Efficient Clock Drift Corrections and Self-Surveys for Nimble Nodes

Summary Although a GNSS chip remains an essential component of the next generation of small land seismic recording nodes, their power consumption is high compared to other aspects of the electronics. To maximize the lifetime of the battery and minimize node size and weight, GNSS use should be optimized. We use two field trial examples from the development of the latest generation of land seismic receivers to show how GNSS usage can be optimized without compromising on timing accuracy or the ability of the nodes to self-survey to an accuracy sufficient for seismic processing. Without temperature calibration, we find that as few as four time-checks per day are sufficient to ensure that sample time errors are less than ±1ms. With temperature calibration, GNSS hiatuses of up to several days can be corrected. For short surveys, the lower limit on the number of fixes may be set by positional requirements, with at least 60 measurements being required to measure X, Y and Z to within ±2m.