A method can include receiving seismic data acquired by a sensor unit responsive to emission of seismic energy in a frequency sweep of a duration having a duration time; correlating the seismic data and individual portions of the frequency sweep that correspond to individual time windows to generate individual sets of correlated seismic data; for a common event, identifying a corresponding event time in each of the individual sets of correlated seismic data; and determining a clock drift time based at least in part on the event times.

A system and method for estimating clock drift in underwater instruments is provided. The method can include transmitting a signal from a source to a plurality of underwater receivers or a single receiver. Upon recovery of the underwater receivers, an initial sampling frequency value can be used to generate received data waveforms from data stored on each underwater device. The generated received waveforms can be used to generate a channel estimate for each receiver, and the channel estimates can be used to provide an estimate of the source motion during the transmission. The estimated source motion can then be used to estimate the clock drift.

The invention relates to a method, system and apparatus for synchronizing the time of time series data acquired from a wellbore sensor relative to a reference time series. This comprises acquiring a first time series from a sensor in a wellbore, acquiring a reference time series and determining a linear moveout time correction to apply to the first time series. The linear moveout time correction is equal to the depth of the wellbore sensor divided by the signal propagation velocity. The linear moveout correction is applied to the first time series. The first time series is cross-correlated with the reference time series to determine a cross-correlation time correction to apply to the first time series and the cross-correlation time correction is applied to the first time series to obtain a cross-correlation corrected time series. Dynamic time warping and dynamic cross-correlation may be used to adjust for clock drift.

Respective embodiments disclosed herein include methods and apparatuses (1) for surveying a mine bench or other material body using at least seismic data obtained via geophone and measurement module data synchronized via a wireless link; (2) for generating hyperspectral panoramic imaging data of a blast hole or other borehole; or (3) for allowing a neural network to facilitate a differential blast design that targets a first bench part more weakly than the differential blast design targets a second bench part (along the same mine bench) at least partly based on data indicative of a much higher concentration of a valuable material in the second bench part than in the first.

In some examples, a sensor node comprises a sensor to measure survey data of a target structure. The sensor node receives a wireless synchronization signal, and synchronizes an operation of the sensor node based on the wireless synchronization signal.

A method includes receiving data indicative of outputs of first and second seismic sensors. The outputs include components corresponding to the detection by the first and second seismic sensors of first and second seismic signals. In addition, the method includes identifying, relative to a first clock in the first seismic sensor, a first time associated with a time of arrival of the first seismic signal at the first seismic sensor, and a second time associated with a time of arrival of the second seismic signal at the first seismic sensor. Further, the method includes identifying, relative to a second clock in the second seismic sensor, a third time associated with a time of arrival of the first seismic signal at the second seismic sensor, and a fourth time associated with a time of arrival of the second seismic signal at the second seismic sensor. Still further, the method includes determining an offset of the first clock relative to the second clock using the first, second, third and fourth times.

The invention falls within the field of the techniques for manufacturing seismic monitoring systems and is applicable to structures related to civil engineering. The accelerometric sensor comprises one or more accelerometers (2a, 2b); a main microprocessor (7); a control microprocessor (8); a temperature sensor (3); a CAN bus driver (4); two connectors (5), one input and one output, of a CAN bus line; an input clock circuit (11); an error signaling circuit (10); a power supply unit (9); a container element (12), which at its interior contains the above components.

A seismic system that includes a seismic source configured to generate a first seismic signal and a second seismic signal in a formation adjacent the seismic source. A first downhole sensing device disposed in a first borehole configured to detect the first seismic signal and the second seismic signal in the formation; and a first surface acquisition system is in communication with the first downhole sensing device. The first surface acquisition system is configured to: determine a first reference transit time based at least in part on detection of the first seismic signal by the first downhole sensing device; a first subsequent transit time based at least in part on detection of the second seismic signal by the first downhole sensing device; and

whether a synchronization variation is expected to be present based at least in part on the first reference transit time and the first subsequent transit time.

A technique facilitates accumulation of information via arrays of seismic tools to enable improved assessment of subterranean reservoirs. A plurality of seismic tool arrays may be combined to increase the quantity of downhole seismic tools, e.g. sensors. The seismic tool arrays are synchronized, via downhole clock synchronization technology, in a manner which enhances seismic data collection via the combined seismic tool arrays. In drilling applications, the seismic tool arrays may be combined with a bottom hole assembly. For example, multiple seismic tool arrays may be combined in a logging-while-drilling platform.

A time synchronization system includes: a position information acquisition unit configured to acquire installation position information related to an installation position of a time synchronization target whose time is synchronized; a time synchronization signal acquisition unit configured to receive a positioning signal transmitted from a positioning satellite as a time synchronization signal and acquire, from the time synchronization signal, transmission position information related a position of the positioning satellite and transmission time information at timing when the time synchronization signal is transmitted; and a signal processing unit configured to calculate synchronized time information for the time synchronization target based on the installation position information of the time synchronization target and the transmission position information and transmission time information from the time synchronization signal, and transmit the synchronized time information to the time synchronization target.