Systems and methods for seismic data acquisition

Abstract

A seismic data acquisition unit includes circuitry to detect and digitize a seismic signal, and timing circuitry to control a time of acquisition of each sample of the seismic signal. The timing circuitry include a voltage controlled oscillator (VCO), a local clock incremented by the VCO, and a reference time receiver. The timing circuitry powers on the reference time receiver to generate a reference time value based on signals received from a reference time source, and measures time deviation of the local clock from the reference time value. The timing circuitry determines an adjustment value to apply to the VCO over a time interval during which the reference time receiver is not powered on. The adjustment value is selected to gradually bring the local clock into synchronization with the reference time source over the time interval at a time that the reference time receiver is to be next powered on.