Posted: 9/15/2010 11:52:26 AM EDT
| I have always wondered...What about flashlights and batteries? Will they survive? |
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How hard would it be to make a standard garden shed into a faraday cage? Seems to me that it would be minimally intrusive and all encompassing for your EMP needs... The goal is a continuous, unbroken metal barrier completely surrounding (and insulated from) the items you want to protect. Weak points in a garden shed would be the corners, where the roof meets the side walls, the door, any windows, the floor, and any wiring that happens to be run to the shed. I'm guessing it could be done, but it'd probably be a lot of work. |
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Flashlights will be fine. Basically, most common belief is that only things plugged into the grid are at risk. It is likely, but not certain, that most vehicles will be ok. It takes a lot of wire length to pick up sufficient transients to fry most electronics; and most devices simply don't have enough wiring to pick up enough transients from the EMP to kill any microprocessors or IC's. |
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Flashlights will be fine. Basically, most common belief is that only things plugged into the grid are at risk. It is likely, but not certain, that most vehicles will be ok. It takes a lot of wire length to pick up sufficient transients to fry most electronics; and most devices simply don't have enough wiring to pick up enough transients from the EMP to kill any microprocessors or IC's. Big +1 |
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Quoted: I wonder if a mod could post an EMP FAQ at the top of this forum; the question comes up constantly....and an expert perhaps (like ar_jedi) could perhaps be persuaded to write a small blurb...Quoted: Flashlights will be fine. Basically, most common belief is that only things plugged into the grid are at risk. It is likely, but not certain, that most vehicles will be ok. It takes a lot of wire length to pick up sufficient transients to fry most electronics; and most devices simply don't have enough wiring to pick up enough transients from the EMP to kill any microprocessors or IC's. Big +1 |
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Flashlights will be fine. Basically, most common belief is that only things plugged into the grid are at risk. It is likely, but not certain, that most vehicles will be ok. It takes a lot of wire length to pick up sufficient transients to fry most electronics; and most devices simply don't have enough wiring to pick up enough transients from the EMP to kill any microprocessors or IC's. Even one device capable of picking up microwaves from an EMP can transmit that current to every other device on a board. I'm taking about ICs here, not wiring. The ICs themselves can serve as antennae and destroy nearly everything else on a circuit board. Most modern vehicles will NOT be OK. |
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Even one device capable of picking up microwaves from an EMP can transmit that current to every other device on a board. I'm taking about ICs here, not wiring. The ICs themselves can serve as antennae and destroy nearly everything else on a circuit board.
Most modern vehicles will NOT be OK. EMP pulse energy is very long wavelength and will induct lots of current into long conductor lengths. So power lines and buried telephone cables are at risk. The long wavelength means short conductors (PC traces, IC leads) will not pick up much energy. Go to the wiki and check out EMP. There are examples of what the former Soviet Union experienced during tests over settled territory. Pretty much anything connected to the power grid is going to be toast along with the telephone system. HF amateur longwire and other large outside antennas could bring it inside. Cell phones, cars and WT's will probably be okay. Since most cars have metal doors, fenders, and hoods, they have a measure of shielding that should prevent damage and some tests showed only a temporary cutout of the ignition system in a few makes. Makes you wonder what your copper plumbing system is going to do? RS |
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The EMP hazard is blown out of proportion by multiple orders of magnitude.
