Biologically inspired direction‐finding for short baseline

Abstract

The optimal implementation for a biologically inspired coupling structure to overcome the limitation of short baseline direction-finding is determined. This approach is inspired by the Ormia ochracea, a parasitoid insect living in North America. It can locate the crickets’ call accurately with the very small distance between its ears far beyond the accuracy of an interferometer with the same baseline. This outstanding performance depends on the mechanical coupling in its auditory system. The first research focus is on the mechanism of the coupling structure, considering not only the amplification on phase difference but also the effect on output power, which leads to the performance improvement in comparison with the traditional method. Then, the biologically inspired coupling structure is optimised to achieve the best direction-finding performance in crickets’ sound frequency, reducing the estimation error by 75% when the signal incident at boresight. To implement the actual coupling structure with optimal direction-finding performance, both the analogue circuit and the digital filter implementation are discussed, and the latter attains the theoretical optimal performance. Finally, a direction-finding system prototype is carried out to verify the advantage of digitally implemented coupling structure, and the measurement result approximates the corresponding Cram e ́ r–Rao lower bound.