Is it possible to use cable shielding as telecomm media?

[tony_lth]

Hi, Gurus,
In power cable failure detection, using a ring to receive patial discharge signal. The receiving band is about 3M~30MHz.
So reversly, i think it is possible to use the ring to transmit 3M~30MHz signal over the cable, thus forming a telecomm TX/RX system.

The system has the following spec:
1. Not using any cable core.
2. No need to destroy the cable.
3. Just use a ring to embrace over the power cable.

Then problem is:
1. Is it possible?
2. If using 20MHz as carrier, and using OFDM & veterbi decoders etc, how far it can transmit?

Best,
Tony Liu

 

[FvM]

Presume you are asking about medium voltage (5 - 20 kV) supply lines because of the shield.

The shield forms a transmission line with earth ground which will be very lossy. Thus I won't expect more than a few 10 to 100 m reach. Nevertheless the system needs to comply with regulations for conducted RF interferences unless you can use a licensed radio band.

 

[tony_lth]

Hi, FvM,
Thanks for the reply.
If using two cable's shielding, the two shielding forms a transmission line, is it possible?
And, is it possible to using some IMS bands on these two shielding?
Best,
Tony Liu

 

[Aussie Susan]

What is the problem you are trying to solve that you think what you describe at the start of this thread is the solution?
The systems I've seen for cable fault finding send a short pulse down the cable and measure the time for the reflection to come back. This uses the fact that the pulse will travel well where the cable is complete but a discontinuity will cause a reflection. I'm not sure that this is necessarily related to a signal of any particular frequency range.
Susan

 

[PlanarMetamaterials]

What hasn't been mentioned here is using non-transmission-line modes. A single cable will support a TM-type mode (ref), which will propagate along a single conductor, unassociated with the ground. Using this system as a communications link is not new (see references on the wiki page).