CargoNet is a system of sensate active RFID tags for supply-chain management and security applications, necessitated by the current lack of commercial platforms capable of monitoring the state of shipments at the crate and case level. To make a practical prototype, off-the-shelf components and custom-designed circuits that minimize power consumption and cost were assembled and integrated into an interrupt-driven system that can monitor, log, and report environmental conditions inside a shipping crate while consuming only 23.7 microwatts of average power.
This power consumption was achieved by using the energy present in sudden, non-periodic stimuli---such as shocks and loud sounds---to actuate the sensor and wake the microcontroller (quasi-passive wakeup). The number of wakeups was further reduced by varying the wakeup threshold in response to changing conditions (dynamic thresholds). To prove the feasibility of the system, the tags were tested in the laboratory and aboard transport conveyances.
