cable communication link (5b) for drill string (6) comprising adapter unions (9) spaced in the drill string (6) and a cable connecting them to communicate a signal therebetween. Cable communication link (5b) may be drill pipe assemblies (8) interconnected in the drill string (6) between adapter unions to form a channeled communication link (5a), the wired communication link (5b) establishing a path to the communications link channeled (5a) for transmitting a signal through the drill string (6). Cable communication link (5b) can be in a non-wired section of drill string (6) disposed between adapter unions (9), cable communication link (5b) establishing a path for transmitting a signal through the non-wired section of drill string (6).