They snap on the wires, they are called chokes. You see these doohickies on lots of controller type stuff. If you have sony handy cam or digital camera it's on that too. The USB to Camera cable.

But this is only if you think it's noise, which it certain can be.

Here is one for Coax. But they make lots of sizes.

http://www.radioshack.com/product.as...t%5Fid=273-105