Communication Needs

Is there a way to scan for fibre optic cable that has been laid in the ground?

I have looked and work in construction /night watch and so far only able to find pipes or things with metal detector problem is fibre optics are ussualy laid without any metal good and bad since impossible to find atleast so far that I know. I have an idea for using laser to detect by using pulse but looking if there is already a design out there I just not finding thanks. lol i am in planning designs and research but so far u can call any company and hey dont know were their own lines are 90% of the time and the m-scopes we use are like 15k and they dont pick up the cables at all picks up a pipe though and anything else that has slightest bit of metal. thanx for answers and if u have idea's would love to hear like i said currently trying to design since i Cannot find any product out there to find fibre optic cable thats in the ground-work gas pipeline so we dig alot thanx will have to look into the radar i think it may disrupt the cabel signals though and lol trying not to do that or cut them up but just wish they knew were they were laid takes them forever so we just ussually get clearance to dig and if we break we fix like ussual we have a metro tech that u connect to a coper wire that goes down to the wire but when this is not present there is no way to find it beside wait for company or dig slow and dont break it. so far the dopplar radar looks like it might be of use how about a frequency finder since if it has information sending through it wont it have a frequency I have extended the closing on this since yet to get post saying there is a patent out there on anything to find them without connectiong to a lead wire. I thank all of you for your answers and time in this matter. I have much to think about thank you ^v^

Public Comments

1. How is a laser going to penetrate ground, and in any case you would need to connect the light through the cable to see it at the other end of the cable. Just hitting laser light on the casing of a F.O. cable is not going to do much. I think you need to think this through a bit more. F.O. cables are usually laid down by telecommunications companies, so you have to write to them and ask for any plan prints of their cables in the area you are working in.
2. there is wire in the cable shielding it from stones and stuff that will cut it and making it able to be pulled through the dirt or the conduit. so it can be found by metal detector but it is very hard since the wire is not heavy gauge like a copper power wire. you could use ground radar if you can get it to go that deep.?
3. Maybe a Doppler radar kind of device instead of laser?
4. Usualy a locator cable is burried with ther fiber optic cable. THe copper wire of the locator cable is available at both ends of the run to be connected to a radio transmitter. The copper wire then acts as a broadcast antenna and a detector can then follow the signal along the path where the cable is burried. For break detection of a fiber optic cable a OTDR (Optical Time Domain Reflectometer) uses a laser pulse that travels down the cable. Imperfections in the cable cause a reflection and the time of flight gives a distance to the disturbance.
5. I think that metal detectors could have problems simply because the fiber is buried deep, and as another answer says, when there is metal it may be just a drain wire so there isn't much of it. There are often copper wires in a fiber cable too. These can be located with a normal cable tracer for telephone wire cables where practical. As armour is often inside the outer plastic sheath and so insulated, it could be used for some kind of AC signal tracing with a ground return. It might even work if it is not insulated, just limited range. There is little point trying to use laser light or signals in the fiber which are strongly confined to the fiber itself. The ground radar measures electrical and magnetic properties of the soil. It is most unlikely to cause any damage. It is looking for soil disturbances, especially where someone has back filled a trench with different materials. You may have seen them on TV used with archeology. Doubt they are cheap. Unfortunately a lot of fiber is laid with a mole-board plough, minimal disturbance. It seems strange that there are no proper records of cable locations etc. Maybe the owner of a building doesn't know, but someone probably does, the company providing the cable. Finding gas distribution pipes (those small high pressure plastic pipes only about 6mm diameter) must have similar issues. Maybe you can hear the gas flow with a sensitive microphone on a quiet day.