|Wireless remote data
Technologies and sample systems that gather sensor data across distances, usually via radio links. This includes general telemetry and SCADA (supervisory control and data acquisition), especially for gathering data about wildlife, natural resources, and distributed energy systems.
Friday, May 07, 2004
PMICRO Temperature recorder
: Cheezy wired temperature sensor gear that uses SNMP and ethernet for data collection. Very cheap: $200 per ethernet collection box, wired to up to 16 daisy-chained $15-25 sensors. 4:49:16 PM
Internet-Enabled Wireless Web Sensor Network (WWSN)
: "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." User manual and pricing online, currently $895 for wifi or ethernet base station, $395 for temperature/humidity node, $2495 for 3 node, base station and software." 4:21:32 PM
How Secure Is Secure?
Simple description of 802.11 and other signal processing, and how more advanced signal processing like direct-sequence spread spectrum (DSSS) can enhance security. In effect, the signal can disappear below the noise level, and only be detected by knowing where to look (which frequencies and time slots) in advance. 4:07:34 PM