3,252 research outputs found
Digital seismo-acoustic signal processing aboard a wireless sensor array for volcano monitoring
This work describes the design and implementation of a low cost wireless sensor array utilizing digital processing to conduct autonomous real-time seismo-acoustic signal analysis of earthquakes at actively erupting volcanoes. The array consists of (1) three sensor nodes, which comprise seismic and acoustic sensors, (2) a GPS-based time synchronization node, and (3) a base receiver node, which features a communication channel for long distance telemetry. These nodes are based on the Moteiv TMote Sky wireless platform. The signal analysis accomplishes Real-time Seismic-Amplitude Measurement (RSAM) and Seismic Spectral-Amplitude Measurement (SSAM) calculations, and the extraction of triggered arrival time, event duration, intensity, and a decimated version of the triggered events for both channels. These elements are fundamental descriptors of earthquake activity. The processed data from the sensor nodes are transmitted back to the central node, where additional processing may be performed. This final information can be transmitted periodically via low bandwidth telemetry options
Earthquake Early Warning and Beyond: Systems Challenges in Smartphone-based Seismic Network
Earthquake Early Warning (EEW) systems can effectively reduce fatalities,
injuries, and damages caused by earthquakes. Current EEW systems are mostly
based on traditional seismic and geodetic networks, and exist only in a few
countries due to the high cost of installing and maintaining such systems. The
MyShake system takes a different approach and turns people's smartphones into
portable seismic sensors to detect earthquake-like motions. However, to issue
EEW messages with high accuracy and low latency in the real world, we need to
address a number of challenges related to mobile computing. In this paper, we
first summarize our experience building and deploying the MyShake system, then
focus on two key challenges for smartphone-based EEW (sensing heterogeneity and
user/system dynamics) and some preliminary exploration. We also discuss other
challenges and new research directions associated with smartphone-based seismic
network.Comment: 6 pages, conference paper, already accepted at hotmobile 201
Data aggregation in wireless sensor networks
Energy efficiency is an important metric in resource constrained wireless sensor networks (WSN). Multiple approaches such as duty cycling, energy optimal scheduling, energy aware routing and data aggregation can be availed to reduce energy consumption throughout the network. This thesis addresses the data aggregation during routing since the energy expended in transmitting a single data bit is several orders of magnitude higher than it is required for a single 32 bit computation. Therefore, in the first paper, a novel nonlinear adaptive pulse coded modulation-based compression (NADPCMC) scheme is proposed for data aggregation. A rigorous analytical development of the proposed scheme is presented by using Lyapunov theory. Satisfactory performance of the proposed scheme is demonstrated when compared to the available compression schemes in NS-2 environment through several data sets. Data aggregation is achieved by iteratively applying the proposed compression scheme at the cluster heads. The second paper on the other hand deals with the hardware verification of the proposed data aggregation scheme in the presence of a Multi-interface Multi-Channel Routing Protocol (MMCR). Since sensor nodes are equipped with radios that can operate on multiple non-interfering channels, bandwidth availability on each channel is used to determine the appropriate channel for data transmission, thus increasing the throughput. MMCR uses a metric defined by throughput, end-to-end delay and energy utilization to select Multi-Point Relay (MPR) nodes to forward data packets in each channel while minimizing packet losses due to interference. Further, the proposed compression and aggregation are performed to further improve the energy savings and network lifetime --Abstract, page iv
- …