If a thunderstorm has been over your house you've already experienced as much EMP as a high altitude nuclear-induced EMP event would produce. A typical lightning strike 3/8ths of a mile away is about the same intensity as a HA-NEMP event, although with a somewhat higher frequency distribution so the lightning is more potentially damaging. Even the power distribution risk is tremendously overstated IMO, as modern electrical distribution systems in most places have fast lightning surge suppression devices at regular intervals throughout the system. These suppressors would tend to dump EMP energy to ground before it could accumulate to any appreciable degree. There are known tests where many common current model automobiles have been subjected to HA-NEMP simulations and continued to operate normally, I'm not sure why there is such a paranoia that such simple devices as a flashlight and batteries would be damaged. If you're close enough to a low-altitude nuclear explosion for EMP to be a problem for your electronics, EMP is the least of your concerns. |
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Even one device capable of picking up microwaves from an EMP can transmit that current to every other device on a board. I'm taking about ICs here, not wiring. The ICs themselves can serve as antennae and destroy nearly everything else on a circuit board. Most modern vehicles will NOT be OK. Microwave EMP energy has a very short range. There is no such thing as a "large" microwave EMP weapon - its effects are limited to very small areas. So, unless you happen to be staying overnight in the White House or some other high-value target, your chances of being within range of a microwave EMP weapon are slim-to-none. Conversely, "large" EMP weapons use a nuclear bomb, exploded at very high altitude. This can produce EMP effects for many hundreds of miles in all directions. However, the EMP generated by a high-altitude nuke detonation is low-frequency in nature, and thus only induces a significant voltage spike in very long conductors. In devices that aren't connected to any long conductors, almost no electrical spike is generated due to EMP, and thus the device is unlikely to be damaged. Most small electronic devices (i.e., cell phones, portable radios, PDAs, laptop computers, digital wristwatches, flashlights, electronic combination locks on safes, red dot sights, etc.) would fall into this category - The few inches (or fractions of an inch) of conductors present in these devices is simply too short to intercept any significant amount of the EM pulse, and thus no damaging voltage spike is generated within them. Similarly, the short length of the wires present in most vehicles (automobiles, motorcycles, ATVs, etc.) also intercepts very little of the EM pulse - and thus, is unlikely to be damaged. Also, the wiring in most vehicles is partially shielded by the vehicle's metal body (thereby further reducing the strength of a voltage spike induced), and all vehicle electrical systems are designed to deal with the high voltage spikes normally produced by the ignition system, motor brushes, relay and solenoid coils, etc. Here's an excerpt from the Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack, Chapter 6, Page 115:  Again, the results demonstrated that even modern automobiles are unlikely to sustain any significant EMP damage. BOTTOM LINE: Most motor vehicles and portable electronic devices stand a good chance of being usable after a EMP burst, even without taking any special precautions beforehand. However, the electric, telephone and cable utilities are very vulnerable to EMP damage (as are any appliances that happen to be connected to them when the EMP occurs). Consequently, there is no guarantee that you'll have utility power, telephone service, cable TV, cell phone or internet service after an EMP burst. Services that rely on these utilities (police, fire, ambulance, traffic signals, city water and sewer) may also be interrupted. Additional reading: Federation of American Scientists: Nuclear Weapon EMP Effects Glasstone's Blog |
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If a thunderstorm has been over your house you've already experienced as much EMP as a high altitude nuclear-induced EMP event would produce. A typical lightning strike 3/8ths of a mile away is about the same intensity as a HA-NEMP event, although with a somewhat higher frequency distribution so the lightning is more potentially damaging. . Only lightning strikes produce EMP. A passing thunderstory is not a good analogy, A near by piss in your pants lightning strike is. And lightning has lower frequency components than EMP. Longer rise time= lower spectrial distribution. One isn't necessarly more damaging than the other, but EMP is harder to protect against (faster rise time requires better protectors.) |
