Development of a Low-Power Underwater NFC-Enabled Sensor Device for Seaweed Monitoring

Seaweed Growth Monitoring with a Low-Cost Vision-Based System

In this paper, we introduce a method for automated seaweed growth monitoring by combining a low-cost RGB and stereo vision camera. While current vision-based seaweed growth monitoring techniques focus on laboratory measurements or above-ground seaweed, we investigate the feasibility of the underwater imaging of a vertical seaweed farm. We use deep learning-based image segmentation (DeeplabV3+) to determine the size of the seaweed in pixels from recorded RGB images. We convert this pixel size to meters squared by using the distance information from the stereo camera. We demonstrate the performance of our monitoring system using measurements in a seaweed farm in the River Scheldt estuary (in The Netherlands). Notwithstanding the poor visibility of the seaweed in the images, we are able to segment the seaweed with an intersection of the union (IoU) of 0.9, and we reach a repeatability of 6% and a precision of the seaweed size of 18%.

Phase Detection and Modulation Improvement for Active Load Modulation during Continuous Transmission

The paper covers one of the communication technologies used in wireless sensor networks. We have presented improvements in existing radio frequency identification (RFID) systems to address the problem of the phase selection in active load modulation (ALM). The phase selection affects the interoperability of communication devices and has to be addressed in the design phase of a new tag. A novel transmission method is presented to make the phase selection irrelevant for device interoperability. A second solution is shown to improve the existing system synchronization, which allows operation with arbitrary selected phase. A mathematical analysis of signals present on the antenna was used together with the reference reader model to perform an analysis of proposed improvements. We proved that the proposed transmission method is less affected by phase selection. Furthermore, we demonstrated that existing system improvement allows synchronization and operation at an arbitrarily selected phase despite the continuous transmission and large signal-to-interference ratio.