Bio-Inspired Covert Active Sonar Strategy

Abstract

The covertness of the active sonar is a very important issue and the sonar signal waveform design problem was studied to improve covertness of the system. Many marine mammals produce call pulses for communication and echolocation, and existing interception systems normally classify these biological signals as ocean noise and filter them out. Based on this, a bio-inspired covert active sonar strategy was proposed. The true, rather than man-made sperm whale, call pulses were used to serve as sonar waveforms so as to ensure the camouflage ability of sonar waveforms. A range and velocity measurement combination (RVMC) was designed by using two true sperm whale call pulses which had excellent range resolution (RR) and large Doppler tolerance (DT). The range and velocity estimation methods were developed based on the RVMC. In the sonar receiver, the correlation technology was used to confirm the start and end time of sonar signals and their echoes, and then based on the developed range and velocity estimation method, the range and velocity of the underwater target were obtained. Then, the RVMC was embedded into the true sperm whale call-train to improve the camouflage ability of the sonar signal-train. Finally, experiment results were provided to verify the performance of the proposed method.

Whistle detection and classification for whales based on convolutional neural networks

“…Compared with the existing methods presented in Section 1, the proposed method shows a better classification performance for both whale species. Moreover, although the proposed method is used here for whistle detection and classification of only killer whales and long-finned pilot whales, it is not limited to this application and can be easily adapted for other whale or dolphin species that can produce whistles or other sounds; it can also be employed to perform some preliminary work in passive acoustic observation applications for whale or dolphin species, such as range and seasonal occurrence measurement, abundance estimation, and population structure determination, together with some bio-inspired underwater detection or communication systems [32][33][34][35][36][37][38][39].…”

Acoustic projectors make covert bioacoustic chirplet signals discoverable

“…In the same way biomimicking communications help covertness, the playback of sperm whale songs can help active sonars remain undetected. While Jiang et al propose to employ sperm whale call pulses as a sonar signal 16 , Sun et al 17 re-engineer a sperm whale click sequence through time hopping and frequency hopping, in order to disguise sonar-like sequences with better detection properties amidst actual (played back) click sequences. The approach of Liu et al 18 combines biomimicking communications and low-probability of detection principles by superimposing a whale sound to an information-carrying direct-sequence spread spectrum (DSSS) signal.…”

“…Our work informs biomimicking system design based on engineered as well as played-back animal sounds by evaluating how the emitted signals really resemble natural sounds. In fact, time-based signal modulations 10 , 17 , 19 , frequency-based modulations 9 , 13 , and even direct playback 12 , 16 can be put in jeopardy if the last element of the transmitter chain (i.e., the transducer) exposes the emitted signal as a non-natural one.…”

A Bioinspired Twin Inverted Multiscale Matched Filtering Method for Detecting an Underwater Moving Target in a Reverberant Environment

“…As mammal sounds are ubiquitous in nature, they can be used as carriers for covert detection signals. Jiang designed a target range and velocity measurement combination (RVMC) method by using two true sperm whale call pulses which had an excellent range resolution (RR) and large Doppler tolerance [6]. They used true call pulses to ensure the camouflage ability of sonar waveforms.…”