Staying in Sync

 
Published: 15 June 2008

Accurate time stamps on data collected at the ARM sites are very important for confidence in using the measurements for research. At the dispersed facilities across the ARM Southern Great Plains site, making sure all the instruments and their associated data logging systems are on the same clock is no easy task. Due to their remote locations, many of these field facilities still rely on dialup Internet connections and are susceptible to frequent power outages. After uncovering a minor but pervasive offset in time records, SGP site operations staff quickly diagnosed the problem and set about implementing a solution. New synchronization software installed throughout the site will ensure that future automatic clock resets account for any “drift” between the instrument hardware and data collection systems, keeping SGP site data in sync.

GPS receivers are installed at all the extended facilities throughout the SGP domain.

In February, SGP site operations staff discovered the flaw in the time-sync process used at the extended and intermediate facilities. During system startups or reboots, the method used for data transport—an Ethernet-based serial port—was causing clock instability. In addition, the startup process did not include access to the highly precise global positioning system (GPS) time signal available from the GPS receivers at each facility. In cooperation with various ARM instrument mentors, SGP site operations staff identified a commercial synchronization product from the same vendor that manufactures the GPS time servers at the ARM ground sites. The new time synchronization software runs independent of offsite network connections, minimizing the risk of incorrect time settings, particularly where offsite communications are less reliable. Testing of the synchronization software in March proved very consistent, leading to its current installation at all SGP extended and intermediate facilities.