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> Capacitance/Proximity Wire, How do you beat it?
ZeroPoint
post Mar 2 2010, 01:02 AM
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Looking at ways to secure a compound I found capacitance wire, also called proximity wire. According to the rules, it detects the electrical charge of any metahuman or animal that passes within 2 meters of it. I then started thinking about what means the group would have of getting past it. There are no methods mentioned in the books at all, so I thought about how it must work. Being as it detects electrical charge of nearby bodies, it must work by interecting a meat bodies electromagnetic field. And being called capacitance wire, I'm going to assume it works along the same principle as a capacitor, where the wire is one conductor, the meat body is the second conductor, and the 'air gap' or whatever lies between them functions as the Insulator (or dielectric if my memory of circuits serves me well). In which case, as the unwitting meatbag approaches the wire and their fields interact, a difference in voltage appears and thus a charge becomes present in the air between. When said reaction occurs, alarms go off, security meatsacks appear and bloody fleshy bodies get shot to smaller chunks of flesh.

So, my question to the community would be...How do you get past it without being able to hack the system so no alarm is sent, or without using magic?

I have some thoughts on this, but my understanding of how it theoretically works and may be interacted with could be faulty (It is rumored that I've been wrong once before).

One method I've thought of would be fooling it I guess. But that all depends on how it would work and interact with other electronics/devices that emit electromagnetic fields (almost everything electric). The metahuman/animal body has to have an extremely low energy electromagnetic field. So, would proximity wire only trigger on low voltage changes, or would any voltage change cause it trigger? I would think it would be the latter or otherwise drones would be able to stroll past without triggering it...which according to the RAW they don't. Which could just be asking for trouble. But on the other hand, perhaps if it would detect just any old voltage change, you might get false positives left and right whenever someone in the room next over turns on their microwave. So, another question would be if it can differentiate between more than one field. I would think no, and if it only detects fields that cause a low voltage change, then it could be defeated by carrying a really big magnet. Or an ECM. Which would be just too easy.

Or perhaps electromagnetic shielding would be the way to go.

Anyway, that's as much thought as I can put into it at the moment. Let me know what you folks think. Am I mistaken on how it might work? something else I should consider (other than not going within 2 meters of it)?
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Draco18s
post Mar 2 2010, 01:08 AM
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QUOTE (ZeroPoint @ Mar 1 2010, 08:02 PM) *
Or perhaps electromagnetic shielding would be the way to go.


Really what you need here is either (i.e. one would work, likely not the other, but I don't know which):
A Faraday cage
A piece of insulating material (aka Styrofoam)

Edit:
Wikipedia seems to support option B. Maybe. Definitely. By using the electromagnetic insulating material, you artificially increase the detected distance between the sensor and the (meta)human body.
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Karoline
post Mar 2 2010, 01:15 AM
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Remembering back to my physics II class (Only a few years ago, but I hated EM stuff), I think what is happening is that humans have an electromagnetic field around then, and when an electromagnetic field passes by a wire, it creates a charge (or current or something) in the wire. If the wire was set up properly, I'm guessing you could detect that charge (or current or whatever).

Now, the reason a drone wouldn't set the wire off, is because electronics are set up so that current runs in opposite directions on all wires. Basically you have a wire taking current one direction, and then you have another wire surrounding it that takes current in the opposite direction, and this cancels out the EMF that it would be putting out otherwise. This could just be for big wires and such, and not individual electronics because I'm reasonably sure that electronics do put out EMFs.

Anyway, presuming that it is the EMF that humans (And other living being) put out, you would have to figure out some way to disrupt the EMF around yourself. Some kind of electro magnet might be able to help cancel out your EMF, though you might have to hold it out in the direction you want to cancel out your EMF, as I don't think it could simply nullify your field entirely.

Clipping the wire might also work, but I'm guessing it would detect if anything ever cut the wire. An insulent might work. Cover the wire in rubber or something like that. Reasonably sure that will stop the EMF reaching the wire and thus from creating the current that activates the alarm. Since drones are immune to it you could perhaps have a drone carry some electricians tape and cover up the wire. Might be enough.

I'd need a better understanding of EM and/or a working model to fiddle with to be any more certain about ways to subvert it.
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ZeroPoint
post Mar 2 2010, 01:22 AM
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Faraday cage was what I was thinking as well.

I don't know if insulating material would do much....don't know though.
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Draco18s
post Mar 2 2010, 01:31 AM
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QUOTE (ZeroPoint @ Mar 1 2010, 08:22 PM) *
I don't know if insulating material would do much....don't know though.


Give that you can use capacitance to detect the thickness of a non-conductive material (insulator) by detecting the proximity of a human body and the difference in charge between that much air and [some amount of air]+[insulating thickness] I think it would work (because the insulating material reduces the charge in the sensor's wire, which in effect "increases" the distance the target is from the sensor, so if its set to go off when you're 2 feet away and the material you're using adds "1 foot worth of air"* per inch, then you need 2" of the material in order to be "right on top of it"...at least, in that direction).

