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2.3.2. Synchronizing Source Information and Time Stamps
ОглавлениеData acquisition can generally be separated into either passive or active systems. For active systems, such as VSP and surface seismic acquisition, the firing of seismic sources is under control of the operator. In passive systems, data acquisition starts, and the desired signals (e.g., earthquakes or ambient noise) are not under our control. Regardless of the application, a reference time signal is necessary; thus, it is important for a global positioning system (GPS) time to be incorporated into the acquired data sets. For active sources, additional information is necessary, such as the origin time of the source, source signature, etc. Some systems directly record this information into the DAS data set in real time, while other systems record this information separately and combine it with DAS data later by comparing the GPS timestamps from DAS and source recording systems.