An apparatus and method for estimating a carrier-to-interference-and-noise ratio of a received signal in an orthogonal frequency division multiplexing system are provided. The method includes extruding a plurality of beams and a plurality of couplers that are loosely assembled together to a fixture having locating pins that are received in pockets formed on the couplers and securing the beams and couplers together to form a chassis. As a result, the technique is able to use correlation data from the multiple hydrophones, in order to detect a fault.