Patent ID: 6173107
Filing Date: 2001-01-09
Classification: G02B

Abstract:
A method of upgrading a communications route between a first ode and a second node remote from the first, a duct extending from the first node to the second node and the duct containing a first transmission line which extends between the first and second nodes, the method comprising the steps of:attaching a supply of compressed gas to the duct at the first node; flowing gas from said supply of compressed gas along the duct from the first node to the second node to cause viscous drag forces to act on the first transmission line, and withdrawing the first transmission line from the duct under the action of said viscous drag forces; introducing a second transmission line into the duct at one of the nodes, supplying compressed gas to the duct at said one of the nodes to cause a flow of gas between said one node and the other node; and advancing the second transmission line from the one node to the other node under the action of viscous drag forces caused by the action on the second transmission line of gas flowing from said one of the nodes towards the other of said nodes; the second transmission line having a larger bandwidth that that of the first transmission line.