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Only lightning strikes produce EMP. A passing thunderstory is not a good analogy, A near by piss in your pants lightning strike is. 3/8ths of a mile away isn't what I'd call "piss in your pants". Quoted:
And lightning has lower frequency components than EMP. Longer rise time= lower spectrial distribution. Not correct. Rise time and frequency distribution are not necessarily correlated. HA-NEMP has a significantly lower frequency distribution curve than lightning, by a couple orders of magnitude or so IIRC. I think the peak frequency for HA-NEMP was something like 10kHz, and lightning something like 1MHz. I posted all the documentation from the DOE websites ages ago. |
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Even one device capable of picking up microwaves from an EMP can transmit that current to every other device on a board. I'm taking about ICs here, not wiring. The ICs themselves can serve as antennae and destroy nearly everything else on a circuit board. Most modern vehicles will NOT be OK. Microwave EMP energy has a very short range. There is no such thing as a "large" microwave EMP weapon - its effects are limited to very small areas. So, unless you happen to be staying overnight in the White House or some other high-value target, your chances of being within range of a microwave EMP weapon are slim-to-none. Conversely, "large" EMP weapons use a nuclear bomb, exploded at very high altitude. This can produce EMP effects for many hundreds of miles in all directions. However, the EMP generated by a high-altitude nuke detonation is low-frequency in nature, and thus only induces a significant voltage spike in very long conductors. In devices that aren't connected to any long conductors, almost no electrical spike is generated due to EMP, and thus the device is unlikely to be damaged. Most small electronic devices (i.e., cell phones, portable radios, PDAs, laptop computers, digital wristwatches, flashlights, electronic combination locks on safes, red dot sights, etc.) would fall into this category - The few inches (or fractions of an inch) of conductors present in these devices is simply too short to intercept any significant amount of the EM pulse, and thus no damaging voltage spike is generated within them. Similarly, the short length of the wires present in most vehicles (automobiles, motorcycles, ATVs, etc.) also intercepts very little of the EM pulse - and thus, is unlikely to be damaged. Also, the wiring in most vehicles is partially shielded by the vehicle's metal body (thereby further reducing the strength of a voltage spike induced), and all vehicle electrical systems are designed to deal with the high voltage spikes normally produced by the ignition system, motor brushes, relay and solenoid coils, etc. Here's an excerpt from the Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack, Chapter 6, Page 115: Again, the results demonstrated that even modern automobiles are unlikely to sustain any significant EMP damage. BOTTOM LINE: Most motor vehicles and portable electronic devices stand a good chance of being usable after a EMP burst, even without taking any special precautions beforehand. However, the electric, telephone and cable utilities are very vulnerable to EMP damage (as are any appliances that happen to be connected to them when the EMP occurs). Consequently, there is no guarantee that you'll have utility power, telephone service, cable TV, cell phone or internet service after an EMP burst. Services that rely on these utilities (police, fire, ambulance, traffic signals, city water and sewer) may also be interrupted. Additional reading: Federation of American Scientists: Nuclear Weapon EMP Effects Glasstone's Blog From what I understand: High alttitude (150-200miles above sea level) nuclear detonations produce gamma rays which strike the ionosphere, the particles in the ionosphere in turn radiate microwaves and these microwaves induce current. Are not microwaves limited to 1 meter or less? |
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From what I understand: High alttitude (150-200miles above sea level) nuclear detonations produce gamma rays which strike the ionosphere, the particles in the ionosphere in turn radiate microwaves and these microwaves induce current. No, virtually all of the energy produced by HEMP (EMP produced by a high-altitude nuclear burst) is produced at frequencies well below the microwave range. Quoted from Part 1 of Dennis Bodson's NIST article on EMP: The energy of a high-altitude EMP is spread over a major part of the RF spectrum. Since the pulse has such a fast rise time and short duration, it covers a broad frequency range exending from 10 kilohertz to 100 megahertz. The electric field remains fairly constant in the 10-kHz to 1-MHz band; it decreases by a factor of 100 in the 1- to 100-MHz band and continues to decrease at a faster rate for frequencies greater than 100 MHz. Most high-altitude EMP energy is at frequencies between 100 KHz and 10 MHz, and 99% lies in the frequency spectrum below 100 MHz.
