Specific apparatus and associated methods are described for use in establishing the positions of locating field detectors and for path mapping within a region for the purpose of tracking andor guiding the movement of an underground boring tool. The first andor second cartridges are arbitrarily mounted on any one of the first and second carriers. The hydrostatic transmission is also adapted to be mounted to at least one of two opposed side members of the vehicle frame. The ion-exchange stationary media include a hydrolytically stable layer, which inhibits surface degradation of the particles in 100% aqueous media. The armor system may feature materials of different stiffness, strength, and strain-to-failure in each ply or a filler between selected plies, including a filler comprising discrete pieces of fabric ply that fit within the cell periphery of a stitching pattern. A basic building block, the probabilities multiplier circuit, used to implement both check node and probability node update circuits can be implemented using Mach-Zehnder delay interferometer.