An improved inspection apparatus includes a control apparatus, a tractor apparatus comprising a tractor and a drive mechanism connected together, the drive mechanism being connected with the control apparatus, a tether apparatus disposed on the tractor and being movable between a deployed position and a retracted position, and a buoy apparatus. Audience seating in the theater faces outwardly in an \u201cinverted-theater-in-the-round\u201d arrangement. The cross-chamber maximum refractory value is derived from a peak amplitude measurement of the far-field signal resulting from the cross-chamber event. The phase array circuitry generates multiple saw tooth signals according to the code signal.