 Again, this means that a long conductor is required to intercept any significant amount of HEMP energy. The conductor lengths present in most portable electronic devices are W-A-A-A-A-Y too short to qualify. |
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Even one device capable of picking up microwaves from an EMP can transmit that current to every other device on a board. I'm taking about ICs here, not wiring. The ICs themselves can serve as antennae and destroy nearly everything else on a circuit board. Most modern vehicles will NOT be OK. Microwave EMP energy has a very short range. There is no such thing as a "large" microwave EMP weapon - its effects are limited to very small areas. So, unless you happen to be staying overnight in the White House or some other high-value target, your chances of being within range of a microwave EMP weapon are slim-to-none. Conversely, "large" EMP weapons use a nuclear bomb, exploded at very high altitude. This can produce EMP effects for many hundreds of miles in all directions. However, the EMP generated by a high-altitude nuke detonation is low-frequency in nature, and thus only induces a significant voltage spike in very long conductors. In devices that aren't connected to any long conductors, almost no electrical spike is generated due to EMP, and thus the device is unlikely to be damaged. Most small electronic devices (i.e., cell phones, portable radios, PDAs, laptop computers, digital wristwatches, flashlights, electronic combination locks on safes, red dot sights, etc.) would fall into this category - The few inches (or fractions of an inch) of conductors present in these devices is simply too short to intercept any significant amount of the EM pulse, and thus no damaging voltage spike is generated within them. Similarly, the short length of the wires present in most vehicles (automobiles, motorcycles, ATVs, etc.) also intercepts very little of the EM pulse - and thus, is unlikely to be damaged. Also, the wiring in most vehicles is partially shielded by the vehicle's metal body (thereby further reducing the strength of a voltage spike induced), and all vehicle electrical systems are designed to deal with the high voltage spikes normally produced by the ignition system, motor brushes, relay and solenoid coils, etc. Here's an excerpt from the Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack, Chapter 6, Page 115: Again, the results demonstrated that even modern automobiles are unlikely to sustain any significant EMP damage. BOTTOM LINE: Most motor vehicles and portable electronic devices stand a good chance of being usable after a EMP burst, even without taking any special precautions beforehand. However, the electric, telephone and cable utilities are very vulnerable to EMP damage (as are any appliances that happen to be connected to them when the EMP occurs). Consequently, there is no guarantee that you'll have utility power, telephone service, cable TV, cell phone or internet service after an EMP burst. Services that rely on these utilities (police, fire, ambulance, traffic signals, city water and sewer) may also be interrupted. Additional reading: Federation of American Scientists: Nuclear Weapon EMP Effects Glasstone's Blog That is a crock. Did anyone else see that episode of Future Weapons where they were at an EMP testing facility. Mac drove a car through the EMP simulator and it died. He could not get the car started again. The headlights came on, but the engine wouldn't start. |
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One thing that I wonder about: they tested cars up to 50kv/m. Is that the upper range of likely EMP intensity, or just the highest that the facility could test and it's possibly a real EMP might be stronger?
I have some limited knowledge of this subject, and would like to learn more. 
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I would like to add to what billclo asked with the following. What is the danger? If the effects produced by EMP simulators are minimal, where did the whole idea of it come from as a possible threat? It had to originate somewhere as "hey this is a problem". If it is theoretically able to be dis-proven as to the level of damage that may occur, why was it ever introduced as a threat that we need to worry? Is it just a scare tactic?
Please don't go into a general history of nuclear testing. I am more concerned with specifics and at what point someone realized there was a problem and why. |
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Even one device capable of picking up microwaves from an EMP can transmit that current to every other device on a board. I'm taking about ICs here, not wiring. The ICs themselves can serve as antennae and destroy nearly everything else on a circuit board. Most modern vehicles will NOT be OK. Microwave EMP energy has a very short range. There is no such thing as a "large" microwave EMP weapon - its effects are limited to very small areas. So, unless you happen to be staying overnight in the White House or some other high-value target, your chances of being within range of a microwave EMP weapon are slim-to-none. Conversely, "large" EMP weapons use a nuclear bomb, exploded at very high altitude. This can produce EMP effects for many hundreds of miles in all directions. However, the EMP generated by a high-altitude nuke detonation is low-frequency in nature, and thus only induces a significant voltage spike in very long conductors. In devices that aren't connected to any long conductors, almost no electrical spike is generated due to EMP, and thus the device is unlikely to be damaged. Most small electronic devices (i.e., cell phones, portable radios, PDAs, laptop computers, digital wristwatches, flashlights, electronic combination locks on safes, red dot sights, etc.) would fall into this category - The few inches (or fractions of an inch) of conductors present in these devices is simply too short to intercept any significant amount of the EM pulse, and thus no damaging voltage spike is generated within them. Similarly, the short length of the wires present in most vehicles (automobiles, motorcycles, ATVs, etc.) also intercepts very little of the EM pulse - and thus, is unlikely to be damaged. Also, the wiring in most vehicles is partially shielded by the vehicle's metal body (thereby further reducing the strength of a voltage spike induced), and all vehicle electrical systems are designed to deal with the high voltage spikes normally produced by the ignition system, motor brushes, relay and solenoid coils, etc. Here's an excerpt from the Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack, Chapter 6, Page 115: Again, the results demonstrated that even modern automobiles are unlikely to sustain any significant EMP damage. BOTTOM LINE: Most motor vehicles and portable electronic devices stand a good chance of being usable after a EMP burst, even without taking any special precautions beforehand. However, the electric, telephone and cable utilities are very vulnerable to EMP damage (as are any appliances that happen to be connected to them when the EMP occurs). Consequently, there is no guarantee that you'll have utility power, telephone service, cable TV, cell phone or internet service after an EMP burst. Services that rely on these utilities (police, fire, ambulance, traffic signals, city water and sewer) may also be interrupted. Additional reading: Federation of American Scientists: Nuclear Weapon EMP Effects Glasstone's Blog That is a crock. Did anyone else see that episode of Future Weapons where they were at an EMP testing facility. Mac drove a car through the EMP simulator and it died. He could not get the car started again. The headlights came on, but the engine wouldn't start. Because TV has never falsified or misrepresented what thay show <Cough>Model Rocket Engines</Cough> especially that show  .
