Wireless Sensors

Radio Frequency IDentification tags are tiny micro-computer systems that contain software, and permanent memory stores. They transmit and receive data and have their own built-in power generators which are activated by a high-intensity burst of electromagnetic radiation from handheld reader at a distance of less than two meters. The RFIDs respond with short bursts of data.

The RFIDs are comprised of:

a Silicon microprocessor - These chips vary in size depending on their purpose
a Metal coil - Made of copper or aluminum wire that is wound into a circular pattern on the transponder, this coil acts as the tag's antenna. The tag transmits signals to the reader, with read distance determined by the size of the coil antenna. These coil antennas can operate at 13.56 MHz.
an Encapsulating material - glass or polymer material that wraps around the chip and coil

RFIDs already cost as little as 25 cents, are expected to fall to less than 5 cents by 2005. They promise real-time asset tracking with no need for manual data entry.

The RFIDs described above are ‘passive’; they must be awakened and may not need their own power source, instead using an induction coil. There are also ‘active’ RFIDs that require a power source and are always ‘on’.

The RFIDs can carry serial numbers, manufacturers’ codes, country of origin, date of installation, and maintenance histories of the parts, from seats to jet engines. As the applications mature, more data will be added. The advantage of RFIDs over current stamped plates and bar codes is that they are updateable and reusable. They are accessible in real-time using handheld scanners and can carry large amounts of detail.

Compared to Wireless Sensors, they have little intelligence to perform programmable tasks or to interact with other microprocessors.

What Are Wireless Sensor Networks ?

Let us use an industry quote from www.xbow.com to introduce wireless sensor networks:

“The convergence of intelligent sensors, computing and wireless communications are enabling businesses to gain visibility of their assets and processes which allow them to respond faster and smarter to changes and improve performance.”

The wireless sensor platform is a micro electro mechanical system ( MEMS ) that consists of:

They are programmable, can store a limited amount of data, can talk to other motes and can upload / download to a central base station. Because of the low-power requirement to keep them small and inexpensive, they are limited instruction set processors. Therefore, they use the new TinyOS operating system.

The 'motes' support two-way mesh radio networks, which allows them to route the data traffic or avoid malfunctioning nodes.

Because they are low-power and limited-instruction set, the motes must use TinyOS and assembly-level languages. This means that existing software for other handheld devices and laptops is NOT USABLE or portable to the motes.

The market for Wireless Sensors will be driven by the ability of software developers to deliver the necessary applications quickly and reliably … but in this new paradigm. The emerging area of research and development is led by work at UC Berkeley (creators of TinyOS) and UCLA’s Center for Embedded Network Sensing.

We can work with you to create a working field prototype for your application