High-quality time information is critical to the operation of a seismic network. Although each Quanterra datalogger contains an internal clock, the accuracy of the external clocks are much higher. The Quanterra uses the external clock as an absolute time base. If the external clock fails, the Quanterra clock is used until the external clock is replaced.
In the initial deployment of the BDSN, we used GOES clocks in order to maintain high-quality timing on our seismic data. During the mid-to-late 1990s, we began replacing the GOES clocks with (Global Positioning System) clocks. At this point, all external clocks in the BDSN, HFN, and HRSN use GPS timing.
This photograph illustrates a typical GOES clock installation.