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What is the danger? If the effects produced by EMP simulators are minimal, where did the whole idea of it come from as a possible threat? EMP effects are far from minimal - Just one high-altitude nuclear (HEMP) burst could cause blackouts over a large percentage of the entire nation, damage our telecommunications infrastructure, disrupt radio communications, damage or destroy most appliances and consumer electronic devices that are plugged in to AC power or phone lines, and possibly damage enough of our power transmission grid to leave us without electricity for many months. However, the HEMP threat to small, portable devices has been greatly overblown. Part of this confusion is due to the fact that EMP can also be generated by short-range microwave weapons - and microwaves are indeed capable of damaging small, portable devices. Folks tend to ignore the short-range part, assuming that microwave weapons have the same wide-ranging effects of HEMP. In reality, only a very, very small percentage of all Americans live close enough to a target where microwave EMP weapons might be used to be affected by them. Conversely, just about all of us live within range of HEMP weapons - and thus, HEMP effects are what we should be concerned with. |
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One thing that I wonder about: they tested cars up to 50kv/m. Is that the upper range of likely EMP intensity, or just the highest that the facility could test and it's possibly a real EMP might be stronger? I have some limited knowledge of this subject, and would like to learn more. EMP can be that strong in the immediate proximity to a nuclear explosion. Simulators are used to test equipment, aircraft, etc that may need to be survivable in that environment. High altitude nuclear-generated wide area EMP is much lower in intensity (and radio frequency distribution) and poses significantly less threat to most things. If your car is rendered inoperable due to nuclear EMP, it's only going to be a problem for a couple seconds before it's destroyed by the blast wave. EMP and "dirty bombs" are the two boogie-men under the SF bed. I've tried my best, hopefully someone someday will be able to turn on the light. Quoted:
I would like to add to what billclo asked with the following. What is the danger? If the effects produced by EMP simulators are minimal, where did the whole idea of it come from as a possible threat? It had to originate somewhere as "hey this is a problem". If it is theoretically able to be dis-proven as to the level of damage that may occur, why was it ever introduced as a threat that we need to worry? Is it just a scare tactic? Please don't go into a general history of nuclear testing. I am more concerned with specifics and at what point someone realized there was a problem and why. When the US tested high altitude (space) nuclear weapon detonations it was found that some EMP effects were observed long distances away (Hawaii). This effect was examined and evaluated both as a potential weapon effect on an adversary as well as a risk assessment. The risk is not zero. Like so many other things, a hypothetical or minimal risk becomes vastly overstated due to media attention/fiction, lack of knowledge and critical thinking/risk assessments, and the mystique about nuclear weapons. |
| I was under the impression that a nuclear weapon detonated 300 miles above the earths atmosphere over Kansas would knock out the entire electrical grid of the United States. No lights, no sewage treatment, no running water. Might as well say no grocery stores too. The chaos induced by the situation is the weapon itself. |
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I was under the impression that a nuclear weapon detonated 300 miles above the earths atmosphere over Kansas would knock out the entire electrical grid of the United States. No lights, no sewage treatment, no running water. Might as well say no grocery stores too. The chaos induced by the situation is the weapon itself. It could affect a pretty large chunk of it, anyway. 
