| 摘要 |
A toneable conduit including an elongate polymeric tube having a sidewall with an interior surface and an exterior surface. The interior surface defines a main channel. A sub-channel, smaller in cross sectional area than the main channel, extends longitudinally between the exterior and interior surfaces of the tube. A continuous toning signal wire is located within the sub-channel. The sub-channel has a larger cross sectional area than a cross sectional area of the toning signal wire and the toning signal wire follows a zigzagging or undulating path within the sub-channel. Alternatively, the sub-channel and toning signal wire have a substantially common cross sectional area and both follow a zigzagging or undulating path from one end of the toneable conduit to the other end. In both embodiments, a given length of toneable conduit will include a length of toning signal wire exceeding that given length. |
