Matched field processing by using a short vertical array: experimental results in deep water

The detection and localization of a vertical line array against a submerged target, including their hardware implementation technology, have been paid more and more attentions since 1980s. In this paper, matched field processing for moving source by using short vertical array in deep water is presented. During the joint China-Russia Pacific Ocean experiment in October 1995, the 100 m-deep source was towed by one ship at a speed of 6 knots, and transmitted pulsed CW signals of 112 Hz and 406 Hz. The data receiving system was a satellite-buoy underwater measurement system with a 16-element vertical line array. The 16-element vertical array approximately spanned small part of the water column from 200 to 230 m, and the water depth is about 5000 m. The experiment showed that the receiving system could work reliably and stable for a long time, and the data was collected with very good quality. MFP methods are a generalized form of beam-forming, which incorporates the propagation physics directly into the array processing. In this paper, the Bartlett processor is used for the matched-field source localization. The forward model is WKBZ normal mode approach, which is based on the generalized phase integration approximation of eigen-functions. Under the same sound speed structure, source frequency and accuracy, the WKBZ normal mode model has the advantage of less computational time. The distances between the satellite-buoy system and the ship are determined by the satellite GPS system. The matched-field localization results show that the estimated distances between the source and the satellite-buoy system are in good agreement with GPS ranging, and the source is successfully localized at ranges up to 64 km. In addition to the source localization, the measured TL data are in good agreement with the calculated ones based on the WKBZ model.