that was post #19 after much asking and there is still a lot of information missing.
Well, what is a single wire “used in pairs”? This must be a trick question similar to the sound of one hand clapping.
I insist there is just too much information missing here. The answer is that you cannot send a usable signal using one wire. You might as well use radio.
If then we want to continue the investigation we need more information.
There is NO need to keep it vague. The question is perfectly simple and to think some bad guy can use this to do bad things is silly. This is pretty much like asking “can I turn on a light using just one wire?” or “how can I learn Chinese?” or “how can I sharpen a knife?”.
Very true
In that case you understand the basics already.
Here I begin to have trouble with what you are saying. A “thread-thick uninsulated copper wire” is not going to be visible at any significant distance and I doubt it can be strung reliably “across great distances”.
If you take thin copper wire used in windings it is insulated with special varnish. You can probably not tell at first sight if it is insulated or not and you would have to hold it in your hand to know whether there are one or more strands. Anything visible from a certain distance and which can be reliably strung “across great distances” is thicker than you think and can well have more than one conductor.
No need to be vague. This is so basic it is pretty much high school project stuff. I guarantee the insurgents know all this well.
Most probably you are just assuming bad information. Get a sample of the wire and give us reliable information and we can give you much better responses.
I’ve held the wire in my hand. it is a single strand no thicker than fishing line. If it is insulated, it is either from some shellac as suggested or from a thin layer of oxydation described upthread. There is no apparent insulation on this wire.
The “single wire used in pairs” is not an oxymoron. If your run your lead wire via one path out the front of a house, and your return wire goes an entirely different direction and loops all the way around and comes back through the rear of a house, then a person could easily only notice one single, isolated wire.
What information is missing? Can a device send a signal across a single strand of copper wire or not? It’s pretty cut and dry.
Is there a set up that doesn’t involve ground stakes which will allow a low voltage current to travel across a single wire? If so, what is involved in such a set up? Some kind of capacitor? Some kind of current spike at one end that causes a noticeable change in the wire itself on the other end?
Now, most likely, they never were using a single wire. It was just a dual wire system with an unnoticed or undetected second wire. If that’s the case, the mystery is solved.
However, the original question of the OP is still valid. The question is that of electrical engineering and not necessarily IEDs. Can such a set up using one single wire be made simply, and inexpensively? Is it something highschool-project simple. Or does it require and advanced understanding of resistance, capacitance, etc…
Or is it simply impossible without ground stakes and other such complicated stuff?
There is a somewhat obscure type of microwave (theoretically possible, but not practical at longer wavelengths) transmission line known as G-linethat consists of a single insulated conductor. Signals are launched onto the wire using a horn antenna at each end. Only very large radius bends may be accomidated, to the point that catenary sagging of the wire by gravity may be a problem. If the wire can be kept straight enough, though, G-line is reputed to have very low loss.
Additionally, microwave waveguides consist of one conductor with a peculiar cross section.
Finally, it is possible to build a waveguide with a just a dielectric rod…no conductor at all. Optical fibers are a short wavelength example.
I suppose IEDs can be set off by radio but that it is less reliable as western vehicles carry jamming devices. Using DC and a couple of wires would be much more reliable but also more difficult to set up and more easily detected (I do not know if the cost would come in as an issue).
A single thin wire would be good as it is cheap, easy to set up and not so easy to detect. I suppose you might try something intermediate between DC and radio. Maybe something like a few Khz could be sent down the wire reliably enough to be used. Still, it would depend on the distance and other factors. The wire is going to act as an antenna and will radiate power but it should not be a problem is sufficient power is pumped in. The other problem is that the wire would act a a receiving antenna and if precautions are not taken could signal at the wrong time. But it is easy in electronics to design some protection. Phone DTMF tones are exactly designed for this type of redundancy.
If I had to start working on such a project I would test something like DTMF modulating a carrier of some tens of Khz. I think it might work. Then it would be a question of improving the design for optimum performance.
Coincidentally I have been thinking of something similar for some time now. I have a friend who lives out in the middle of nowhere and would like to have some warning when a car enters the road leading to the house. Setting up the car detection is extremely easy with a loop buried under the road but sending the signal to the house is a bit more tricky. It is a long distance and wire is out of the question. It is going to have to be radio but I am thinking there has to be some kind of cheap, standard, ready-made, remote control which we can use rather than having to design and build something specifically for this. Luckily we do not have to worry about radio jammers from enemy forces. Or at least not yet.
I guess you had a 50/50 chance of being right, but you’re not. I did indeed read the thread; posting would be pointless otherwise.
At no point has Bear or anybody said they’ve found the other end of the wire, determined what it’s attached to and proven there is no ground stake. I was suggesting that as the technology for a single wire with ground return has been around for years, it’s not unlikely that IED planters would know about it.
Hard to say. If the distance you’re talking about is prohibitive from a direct connection standpoint, most off the shelf radio equipment might not have the power, anyway, to comply with FCC regs. I mean in the “FM/AM” sense. Surely there are powerful enough remote controls, but rigging them to conserve energy might be problematic, though triggering a buzzer would be trivial at the house end. Ideally you’d use a solar cell and battery setup. Is it the length of the wire you’re concerned with (e.g., use fiber?) or the work involved in laying so much cable of any kind?
It is not practical to string anything, fiber or wire, all the way. The idea would be to send a burst of RF when a car is detected. There is no need for permanent transmission. Actually it would be the car-detecting coil what would be consiming energy all the time, even if very little.
AS for the signalling, this is in the middle of nowhere and not in the USA and, as I say, it would be a very infrequent burst of RF which would not last over one second so I doubt licansing would be a problem.
Building an AM transmitter which sends a carrier modulated by a couple of tones is trivial and detecting the signal is also easy. But it is for a friend and I am too lazy to do it from scratch. I might wait until I see some remote control which might work. Even a low power RF remote might work if fit with a suitable antenna or further amplification. I am thinking a garage-opener type remote. In fact I have some such remotes but I am even to lazy to go and do some testing to see how they perform and how their range could be improved.