Abstract
Traditional bearing estimation systems exploit relative time delays across an array of sensors to localize a target. While highly effective, such systems are costly and cumbersome. Yovel et al. (Science, 2010) found that bats steer their echolocation beams off axis to maximize the Fisher information, implying that spectral magnitude cues improve target localization. This presentation shares experiments demonstrating a man-made system estimating a target's bearing from echo spectrum magnitude-information using a single directional sensor with frequency dependence over the bandwidth of the signal. The output of a 31-element microphone array steered to broadside serves as the frequency dependent directional sensor. Moving a source transmitting a linear FM chirp across a range of angles estimates the beampattern of the receiver. Maximum likelihood estimation using these recorded replicas gives the mean-squared error (MSE) as a function of angle. The MSE is compared with the Cramer-Rao lower bound. Moving away from broadside reduces the received SNR, but paradoxically the MSE exhibits local minima. These MSE local minima are consistent with the optimal angles observed in previous research simulating the impact of magnitude cues (Kloepper et al., JASA-EL, 2018; Tidwell et al., IEEE SSPD, 2019). [Work supported by ONR MURI Program.]