A tale of two synchronizing clocks

A specific application for wastewater monitoring and actuation, called CSOnet, deployed city-wide in a mid-sized US city, South Bend, Indiana, posed some challenges to a time synchronization protocol. The nodes in CSOnet have a low duty cycle (2% in current deployment) and use an external clock, called the Real Time Clock (RTC), for triggering the sleep and the wake-up. The RTC has a very low drift (2 ppm) over the wide range of temperature fluctuations that the CSOnet nodes have, while having a low power consumption (0.66 mW). However, these clocks will still have to be synchronized occasionally during the long lifetime of the CSOnet nodes and this was the problem we confronted with our time synchronization protocol. The RTC to fit within the power and the cost constraints makes the tradeoff of having a coarse time granularity of only 1 second. Therefore, it is not sufficient to synchronize the RTC itself—that would mean a synchronization error of up to 1 second would be possib...

• Type: Conference
• Year: 2009
• Where: SENSYS
• Authors: Jinkyu Koo, Rajesh Krishna Panta, Saurabh Bagchi, Luis Antonio Montestruque
• Keywords: SENSYS 2009, Synchronization Protocol, Time Synchronization, Time Synchronization Protocol