Cargo-Tracking System Combines RFID, Sensors, GSM and Satellite

A box measuring about 8 inches wide by 11 inches long was attached to the two refrigerated containers used in the test on the ship, which spent about three weeks at sea while sailing from Shanghai to Singapore and back. The box contained an active RFID transponder wired to two sensors—one for documenting whether the container door was opened or closed, another for monitoring the temperature inside the refrigerated containers.

Each container's RFID tag transmitted its ID number and sensor data to an RFID reader, which then forwarded that information via a GSM base station to an on-board control system, and via satellite to the ground system monitored by a central surveillance center.

Stefan von der Heide

The information included messages about the status of the containers, such as temperatures and location (calculated via GPS). If a container was opened and the sensor indicated a drop or rise in temperature beyond acceptable levels, a system alarm sounded at the surveillance center.

"The surveillance center then informs the end customer," von der Heide says. "However, if the end customer is interested, the tracking box can send an alarm message directly to the end customer's mobile phone."

During the test, the partners faced poor satellite service due to bad weather and a lack of capacity on the satellite. Otherwise, von der Heide says, the system worked without fail.

A similar system was tested by the U.S. Department of Transportation's Transportation Security Agency (TSA) in 2003 (see U.S. Tests Satellite Security System).