However, the only effect it would have on flashlights and batteries is that we'd be using them a lot more often... 
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I was under the impression that a nuclear weapon detonated 300 miles above the earths atmosphere over Kansas would knock out the entire electrical grid of the United States. No lights, no sewage treatment, no running water. Might as well say no grocery stores too. The chaos induced by the situation is the weapon itself. That impression would be wrong and that's what is so maddening about trying to get people to make rational choice on this subject. Makes for an interesting fictional SHTF novel, but is just that, fiction. Not say there is no prospect for damage, but the idea that a HA-NEMP could reduce a large area to the stone age is just not supported by facts. A megaton range thermonuclear weapon would be far more destructive to the US if airburst detonated over any major city rather than 300 miles over Kansas (despite my opinion of Kansas  )
A high intensity solar CME aurora event would be more destructive and much more widespread than an HA-NEMP attack. By the way, if you want to see HA-NEMP happen, watch "The Atomic Bomb Movie", the compilation of film clips of nuclear testing. There is a shot there of some people out on the beach in Hawaii waiting to see the explosion and listening to an AM radio when the explosion happens. The radio makes a noise then goes silent (the AGC in the radio)... slowly comes back up to static as the ionospheric disruption has disrupted the AM propagation. Over the course of a few seconds the signal returns. The long and short of "EMP" is that there is nothing you can do other than what you should already be doing to protect your home from lightning damage anyway, and general preparedness for power outages and other potentially extended disaster situations. |
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I was under the impression that a nuclear weapon detonated 300 miles above the earths atmosphere over Kansas would knock out the entire electrical grid of the United States. No lights, no sewage treatment, no running water. Might as well say no grocery stores too. The chaos induced by the situation is the weapon itself. That impression would be wrong and that's what is so maddening about trying to get people to make rational choice on this subject. Makes for an interesting fictional SHTF novel, but is just that, fiction. Not say there is no prospect for damage, but the idea that a HA-NEMP could reduce a large area to the stone age is just not supported by facts. A megaton range thermonuclear weapon would be far more destructive to the US if airburst detonated over any major city rather than 300 miles over Kansas (despite my opinion of Kansas )
A high intensity solar CME aurora event would be more destructive and much more widespread than an HA-NEMP attack. By the way, if you want to see HA-NEMP happen, watch "The Atomic Bomb Movie", the compilation of film clips of nuclear testing. There is a shot there of some people out on the beach in Hawaii waiting to see the explosion and listening to an AM radio when the explosion happens. The radio makes a noise then goes silent (the AGC in the radio)... slowly comes back up to static as the ionospheric disruption has disrupted the AM propagation. Over the course of a few seconds the signal returns. The long and short of "EMP" is that there is nothing you can do other than what you should already be doing to protect your home from lightning damage anyway, and general preparedness for power outages and other potentially extended disaster situations. Thanks for the more reassuring explanations. I expect an EMP event would have significant impact, but at least everything electronic won't be toast. Now just the electric grid probably going down, and commerce/food transport being affected would be bad enough, but at least I'll be able to drive and fool around with my portable electronics.
