First Year Performance Paper - Section 2.3.4
The cable system was designed to maintain a Faraday shield around the system and to provide optimum performance subject to constraints imposed by the conditions of delivery and deployment.
The cable system consists of the following main components: Surface to DOM Cable Assembly, Surface Junction Box Assembly, IceTop Cables, Surface Cable Assembly and Counting House Cable Assemblies. The cables meet at the Surface Junction Box, which is made of stainless steel and has a removable lid. The Surface to DOM Cable Assembly is the largest and longest cable in the system. It provides power and communications to the DOMs and all other In-Ice sensors from the Surface Junction Box. To reduce the weight and cost of the cabling, each pair of adjacent DOMs communicates with the surface over a single twisted pair. Two twisted pairs are combined to form a "quad". The cable is 2540 meters in length, contains 18 quads, four bundles of 3 twisted pairs, and two 25 kN strength members. One of the strength members runs down the center of the cable and the other is woven into the outer sheath.
There are 30 breakouts, each providing two connection points for DOMs. A breakout is made by slicing open the outer sheaths of the cable, cutting quads and service wires, attaching the wires to connectors, and re-sealing the cable. The connectors used for DOM connections are waterproof to 10,000 psi (680 atm). For the connections on the Surface Junction Box end of the cable, the quads and twisted pair bundles are attached to military specifications, round, metal shell connectors.
Since the DOMs all communicate independently, cross-talk is a potential source of errors in communication and timing. Cross-talk suppression requires careful mechanical assembly of the cable, as mechanical asymmetries or imperfections in the twisted quad configuration introduce cross-talk. Care is also required during deployment to avoid distorting the cable elements. The requirements for the cable are that near-end and far-end cross-talk be suppressed by more than 50 dB and 30 dB, respectively.