发明名称 Land based seismic data acquisition unit
摘要 A wireless seismic data acquisition unit with a wireless receiver providing access to a common remote time reference shared by a plurality of wireless seismic data acquisition units in a seismic system. The receiver is capable of replicating local version of remote time epoch to which a seismic sensor analog-to-digital converter is synchronized. The receiver is capable of replicating local version of remote common time reference for the purpose of time stamping local node events. The receiver is capable of being placed in a low power, non-operational state over periods of time during which the seismic data acquisition unit continues to record seismic data, thus conserving unit battery power. The system implements a method to correct the local time clock based on intermittent access to the common remote time reference. The method corrects the local time clock via a voltage controlled oscillator to account for environmentally induced timing errors. The invention further provides for a more stable method of correcting drift in the local time clock.
申请公布号 US9562984(B2) 申请公布日期 2017.02.07
申请号 US201314089161 申请日期 2013.11.25
申请人 FAIRFIELD INDUSTRIES INCORPORATED 发明人 Ray Clifford H.;Fisseler Glenn D.;Guyton William
分类号 G01V1/00;G01V1/36;G01V1/24 主分类号 G01V1/00
代理机构 Foley & Lardner LLP 代理人 Foley & Lardner LLP ;De Vellis James
主权项 1. A method of providing a stable timing signal for a seismic data acquisition unit, comprising: generating, via a local oscillator of the seismic data acquisition unit, a local timing signal; receiving, by a wireless receiver of the seismic data acquisition unit, an external time reference; disciplining, via the wireless receiver, the local oscillator based on the external time reference; determining a frequency error of the local oscillator by differencing time stamps of the external time reference over a frequency measurement time interval, wherein the frequency measurement time interval corresponds to a frequency accuracy for a variable time stamp uncertainty; measuring, via at least one environmental sensor, at least one environmental parameter for the seismic data acquisition unit, the at least environmental parameter including an inclination of the seismic data acquisition unit; storing, in a memory element of the seismic data acquisition unit, a data structure comprising (i) the frequency error, (ii) the time stamps from the external time reference, and (iii) measured environmental parameters encountered over the frequency measurement time interval; and during a time interval in which the wireless receiver is disabled, adjusting a frequency of the local oscillator to correct for at least one timing error using data stored in the data structure.
地址 Sugar Land TX US