The influence of flight speed on the ranging performance of bats using frequency modulated echolocation pulses

Many species of bat use ultrasonic frequency modulated (FM) pulses to measure the distance to objects by timing the emission and reception of each pulse. Echolocation is mainly used in flight. Since the flight speed of bats often exceeds 1% of the speed of sound,Doppler effects will lead to compression of the time between emission and reception as well as an elevation of the echo frequencies, resulting in a distortion of the perceived range. This paper describes the consequences of these Doppler effects on the ranging performance of bats using different pulse designs. The consequences of Doppler effects on ranging performance described in this paper assume bats to have a very accurate ranging resolution, which is feasible with a filterbank receiver. By modeling two receiver types, it was first established that the effects of Doppler compression are virtually independent of the receiver type. Then, used a cross-correlation model was used to investigate the effect of flight speed on Doppler tolerance and range–Doppler coupling separately. This paper further shows how pulse duration, bandwidth, function type, and harmonics influence Doppler tolerance and range–Doppler coupling. The influence of each signal parameter is illustrated using calls of several bat species. It is argued that range–Doppler coupling is a significant source of error in bat echolocation, and various strategies bats could employ to deal with this problem, including the use of range rate information are discussed.

‘Ngulluck Katitj Wah Koorl Koorliny/ Us mob going along learning to research together’ : drawing on action research to develop a literature review on Indigenous gendered health and wellbeing

This paper describes the collaborative work practices of the Health and Wellbeing Node within the National Indigenous Research and Knowledges Network (NIRAKN). The authors reflect on the processes they used to research and develop a literature review. As a newly established research team, the Health and Wellbeing Node members developed a collaborative approach that was informed by Action Research practices and underpinned by Indigenous ways of working. The authors identify strong links between Action Research and Indigenous processes. They suggest that, through ongoing cycles of research and review, the NIRAKN Health and Wellbeing Node developed a culturally safe, respectful and trulycollaborative way of working together and forming the identity of their work group. In this paper, they describe their developing work processes and explain the way that pictorial conceptual models contributed to their emerging ideas.