said fire circuit, said fire circuit comprising means for applying energy from said energy source to said blasting cap.
2. The apparatus of claim 1 wherein said conditioning means comprises bias means for providing feedback to said microphone, by providing a fourth signal to said microphone.
3. The apparatus of claim 2 wherein said bias means further comprises an output voltage limiter, wherein said output voltage limiter comprises a first, a second, a third and a fourth diode, the anode of said first diode being electrically connected to cathode of said second diode, the cathode of said first diode being electrically connected to the output of said microphone, the anode of said second diode being electrically connected to ground, the anode of said third diode being electrically connected to the output of said microphone, the cathode of said third diode being electrically connected to the anode of said fourth diode, the cathode of said fourth diode being electrically connected to said ground.
4. The apparatus of claim 2 wherein said conditioning means further comprises gain means for increasing the level of said first signal, said gain means comprising a first and a second operational amplifier, said first operational amplifier being a non-inverting operational amplifier, said second operational amplifier being an integrating amplifier, said first signal from said microphone being input into said non-inverting amplifier, said non-inverting amplifier providing a fifth signal, said fifth signal further being provided to said integrating amplifier, said integrating amplifier providing a sixth signal to said non-inverting amplifier and to said microphone.
5. The apparatus of claim 1 wherein said bandpass filter further comprises a passive filter, said passive filter comprising a first and a second resistor and a first and a second capacitor, said passive filter being connected in an electrical network with terminals A, B and C, said first resistor being electrically connected between said terminals A and B, said second resistor being electrically connected between said terminals B and C, said first capacitor being electrically connected between said terminal B and ground, said second capacitor being electrically connected between said terminal C and said ground, said conditioned first signal being provided to said terminal A, said terminal C providing said second signal.
6. The apparatus of claim 5 wherein said detector comprises a third operational amplifier, said third operational amplifier being a comparator.
7. The apparatus of claim 1 further comprising logic means electrically located between said acoustic sensor and said output circuit for allowing passage of said third signal to said output circuit after a predetermined time counted by a first counter therein.
8. The apparatus of claim 7 further comprising a first oscillator for providing an oscillating signal to said first counter, said oscillator comprising means for beginning oscillating when an initiating switch is placed in an on position, said counter counting said oscillations.
9. The apparatus of claim 8 further comprising a second oscillator and wherein said logic means further comprises a second counter, said second oscillator comprising means for beginning oscillating with said first oscillator, said logic means comprising means for allowing passage of said third signal when both said first and said second counters count out said first predetermined time.
10. The apparatus of claim 9 wherein said first and second counters count a second predetermined time, said logic means comprising means for creating a fire signal substantially similar to said third signal and supplying it to said output circuit after said second predetermined time.
11. An autonomous detonation system comprising:
(a) an acoustic sensor comprising a microphone, a bandpass filter and a detector, said microphone comprising means for sensing an explosion of a primary charge and for producing a first signal, said acoustic sensor comprising conditioning means for receiving and conditioning said first signal and for applying a conditioned first signal to said bandpass filter, said bandpass filter comprising means for passing a predetermined frequency band of said conditioned first signal, thus forming a second signal, said predetermined frequency band being characteristic of an acoustic signal produced by the explosion of said primary charge, said second signal being provided to said detector, said detector comprising means for sensing said second signal and for producing a third signal;
(b) a blasting cap;
(c) an output circuit comprising an energy source and a fire circuit adapted to be connected to said blasting cap, wherein said third signal is input into said fire circuit, said fire circuit comprising means for applying energy from said energy source to said blasting cap; and (d) an explosive, wherein said blasting cap detonates said explosive upon said energy from said energy source being applied to said blasting cap.
(a) an acoustic sensor comprising a microphone, a bandpass filter and a detector, said microphone comprising means for sensing an explosion of a primary charge and for producing a first signal, said acoustic sensor comprising conditioning means for receiving and conditioning said first signal and for applying a conditioned first signal to said bandpass filter, said bandpass filter comprising means for passing a predetermined frequency band of said conditioned first signal, thus forming a second signal, said predetermined frequency band being characteristic of an acoustic signal produced by the explosion of said primary charge, said second signal being provided to said detector, said detector comprising means for sensing said second signal and for producing a third signal;
(b) a blasting cap;
(c) an output circuit comprising an energy source and a fire circuit adapted to be connected to said blasting cap, wherein said third signal is input into said fire circuit, said fire circuit comprising means for applying energy from said energy source to said blasting cap; and (d) an explosive, wherein said blasting cap detonates said explosive upon said energy from said energy source being applied to said blasting cap.