Aside from putting some electronics in a shielded container, I don't see much I can practically do about EMP anyways. I'm more worried about more likely events. |
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I would like to add to what billclo asked with the following. What is the danger? If the effects produced by EMP simulators are minimal, where did the whole idea of it come from as a possible threat? It had to originate somewhere as "hey this is a problem". If it is theoretically able to be dis-proven as to the level of damage that may occur, why was it ever introduced as a threat that we need to worry? Is it just a scare tactic? Please don't go into a general history of nuclear testing. I am more concerned with specifics and at what point someone realized there was a problem and why. There are people that have a need to be afraid of something––oh hi "chicken little"......Our economy depends on transportation, so anything that someone can convince a "chicken little" that the economy is at risk––generally quickly followed with a sale announcement for a survival kit.....EMP makes good survival fiction |
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Only lightning strikes produce EMP. A passing thunderstory is not a good analogy, A near by piss in your pants lightning strike is. 3/8ths of a mile away isn't what I'd call "piss in your pants". Quoted:
And lightning has lower frequency components than EMP. Longer rise time= lower spectrial distribution. Not correct. Rise time and frequency distribution are not necessarily correlated. HA-NEMP has a significantly lower frequency distribution curve than lightning, by a couple orders of magnitude or so IIRC. I think the peak frequency for HA-NEMP was something like 10kHz, and lightning something like 1MHz. I posted all the documentation from the DOE websites ages ago.[/quote Sorry, every souce I have ever seen form college EMC class to NCS literature to IEEE transactions to DOD Standards specify a much broader frequency spectrium. Without going into the math, EMP is measured in nanoseconds, lightning in milisconds. EMP is formed at the speed of light (by moving electrons, photons, and neutrons), lightning requires ionaziation of the air to reach peak current. EMP really looks like a pulse, lightining looks more like a time domain DC discharge, which in a way it is. They only crediable explanation I've seen for the frequency distribution is that coherent compton electrons from prompt gammas form a pulse about 10 nanoseconds, which produces coherent radiation to a theoritical maximum of 100 Mhz. Weaker compton electrons from the prompt gammas plus scattered gammas add a non coherent field on top of this, which pushes the spectrum into the GHz range, at a much reduced amplitude. Buy that explanation or not, allmost everybody offers the same numbers: Flat response to 1 MHz, 10 db/Decade rolloff from 1 to 100 MHz, and 20 dB/decade afterwards. Lightning starts dropping off below 1 MHz |
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Only lightning strikes produce EMP. A passing thunderstory is not a good analogy, A near by piss in your pants lightning strike is. 3/8ths of a mile away isn't what I'd call "piss in your pants". Quoted:
And lightning has lower frequency components than EMP. Longer rise time= lower spectrial distribution. Not correct. Rise time and frequency distribution are not necessarily correlated. HA-NEMP has a significantly lower frequency distribution curve than lightning, by a couple orders of magnitude or so IIRC. I think the peak frequency for HA-NEMP was something like 10kHz, and lightning something like 1MHz. I posted all the documentation from the DOE websites ages ago.[/quote Sorry, every souce I have ever seen form college EMC class to NCS literature to IEEE transactions to DOD Standards specify a much broader frequency spectrium. Without going into the math, EMP is measured in nanoseconds, lightning in milisconds. EMP is formed at the speed of light (by moving electrons, photons, and neutrons), lightning requires ionaziation of the air to reach peak current. EMP really looks like a pulse, lightining looks more like a time domain DC discharge, which in a way it is. They only crediable explanation I've seen for the frequency distribution is that coherent compton electrons from prompt gammas form a pulse about 10 nanoseconds, which produces coherent radiation to a theoritical maximum of 100 Mhz. Weaker compton electrons from the prompt gammas plus scattered gammas add a non coherent field on top of this, which pushes the spectrum into the GHz range, at a much reduced amplitude. Buy that explanation or not, allmost everybody offers the same numbers: Flat response to 1 MHz, 10 db/Decade rolloff from 1 to 100 MHz, and 20 dB/decade afterwards. Lightning starts dropping off below 1 MHz Sure you're looking at the numbers for a high altitude induced EMP versus a direct short-range EMP? |
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Quoted: I have always wondered...What about flashlights and batteries? Will they survive? Considering that modern computerized cars 'survive' EMP-exposure testing... There's no reason why not... 'Lights Out' is bad, low-grade scare-fiction... Of course, they won't survive the ICBMs that come in right behind any 'EMP' - EMP attack is a first-strike weapon - covering fire for all-out nuclear war. That's the only viable scenario. |
