Aug 26 2010
A research team headed by Dr. Dan Stancil has discovered a novel method to enhance wireless monitoring by HVAC (heating, ventilating and air-conditioning) ducts, to be used in applications for health, safety and climate control purposes.
The research team consisted of Stancil’s former Carnegie Mellon students, Benjamin Henty of Johns Hopkins University Applied Physics Lab; Pavel Nikitin of Intermec Technologies Corporation; and Darmindra Arumugam and Matthew Chabalko of Carnegie Mellon University. This discovery could prove to be a boon for building constructors and building managers, as the system is wireless and can be installed with ease. This results in reduction of both time and cost.
RFID (radio-frequency identification) tags with integrated sensors are used to send data to a reader system, which is centralized and has a radio antenna to receive the data from the lightweight tags. The electronic reader unleashes a radio wave with a definite frequency, and when the RFID tag collects the transmission, it soaks up the energy from the transmission and counters the reader by a wave reflection.
According to Dr. Dan Stancil, this technology can be put to use in many applications with regard to smoke detectors, sensors that can monitor radiological, biological, and chemical agents, carbon-monoxide monitors and so on.
The researchers concentrated mainly on UHF (ultrahigh-frequency) RFID systems, ranging between 908 and 928 MHz band in the North American region, and varied frequencies in other regions in the world. Outdoors, the UHH RFID needs to be positioned close to the reader (within 5-10 m) to react to a transmission. But if the building’s HVAC system is used, then the UHF RFID can be placed at a distance of 30 m from the reader.
Dr. Stancil observes that, as readily accessible infrastructure is being used, circumventing the installation cost and efforts required by conventional sensors would balance the price of readers and RFID tags. To illustrate this, he takes the case of the present-day climate-control units. These units consist of thermometers positioned all through a building and linked to a centralized monitor via widespread wires. If RFID tags, inclusive of temperature sensors, are dispensed all over the building with short antennas linking them to an already existing HVAC duct system in the building, the temperature readings from the tags would then be transmitted to the readers through the ducts.
As the HVAC ductwork is made up of hollow pipes made of metal, they prove to be a first-rate channel for the radio transmissions. The researchers experimented on 30-m pipes and observed that the pipes protected the waves from getting dispersed plus preserved robust signals over long distances. The maximum distance for a tag to work efficiently, from the reader, is yet to be determined.
The proceedings of the IEEE will publish the research findings in its September release.
Source: http://www.ncsu.edu/