EMP and communication

Discussion in 'The Science Forum' started by happybonzo, Feb 18, 2011.

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  1. We had some people around last night and one of them started dripping on about Electro Magnetic Pulse. He was saying that anything with a transistorised circuit of any sort, no TV, no radio, my MP3/MP4 with all my "art" collection etc.
    I didn't know enough to argue and, quite frankly, wasn't that interested at the time.
    When I got to thinking about it, was he right? I always understood that micro electronics would be permanently damaged but how would radio communication be maintained if only to get the Government announcement of "Good luck everyone"
  2. As I understand it, if equipment is switched off at the time of an EMP the chances of it working afterwards are vastly improved.
  3. Depends on the architecture... remember how a current and voltage creates an electric field? When the wonderful thing about the laws of physics is that they also work in reverse*. So a big electric field (from EMP) will create a massive current and voltage in your devices.

    For semiconductors (i.e. most electronics, including Comms) which usually work with tiny currents and voltages this means they get fried, and become ornaments or expensive door stops. They might survive if you can shield them well enough in a faraday cage (a metal box).

    This is why, as rumour has it, Russia maintains the capability to manufacture valves (the 'macro' precursor of micro semiconductor transisitors). Make your circuits out of big chunky wires that can support a lot of power, and EMP won't be enough to fry them...

    * well, virtually of them, there's probably an exception or two...
  4. Wouldn't have thought so... the EMP on its own should generate a current that will swap the operating current.
  5. I recalled being told on my Platoon Signallers' Cadre (1976) that the Soviets would be OK for comms after a nuclear detonation because their radios operated off valves, but we'd be stuffed because our radios were high tech and stuffed with transistors instead. I found out recently via an ARRSE thread that the A41 Mk2, which we were using at the time, was also filled with valves...
  6. Somebody ought to fry kgb-residents chips. Or maybe someone can invent a kind of emp that would disable his auto-deny-everything circuit.
  7. I'm a total laymen when it comes to electronics but I believe the idea was to have electronics for signals hardened and use microwave communications between the various 'surviving' sectors of the UK Civil Defence organisation. Backbone was the name of the project to set this up and there are still quite a few towers still around, one at Carlton Scroop in Lincolnshire quite close to my folks' house. This website has more information than you can read without having a brain aneurism:

  8. Aren't those boxes under the antennas on the land rovers some form of EMP hardening?

    EMP is a good strategic weapon. In fact it is rumoured that many US and Soviet satelites during the cold war contained nuclear EMP weapons, that would have been the first phase of any nuclear attack, and maybe the only phase, as they would do enough damage to a modern industrialized society alone. Whilst it is extremely expensive to harden up mainframes computer networks, radio & microwave nets, national grid systems etc; to say, for example 100 mV, it is easy to generate an EMP pulse high up in the atmosphere that exceeds 100mV, or 200mV to be sure.

    No national grid power. No banking. No ATMs. No PCs. No TV. No electronic ignition in cars manufactured after the mid 70s. No air travel as GPS will likely be fried, as will the cockpit instrumentation and flight controls of most civil airliners. No ATC systems or radar, unless EMP-hardened by the military, and only if adequately so. In a millisecond, we are in the stone age, but no radiation, no damage to buildings, no death from blast or heat. Recovery will be possible, but further attacks will put us back where we started again, and could be mounted easily. A humane weapon of mass destruction/disruption?

    Potentially, a terrorist attack on a major commercial sector using an EMP weapon in Wall Street/City of London etc; could be even more costly than a radiation dirty bomb, chemical or biological attack. The former potentially can wreak financial havoc worldwide, but the latter would probably kill few, even none, and just be a major PITA to clean up afterwards.

    Didn't the Russians do some research this area in the 80s? Project 'Molniya' or 'Black Lightning'?
  9. maguire

    maguire LE Book Reviewer

    I was always under the understanding that as long as the equipment was switched off during the detonation it should be serviceable afterwards. not true?
  10. Yes, but I think if antennas are extended it might still be damaged, and I think there is still risk of EMP attenuation* in cables etc at high EMP voltages.

    Trouble is, many systems will be on stag, or in case of civvy systems like ATC radar, national grid etc, they are constantly on. If a satellite in orbit drops an EMP warhead into the troposphere, what warning are the military or civillians likely to get? Repair and recovery is possible, and even easy in some cases, but its the sheer widespread scale of the damage that is the problem.

    *That might be bollocks. I did Chemistry and biology Didn't get physics at all at school/college
  11. I must admit since finding ARRSE after nearly 15 years in the wilderness outside of a military comms zone, I was amazed for this very reason to find out how much the military now used electronic equipment, not just for comms but also for record keeping etc. I remember the lectures we had during basic on NBC warfare and being told then that even if you were outside the radius of any physical damage done by a nuclear detonation, the resultant EMP would knock out any electronic equipment. Didn't go into any details but we were just nursey types so they probably thought (rightly) it would go over our heads. I have since assumed that either modern equipment has been developed to withstand this event (as noted above, it would disable most developed countries) or the military had the money to invest in shielding against it.

    Worringly, it seems I assumed wrong...
  12. My bold... (Two extra full stops to make up the ten letters)
  13. The smashing bit about EMP is that it has a greater radius than the blast area and doesn't depend on the wind to carry fall out. So you can drop your bomb in a lightly defended area and wait for the enemy's politicians to surrender by sending a message attached to a carrier pigeon.

    Such is the impact of loss of communications that the only way to avoid defeat is to retaliate in a like fashion before the first bang. That way neither side wins and the cockroaches rule the earth.
  14. Is it true that EMP can be produced by natural phenomena (solar flares, etc)? Or is that just media scaremongering?
  15. IIRC High solar activity can cause vast electromagnetic fields radiating into space and does affect power transmission grids .