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Quoted: I was under the impression that a nuclear weapon detonated 300 miles above the earths atmosphere over Kansas would knock out the entire electrical grid of the United States. No lights, no sewage treatment, no running water. Might as well say no grocery stores too. The chaos induced by the situation is the weapon itself. 300mi up is outside the capability of a 'rogue state' with 'just one' nuke... It requires ICBM capability (NO, a TBM like a Scud won't work) - so unless TSHTF with Russia or China, it just won't happen any time soon... And it's essentially impossible for 'terrorists' to carry out, unless they do so by taking control of a country with ICBMs. |
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Quoted: Quoted: I was under the impression that a nuclear weapon detonated 300 miles above the earths atmosphere over Kansas would knock out the entire electrical grid of the United States. No lights, no sewage treatment, no running water. Might as well say no grocery stores too. The chaos induced by the situation is the weapon itself. 300mi up is outside the capability of a 'rogue state' with 'just one' nuke... It requires ICBM capability (NO, a TBM like a Scud won't work) - so unless TSHTF with Russia or China, it just won't happen any time soon... And it's essentially impossible for 'terrorists' to carry out, unless they do so by taking control of a country with ICBMs. Basically this is correct.... there are really long odds of a rogue state capability to do this.... not IMpossible, but really, really, really, unlikely. More likely, and what everyone should talk about rather than EMP's.... is solar storms similar to a Carrington event... which would also likely fry our communications and power distribution systems.... (and regime change or disarmament won't eliminate that possibility either) |
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Quoted: Quoted: Quoted: I was under the impression that a nuclear weapon detonated 300 miles above the earths atmosphere over Kansas would knock out the entire electrical grid of the United States. No lights, no sewage treatment, no running water. Might as well say no grocery stores too. The chaos induced by the situation is the weapon itself. 300mi up is outside the capability of a 'rogue state' with 'just one' nuke... It requires ICBM capability (NO, a TBM like a Scud won't work) - so unless TSHTF with Russia or China, it just won't happen any time soon... And it's essentially impossible for 'terrorists' to carry out, unless they do so by taking control of a country with ICBMs. Basically this is correct.... there are really long odds of a rogue state capability to do this.... not IMpossible, but really, really, really, unlikely. More likely, and what everyone should talk about rather than EMP's.... is solar storms similar to a Carrington event... which would also likely fry our communications and power distribution systems.... (and regime change or disarmament won't eliminate that possibility either) True... |
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Quoted: Quoted: Sure you're looking at the numbers for a high altitude induced EMP versus a direct short-range EMP? Yep. There's a whole lot less interest in short range emp until recently when non nuclear EMP generators have attracted a little bit of attention. 'Non-nuclear' generators are lab equipment, not a viable weapon. |
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The EMP hazard is blown out of proportion by multiple orders of magnitude. If a thunderstorm has been over your house you've already experienced as much EMP as a high altitude nuclear-induced EMP event would produce. A typical lightning strike 3/8ths of a mile away is about the same intensity as a HA-NEMP event, although with a somewhat higher frequency distribution so the lightning is more potentially damaging. Even the power distribution risk is tremendously overstated IMO, as modern electrical distribution systems in most places have fast lightning surge suppression devices at regular intervals throughout the system. These suppressors would tend to dump EMP energy to ground before it could accumulate to any appreciable degree. There are known tests where many common current model automobiles have been subjected to HA-NEMP simulations and continued to operate normally, I'm not sure why there is such a paranoia that such simple devices as a flashlight and batteries would be damaged. If you're close enough to a low-altitude nuclear explosion for EMP to be a problem for your electronics, EMP is the least of your concerns. I hope you are right. W/O vehicles I am so screwed. |
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Sure you're looking at the numbers for a high altitude induced EMP versus a direct short-range EMP? Yep. There's a whole lot less interest in short range emp until recently when non nuclear EMP generators have attracted a little bit of attention. 'Non-nuclear' generators are lab equipment, not a viable weapon. Would you care to cite your info source? |
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Quoted: Quoted: Quoted: Quoted: Sure you're looking at the numbers for a high altitude induced EMP versus a direct short-range EMP? Yep. There's a whole lot less interest in short range emp until recently when non nuclear EMP generators have attracted a little bit of attention. 'Non-nuclear' generators are lab equipment, not a viable weapon. Would you care to cite your info source? Same back at you - find me an example that isn't Popular Mechanics, or a bad tech-thriller novel, of a conventional, weaponizable EMP. The last time I posted that, I had someone google 'EMP gun' thinking they'd proved me wrong - what they found, was a large piece of lab equipment designed to generate EMP for test-purposes. As practical 'electric weapons' go, the USAF has a bomb that will short out power lines, but it does this by scattering conductive carbon-fiber filaments over the wires, not by 'EMP'.... |