12. The apparatus of claim 11 further characterized by said primary charge being C4 explosive.
13. The apparatus of claim 12 further characterized by said explosive being C4 explosive.
14. A detonation device for detonating a blasting cap, comprising:
sensing means for sensing an acoustic signal of an explosion of a primary charge and for generating a sensing means signal corresponding thereto;
control means for receiving said sensing means signal and generating a fire signal as a function of a predetermined frequency band characteristic of said acoustic signal of said explosion of said primary charge and as a function of a predetermined signal threshold level characteristic of said acoustic signal of said explosion of said primary charge; and fire means coupled to said blasting cap for receiving said fire signal and detonating said blasting cap.
sensing means for sensing an acoustic signal of an explosion of a primary charge and for generating a sensing means signal corresponding thereto;
control means for receiving said sensing means signal and generating a fire signal as a function of a predetermined frequency band characteristic of said acoustic signal of said explosion of said primary charge and as a function of a predetermined signal threshold level characteristic of said acoustic signal of said explosion of said primary charge; and fire means coupled to said blasting cap for receiving said fire signal and detonating said blasting cap.
15. A detonation device according to claim 14 wherein said sensing means comprises a microphone.
16. A detonation device according to claim 14 wherein said control means comprises:
conditioning means for receiving said sensing means signal, applying feedback to said microphone as a function thereof, and for providing gain for said sensing means signal, a conditioned signal resulting therefrom;
and filter means for receiving said conditioned signal and for passing to a detector only that portion of said conditioned signal having a frequency within said predetermined frequency band, said detector comparing said portion of said conditioned signal to said predetermined signal threshold level and generating said fire signal if said threshold level is exceeded.
conditioning means for receiving said sensing means signal, applying feedback to said microphone as a function thereof, and for providing gain for said sensing means signal, a conditioned signal resulting therefrom;
and filter means for receiving said conditioned signal and for passing to a detector only that portion of said conditioned signal having a frequency within said predetermined frequency band, said detector comparing said portion of said conditioned signal to said predetermined signal threshold level and generating said fire signal if said threshold level is exceeded.
17. A detonation device according to claim 14 wherein said control means comprises:
pre-timer logic means for preventing said generation of said fire signal until a first predetermined time has expired after initiating said detonation device;
and post-timer logic means for generating said fire signal after a second predetermined time has expired after initiating said detonation device, said post-timer logic means being prevented from generating said fire signal until after said first predetermined time has expired.
pre-timer logic means for preventing said generation of said fire signal until a first predetermined time has expired after initiating said detonation device;
and post-timer logic means for generating said fire signal after a second predetermined time has expired after initiating said detonation device, said post-timer logic means being prevented from generating said fire signal until after said first predetermined time has expired.
18 18. A detonation device according to claim 14 wherein said fire means comprises an energy source and a fire circuit coupled to said blasting cap, said fire circuit comprising means for receiving said fire signal and for applying energy from said energy source to said blasting cap for detonation thereof.
19. A detonation device according to claim 14 wherein said primary charge comprises a C4 explosive.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US52592990A | 1990-05-21 | 1990-05-21 | |
| US07/525,929 | 1990-05-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2041743A1 true CA2041743A1 (en) | 1991-11-22 |
Family
ID=24095201
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2041743 Abandoned CA2041743A1 (en) | 1990-05-21 | 1991-05-02 | Autonomous acoustic detonation device |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0458178A3 (en) |
| CA (1) | CA2041743A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6247408B1 (en) * | 1999-11-08 | 2001-06-19 | The United States Of America As Represented By The Secretary Of The Army | System for sympathetic detonation of explosives |
| AU2016354618B2 (en) * | 2015-11-09 | 2021-10-21 | Detnet South Africa (Pty) Ltd | Wireless detonator |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4081785A (en) * | 1974-02-13 | 1978-03-28 | The United States Of America As Represented By The Secretary Of The Air Force | Dual class amphibious target discriminator |
| DE2838806A1 (en) * | 1978-09-06 | 1980-03-20 | Dynamit Nobel Ag | VIBRATION TRANSMITTING SYSTEM FOR IGNITION SYSTEMS |
| DE3045837C2 (en) * | 1980-12-05 | 1984-01-05 | Diehl GmbH & Co, 8500 Nürnberg | Ignition circuit for explosive devices |
| DE3840732A1 (en) * | 1988-12-02 | 1990-06-07 | Krupp Atlas Elektronik Gmbh | WAKE-UP DEVICE RESPECTING CHAIN VEHICLES |
-
1991
- 1991-05-02 CA CA 2041743 patent/CA2041743A1/en not_active Abandoned
- 1991-05-15 EP EP19910107842 patent/EP0458178A3/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP0458178A2 (en) | 1991-11-27 |
| EP0458178A3 (en) | 1992-10-21 |
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