Designing Linear FM Active Sonar Waveforms for Continuous Line Source Transducers to Maximize the Fisher Information at a Desired Bearing

Abstract

Several authors previously found that echolocating animals aim their sonar beam askew of the target of interest. Analysis found the animals' beam aiming strategy maximized the Fisher Information (FI) about the target bearing encoded in the frequency spectrum of the received echoes by the transmitter's frequency dependent beampatterns. This paper reverses the focus from analysis to synthesis. We present design methods to maximize the FI of the bearing estimate at a desired angle using linear frequency modulated (LFM) waveforms transmitted by a continuous line source (CLS) transducer. If the center frequency of the transmitted chirp is sufficiently larger than the bandwidth, the angle maximizing the bearing FI is solely determined by the center frequency. Numerical simulations confirm the effectiveness of the proposed methods for several bearings and waveforms.