An apparatus and method for reducing interference over a common communication medium, wired or wireless is provided. At least one depression is formed in the outside wall of the pump to strengthen the wall. The radial waveguide distributes signals between the first signal coupling locus and the second signal coupling loci. The engaging clamp provides a stronger, more reliable mechanical connection between the printed circuit board assembly and the RJ connector. This position is a parallel translation error. A first one-way ratchet wheel is mounted at a bottom end of the driving axle.