Patent ID: 7633834

Claim:
A method of seismic surveying of an earth formation, the method comprising: (a) generating a first signal at a first time at a first location and propagating a first seismic wave through the earth formation, the first signal being defined at least in part by a measurement of the first time and comprising a plurality of patterns, each pattern comprising a plurality of pulses; (b) receiving a second signal comprising a direct arrival of the first propagating seismic wave on a bottomhole assembly (BHA) at a first depth; (c) determining from the second signal, the first signal and a time of arrival of the first signal on a downhole clock a propagation time for the propagating seismic wave from the first location to the BHA, wherein determining the propagation time includes producing an output signal by: (i) partitioning the second signal into a plurality of patterns, each of the partitioned plurality of patterns corresponding to one of the plurality of patterns of the first signal, (ii) cross-correlating the partitioned patterns of the first and second signals, and (iii) combining the partitioned patterns of the first and second signals.