Waterproof signal cable structure

A waterproof cable 1 comprising: a set of twisted pair (11, Fig. 3) strands 10, the twisted pairs enclosing a centre portion 100; an outer insulation tube 20; an outer ring portion 101 defined between the outer insulation tube and the set of strands; and a water swellable powder 30 distributed in the outer ring portion. The water swellable powder may be: a super absorbent polymer obtained by polymerizing acrylates; evenly distributed in the outer ring portion; or distributed along an outer peripheral surface of the set of strands in a direction of longitudinal extension by an electrostatic powder machine. The twisted wires 12 may comprise four pairs be arranged in a ring to define the centre portion 100. Each of the wires may comprise a signal core wire 121 and insulation layer 122. The outer insulation tube may be comprised of polyvinyl chloride or thermoplastic elastomer. A cross-shaped spacer 40 may be disposed between each of the twisted pairs