Percussive signal transmission tubes, of contrasting color, are joined along adjacent longitudinally extending portions by an adhesive bead of polymeric material. The tubes can be separated in the field and are provided on spools without any sheath. A small diameter (0.10 inch) tube can be used to reduce...http://www.google.de/patents/US7162957?utm_source=gb-gplus-sharePatent US7162957 - Redundant signal transmission system and development method
