Scaleable, Wireless Web-Enabled Sensor Networks

摘要

Our goal was to develop a long life, low cost, scalable wireless sensing network, which collects and distributes data from a wide variety of sensors over the Internet. Time division multiple access was employed with 418 MHz RF transmitter nodes, each w/unique 16 bit address, to communicate digital data to a single receiver, with range 1/3 mile. One thousand five channel nodes can communicate to one receiver with a 30 minute update. Current draw (sleep) is 20 microamps, allowing 5 year battery life w/one 3.6 volt Li-Ion AA size battery. The network nodes (4.3 x 2.4 x 1 inches, -40 to 85 C operating) include sensor excitation (AC or DC), multiplexer, instrumentation amplifier, 16 bit A/D converter, microprocessor, and RF link. They are compatible with thermocouples, strain gauges, load/torque transducers, inductive/capacitive sensors. The receiver includes a single board computer (SBC) with Ethernet capability, internet file transfer protocols (XML/HTML), and data storage. The receiver detects data from specific nodes, performs error checking, records the data. The web server interrogates the SBC (from Microsoft's Internet Explorer or Netscape's Navigator) to distribute data. This system can collect data from thousands of remote sensors on a smart structure, and data can be shared by an unlimited number of users.