Lessons for Radar

Echolocating mammals such as bats, whales and dolphins have been using waveform diversity for over 50 million years. Synthetic systems such as sonar and radar have existed for fewer than 100 years. Given the extraordinary capability of echolocating mammals it seems self-evident that designers of radar (and sonar) systems may be able to learn lessons that may potentially revolutionize current radar-based capability leading to truly autonomous navigation, collision avoidance, and automatic target classification. Echolocating mammals have been little studied in relation to the operation of radar and sonar systems. In this article, we introduce a range of strategies employed by bats and consider how these might be exploitable in the radar systems of tomorrow. Specifically, we concentrate on the functions necessary for autonomous navigation. Echolocating mammals are known to vary their waveforms via modification to the pulse-repetition frequency (PRF), also known to biologists as pulse-repetition rate (PRR), power, and frequency content of their transmitted waveforms. This has enabled them to evolve highly sophisticated orientation techniques and the ability to successfully forage for food. Moreover, recent developments in technology mean that it is now possible to replicate these parametric variations in synthetic sensing systems such as radar and sonar.

Relationships Between Flight, Echolocation, and Autonomous Navigation

Echolocation and flight occur simultaneously in bats, and flight performance feeds back to influence echolocation signal design. While the former might be true of airborne radar systems, the latter aspect (i.e., feedback) most certainly is not. However, such feedback is part of a truly intelligent system and probably represents one of the major sensor research challenges for the future. It certainly seems to be a key component in determining total system performance. Bats typically produce one call per wing beat when searching for prey or commuting as this minimises the cost of producing energetically expensive sound pulses [5]. Autonomously guided vehicles can obviously be free of this constraint, but must still solve the challenges of separating pulse and echo, either in time (as used by many bats), or in frequency.