ONR/Hughes High Speed Towed Array System (HSTAS)

During the reporting period (FY 1977), a High Speed Towed Array System (HSTAS) was conceived, designed, and fabricated. The system was successfully sea tested in July of 1977 in Exuma Sound in the Bahamas aboard the R/V Harris. In addition to the test being successful from the point of view of equipment operability at sea, the following program goals were achieved: a) The self noise results revealed that the 6 inch diameter module (FAM) was always quieter than the 3 inch modules, reaching a peak differential of approximately 15 dB in the frequency range between 80 Hz and 250 Hz at 18 knots towspeed. b) The demonstration (at sea) of the ability to eliminate ownship radiated noise interference from beam outputs by means of an adaptive filter employed as a noise canceller. Specifically, in the case of a broadband interfering signal, a maximum cancellation of 15 dB was achieved, while for the narrowband case the cancellation was 18 dB. For this latter effort, the R/V Harris was augmented acoustically by towing the HX-90 noise source.