*A foot of air has a certain amount of electrical resistance, an inch of some other material might have the same resistance, which is what I mean here.
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ZeroPoint
post Mar 2 2010, 01:39 AM
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EMFs generally are not appreciably affected by insulating materials. Insulation is used on wire to protect it and keep it from shorting. In networking, Cat5 (standard ethernet cable) and similar types of networking cable are whats called twisted pair....because each pair of wires is twisted around eachother at a very specific rate of turns per (unit of measurement) in order to cancel out their EMF. It doesn't work perfectly and only keeps the wires from interfering with eachother. The cable as a whole still produces its own EMF and is vulnerable to outside EMFs. Shielded twisted pair is used when that can be a problem. In this case, the whole thing is wrapped in a conductive material which blocks its own field and prevents outside electric fields from interfering with the wire, which through induction (which is what you are talking about karoline) would change current levels and thus introduce noise to the line.
Which would make since to me....except that had to call it capacitance wire which works along the same sort of principle....sorta except through a change of voltage.
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Daylen
post Mar 2 2010, 01:40 AM
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or use a vann de graff generator judiciouly to set it off alot over a week period and drive security and maintinence insane trying to find the problem. oh and I guess at somepoint after they start ignoring the alarm or diable it you could go ahead and break in... or find another part of their system to have fun with.
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ZeroPoint
post Mar 2 2010, 01:51 AM
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QUOTE (Draco18s @ Mar 1 2010, 08:31 PM) *
Give that you can use capacitance to detect the thickness of a non-conductive material (insulator) by detecting the proximity of a human body and the difference in charge between that much air and [some amount of air]+[insulating thickness] I think it would work (because the insulating material reduces the charge in the sensor's wire, which in effect "increases" the distance the target is from the sensor, so if its set to go off when you're 2 feet away and the material you're using adds "1 foot worth of air"* per inch, then you need 2" of the material in order to be "right on top of it"...at least, in that direction).

*A foot of air has a certain amount of electrical resistance, an inch of some other material might have the same resistance, which is what I mean here.



If we are assuming the air gap is acting as a resistor for a circuit you would definitely be right. But since we are talking about the interection between electromagnetic fields...I think you would need a lot of insulating material. I'm not gonna say your wrong though, I'm not as familiar with capacitance as I am with Induction.

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Acidsaliva
post Mar 2 2010, 01:53 AM
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Throw a stunned devil rats at it over time. Make lots of false positives as Daylen mentions.

On the night of the run pay a squatter / chiphead (IMG:style_emoticons/default/nuyen.gif) $10 to approach from the side of the compound opposite to your site of infiltration, to set off the alarms .


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Draco18s
post Mar 2 2010, 02:10 AM
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QUOTE (ZeroPoint @ Mar 1 2010, 08:51 PM) *
If we are assuming the air gap is acting as a resistor for a circuit you would definitely be right. But since we are talking about the interection between electromagnetic fields...I think you would need a lot of insulating material. I'm not gonna say your wrong though, I'm not as familiar with capacitance as I am with Induction.


I was basing my explanation on the wikipedia article (short as it is) on Proximity Detectors that use Mutual Capacitance. The latter describes a method for determining the thickness of an "insulating barrier" with respect to the measured capacitance level of a conductor on the other side based on how much air it would take to have the same reading.
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Ghremdal
post Mar 2 2010, 02:20 AM
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If you have the time, and the wires are out in the open you could use telescopic tools to cut/modify the wire. However the damn thing must be ultra sensitive to even detect a meatbags EM field, thus you would have to time the cuts perfectly. Setting up a additional loop that gets turned on when you cut the wire would be tricky but doable.

Also AFAIK capacitive sensors don't work very well in a unclean enviroment. Sabotaging the air conditioning system could give you a whole lot of false positives (like everywhere, what the system could be set to ignore) or could even disable the sensors from working.
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Daylen
post Mar 2 2010, 02:26 AM
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capacitance is really a phenomina of electrostatics. magnetism is an evil beast that gorges on time and souls slowly turning its victems insane from contemplations of things not ment for mortals...
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Daylen
post Mar 2 2010, 02:30 AM
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QUOTE (Ghremdal @ Mar 2 2010, 03:20 AM) *
If you have the time, and the wires are out in the open you could use telescopic tools to cut/modify the wire. However the damn thing must be ultra sensitive to even detect a meatbags EM field, thus you would have to time the cuts perfectly. Setting up a additional loop that gets turned on when you cut the wire would be tricky but doable.

