Preliminary study of low-cost GPS receivers for time synchronization of wireless sensor networks

Growing public concern regarding the health of the aging civil infrastructure has spurred research in structural health monitoring (SHM). Recent advances in wireless smart sensor (WSS) technology has significantly lowered the cost of SHM systems and resulted in WSS being successfully implemented at full-scale. However, assuring accurate time-synchronized WSS nodes in a network is still a challenging problem. Generally, WSS synchronization is realized by communicating a sensors' CPU clock information over the network. However, such a synchronization approach becomes more challenging as the network size increases. Reliable communication is not easily achieved due to longer communication distance, larger numbers of sensors, and complexity of a distributed sensor network. Moreover, CPU clocks may not be sufficiently reliable for accurate time-synchronization due to substantial tolerance errors in crystal and/or temperature effects. In this study, the use of low-cost GPS receivers for time synchronizing WSSs is explored to resolve these issues. GPS sensors offer the potential to provide high-accuracy synchronization - nano-second level even with low-cost GPS receivers. The GPS-assisted time synchronization approach overcomes network communication limitations to realize time-synchronization in large-scale networks of WSS.