Sense and Respond Networks for Agile, Secure DistributionSeptember 1, 2006 By: Chris Stephenson Sensors
Advances in RFID and sensor technologies' ability to communicate with each other in a network environment are redefining the concept of visibility throughout the supply chain.
As sensor, RFID, and GPS-based location systems become increasingly interoperable, manufacturers are better able to monitor the location and condition of incoming and outgoing shipments within the context of the total supply chain. These "sense and respond" networks can help improve the security, quality, and integrity of products moving through the supply chain, including perishable foods, temperature-sensitive high-tech equipment, hazardous materials, and equipment prone to humidity-induced erosion (Figure 1).
An Evolutionary Process
In the past, sense and respond networks were used primarily by the military and generally referred to RFID and other networks that identified the location and inventory levels of supplies. These networks enabled the armed forces to replenish critical supplies by placing immediate orders via the network, linking factory to foxhole. When homeland security concerns intensified following 9/11, industry accelerated the development of active RFID and sensor technologies to detect and alert personnel of security breaches of cargo containers, which are used to transport 90% of world trade.
Figure 1. Sense and respond networks automatically track containers via a Web-based information service
With security as the catalyst, many sensor technologies have been integrated with automatic identification and data collection (AIDC) platforms to evaluate and respond to all manner of environmental changes affecting the container and its contents, providing visibility from the source manufacturer to distribution centers and the final destination. Nanotechnology also is helping to create minute sensors that can gauge changes in levels of vapor or gas fumes, which provide a more granular means for detection and response.
Today, sense and respond networks consist of all types of automated wireless technologies working independently or together to identify, locate, and detect the security or condition of objects as they move through the supply chain. These networks then transmit their data to a centralized information system.
Modeled after the Defense Department's In-Transit Visibility (ITV) network (the world's largest active RFID-based tracking system), commercial RFID-based networks contain layers of AIDC technologies, especially sensor technologies. The centerpiece of these networks remains the active RFID device, a battery-powered RFID tag or seal that can communicate with fixed or handheld readers over ranges up to 300 ft., an ideal distance for extended supply chains.
Because of the global nature of supply chains, it's critical for the AIDC technologies to be based on international standards accepted throughout the world. The sense and respond supply chain networks gaining the most momentum use active RFID operating at 433.92 MHz and based on ISO 18000-7 standards, which has proven to perform best in metal-rich environments, such as around containers and seaports. The radio waves transmitting data at this frequency can bend around metal, unlike RFID signals using other frequencies, where metal can interfere with the transmission.
Another advantage of active RFID tags is their ability to store and transmit large amounts of data—up to 128 KB, which can encompass not only the entire manifest of a container but also its routing schedule and sensor data, essential in a sense and respond network.
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