Drill string adapter and method for inground signal coupling

An apparatus for use in a system in which an inground tool is moved through the ground in a region for performing an inground operation, said system including a drill rig and a drill string which extends between said inground tool and said drill rig and is configured for extension and retraction from said drill rig, said drill string being made up of a plurality of electrically conductive drill pipe sections for removable attachment to one another and to the inground tool to form a plurality of joints, and said inground tool includes an electronics package for at least one of generating and receiving a data signal relating to the operation of the inground tool, said apparatus comprising:

• a coupling adapter having an adapter body that is removably insertable at one of the joints and said adapter body including a sidewall having a sidewall thickness such that said sidewall defines (i) an annular recess for receiving a current transformer, (ii) an internal passage which provides for said flow of drilling fluid through the adapter at any installed location of the adapter in said drill string and (iii) a sidewall aperture extending through said sidewall thickness and spaced apart from the annular recess on the adapter body;
• and
• a high pressure electrical connector that is received substantially within said sidewall aperture to form an electrical connection that couples the data signal between the inground tool and the current transformer through said sidewall aperture in electrical isolation from the coupling adapter while sealing the drilling fluid within the internal passage of the coupling adapter.