The WQC-6, a communications transducer for Trident Submarines, was designed and built for the Navy by Active Signal Technologies and is shown in the Figure below.
Its operating band is the WQC low frequency band, but it also covers the UQC band, making it a dual purpose transducer. The critical element of the design is the shell material for this Class IV transducer which is a graphite composite shell that enables a broader band response without sacrificing power and efficiency. The unit was tested for qualification purposes at Dodge Pond using shells from a new vendor and clearly retained its depth, power, and bandwidth capability. Specifically, it was tested using the acoustically transparent tank to be uniformly responsive from the surface to 330 PSI, survive to 440 PSI and return to normal operation after hydrostatic testing. It also had to develop 200 dB without stressing the ceramics to 7 V/mil, and had to have a Q of approximately 4 at resonance which is approximately 2 kHz.
The enabling technologies for most of the Active Signal devices have their roots in the members’ background in the transducers and materials groups in Martin Marietta and the later Lockheed Martin Corporation. The focus of these transducer initiatives was the development of the highest power density devices for a particular application. Since the governing elements are the driving materials, the engineering and technical team focused on materials such as Terfenol-D and PMN. During the course of transducer development, devices using these materials were produced for the Navy for submarine Noise Augmentation purposes, for the Woods Hole Oceanographic Institute, for advanced littoral water applications for the Navy, and as described above for the Trident submarine fleet. These devices have been tested as surface units, but also, where necessary, operated at depths to 5000 ft with proper depth compensation systems. While Active Signal continues to build transducers in small numbers, its focus has shifted to transition the technology to ultra high sensitivity and ambient noise immune medical devices.