What if the cable gets cut? - page 7

[Alexey Volchanskiy]

Vitalii Ananev:
If the cable is a government communication cable, it is not so easy to get to it unnoticed. Usually such cable has a special sheath in which there is an airless space and every meter there are sensors. In case of breach of sheathing integrity sensors signalize and the place of breach is easy to detect.

I read how to read information from optical fibre. There are at least 3 ways,

1. The cable is stripped from the sheath to the fiber itself and it is bent to a radius of about 1 cm. At the bend part of the beam comes out

2. The cable is cleaned from the sheath to the fibre, the fibre's reflective layer is peeled off and the reading fibre, also peeled off, is applied to it.

3. The cable is cleaned from the sheath to the fibre itself and the fibre is irradiated with some tricky laser, I'm not a physicist and don't understand the process. The interference is somehow used to capture the data.

[Alexandr Bryzgalov]

Alexey Volchanskiy:

I've read up on how to read a fibre optic. There are at least 3 ways,

1. The cable is peeled back from the sheath to the fiber itself and it is bent to a radius of about 1 cm. At the bend part of the beam comes out

2. The cable is cleaned from the sheath to the fibre, the fibre's reflective layer is peeled off and the reading fibre, also peeled off, is applied to it.

3. The cable is cleaned from the sheath to the fibre itself and the fibre is irradiated with some tricky laser, I'm not a physicist and don't understand the process. The interference is somehow used to capture the data.

All three methods are contact, underwater bending the cable into a half ring with a radius of 1 cm I think will be a problem

[Vitalii Ananev]

Alexey Volchanskiy:

I've read up on how to read fibre optics. There are at least 3 ways,

1. The cable is peeled off the sheath to the fiber itself and it is bent to a radius of about 1 cm. At the bend part of the beam comes out

2. The cable is cleaned from the sheath to the fibre, the fibre's reflective layer is peeled off and the reading fibre, also peeled off, is applied to it.

3. The cable is cleaned from the sheath to the fibre itself and the fibre is irradiated with some tricky laser, I'm not a physicist and don't understand the process. The interference is somehow used to capture the data.

Some kind of tricky soldering iron is used to connect fibre optic cables. But the thing is that for special communications this cable is encased in a sheath, if it gets damaged it will be immediately known. Even if it is not a government communication, I think there is something similar there too, so that if the cable breaks, you can immediately localize the location of the break, instead of crawling all over the cable and looking for the location of the damage.

[Alexey Busygin]

Alexey Volchanskiy:

I've read up on how to read fibre optics. There are at least 3 ways,

1. The cable is peeled back from the sheath to the fiber itself and it is bent to a radius of about 1 cm. At the bend part of the beam comes out

2. The cable is cleaned from the sheath to the fibre, the fibre's reflective layer is peeled off and the reading fibre, also peeled off, is applied to it.

3. The cable is cleaned from the sheath to the fibre itself and the fibre is irradiated with some tricky laser, I'm not a physicist and don't understand the process. The interference is somehow used to capture the data.

So what's the point of plugging in, if before you can even decode the signal, the leakage is eliminated.

[Alexey Volchanskiy]

Vitalii Ananev:
Some kind of tricky soldering iron is used to connect fibre optic cables. But the thing is that for special communications this cable is encased in a sheath which, if damaged, will be immediately known. Even if it's not a special connection, I think there is something similar in it so that if the cable breaks it's possible to localize the point of breakage at once and not to crawl all over the cable and look for the place of damage.

I don't know about fibre, on copper lines they send a nanosecond pulse and measure the reflection time from the break. You can determine the location quite accurately from the time. There will probably be a reflection on the fibre as well?

[Vitalii Ananev]

Alexey Volchanskiy:
I don't know about fibre, on copper lines they send a nanosecond pulse and measure the reflection time from the break. You can determine the location quite accurately from the time. There will probably be a reflection on the fibre too?

I don't know how it's all implemented, it's just my guess.

[Dmitry Fedoseev]

Alexey Volchanskiy:
I don't know about fibre, on copper lines they send a nanosecond pulse and measure the reflection time from the break. You can determine the location quite accurately from the time. There will probably be a reflection on the fibre too?

They shine a laser and you can see the break. What are the intricacies there I don't know.

[Alexey Volchanskiy]

Vitalii Ananev:
I don't know how it's all implemented, it's just my guess.

Here is an article about the spy sub http://habrahabr.ru/post/176687/

Really, it's not clear where do they put the data? You can't send it to a data centre on land, and writing it on a boat and then taking it to a data centre is not good either... it's not clear.