A survey of visual sensor network platforms <s> Meerkats <s> We introduce Meerkats, a wireless network of batteryoperated camera nodes that can be used for monitoring and surveillance of wide areas. One distinguishing feature of Meerkats (when compared, for example, with systems like Cyclops [10]) is that our nodes are equipped with sufficient processing and storage capabilities to be able to run relatively sophisticated vision algorithms (e.g., motion estimation) locally and/or collaboratively. In previous work [9, 8, 7] we analyzed the energy consumption characteristics of the Meerkats nodes under different duty cycles, involving different power states of the system’s components. In this paper we present an analysis of the performance of the surveillance system as a function of the image acquisition rate and of the synchronization between cameras nodes. Our ultimate goal is to optimally balance the trade-off between application-specific performance requirements (e.g., event miss rate) and network lifetime (as a function of the energy consumption characteristics of each node). <s> BIB001 </s> A survey of visual sensor network platforms <s> Meerkats <s> In this work we characterize the energy consumption of a visual sensor network testbed. Each node in the testbed consists of a "single-board computer", namely Crossbow's Stargate, equipped with a wireless network card and a Webcam. We assess energy consumption of activities representative of the target application (e.g., perimeter surveillance) using a benchmark that runs (individual and combinations of) "basic" tasks such as processing, flash memory access, image acquisition, and communication over the network. In our characterization, we consider the various hardware states the system switches through as it executes these benchmarks, e.g., different radio modes (sleep, idle, transmission, reception), and Webcam modes (off, on, and acquiring image). We report both steady-state and transient energy consumption behavior obtained by direct measurements of current with a digital multimeter. We validate our measurements against results obtained using the Stargate's on-board energy consumption measuring capabilities. <s> BIB002
The information for Meerkats BIB001 BIB002 is organized under the following headings: Figure 6 shows the hardware architecture of Meerkats BIB001 . The Meerkats testbed consists of Meerkats nodes designated as ordinary VSN nodes and a laptop acting as a data sink. Meerkats nodes are built on top of a Crossbow Stargate platform [10] , which features a CPU operating at 400 MHz with 32 MB FLASH memory and 64 MB RAM on the main board. The camera can capture VGA (640×480) quality image frames. The communication module is an Orinoco Gold IEEE 802.11b PCMCIA wireless card.