A remotely controlled, traction wheel driven, transporter moves inspection equipment within a walled cavity to check internal structural features. The mold comprises a cylindrical wall connected to a bottom wall to define a hollow, unitary cylindrical container for receiving concrete to form a test specimen. The control unit in the communication system utilizes the knowledge to schedule the data transmission without the need for the subscriber station to transmit to request schedule for the transmission. The apertures may be preformed or formed after a layer of the material of which the solder mask is comprised has been disposed on the substrate.