Alexander Kölpin

From radio telemetry to ultra-low-power sensor networks: tracking bats in the wild

Sensor networks have successfully been used for wildlife monitoring and tracking of different species. When it comes to small animals such as smaller birds, mammals, or even insects, the current approach is to use extremely lightweight RF tags located using radio telemetry. A new quantum leap in technology is needed to overcome this limitation and enable new ways to observe larger numbers of small animals. In an interdisciplinary team, we are working on the different aspects of such a new technology. In particular, we report on our findings on a sensor- network-based tracking solution for bats. Our system is based on integrated localization and wireless communication protocols for ultra-low-power systems. This requires coding techniques for improved reliability as well as ranging solutions for tracking hunting bats. We address the technological and methodical problems related to system design, software support, and protocol design. First field experiments have been conducted that showcase the capabilities of our system.

A sixport receiver's analog front-end for the K-band based on a rapid-prototyped PCB

Within the scope of the research project presented in this paper an alternative architecture to mixing based receivers like hetero- or homodyne receivers is investigated: the sixport receiver. The theoretical aspects of the system concept are shown and the structure of the analog front-end is presented supported by measurement results. The analog front-end is based on a microwave circuit with a carrier frequency of 24 GHz and constructed as a PCB milled by a circuit board plotter

A Six-Port Receiver's Analog Front-End of Reduced Size Based on a Multi-Layer Layout

In this paper a compact front-end of a six-port receiver is presented based on a multi-layer circuit topology. For higher frequencies the six-port receiver architecture offers a good alternative to common receiver concepts. One drawback is the occupied size of the microwave couplers used in the analog front-end depending normally directly on the wave length and is opposed to an implementation of the passive six-port structure on a MMIC. With the results of the investigations presented in this paper a reduction in size of the six-ports transmission line structure of about 79% is achievable. The performance of the proposed multi-layer structure is compared to the common planar topology and shows only slight degradation.

BATS: Adaptive Ultra Low Power Sensor Network for Animal Tracking

In this paper, the BATS project is presented, which aims to track the behavior of bats via an ultra-low power wireless sensor network. An overview about the whole project and its parts like sensor node design, tracking grid and software infrastructure is given and the evaluation of the project is shown. The BATS project includes a lightweight sensor node that is attached to bats and combines multiple features. Communication among sensor nodes allows tracking of bat encounters. Flight trajectories of individual tagged bats can be recorded at high spatial and temporal resolution by a ground node grid. To increase the communication range, the BATS project implemented a long-range telemetry system to still receive sensor data outside the standard ground node network. The whole system is designed with the common goal of ultra-low energy consumption while still maintaining optimal measurement results. To this end, the system is designed in a flexible way and is able to adapt its functionality according to the current situation. In this way, it uses the energy available on the sensor node as efficient as possible.

Comparison of laser safe scanning patterns for second generation LiDAR deflection units

The calculation of the maximum permissible optical energy for two scanning patterns of miniaturized scanning LiDAR systems is presented. The scanning patterns are selected to be suitable for next generation systems based on MEMS mirrors and Optical Phased Arrays alike. Two different wavelengths are compared. Based on the current version of the laser safety standard IEC 60825-1 the maximum energy is determined for the two patterns and two wavelengths. For a wavelength of 1550 nm no differences are revealed. At 905 nm, patterns allowing a large spatial and temporal separation between subsequent measurements are favored.