Transmission of underground or underwater measurements - to surface receivers, e.g. for underground gas storage

摘要

Transmission of information from a buried or submerged body e.g. a metal pipe incorporated in a wall or pipeline for the storage or transport of combustible gas and pref. of very great length relative to its transverse dimensions, with a conducting surface imperfectly insulated w.r.t. to the surrounding medium is by (a) applying a p.d. between two longitudinally spaced points on the conducting surface, modulated as a function of the information to be transmitted in such a way that the body, behaves as a dipole of variable electrical moment generating a quasi-stationary system of equipotential surfaces in the surrounding medium, and (b) detecting the potential thus induced between two spaced points and de-modulating its variations to recover the transmitted information.