Also AFAIK capacitive sensors don't work very well in a unclean enviroment. Sabotaging the air conditioning system could give you a whole lot of false positives (like everywhere, what the system could be set to ignore) or could even disable the sensors from working.


not so fast. if the circuit is made by anyone but a toddler they will measure the resistance to within a stupid precision. meaning any splice you do will change this value and trip an alarm. also if it was me making it I'd try to use coaxial cable instead of monofilimant to completely vex anyone trying such a stunt.
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Draco18s
post Mar 2 2010, 02:37 AM
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Whoops. Missed putting out the link to the Capacitive Displacement Sensor that I was referring to. FireFox 3.6 opens new tabs differently than 3.5 did, so I missed grabbing the URL from that tab.
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Neraph
post Mar 2 2010, 07:44 AM
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As far as RL goes, I'm not too sure how to beat capacitance wire. As far as Shadowrun is concerned, you're supposed to use an Infiltration Test.
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Fix-it
post Mar 2 2010, 07:49 AM
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QUOTE (Neraph @ Mar 2 2010, 01:44 AM) *
As far as RL goes, I'm not too sure how to beat capacitance wire. As far as Shadowrun is concerned, you're supposed to use an Infiltration Test.


and time your operation to occur during nasty weather.
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nezumi
post Mar 2 2010, 02:48 PM
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There are a few ways I can think of. On the easy level -
Try to alter the environment. In the case of rain or heavy humidity, there's goign to be interference. If you can fill the area with a low-insulation material (like water vapor), it'll be like chaff. On the other hand, try to fill the area with a gas which is highly insulative (halon?) and it will let you get closer.

Use drones to get close enough to interfere.

Use cover, like a herd of deer, another gang, or the generator, mentioned above. Paint a few spots around there with peanut butter and they'll be plagued with deer and rodents for a week.

Cause an 'accidental' disruption in service - a tree falls over the fence and crushes it.
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Sengir
post Mar 2 2010, 03:54 PM
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The way I understand it, the wires work somehow like a Theremin: The wire is one plate of the capacitor, a body coming close enough is the second and changes in the capacity are noticable. So how does one avoid becoming the unwilling ground plate of a capacitor? Insulation would be my best guess, but if an isolator (with a permittivity different from the ambient air) comes close enough to the wire, that would still trigger an alarm.
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Cheshyr
post Mar 2 2010, 04:32 PM
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Get an Air Elemental to (compress/remove?) the air around the wire. Changing the dielectric reduces the capacitive coupling, which would reduce the effective range of the sensor.

In real life, the secret would be to change the characteristics of the air around the wire. This might involve changing pressure, or introducing other air-state elements that interfere with capacitive coupling. A de-ionizer might work for a short duration in a small confined room, but air re-ionized extremely quickly.

Shorting a wire makes it's capacitance negligible.

The prudent action would be a socially engineered solution. Multiple false positives during the week, and a little bit of sensor rework during one of these active alarms, followed by entry from an alternate route entirely.
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Karoline
post Mar 2 2010, 04:38 PM
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Given that 'Make a bunch of false positives' seems to be the most common solution, I can't help but think this tech would be more trouble than it is worth for most companies, if placed outside. If they're sensitive enough to pick up a human at 2 meters, I figure changing air pressure, someone in the building turning on or off the lights, and tons of other things are going to give this thing constant false positives.

I figure you're mostly going to encounter this in the underground complex at the end of a corridor that no one is ever supposed to go down to without clearing it with security first and so on. Basically you'll only encounter this on the most high security areas of the most high security facilities.

And as someone said, this is all the pervue of the infiltration skill. Just because we can't think of something that would work doesn't mean our characters trained in infiltration wouldn't be able to figure something out.
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hobgoblin
post Mar 2 2010, 05:03 PM
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i envision a micro-drone with alligator clamps and such (IMG:style_emoticons/default/wink.gif)
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nezumi
post Mar 2 2010, 05:52 PM
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QUOTE (Karoline @ Mar 2 2010, 11:38 AM) *
Given that 'Make a bunch of false positives' seems to be the most common solution, I can't help but think this tech would be more trouble than it is worth for most companies, if placed outside. If they're sensitive enough to pick up a human at 2 meters, I figure changing air pressure, someone in the building turning on or off the lights, and tons of other things are going to give this thing constant false positives.


The only cases you're going to use it are:
1) Low traffic areas (especially in conjunction with another form of automated security, such as keycodes or cameras).
2) As a method of defeating invisibility
3) As a time-based control (the building closes at 6pm, so any cars that park in the lot at 7 should be logged and reported to security).
4) To monitor a large stretch of fence in a low-traffic area, especially in conjunction with other automated recon devices, or dispersed patrols (such as at a border fence - it's just too far to monitor with cameras. So monitor it all with this line, then you have drones or patrols who are already out there, doing nothing but patrolling or droning, mark that point as their next stop - not as a full security hustle.) This one expects 99% of reports to be false positives, and operates on that assumption.
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Draco18s
post Mar 2 2010, 06:52 PM
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Not to mention that if all* the sensors report a reading at the same time or within fractions of a second of each other, you can ignore them: its environmental.

*Realistically, more than 30
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Neraph
post Mar 2 2010, 09:20 PM
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QUOTE (Karoline @ Mar 2 2010, 10:38 AM) *
And as someone said, this is all the pervue of the infiltration skill. Just because we can't think of something that would work doesn't mean our characters trained in infiltration wouldn't be able to figure something out.

Exactly. Like a Threshold 3 or 4 (working off the SR4 Thresholds).
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Daylen
post Mar 2 2010, 10:22 PM
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I expect it to be the on switch at the top of a meat grinder.
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