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Description:
Combining direct sensor inputs and microprocessor based transmitters employing time division multiple access (TDMA) techniques, this system allows large networks of remote transmitters to communicate digital data to a single receiver.
A sleep timer with random wake-up allows multiple periodic transmitters to operate on the same communications channel (418 MHz RF) with a very low collision probability. Each transmitter includes sensor signal conditioning, multiplexer, 16 bit A/D converter, microprocessor, and RF link. The transmitters are compatible with a wide variety of sensors, including thermocouples (cold junction compensated), strain gauges, load cells, torque transducers, and displacement transducers (DVRT's).
The receiver includes a single board computer (SBC) with Ethernet capability, built in XML and HTML (internet enabled) file transfer protocols, and data storage capability. The web server interrogates the SBC from a standard web browser (MicroSoft's Internet Explorer or Netscape's Navigator) to receive multi-channel sensor data from the SBC in extensible mark-up language (XML) format.
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Applications
Civil structural monitoring (strain, fatigue and corrosion)
Industrial sensing networks (temperature, pressure, displacement, tilt)
Agricultural maintenance networks (temperature, humidity, etc.)
Environmental site monitoring (MEMs chemical sensors)
Military security networks (infra-red, magnetic, seismic)
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