IDBR: Bat-mounted Recording and Wireless Transmission of Ultrasonic Calls

蝙蝠的声学通信和回声定位是动物界中最复杂和技术上最令人印象深刻的感觉能力之一。对蝙蝠的研究对于深入了解这些能力以及了解蝙蝠作为农业害虫的捕食者和传染病媒介的作用是重要的。具体地说，分析蝙蝠用于觅食和交流的声学信号对于了解它们的群落结构、狩猎模式和潜在的信号处理能力是必要的。然而，在自然环境中研究蝙蝠叫声的努力受到地面记录设备的限制。由于它们的身体很小，大多数蝙蝠无法携带现有的超声波记录仪器。因此，到目前为止，所有的研究都是在人工实验室条件下使用固定记录设备进行的，或者在野外使用地面记录设备进行的，通常是固定的。这两种方法都有各种严重的缺点。超声波信号是特定于环境的，变化迅速，距离很短，因此固定的记录设备不会捕捉到蝙蝠观察到的相同信号。实验室条件不能模拟复杂的自然环境。在使用地面录音的情况下，通常不可能区分个别蝙蝠的叫声。目标昆虫反射的回声通常太微弱，地面记录设备无法检测到。因此，地面设备获得的信息必然是不完整的。随着最近电子技术的进步，各种各样的微型传感器已经成为可能。该项目将包括开发安装在蝙蝠身上的微型超声波记录设备，用于记录飞行过程中的呼叫和回声。最终的设计将利用定制集成电路(IC)来实现系统总重量在1克以下。该项目将产生一种不同于任何现有仪器的声学监测设备。通过将蝙蝠与换能器之间的距离从几个10‘S米减少到几厘米，本项目开发的仪器将实现信号质量比现有地面记录技术提高几个数量级。此外，目前由于信号衰减而不可行的更远距离的蝙蝠的记录将使用拟议的仪器来实现。安装在蝙蝠上的记录器还将使信号从单个蝙蝠中分离出来，并能够在相当长的距离内跟踪单个蝙蝠。此外，本文的研究还将对超低功耗无线仪器的设计和集成电路设计起到一定的推动作用。该项目提供了在BAT研究方法方面取得突破的潜力。通过使用拟议文书获得的知识将为蝙蝠之间的交流提供重要的见解，这些交流与蝙蝠作为农业害虫捕食者的作用有关，并与公众对蝙蝠作为病媒的作用有关的关注有关。这也将有助于了解蝙蝠的超声波传感能力。该项目中开发的仪器还将用于各种其他科学调查，例如研究鸣禽的歌唱学习或人类婴儿的语言习得。该项目的跨学科性质将为研究生和本科生提供一个在生物学和电子学的交叉点工作的机会。将所提议的电路集成到一个完整的记录系统中，将在处理复杂的片上电子系统方面提供宝贵的实际经验。

Project AbstractThe acoustic communication and echolocation of bats are among the most sophisticated and technically impressive sensory capabilities in the animal world. The study of bats is important to gain insight into these capabilities as well as to understand the roles of bats as predators of agricultural pests and vectors of infectious disease. Specifically, analysis of the acoustic signals used by bats for foraging and communication is necessary to understand their community structure, hunting patterns, and the signal processing underlying their capabilities. However, efforts to study bat calls in natural settings have been limited by the constraints imposed by ground-based recording equipment. Because of their small body sizes most bats are incapable of carrying existing ultrasonic recording instruments. Therefore, all studies to date have been conducted either in artificial laboratory conditions with fixed recording equipment, or in the wild with ground-based, typically stationary, recording equipment. Both methods have a variety of serious shortcomings. Ultrasound signals are context-specific and vary rapidly and over short distances, so a fixed recording device will not capture the same signals observed by a bat. Laboratory conditions cannot mimic the complex natural environment. With the use of ground-based recordings it usually is not possible to separate the calls made by individual bats. The echoes reflected from targeted insects often are too faint to be detected by ground-based recording equipment. As a result, the information obtainable by ground-based equipment is necessarily incomplete. With recent advances in electronics technology, a wide variety of miniaturized sensors have become possible. This project will include the development of miniaturized ultrasonic recording devices to be mounted on bats for recording calls and echoes during flight. The final design will utilize a custom integrated circuit (IC) to achieve a total system weight under 1 g. This project will result in an acoustic monitoring device unlike any existing instrument. By reducing the distance between the bat and the transducer from a few 10's of meters to a few centimeters, the instrumentation developed in this project will realize an improvement in signal quality of several orders of magnitude compared to existing ground-based recording techniques. Furthermore, recordings of more distant bats that are currently infeasible due to signal attenuation will be made practical with the proposed instrument. A bat-mounted recorder will also enable separation of signals from individual bats and the ability to follow an individual bat over a significant distance. Additionally, the proposed research will advance the design of ultra-low-power wireless instrumentation and integrated circuit design. This project offers the potential to introduce a breakthrough in methods for bat research. The knowledge gained through the use of the proposed instrument will provide important insights into communication among bats that are relevant to the role of bats as predators of agricultural pests and to public health concerns regarding bats' role as disease vectors. It will also contribute to the understanding of bats' ultrasonic sensing capacities. The instrumentation developed in this project will also be useful for a wide variety of other scientific investigations, such as the study of song learning in songbirds or language acquisition in human infants. The interdisciplinary nature of the project will provide an opportunity for graduate and undergraduate students to work at the intersection of biology and electronics. The integration of the proposed circuits into a complete recording system will provide valuable practical experience in working with complex electronic systems-on-chip.